I#27 - [IMAPx] Ignore DavMail's CR/LF in BODYSTRUCTURE response

[evolution-data-server.git] / src / libedataserver / e-source-registry.c

/*
 * e-source-registry.c
 *
 * This library is free software: you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation.
 *
 * This library is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
 * for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this library. If not, see <http://www.gnu.org/licenses/>.
 *
 */

/**
 * SECTION: e-source-registry
 * @include: libedataserver/libedataserver.h
 * @short_description: A central repository for data sources
 *
 * The #ESourceRegistry is a global singleton store for all #ESource
 * instances.  It uses file monitors to react to key file creation and
 * deletion events, either constructing an #ESource instance from the
 * newly created key file, or removing from the logical #ESource
 * hierarchy the instance corresponding to the deleted key file.
 *
 * The #ESourceRegistry can be queried for individual #ESource instances
 * by their unique identifier string or key file path, for collections of
 * #ESource instances having a particular extension, or for all available
 * #ESource instances.
 *
 * The #ESourceRegistry API also provides a front-end for the
 * "org.gnome.Evolution.DefaultSources" #GSettings schema which tracks
 * which #ESource instances are designated to be the user's default address
 * book, calendar, memo list and task list for desktop integration.
 *
 * Note: The #ESourceRegistry uses thread default main context from the time
 * of its creation to deliver D-Bus signals, finish operations and so on,
 * thus it requires a running main loop for its proper functionality.
 **/

#include "evolution-data-server-config.h"

#include <glib/gstdio.h>
#include <glib/gi18n-lib.h>

/* XXX Yeah, yeah... */
#define GCR_API_SUBJECT_TO_CHANGE

#include <gcr/gcr-base.h>

/* Private D-Bus classes. */
#include "e-dbus-source.h"
#include "e-dbus-source-manager.h"

#include "e-data-server-util.h"
#include "e-source-collection.h"
#include "e-source-enumtypes.h"

/* Needed for the defaults API. */
#include "e-source-address-book.h"
#include "e-source-calendar.h"
#include "e-source-mail-account.h"
#include "e-source-mail-identity.h"
#include "e-source-memo-list.h"
#include "e-source-task-list.h"

#include "e-source-registry.h"

#define E_SOURCE_REGISTRY_GET_PRIVATE(obj) \
        (G_TYPE_INSTANCE_GET_PRIVATE \
        ((obj), E_TYPE_SOURCE_REGISTRY, ESourceRegistryPrivate))

#define DBUS_OBJECT_PATH "/org/gnome/evolution/dataserver/SourceManager"
#define GSETTINGS_SCHEMA "org.gnome.Evolution.DefaultSources"

/* Built-in data source UIDs. */
#define E_SOURCE_BUILTIN_ADDRESS_BOOK_UID       "system-address-book"
#define E_SOURCE_BUILTIN_CALENDAR_UID           "system-calendar"
#define E_SOURCE_BUILTIN_MAIL_ACCOUNT_UID       "local"
#define E_SOURCE_BUILTIN_MEMO_LIST_UID          "system-memo-list"
#define E_SOURCE_BUILTIN_PROXY_UID              "system-proxy"
#define E_SOURCE_BUILTIN_TASK_LIST_UID          "system-task-list"

/* GSettings keys for default data sources. */
#define E_SETTINGS_DEFAULT_ADDRESS_BOOK_KEY     "default-address-book"
#define E_SETTINGS_DEFAULT_CALENDAR_KEY         "default-calendar"
#define E_SETTINGS_DEFAULT_MAIL_ACCOUNT_KEY     "default-mail-account"
#define E_SETTINGS_DEFAULT_MAIL_IDENTITY_KEY    "default-mail-identity"
#define E_SETTINGS_DEFAULT_MEMO_LIST_KEY        "default-memo-list"
#define E_SETTINGS_DEFAULT_TASK_LIST_KEY        "default-task-list"

typedef struct _AsyncContext AsyncContext;
typedef struct _CreateContext CreateContext;
typedef struct _SourceClosure SourceClosure;
typedef struct _ThreadClosure ThreadClosure;
typedef struct _CredentialsRequiredClosure CredentialsRequiredClosure;

struct _ESourceRegistryPrivate {
        GMainContext *main_context;

        GThread *manager_thread;
        ThreadClosure *thread_closure;

        GDBusObjectManager *dbus_object_manager;
        EDBusSourceManager *dbus_source_manager;

        GHashTable *object_path_table;
        GMutex object_path_table_lock;

        GHashTable *service_restart_table;
        GMutex service_restart_table_lock;

        GHashTable *sources;
        GMutex sources_lock;

        GSettings *settings;

        gboolean initialized;
        GError *init_error;
        GMutex init_lock;

        EOAuth2Services *oauth2_services;
};

struct _AsyncContext {
        ESource *source;
        GList *list_of_sources;
};

/* Used in e_source_registry_create_sources_sync() */
struct _CreateContext {
        GHashTable *pending_uids;
        GMainContext *main_context;
        GMainLoop *main_loop;
};

struct _SourceClosure {
        GWeakRef registry;
        ESource *source;
};

struct _ThreadClosure {
        ESourceRegistry *registry;
        GMainContext *main_context;
        GMainLoop *main_loop;
        GCond main_loop_cond;
        GMutex main_loop_mutex;
        GError *error;
};

struct _CredentialsRequiredClosure {
        GWeakRef registry;
        ESource *source;
        ESourceCredentialsReason reason;
        gchar *certificate_pem;
        GTlsCertificateFlags certificate_errors;
        GError *op_error;
};

enum {
        PROP_0,
        PROP_DEFAULT_ADDRESS_BOOK,
        PROP_DEFAULT_CALENDAR,
        PROP_DEFAULT_MAIL_ACCOUNT,
        PROP_DEFAULT_MAIL_IDENTITY,
        PROP_DEFAULT_MEMO_LIST,
        PROP_DEFAULT_TASK_LIST
};

enum {
        SOURCE_ADDED,
        SOURCE_CHANGED,
        SOURCE_REMOVED,
        SOURCE_ENABLED,
        SOURCE_DISABLED,
        CREDENTIALS_REQUIRED,
        LAST_SIGNAL
};

/* Forward Declarations */
static void     source_registry_add_source      (ESourceRegistry *registry,
                                                 ESource *source);
static void     e_source_registry_initable_init (GInitableIface *iface);

/* Private ESource function, for our use only. */
void            __e_source_private_replace_dbus_object
                                                (ESource *source,
                                                 GDBusObject *dbus_object);

static guint signals[LAST_SIGNAL];

/* By default, the GAsyncInitable interface calls GInitable.init()
 * from a separate thread, so we only have to override GInitable. */
G_DEFINE_TYPE_WITH_CODE (
        ESourceRegistry,
        e_source_registry,
        G_TYPE_OBJECT,
        G_IMPLEMENT_INTERFACE (
                G_TYPE_INITABLE, e_source_registry_initable_init)
        G_IMPLEMENT_INTERFACE (
                G_TYPE_ASYNC_INITABLE, NULL))

static void
async_context_free (AsyncContext *async_context)
{
        if (async_context->source != NULL)
                g_object_unref (async_context->source);

        g_list_free_full (
                async_context->list_of_sources,
                (GDestroyNotify) g_object_unref);

        g_slice_free (AsyncContext, async_context);
}

static CreateContext *
create_context_new (void)
{
        CreateContext *create_context;

        create_context = g_slice_new0 (CreateContext);

        create_context->pending_uids = g_hash_table_new_full (
                (GHashFunc) g_str_hash,
                (GEqualFunc) g_str_equal,
                (GDestroyNotify) g_free,
                (GDestroyNotify) NULL);

        create_context->main_context = g_main_context_new ();

        create_context->main_loop = g_main_loop_new (
                create_context->main_context, FALSE);

        return create_context;
}

static void
create_context_free (CreateContext *create_context)
{
        g_main_loop_unref (create_context->main_loop);
        g_main_context_unref (create_context->main_context);
        g_hash_table_unref (create_context->pending_uids);

        g_slice_free (CreateContext, create_context);
}

static void
source_closure_free (SourceClosure *closure)
{
        g_weak_ref_clear (&closure->registry);
        g_object_unref (closure->source);

        g_slice_free (SourceClosure, closure);
}

static void
thread_closure_free (ThreadClosure *closure)
{
        /* The registry member is not referenced. */

        g_warn_if_fail (!g_main_context_pending (closure->main_context));

        g_main_context_unref (closure->main_context);
        g_main_loop_unref (closure->main_loop);
        g_cond_clear (&closure->main_loop_cond);
        g_mutex_clear (&closure->main_loop_mutex);

        /* The GError should be NULL at this point,
         * regardless of whether an error occurred. */
        g_warn_if_fail (closure->error == NULL);

        g_slice_free (ThreadClosure, closure);
}

static void
credentials_required_closure_free (gpointer ptr)
{
        CredentialsRequiredClosure *closure = ptr;

        if (closure) {
                g_weak_ref_clear (&closure->registry);
                g_object_unref (closure->source);
                g_free (closure->certificate_pem);
                g_clear_error (&closure->op_error);

                g_slice_free (CredentialsRequiredClosure, closure);
        }
};

G_LOCK_DEFINE_STATIC (singleton_lock);
static GWeakRef singleton;

static ESourceRegistry *
source_registry_dup_uninitialized_singleton (void)
{
        ESourceRegistry *registry;

        G_LOCK (singleton_lock);

        registry = g_weak_ref_get (&singleton);
        if (registry == NULL) {
                registry = g_object_new (E_TYPE_SOURCE_REGISTRY, NULL);
                g_weak_ref_set (&singleton, registry);
        }

        G_UNLOCK (singleton_lock);

        return registry;
}

static gchar *
source_registry_dbus_object_dup_uid (GDBusObject *dbus_object)
{
        EDBusObject *e_dbus_object;
        EDBusSource *e_dbus_source;

        /* EDBusSource interface should always be present. */
        e_dbus_object = E_DBUS_OBJECT (dbus_object);
        e_dbus_source = e_dbus_object_peek_source (e_dbus_object);

        return e_dbus_source_dup_uid (e_dbus_source);
}

static void
source_registry_object_path_table_insert (ESourceRegistry *registry,
                                          const gchar *object_path,
                                          ESource *source)
{
        GHashTable *object_path_table;

        g_return_if_fail (object_path != NULL);
        g_return_if_fail (E_IS_SOURCE (source));

        object_path_table = registry->priv->object_path_table;

        g_mutex_lock (&registry->priv->object_path_table_lock);

        g_hash_table_insert (
                object_path_table,
                g_strdup (object_path),
                g_object_ref (source));

        g_mutex_unlock (&registry->priv->object_path_table_lock);
}

static ESource *
source_registry_object_path_table_lookup (ESourceRegistry *registry,
                                          const gchar *object_path)
{
        GHashTable *object_path_table;
        ESource *source;

        g_return_val_if_fail (object_path != NULL, NULL);

        object_path_table = registry->priv->object_path_table;

        g_mutex_lock (&registry->priv->object_path_table_lock);

        source = g_hash_table_lookup (object_path_table, object_path);
        if (source != NULL)
                g_object_ref (source);

        g_mutex_unlock (&registry->priv->object_path_table_lock);

        return source;
}

static gboolean
source_registry_object_path_table_remove (ESourceRegistry *registry,
                                          const gchar *object_path)
{
        GHashTable *object_path_table;
        gboolean removed;

        g_return_val_if_fail (object_path != NULL, FALSE);

        object_path_table = registry->priv->object_path_table;

        g_mutex_lock (&registry->priv->object_path_table_lock);

        removed = g_hash_table_remove (object_path_table, object_path);

        g_mutex_unlock (&registry->priv->object_path_table_lock);

        return removed;
}

static void
source_registry_service_restart_table_add (ESourceRegistry *registry,
                                           const gchar *uid)
{
        GHashTable *service_restart_table;

        g_return_if_fail (uid != NULL);

        service_restart_table = registry->priv->service_restart_table;

        g_mutex_lock (&registry->priv->service_restart_table_lock);

        g_hash_table_add (service_restart_table, g_strdup (uid));

        g_mutex_unlock (&registry->priv->service_restart_table_lock);
}

static gboolean
source_registry_service_restart_table_remove (ESourceRegistry *registry,
                                              const gchar *uid)
{
        GHashTable *service_restart_table;
        gboolean removed;

        g_return_val_if_fail (uid != NULL, FALSE);

        service_restart_table = registry->priv->service_restart_table;

        g_mutex_lock (&registry->priv->service_restart_table_lock);

        removed = g_hash_table_remove (service_restart_table, uid);

        g_mutex_unlock (&registry->priv->service_restart_table_lock);

        return removed;
}

static GList *
source_registry_service_restart_table_steal_all (ESourceRegistry *registry)
{
        GHashTable *service_restart_table;
        GList *list;

        service_restart_table = registry->priv->service_restart_table;

        g_mutex_lock (&registry->priv->service_restart_table_lock);

        list = g_hash_table_get_keys (service_restart_table);
        g_hash_table_steal_all (service_restart_table);

        g_mutex_unlock (&registry->priv->service_restart_table_lock);

        return list;
}

static gboolean
source_registry_sources_remove (ESourceRegistry *registry,
                                ESource *source)
{
        const gchar *uid;
        gboolean removed;

        uid = e_source_get_uid (source);
        g_return_val_if_fail (uid != NULL, FALSE);

        g_mutex_lock (&registry->priv->sources_lock);

        removed = g_hash_table_remove (registry->priv->sources, uid);

        g_mutex_unlock (&registry->priv->sources_lock);

        return removed;
}

static ESource *
source_registry_sources_lookup (ESourceRegistry *registry,
                                const gchar *uid)
{
        ESource *source;

        g_return_val_if_fail (uid != NULL, NULL);

        g_mutex_lock (&registry->priv->sources_lock);

        source = g_hash_table_lookup (registry->priv->sources, uid);

        if (source != NULL)
                g_object_ref (source);

        g_mutex_unlock (&registry->priv->sources_lock);

        return source;
}

static GList *
source_registry_sources_get_values (ESourceRegistry *registry)
{
        GList *values;

        g_mutex_lock (&registry->priv->sources_lock);

        values = g_hash_table_get_values (registry->priv->sources);

        g_list_foreach (values, (GFunc) g_object_ref, NULL);

        g_mutex_unlock (&registry->priv->sources_lock);

        return values;
}

static GNode *
source_registry_sources_build_tree (ESourceRegistry *registry)
{
        GNode *root;
        GHashTable *index;
        GHashTableIter iter;
        gpointer key, value;

        g_mutex_lock (&registry->priv->sources_lock);

        root = g_node_new (NULL);
        index = g_hash_table_new (g_str_hash, g_str_equal);

        /* Add a GNode for each ESource to the index. */
        g_hash_table_iter_init (&iter, registry->priv->sources);
        while (g_hash_table_iter_next (&iter, &key, &value)) {
                ESource *source = g_object_ref (value);
                g_hash_table_insert (index, key, g_node_new (source));
        }

        /* Traverse the index and link the nodes together. */
        g_hash_table_iter_init (&iter, index);
        while (g_hash_table_iter_next (&iter, NULL, &value)) {
                ESource *source;
                GNode *source_node;
                GNode *parent_node;
                const gchar *parent_uid;

                source_node = (GNode *) value;
                source = E_SOURCE (source_node->data);
                parent_uid = e_source_get_parent (source);

                if (parent_uid == NULL || *parent_uid == '\0') {
                        parent_node = root;
                } else {
                        parent_node = g_hash_table_lookup (index, parent_uid);
                        g_warn_if_fail (parent_node != NULL);
                }

                /* Should never be NULL, but just to be safe. */
                if (parent_node != NULL)
                        g_node_append (parent_node, source_node);
        }

        g_hash_table_destroy (index);

        g_mutex_unlock (&registry->priv->sources_lock);

        return root;
}

static void
source_registry_settings_changed_cb (GSettings *settings,
                                     const gchar *key,
                                     ESourceRegistry *registry)
{
        /* We define a property name that matches every key in
         * the "org.gnome.Evolution.DefaultSources" schema. */
        g_object_notify (G_OBJECT (registry), key);
}

static gboolean
source_registry_source_changed_idle_cb (gpointer user_data)
{
        SourceClosure *closure = user_data;
        ESourceRegistry *registry;

        registry = g_weak_ref_get (&closure->registry);

        if (registry != NULL) {
                g_signal_emit (
                        registry,
                        signals[SOURCE_CHANGED], 0,
                        closure->source);
                g_object_unref (registry);
        }

        return FALSE;
}

static gboolean
source_registry_source_notify_enabled_idle_cb (gpointer user_data)
{
        SourceClosure *closure = user_data;
        ESourceRegistry *registry;

        registry = g_weak_ref_get (&closure->registry);

        if (registry != NULL) {
                if (e_source_get_enabled (closure->source)) {
                        g_signal_emit (
                                registry,
                                signals[SOURCE_ENABLED], 0,
                                closure->source);
                } else {
                        g_signal_emit (
                                registry,
                                signals[SOURCE_DISABLED], 0,
                                closure->source);
                }
                g_object_unref (registry);
        }

        return FALSE;
}

static void
source_registry_source_changed_cb (ESource *source,
                                   ESourceRegistry *registry)
{
        GSource *idle_source;
        SourceClosure *closure;

        closure = g_slice_new0 (SourceClosure);
        g_weak_ref_init (&closure->registry, registry);
        closure->source = g_object_ref (source);

        idle_source = g_idle_source_new ();
        g_source_set_callback (
                idle_source,
                source_registry_source_changed_idle_cb,
                closure, (GDestroyNotify) source_closure_free);
        g_source_attach (idle_source, registry->priv->main_context);
        g_source_unref (idle_source);
}

static void
source_registry_source_notify_enabled_cb (ESource *source,
                                          GParamSpec *pspec,
                                          ESourceRegistry *registry)
{
        GSource *idle_source;
        SourceClosure *closure;

        closure = g_slice_new0 (SourceClosure);
        g_weak_ref_init (&closure->registry, registry);
        closure->source = g_object_ref (source);

        idle_source = g_idle_source_new ();
        g_source_set_callback (
                idle_source,
                source_registry_source_notify_enabled_idle_cb,
                closure, (GDestroyNotify) source_closure_free);
        g_source_attach (idle_source, registry->priv->main_context);
        g_source_unref (idle_source);
}

static gboolean
source_registry_source_credentials_required_idle_cb (gpointer user_data)
{
        CredentialsRequiredClosure *closure = user_data;
        ESourceRegistry *registry;

        registry = g_weak_ref_get (&closure->registry);

        if (registry != NULL) {
                g_signal_emit (
                        registry,
                        signals[CREDENTIALS_REQUIRED], 0,
                        closure->source, closure->reason, closure->certificate_pem,
                        closure->certificate_errors, closure->op_error);

                g_object_unref (registry);
        }

        return FALSE;
}

static void
source_registry_source_credentials_required_cb (ESource *source,
                                                ESourceCredentialsReason reason,
                                                const gchar *certificate_pem,
                                                GTlsCertificateFlags certificate_errors,
                                                const GError *op_error,
                                                ESourceRegistry *registry)
{
        GSource *idle_source;
        CredentialsRequiredClosure *closure;

        closure = g_slice_new0 (CredentialsRequiredClosure);
        g_weak_ref_init (&closure->registry, registry);
        closure->source = g_object_ref (source);
        closure->reason = reason;
        closure->certificate_pem = g_strdup (certificate_pem);
        closure->certificate_errors = certificate_errors;
        closure->op_error = op_error ? g_error_copy (op_error) : NULL;

        idle_source = g_idle_source_new ();
        g_source_set_callback (
                idle_source,
                source_registry_source_credentials_required_idle_cb,
                closure, credentials_required_closure_free);
        g_source_attach (idle_source, registry->priv->main_context);
        g_source_unref (idle_source);
}

static ESource *
source_registry_new_source (ESourceRegistry *registry,
                            GDBusObject *dbus_object)
{
        GMainContext *main_context;
        ESource *source;
        const gchar *object_path;
        GError *local_error = NULL;

        /* We don't want the ESource emitting "changed" signals from
         * the manager thread, so we pass it the same main context the
         * registry uses for scheduling signal emissions. */
        main_context = registry->priv->main_context;
        source = e_source_new (dbus_object, main_context, &local_error);
        object_path = g_dbus_object_get_object_path (dbus_object);

        /* The likelihood of an error here is slim, so it's
         * sufficient to just print a warning if one occurs. */
        if (local_error != NULL) {
                g_warn_if_fail (source == NULL);
                g_critical (
                        "ESourceRegistry: Failed to create a "
                        "data source object for path '%s': %s",
                        object_path, local_error->message);
                g_error_free (local_error);
                return NULL;
        }

        g_return_val_if_fail (E_IS_SOURCE (source), NULL);

        /* Add the ESource to the object path table immediately. */
        source_registry_object_path_table_insert (
                registry, object_path, source);

        return source;
}

static void
source_registry_unref_source (ESource *source)
{
        g_signal_handlers_disconnect_matched (
                source, G_SIGNAL_MATCH_FUNC, 0, 0, NULL,
                source_registry_source_changed_cb, NULL);

        g_signal_handlers_disconnect_matched (
                source, G_SIGNAL_MATCH_FUNC, 0, 0, NULL,
                source_registry_source_notify_enabled_cb, NULL);

        g_signal_handlers_disconnect_matched (
                source, G_SIGNAL_MATCH_FUNC, 0, 0, NULL,
                source_registry_source_credentials_required_cb, NULL);

        g_object_unref (source);
}

static void
source_registry_add_source (ESourceRegistry *registry,
                            ESource *source)
{
        const gchar *uid;

        /* This is called in the manager thread during initialization
         * and in response to "object-added" signals from the manager. */

        uid = e_source_get_uid (source);
        g_return_if_fail (uid != NULL);

        g_mutex_lock (&registry->priv->sources_lock);

        /* Check if we already have this source in the registry. */
        if (g_hash_table_lookup (registry->priv->sources, uid) != NULL) {
                g_mutex_unlock (&registry->priv->sources_lock);
                return;
        }

        g_signal_connect (
                source, "changed",
                G_CALLBACK (source_registry_source_changed_cb),
                registry);

        g_signal_connect (
                source, "notify::enabled",
                G_CALLBACK (source_registry_source_notify_enabled_cb),
                registry);

        g_signal_connect (
                source, "credentials-required",
                G_CALLBACK (source_registry_source_credentials_required_cb),
                registry);

        g_hash_table_insert (
                registry->priv->sources,
                g_strdup (uid), g_object_ref (source));

        g_mutex_unlock (&registry->priv->sources_lock);
}

static gboolean
source_registry_object_added_idle_cb (gpointer user_data)
{
        SourceClosure *closure = user_data;
        ESourceRegistry *registry;

        registry = g_weak_ref_get (&closure->registry);

        if (registry != NULL) {
                g_signal_emit (
                        registry,
                        signals[SOURCE_ADDED], 0,
                        closure->source);
                g_object_unref (registry);
        }

        return FALSE;
}

static void
source_registry_object_added_by_owner (ESourceRegistry *registry,
                                       GDBusObject *dbus_object)
{
        SourceClosure *closure;
        GSource *idle_source;
        ESource *source;

        g_return_if_fail (E_DBUS_IS_OBJECT (dbus_object));

        source = source_registry_new_source (registry, dbus_object);
        g_return_if_fail (source != NULL);

        /* Add the new ESource to our internal hash table so it can be
         * obtained through e_source_registry_ref_source() immediately. */
        source_registry_add_source (registry, source);

        /* Schedule a callback on the ESourceRegistry's GMainContext. */

        closure = g_slice_new0 (SourceClosure);
        g_weak_ref_init (&closure->registry, registry);
        closure->source = g_object_ref (source);

        idle_source = g_idle_source_new ();
        g_source_set_callback (
                idle_source,
                source_registry_object_added_idle_cb,
                closure, (GDestroyNotify) source_closure_free);
        g_source_attach (idle_source, registry->priv->main_context);
        g_source_unref (idle_source);

        g_object_unref (source);
}

static void
source_registry_object_added_no_owner (ESourceRegistry *registry,
                                       GDBusObject *dbus_object)
{
        ESource *source = NULL;
        gchar *uid;

        uid = source_registry_dbus_object_dup_uid (dbus_object);

        if (source_registry_service_restart_table_remove (registry, uid))
                source = e_source_registry_ref_source (registry, uid);

        if (source != NULL) {
                const gchar *object_path;

                object_path = g_dbus_object_get_object_path (dbus_object);

                source_registry_object_path_table_insert (
                        registry, object_path, source);

                __e_source_private_replace_dbus_object (source, dbus_object);

                g_object_unref (source);

        } else {
                source_registry_object_added_by_owner (registry, dbus_object);
        }

        g_free (uid);
}

static void
source_registry_object_added_cb (GDBusObjectManager *object_manager,
                                 GDBusObject *dbus_object,
                                 ESourceRegistry *registry)
{
        gchar *name_owner;

        name_owner = g_dbus_object_manager_client_get_name_owner (
                G_DBUS_OBJECT_MANAGER_CLIENT (object_manager));

        if (name_owner != NULL)
                source_registry_object_added_by_owner (registry, dbus_object);
        else
                source_registry_object_added_no_owner (registry, dbus_object);

        g_free (name_owner);
}

static gboolean
source_registry_object_removed_idle_cb (gpointer user_data)
{
        SourceClosure *closure = user_data;
        ESourceRegistry *registry;

        registry = g_weak_ref_get (&closure->registry);

        if (registry != NULL) {
                g_signal_emit (
                        registry,
                        signals[SOURCE_REMOVED], 0,
                        closure->source);
                g_object_unref (registry);
        }

        return FALSE;
}

static void
source_registry_object_removed_by_owner (ESourceRegistry *registry,
                                         GDBusObject *dbus_object)
{
        SourceClosure *closure;
        GSource *idle_source;
        ESource *source;
        const gchar *object_path;

        /* Find the corresponding ESource in the object path table.
         * Note that the lookup returns a new ESource reference. */
        object_path = g_dbus_object_get_object_path (dbus_object);
        source = source_registry_object_path_table_lookup (
                registry, object_path);
        g_return_if_fail (E_IS_SOURCE (source));

        /* Remove the ESource from the object path table immediately. */
        source_registry_object_path_table_remove (registry, object_path);

        /* Also remove the ESource from the sources table immediately. */
        if (!source_registry_sources_remove (registry, source)) {
                g_object_unref (source);
                g_return_if_reached ();
        }

        /* Strip the ESource of its GDBusObject. */
        __e_source_private_replace_dbus_object (source, NULL);

        /* Schedule a callback on the ESourceRegistry's GMainContext. */

        closure = g_slice_new0 (SourceClosure);
        g_weak_ref_init (&closure->registry, registry);
        closure->source = g_object_ref (source);

        idle_source = g_idle_source_new ();
        g_source_set_callback (
                idle_source,
                source_registry_object_removed_idle_cb,
                closure, (GDestroyNotify) source_closure_free);
        g_source_attach (idle_source, registry->priv->main_context);
        g_source_unref (idle_source);

        g_object_unref (source);
}

static void
source_registry_object_removed_no_owner (ESourceRegistry *registry,
                                         GDBusObject *dbus_object)
{
        const gchar *object_path;

        object_path = g_dbus_object_get_object_path (dbus_object);

        if (source_registry_object_path_table_remove (registry, object_path)) {
                gchar *uid;

                uid = source_registry_dbus_object_dup_uid (dbus_object);
                source_registry_service_restart_table_add (registry, uid);
                g_free (uid);
        }
}

static void
source_registry_object_removed_cb (GDBusObjectManager *object_manager,
                                   GDBusObject *dbus_object,
                                   ESourceRegistry *registry)
{
        gchar *name_owner;

        name_owner = g_dbus_object_manager_client_get_name_owner (
                G_DBUS_OBJECT_MANAGER_CLIENT (object_manager));

        if (name_owner != NULL)
                source_registry_object_removed_by_owner (registry, dbus_object);
        else
                source_registry_object_removed_no_owner (registry, dbus_object);

        g_free (name_owner);
}

static void
source_registry_name_appeared (ESourceRegistry *registry)
{
        GList *list, *link;

        /* The D-Bus service restarted, and the GDBusObjectManager has
         * just set its "name-owner" property having finished emitting
         * an "object-added" signal for each GDBusObject. */

        list = source_registry_service_restart_table_steal_all (registry);

        for (link = list; link != NULL; link = g_list_next (link)) {
                SourceClosure *closure;
                GSource *idle_source;
                ESource *source;
                const gchar *uid = link->data;

                source = e_source_registry_ref_source (registry, uid);
                if (source == NULL)
                        continue;

                closure = g_slice_new0 (SourceClosure);
                g_weak_ref_init (&closure->registry, registry);
                closure->source = g_object_ref (source);

                idle_source = g_idle_source_new ();
                g_source_set_callback (
                        idle_source,
                        source_registry_object_removed_idle_cb,
                        closure, (GDestroyNotify) source_closure_free);
                g_source_attach (idle_source, registry->priv->main_context);
                g_source_unref (idle_source);

                g_object_unref (source);
        }

        g_list_free_full (list, (GDestroyNotify) g_free);
}

static void
source_registry_name_vanished (ESourceRegistry *registry)
{
        /* This function is just a convenience breakpoint.  The D-Bus
         * service aborted, so the GDBusObjectManager has cleared its
         * "name-owner" property and will now emit a "object-removed"
         * signal for each GDBusObject. */
}

static void
source_registry_notify_name_owner_cb (GDBusObjectManager *object_manager,
                                      GParamSpec *pspec,
                                      ESourceRegistry *registry)
{
        gchar *name_owner;

        name_owner = g_dbus_object_manager_client_get_name_owner (
                G_DBUS_OBJECT_MANAGER_CLIENT (object_manager));

        if (name_owner != NULL)
                source_registry_name_appeared (registry);
        else
                source_registry_name_vanished (registry);

        g_free (name_owner);
}

static gboolean
source_registry_object_manager_running (gpointer data)
{
        ThreadClosure *closure = data;

        g_mutex_lock (&closure->main_loop_mutex);
        g_cond_broadcast (&closure->main_loop_cond);
        g_mutex_unlock (&closure->main_loop_mutex);

        return FALSE;
}

static gpointer
source_registry_object_manager_thread (gpointer data)
{
        GDBusObjectManager *object_manager;
        ThreadClosure *closure = data;
        GSource *idle_source;
        GList *list, *link;
        gulong object_added_handler_id = 0;
        gulong object_removed_handler_id = 0;
        gulong notify_name_owner_handler_id = 0;

        /* GDBusObjectManagerClient grabs the thread-default GMainContext
         * at creation time and only emits signals from that GMainContext.
         * Running it in a separate thread prevents its signal emissions
         * from being inhibited by someone overriding the thread-default
         * GMainContext. */

        /* This becomes the GMainContext that GDBusObjectManagerClient
         * will emit signals from.  Make it the thread-default context
         * for this thread before creating the client. */
        g_main_context_push_thread_default (closure->main_context);

        object_manager = e_dbus_object_manager_client_new_for_bus_sync (
                G_BUS_TYPE_SESSION,
                G_DBUS_OBJECT_MANAGER_CLIENT_FLAGS_NONE,
                SOURCES_DBUS_SERVICE_NAME,
                DBUS_OBJECT_PATH,
                NULL, &closure->error);

        /* Sanity check. */
        g_warn_if_fail (
                ((object_manager != NULL) && (closure->error == NULL)) ||
                ((object_manager == NULL) && (closure->error != NULL)));

        /* If we failed to create the GDBusObjectManagerClient, skip
         * straight to the main loop.  The GError will be propagated
         * back to the caller, the main loop will terminate, and the
         * partially-initialized ESourceRegistry will be destroyed. */
        if (object_manager == NULL)
                goto notify;

        /* Give the registry a handle to the object manager. */
        closure->registry->priv->dbus_object_manager =
                g_object_ref (object_manager);

        /* Now populate the registry with an initial set of ESources. */

        list = g_dbus_object_manager_get_objects (object_manager);

        for (link = list; link != NULL; link = g_list_next (link)) {
                GDBusObject *dbus_object;
                ESource *source;

                dbus_object = G_DBUS_OBJECT (link->data);

                source = source_registry_new_source (
                        closure->registry, dbus_object);

                if (source != NULL) {
                        source_registry_add_source (
                                closure->registry, source);
                        g_object_unref (source);
                }
        }

        g_list_free_full (list, (GDestroyNotify) g_object_unref);

        /* Listen for D-Bus object additions and removals. */

        object_added_handler_id = g_signal_connect (
                object_manager, "object-added",
                G_CALLBACK (source_registry_object_added_cb),
                closure->registry);

        object_removed_handler_id = g_signal_connect (
                object_manager, "object-removed",
                G_CALLBACK (source_registry_object_removed_cb),
                closure->registry);

        notify_name_owner_handler_id = g_signal_connect (
                object_manager, "notify::name-owner",
                G_CALLBACK (source_registry_notify_name_owner_cb),
                closure->registry);

notify:
        /* Schedule a one-time idle callback to broadcast through a
         * condition variable that our main loop is up and running. */

        idle_source = g_idle_source_new ();
        g_source_set_callback (
                idle_source,
                source_registry_object_manager_running,
                closure, (GDestroyNotify) NULL);
        g_source_attach (idle_source, closure->main_context);
        g_source_unref (idle_source);

        /* Now we mostly idle here for the rest of the session. */

        g_main_loop_run (closure->main_loop);

        /* Clean up and exit. */

        if (object_manager != NULL) {
                g_signal_handler_disconnect (
                        object_manager, object_added_handler_id);
                g_signal_handler_disconnect (
                        object_manager, object_removed_handler_id);
                g_signal_handler_disconnect (
                        object_manager, notify_name_owner_handler_id);
                g_object_unref (object_manager);
        }

        /* Make sure the queue is flushed, because items in it can reference
           the main_context, effectively causing it to leak, together with
           its GWakeup ([eventfd]) file descriptor. */
        while (g_main_context_pending (closure->main_context)) {
                g_main_context_iteration (closure->main_context, FALSE);
        }

        g_main_context_pop_thread_default (closure->main_context);

        return NULL;
}

static void
source_registry_set_property (GObject *object,
                              guint property_id,
                              const GValue *value,
                              GParamSpec *pspec)
{
        switch (property_id) {
                case PROP_DEFAULT_ADDRESS_BOOK:
                        e_source_registry_set_default_address_book (
                                E_SOURCE_REGISTRY (object),
                                g_value_get_object (value));
                        return;

                case PROP_DEFAULT_CALENDAR:
                        e_source_registry_set_default_calendar (
                                E_SOURCE_REGISTRY (object),
                                g_value_get_object (value));
                        return;

                case PROP_DEFAULT_MAIL_ACCOUNT:
                        e_source_registry_set_default_mail_account (
                                E_SOURCE_REGISTRY (object),
                                g_value_get_object (value));
                        return;

                case PROP_DEFAULT_MAIL_IDENTITY:
                        e_source_registry_set_default_mail_identity (
                                E_SOURCE_REGISTRY (object),
                                g_value_get_object (value));
                        return;

                case PROP_DEFAULT_MEMO_LIST:
                        e_source_registry_set_default_memo_list (
                                E_SOURCE_REGISTRY (object),
                                g_value_get_object (value));
                        return;

                case PROP_DEFAULT_TASK_LIST:
                        e_source_registry_set_default_task_list (
                                E_SOURCE_REGISTRY (object),
                                g_value_get_object (value));
                        return;
        }

        G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
}

static void
source_registry_get_property (GObject *object,
                              guint property_id,
                              GValue *value,
                              GParamSpec *pspec)
{
        switch (property_id) {
                case PROP_DEFAULT_ADDRESS_BOOK:
                        g_value_take_object (
                                value,
                                e_source_registry_ref_default_address_book (
                                E_SOURCE_REGISTRY (object)));
                        return;

                case PROP_DEFAULT_CALENDAR:
                        g_value_take_object (
                                value,
                                e_source_registry_ref_default_calendar (
                                E_SOURCE_REGISTRY (object)));
                        return;

                case PROP_DEFAULT_MAIL_ACCOUNT:
                        g_value_take_object (
                                value,
                                e_source_registry_ref_default_mail_account (
                                E_SOURCE_REGISTRY (object)));
                        return;

                case PROP_DEFAULT_MAIL_IDENTITY:
                        g_value_take_object (
                                value,
                                e_source_registry_ref_default_mail_identity (
                                E_SOURCE_REGISTRY (object)));
                        return;

                case PROP_DEFAULT_MEMO_LIST:
                        g_value_take_object (
                                value,
                                e_source_registry_ref_default_memo_list (
                                E_SOURCE_REGISTRY (object)));
                        return;

                case PROP_DEFAULT_TASK_LIST:
                        g_value_take_object (
                                value,
                                e_source_registry_ref_default_task_list (
                                E_SOURCE_REGISTRY (object)));
                        return;
        }

        G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
}

static void
source_registry_dispose (GObject *object)
{
        ESourceRegistryPrivate *priv;

        priv = E_SOURCE_REGISTRY_GET_PRIVATE (object);

        if (priv->dbus_object_manager != NULL) {
                g_object_unref (priv->dbus_object_manager);
                priv->dbus_object_manager = NULL;
        }

        if (priv->dbus_source_manager != NULL) {
                g_object_unref (priv->dbus_source_manager);
                priv->dbus_source_manager = NULL;
        }

        /* Terminate the manager thread after GDBus objects,
           because they can schedule GSource-s in the main context there. */
        if (priv->manager_thread != NULL) {
                g_main_loop_quit (priv->thread_closure->main_loop);
                g_thread_join (priv->manager_thread);
                priv->manager_thread = NULL;
        }

        if (priv->thread_closure) {
                thread_closure_free (priv->thread_closure);
                priv->thread_closure = NULL;
        }

        g_hash_table_remove_all (priv->object_path_table);

        g_hash_table_remove_all (priv->sources);

        if (priv->main_context != NULL) {
                while (g_main_context_pending (priv->main_context)) {
                        g_main_context_iteration (priv->main_context, FALSE);
                }
                g_main_context_unref (priv->main_context);
                priv->main_context = NULL;
        }

        if (priv->settings != NULL) {
                g_signal_handlers_disconnect_by_data (priv->settings, object);
                g_object_unref (priv->settings);
                priv->settings = NULL;
        }

        /* Chain up to parent's finalize() method. */
        G_OBJECT_CLASS (e_source_registry_parent_class)->dispose (object);
}

static void
source_registry_finalize (GObject *object)
{
        ESourceRegistryPrivate *priv;

        priv = E_SOURCE_REGISTRY_GET_PRIVATE (object);

        g_hash_table_destroy (priv->object_path_table);
        g_mutex_clear (&priv->object_path_table_lock);

        g_hash_table_destroy (priv->service_restart_table);
        g_mutex_clear (&priv->service_restart_table_lock);

        g_hash_table_destroy (priv->sources);
        g_mutex_clear (&priv->sources_lock);

        g_clear_error (&priv->init_error);
        g_mutex_clear (&priv->init_lock);

        g_clear_object (&priv->oauth2_services);

        /* Chain up to parent's finalize() method. */
        G_OBJECT_CLASS (e_source_registry_parent_class)->finalize (object);
}

static gboolean
source_registry_initable_init (GInitable *initable,
                               GCancellable *cancellable,
                               GError **error)
{
        ESourceRegistry *registry;
        ThreadClosure *closure;
        GError *local_error = NULL;

        registry = E_SOURCE_REGISTRY (initable);

        g_mutex_lock (&registry->priv->init_lock);

        if (registry->priv->initialized)
                goto exit;

        closure = g_slice_new0 (ThreadClosure);
        closure->registry = registry;  /* do not reference */
        closure->main_context = g_main_context_new ();
        /* It's important to pass 'is_running=FALSE' here because
         * we wait for the main loop to start running as a way of
         * synchronizing with the manager thread. */
        closure->main_loop = g_main_loop_new (closure->main_context, FALSE);
        g_cond_init (&closure->main_loop_cond);
        g_mutex_init (&closure->main_loop_mutex);

        registry->priv->thread_closure = closure;

        registry->priv->manager_thread = g_thread_new (
                NULL,
                source_registry_object_manager_thread,
                closure);

        /* Wait for notification that the manager
         * thread's main loop has been started. */
        g_mutex_lock (&closure->main_loop_mutex);
        while (!g_main_loop_is_running (closure->main_loop))
                g_cond_wait (
                        &closure->main_loop_cond,
                        &closure->main_loop_mutex);
        g_mutex_unlock (&closure->main_loop_mutex);

        /* Check for error in the manager thread. */
        if (closure->error != NULL) {
                g_dbus_error_strip_remote_error (closure->error);
                g_propagate_error (&registry->priv->init_error, closure->error);
                closure->error = NULL;
                goto exit;
        }

        /* The registry should now be populated with sources.
         *
         * XXX Actually, not necessarily if the registry service was
         *     just now activated.  There may yet be a small window
         *     while the registry service starts up before it exports
         *     any sources, even built-in sources.  This COULD create
         *     problems if any logic that depends on those built-in
         *     sources executes during this time window, but so far
         *     we haven't seen any cases of that.
         *
         *     Attempts in the past to stop and wait for sources to
         *     show up have proven problematic.  See for example:
         *     https://bugzilla.gnome.org/678378
         *
         *     Leave the runtime check disabled for the moment.
         *     I have a feeling I'll be revisiting this again.
         */
        /*g_warn_if_fail (g_hash_table_size (registry->priv->sources) > 0);*/

        /* The EDBusSourceManagerProxy is just another D-Bus interface
         * that resides at the same object path.  It's unrelated to the
         * GDBusObjectManagerClient and doesn't need its own thread. */
        registry->priv->dbus_source_manager =
                e_dbus_source_manager_proxy_new_for_bus_sync (
                        G_BUS_TYPE_SESSION,
                        G_DBUS_PROXY_FLAGS_NONE,
                        SOURCES_DBUS_SERVICE_NAME,
                        DBUS_OBJECT_PATH,
                        cancellable, &local_error);

        if (local_error != NULL) {
                g_dbus_error_strip_remote_error (local_error);
                g_propagate_error (&registry->priv->init_error, local_error);
                goto exit;
        }

exit:
        registry->priv->initialized = TRUE;
        g_mutex_unlock (&registry->priv->init_lock);

        if (registry->priv->init_error != NULL) {
                GError *init_error_copy;

                /* Return a copy of the same error to
                 * all pending initialization requests. */
                init_error_copy = g_error_copy (registry->priv->init_error);
                g_propagate_error (error, init_error_copy);

                return FALSE;
        }

        return TRUE;
}

static void
e_source_registry_class_init (ESourceRegistryClass *class)
{
        GObjectClass *object_class;

        g_type_class_add_private (class, sizeof (ESourceRegistryPrivate));

        object_class = G_OBJECT_CLASS (class);
        object_class->set_property = source_registry_set_property;
        object_class->get_property = source_registry_get_property;
        object_class->dispose = source_registry_dispose;
        object_class->finalize = source_registry_finalize;

        /* The property names correspond to the key names in the
         * "org.gnome.Evolution.DefaultSources" GSettings schema. */

        /**
         * ESourceRegistry:default-address-book:
         *
         * The default address book #ESource.
         **/
        g_object_class_install_property (
                object_class,
                PROP_DEFAULT_ADDRESS_BOOK,
                g_param_spec_object (
                        "default-address-book",
                        "Default Address Book",
                        "The default address book ESource",
                        E_TYPE_SOURCE,
                        G_PARAM_READWRITE |
                        G_PARAM_STATIC_STRINGS));

        /**
         * ESourceRegistry:default-calendar:
         *
         * The default calendar #ESource.
         **/
        g_object_class_install_property (
                object_class,
                PROP_DEFAULT_CALENDAR,
                g_param_spec_object (
                        "default-calendar",
                        "Default Calendar",
                        "The default calendar ESource",
                        E_TYPE_SOURCE,
                        G_PARAM_READWRITE |
                        G_PARAM_STATIC_STRINGS));

        /**
         * ESourceRegistry:default-mail-account:
         *
         * The default mail account #ESource.
         **/
        g_object_class_install_property (
                object_class,
                PROP_DEFAULT_MAIL_ACCOUNT,
                g_param_spec_object (
                        "default-mail-account",
                        "Default Mail Account",
                        "The default mail account ESource",
                        E_TYPE_SOURCE,
                        G_PARAM_READWRITE |
                        G_PARAM_STATIC_STRINGS));

        /**
         * ESourceRegistry:default-mail-identity:
         *
         * The default mail identity #ESource.
         **/
        g_object_class_install_property (
                object_class,
                PROP_DEFAULT_MAIL_IDENTITY,
                g_param_spec_object (
                        "default-mail-identity",
                        "Default Mail Identity",
                        "The default mail identity ESource",
                        E_TYPE_SOURCE,
                        G_PARAM_READWRITE |
                        G_PARAM_STATIC_STRINGS));

        /**
         * ESourceRegistry:default-memo-list:
         *
         * The default memo list #ESource.
         **/
        g_object_class_install_property (
                object_class,
                PROP_DEFAULT_MEMO_LIST,
                g_param_spec_object (
                        "default-memo-list",
                        "Default Memo List",
                        "The default memo list ESource",
                        E_TYPE_SOURCE,
                        G_PARAM_READWRITE |
                        G_PARAM_STATIC_STRINGS));

        /**
         * ESourceRegistry:default-task-list:
         *
         * The default task list #ESource.
         **/
        g_object_class_install_property (
                object_class,
                PROP_DEFAULT_TASK_LIST,
                g_param_spec_object (
                        "default-task-list",
                        "Default Task List",
                        "The default task list ESource",
                        E_TYPE_SOURCE,
                        G_PARAM_READWRITE |
                        G_PARAM_STATIC_STRINGS));

        /**
         * ESourceRegistry::source-added:
         * @registry: the #ESourceRegistry which emitted the signal
         * @source: the newly-added #ESource
         *
         * Emitted when an #ESource is added to @registry.
         **/
        signals[SOURCE_ADDED] = g_signal_new (
                "source-added",
                G_OBJECT_CLASS_TYPE (object_class),
                G_SIGNAL_RUN_LAST,
                G_STRUCT_OFFSET (ESourceRegistryClass, source_added),
                NULL, NULL, NULL,
                G_TYPE_NONE, 1,
                E_TYPE_SOURCE);

        /**
         * ESourceRegistry::source-changed:
         * @registry: the #ESourceRegistry which emitted the signal
         * @source: the #ESource that changed
         *
         * Emitted when an #ESource registered with @registry emits
         * its #ESource::changed signal.
         **/
        signals[SOURCE_CHANGED] = g_signal_new (
                "source-changed",
                G_OBJECT_CLASS_TYPE (object_class),
                G_SIGNAL_RUN_LAST,
                G_STRUCT_OFFSET (ESourceRegistryClass, source_changed),
                NULL, NULL, NULL,
                G_TYPE_NONE, 1,
                E_TYPE_SOURCE);

        /**
         * ESourceRegistry::source-removed:
         * @registry: the #ESourceRegistry which emitted the signal
         * @source: the #ESource that got removed
         *
         * Emitted when an #ESource is removed from @registry.
         **/
        signals[SOURCE_REMOVED] = g_signal_new (
                "source-removed",
                G_OBJECT_CLASS_TYPE (object_class),
                G_SIGNAL_RUN_LAST,
                G_STRUCT_OFFSET (ESourceRegistryClass, source_removed),
                NULL, NULL, NULL,
                G_TYPE_NONE, 1,
                E_TYPE_SOURCE);

        /**
         * ESourceRegistry::source-enabled:
         * @registry: the #ESourceRegistry which emitted the signal
         * @source: the #ESource that got enabled
         *
         * Emitted when an #ESource #ESource:enabled property becomes %TRUE.
         **/
        signals[SOURCE_ENABLED] = g_signal_new (
                "source-enabled",
                G_OBJECT_CLASS_TYPE (object_class),
                G_SIGNAL_RUN_LAST,
                G_STRUCT_OFFSET (ESourceRegistryClass, source_enabled),
                NULL, NULL, NULL,
                G_TYPE_NONE, 1,
                E_TYPE_SOURCE);

        /**
         * ESourceRegistry::source-disabled:
         * @registry: the #ESourceRegistry which emitted the signal
         * @source: the #ESource that got disabled
         *
         * Emitted when an #ESource #ESource:enabled property becomes %FALSE.
         **/
        signals[SOURCE_DISABLED] = g_signal_new (
                "source-disabled",
                G_OBJECT_CLASS_TYPE (object_class),
                G_SIGNAL_RUN_LAST,
                G_STRUCT_OFFSET (ESourceRegistryClass, source_disabled),
                NULL, NULL, NULL,
                G_TYPE_NONE, 1,
                E_TYPE_SOURCE);

        /**
         * ESourceRegistry::credentials-required:
         * @registry: the #ESourceRegistry which emitted the signal
         * @source: the #ESource that requires credentials
         * @reason: an #ESourceCredentialsReason indicating why the credentials are requested
         * @certificate_pem: PEM-encoded secure connection certificate for failed SSL checks
         * @certificate_errors: what failed with the SSL certificate
         * @op_error: a #GError with a description of the error, or %NULL
         *
         * The ::credentials-required signal is emitted when the @source
         * requires credentials to connect to (possibly remote)
         * data store. The credentials can be passed to the source using
         * e_source_authenticate() function. The signal is emitted in
         * the thread-default main context from the time the @registry was created.
         *
         * Note: This is just a proxy signal for the ESource::credentials-required signal.
         **/
        signals[CREDENTIALS_REQUIRED] = g_signal_new (
                "credentials-required",
                G_TYPE_FROM_CLASS (class),
                G_SIGNAL_RUN_LAST | G_SIGNAL_NO_RECURSE,
                G_STRUCT_OFFSET (ESourceRegistryClass, credentials_required),
                NULL, NULL, NULL,
                G_TYPE_NONE, 5,
                E_TYPE_SOURCE,
                E_TYPE_SOURCE_CREDENTIALS_REASON,
                G_TYPE_STRING,
                G_TYPE_TLS_CERTIFICATE_FLAGS,
                G_TYPE_ERROR);
}

static void
e_source_registry_initable_init (GInitableIface *iface)
{
        iface->init = source_registry_initable_init;
}

static void
e_source_registry_init (ESourceRegistry *registry)
{
        registry->priv = E_SOURCE_REGISTRY_GET_PRIVATE (registry);

        /* This is so the object manager thread can schedule signal
         * emissions on the thread-default context for this thread. */
        registry->priv->main_context = g_main_context_ref_thread_default ();

        /* D-Bus object path -> ESource */
        registry->priv->object_path_table =
                g_hash_table_new_full (
                        (GHashFunc) g_str_hash,
                        (GEqualFunc) g_str_equal,
                        (GDestroyNotify) g_free,
                        (GDestroyNotify) g_object_unref);

        g_mutex_init (&registry->priv->object_path_table_lock);

        /* Set of UID strings */
        registry->priv->service_restart_table =
                g_hash_table_new_full (
                        (GHashFunc) g_str_hash,
                        (GEqualFunc) g_str_equal,
                        (GDestroyNotify) g_free,
                        (GDestroyNotify) NULL);

        g_mutex_init (&registry->priv->service_restart_table_lock);

        /* UID string -> ESource */
        registry->priv->sources = g_hash_table_new_full (
                (GHashFunc) g_str_hash,
                (GEqualFunc) g_str_equal,
                (GDestroyNotify) g_free,
                (GDestroyNotify) source_registry_unref_source);

        g_mutex_init (&registry->priv->sources_lock);

        registry->priv->settings = g_settings_new (GSETTINGS_SCHEMA);

        g_signal_connect (
                registry->priv->settings, "changed",
                G_CALLBACK (source_registry_settings_changed_cb), registry);

        g_mutex_init (&registry->priv->init_lock);

        registry->priv->oauth2_services = e_oauth2_services_new ();
}

/**
 * e_source_registry_new_sync:
 * @cancellable: (allow-none): optional #GCancellable object, or %NULL
 * @error: return location for a #GError, or %NULL
 *
 * Creates a new #ESourceRegistry front-end for the registry D-Bus service.
 * If an error occurs in connecting to the D-Bus service, the function sets
 * @error and returns %NULL.
 *
 * Since 3.12 a singleton will be returned.  No strong reference is kept
 * internally, so it is the caller's responsibility to keep one.
 *
 * Returns: a new #ESourceRegistry, or %NULL
 *
 * Since: 3.6
 **/
ESourceRegistry *
e_source_registry_new_sync (GCancellable *cancellable,
                            GError **error)
{
        ESourceRegistry *registry;

        /* XXX Work around http://bugzilla.gnome.org/show_bug.cgi?id=683519
         *     until GObject's type initialization deadlock issue is fixed.
         *     Apparently only the synchronous instantiation is affected. */
        g_type_ensure (G_TYPE_DBUS_CONNECTION);
        g_type_ensure (G_TYPE_DBUS_PROXY);
        g_type_ensure (G_BUS_TYPE_SESSION);

        registry = source_registry_dup_uninitialized_singleton ();

        if (!g_initable_init (G_INITABLE (registry), cancellable, error))
                g_clear_object (&registry);

        return registry;
}

/* Helper for e_source_registry_new() */
static void
source_registry_init_cb (GObject *source_object,
                         GAsyncResult *result,
                         gpointer user_data)
{
        GTask *task = user_data;
        GError *local_error = NULL;

        g_async_initable_init_finish (
                G_ASYNC_INITABLE (source_object), result, &local_error);

        if (local_error == NULL) {
                g_task_return_pointer (
                        task, g_object_ref (source_object),
                        (GDestroyNotify) g_object_unref);
        } else {
                g_task_return_error (task, local_error);
        }

        g_object_unref (task);
}

/**
 * e_source_registry_new:
 * @cancellable: (allow-none): optional #GCancellable object, or %NULL
 * @callback: (scope async): a #GAsyncReadyCallback to call when the request
 *            is satisfied
 * @user_data: (closure): data to pass to the callback function
 *
 * Asynchronously creates a new #ESourceRegistry front-end for the registry
 * D-Bus service.
 *
 * When the operation is finished, @callback will be called.  You can then
 * call e_source_registry_new_finish() to get the result of the operation.
 *
 * Since 3.12 a singleton will be returned.  No strong reference is kept
 * internally, so it is the caller's responsibility to keep one.
 *
 * Since: 3.6
 **/
void
e_source_registry_new (GCancellable *cancellable,
                       GAsyncReadyCallback callback,
                       gpointer user_data)
{
        ESourceRegistry *registry;
        GTask *task;

        task = g_task_new (NULL, cancellable, callback, user_data);

        registry = source_registry_dup_uninitialized_singleton ();

        g_async_initable_init_async (
                G_ASYNC_INITABLE (registry),
                G_PRIORITY_DEFAULT, cancellable,
                source_registry_init_cb, task);

        g_object_unref (registry);
}

/**
 * e_source_registry_new_finish:
 * @result: a #GAsyncResult
 * @error: return location for a #GError, or %NULL
 *
 * Finishes the operation started with e_source_registry_new_finish().
 * If an error occurs in connecting to the D-Bus service, the function
 * sets @error and returns %NULL.
 *
 * Returns: a new #ESourceRegistry, or %NULL
 *
 * Since: 3.6
 **/
ESourceRegistry *
e_source_registry_new_finish (GAsyncResult *result,
                              GError **error)
{
        g_return_val_if_fail (g_task_is_valid (result, NULL), NULL);

        return g_task_propagate_pointer (G_TASK (result), error);
}

/**
 * e_source_registry_get_oauth2_services:
 * @registry: an #ESourceRegistry
 *
 * Returns: (transfer none): an instance of #EOAuth2Services, owned by @registry
 *
 * Since: 3.28
 **/
EOAuth2Services *
e_source_registry_get_oauth2_services (ESourceRegistry *registry)
{
        g_return_val_if_fail (E_IS_SOURCE_REGISTRY (registry), NULL);

        return registry->priv->oauth2_services;
}

/* Helper for e_source_registry_commit_source() */
static void
source_registry_commit_source_thread (GSimpleAsyncResult *simple,
                                      GObject *object,
                                      GCancellable *cancellable)
{
        AsyncContext *async_context;
        GError *local_error = NULL;

        async_context = g_simple_async_result_get_op_res_gpointer (simple);

        e_source_registry_commit_source_sync (
                E_SOURCE_REGISTRY (object),
                async_context->source,
                cancellable, &local_error);

        if (local_error != NULL)
                g_simple_async_result_take_error (simple, local_error);
}

/**
 * e_source_registry_commit_source_sync:
 * @registry: an #ESourceRegistry
 * @source: an #ESource with changes to commit
 * @cancellable: (allow-none): optional #GCancellable object, or %NULL
 * @error: return location for #GError, or %NULL
 *
 * This is a convenience function intended for use with graphical
 * #ESource editors.  Call this function when the user is finished
 * making changes to @source.
 *
 * If @source has a #GDBusObject, its contents are submitted to the D-Bus
 * service through e_source_write_sync().
 *
 * If @source does NOT have a #GDBusObject (implying it's a scratch
 * #ESource), its contents are submitted to the D-Bus service through
 * either e_source_remote_create_sync() if @source is to be a collection
 * member, or e_source_registry_create_sources_sync() if @source to be an
 * independent data source.
 *
 * If an error occurs, the function will set @error and return %FALSE.
 *
 * Returns: %TRUE on success, %FALSE on failure
 *
 * Since: 3.6
 **/
gboolean
e_source_registry_commit_source_sync (ESourceRegistry *registry,
                                      ESource *source,
                                      GCancellable *cancellable,
                                      GError **error)
{
        GDBusObject *dbus_object;
        ESource *collection_source;
        gboolean collection_member;
        gboolean success;

        g_return_val_if_fail (E_IS_SOURCE_REGISTRY (registry), FALSE);
        g_return_val_if_fail (E_IS_SOURCE (source), FALSE);

        dbus_object = e_source_ref_dbus_object (source);

        collection_source = e_source_registry_find_extension (
                registry, source, E_SOURCE_EXTENSION_COLLECTION);

        collection_member =
                (collection_source != NULL) &&
                (collection_source != source);

        if (dbus_object != NULL) {
                success = e_source_write_sync (source, cancellable, error);
                g_object_unref (dbus_object);

        } else if (collection_member) {
                success = e_source_remote_create_sync (
                        collection_source, source, cancellable, error);

        } else {
                GList *list = g_list_prepend (NULL, source);
                success = e_source_registry_create_sources_sync (
                        registry, list, cancellable, error);
                g_list_free (list);
        }

        if (collection_source != NULL)
                g_object_unref (collection_source);

        return success;
}

/**
 * e_source_registry_commit_source:
 * @registry: an #ESourceRegistry
 * @source: an #ESource with changes to commit
 * @cancellable: (allow-none): optional #GCancellable object, or %NULL
 * @callback: (scope async): a #GAsyncReadyCallback to call when the request
 *            is satisfied
 * @user_data: (closure): data to pass to the callback function
 *
 * See e_source_registry_commit_source_sync() for details.
 *
 * When the operation is finished, @callback will be called.  You can then
 * call e_source_registry_commit_source_finish() to get the result of the
 * operation.
 *
 * Since: 3.6
 **/
void
e_source_registry_commit_source (ESourceRegistry *registry,
                                 ESource *source,
                                 GCancellable *cancellable,
                                 GAsyncReadyCallback callback,
                                 gpointer user_data)
{
        GSimpleAsyncResult *simple;
        AsyncContext *async_context;

        g_return_if_fail (E_IS_SOURCE_REGISTRY (registry));
        g_return_if_fail (E_IS_SOURCE (source));

        async_context = g_slice_new0 (AsyncContext);
        async_context->source = g_object_ref (source);

        simple = g_simple_async_result_new (
                G_OBJECT (registry), callback, user_data,
                e_source_registry_commit_source);

        g_simple_async_result_set_check_cancellable (simple, cancellable);

        g_simple_async_result_set_op_res_gpointer (
                simple, async_context, (GDestroyNotify) async_context_free);

        g_simple_async_result_run_in_thread (
                simple, source_registry_commit_source_thread,
                G_PRIORITY_DEFAULT, cancellable);

        g_object_unref (simple);
}

/**
 * e_source_registry_commit_source_finish:
 * @registry: an #ESourceRegistry
 * @result: a #GAsyncResult
 * @error: return location for a #GError, or %NULL
 *
 * Finishes the operation started with e_source_registry_commit_source().
 *
 * If an error occurred, the function will set @error and return %FALSE.
 *
 * Returns: %TRUE on success, %FALSE on failure
 *
 * Since: 3.6
 **/
gboolean
e_source_registry_commit_source_finish (ESourceRegistry *registry,
                                        GAsyncResult *result,
                                        GError **error)
{
        GSimpleAsyncResult *simple;

        g_return_val_if_fail (
                g_simple_async_result_is_valid (
                result, G_OBJECT (registry),
                e_source_registry_commit_source), FALSE);

        simple = G_SIMPLE_ASYNC_RESULT (result);

        /* Assume success unless a GError is set. */
        return !g_simple_async_result_propagate_error (simple, error);
}

/* Helper for e_source_registry_create_sources() */
static void
source_registry_create_sources_thread (GSimpleAsyncResult *simple,
                                       GObject *object,
                                       GCancellable *cancellable)
{
        AsyncContext *async_context;
        GError *local_error = NULL;

        async_context = g_simple_async_result_get_op_res_gpointer (simple);

        e_source_registry_create_sources_sync (
                E_SOURCE_REGISTRY (object),
                async_context->list_of_sources,
                cancellable, &local_error);

        if (local_error != NULL)
                g_simple_async_result_take_error (simple, local_error);
}

/* Helper for e_source_registry_create_sources_sync() */
static gboolean
source_registry_create_sources_main_loop_quit_cb (gpointer user_data)
{
        GMainLoop *main_loop = user_data;

        g_main_loop_quit (main_loop);

        return FALSE;
}

/* Helper for e_source_registry_create_sources_sync() */
static void
source_registry_create_sources_object_added_cb (GDBusObjectManager *object_manager,
                                                GDBusObject *dbus_object,
                                                CreateContext *create_context)
{
        gchar *uid;

        uid = source_registry_dbus_object_dup_uid (dbus_object);

        if (uid != NULL) {
                g_hash_table_remove (create_context->pending_uids, uid);
                g_free (uid);
        }

        /* The hash table will be empty when all of the expected
         * GDBusObjects have been added to the GDBusObjectManager. */
        if (g_hash_table_size (create_context->pending_uids) == 0) {
                GSource *idle_source;

                idle_source = g_idle_source_new ();
                g_source_set_callback (
                        idle_source,
                        source_registry_create_sources_main_loop_quit_cb,
                        g_main_loop_ref (create_context->main_loop),
                        (GDestroyNotify) g_main_loop_unref);
                g_source_attach (idle_source, create_context->main_context);
                g_source_unref (idle_source);
        }
}

/**
 * e_source_registry_create_sources_sync:
 * @registry: an #ESourceRegistry
 * @list_of_sources: (element-type ESource): a list of #ESource instances with
 * no #GDBusObject
 * @cancellable: (allow-none): optional #GCancellable object, or %NULL
 * @error: return location for a #GError, or %NULL
 *
 * Requests the D-Bus service create new key files for each #ESource in
 * @list_of_sources.  Each list element must be a scratch #ESource with
 * no #GDBusObject.
 *
 * If an error occurs, the function will set @error and return %FALSE.
 *
 * Returns: %TRUE on success, %FALSE on failure
 *
 * Since: 3.6
 **/
gboolean
e_source_registry_create_sources_sync (ESourceRegistry *registry,
                                       GList *list_of_sources,
                                       GCancellable *cancellable,
                                       GError **error)
{
        CreateContext *create_context;
        GVariantBuilder builder;
        GVariant *variant;
        GList *link;
        gulong object_added_id;
        GError *local_error = NULL;

        g_return_val_if_fail (E_IS_SOURCE_REGISTRY (registry), FALSE);

        /* Verify the list elements are all ESources. */
        for (link = list_of_sources; link != NULL; link = g_list_next (link))
                g_return_val_if_fail (E_IS_SOURCE (link->data), FALSE);

        create_context = create_context_new ();
        g_main_context_push_thread_default (create_context->main_context);

        g_variant_builder_init (&builder, G_VARIANT_TYPE_ARRAY);

        for (link = list_of_sources; link != NULL; link = g_list_next (link)) {
                ESource *source;
                gchar *source_data;
                gchar *uid;

                source = E_SOURCE (link->data);
                uid = e_source_dup_uid (source);

                /* Takes ownership of the UID string. */
                g_hash_table_add (create_context->pending_uids, uid);

                source_data = e_source_to_string (source, NULL);
                g_variant_builder_add (&builder, "{ss}", uid, source_data);
                g_free (source_data);
        }

        variant = g_variant_builder_end (&builder);

        /* Use G_CONNECT_AFTER so source_registry_object_added_cb()
         * runs first and actually adds the ESource to the internal
         * hash table before we go quitting our main loop. */
        object_added_id = g_signal_connect_after (
                registry->priv->dbus_object_manager, "object-added",
                G_CALLBACK (source_registry_create_sources_object_added_cb),
                create_context);

        /* This function sinks the floating GVariant reference. */
        e_dbus_source_manager_call_create_sources_sync (
                registry->priv->dbus_source_manager,
                variant, cancellable, &local_error);

        g_variant_builder_clear (&builder);

        /* Wait for an "object-added" signal for each created ESource.
         * But also set a short timeout to avoid getting stuck here in
         * case the registry service adds sources to its orphan table,
         * which prevents them from being exported over D-Bus. */
        if (local_error == NULL) {
                GSource *timeout_source;

                timeout_source = g_timeout_source_new_seconds (2);
                g_source_set_callback (
                        timeout_source,
                        source_registry_create_sources_main_loop_quit_cb,
                        g_main_loop_ref (create_context->main_loop),
                        (GDestroyNotify) g_main_loop_unref);
                g_source_attach (timeout_source, create_context->main_context);
                g_source_unref (timeout_source);

                g_main_loop_run (create_context->main_loop);
        }

        g_signal_handler_disconnect (
                registry->priv->dbus_object_manager, object_added_id);

        g_main_context_pop_thread_default (create_context->main_context);
        create_context_free (create_context);

        if (local_error != NULL) {
                g_dbus_error_strip_remote_error (local_error);
                g_propagate_error (error, local_error);
                return FALSE;
        }

        return TRUE;
}

/**
 * e_source_registry_create_sources:
 * @registry: an #ESourceRegistry
 * @list_of_sources: (element-type ESource): a list of #ESource instances with
 * no #GDBusObject
 * @cancellable: (allow-none): optional #GCancellable object, or %NULL
 * @callback: (scope async): a #GAsyncReadyCallback to call when the request
 *            is satisfied
 * @user_data: (closure): data to pass to the callback function
 *
 * Asynchronously requests the D-Bus service create new key files for each
 * #ESource in @list_of_sources.  Each list element must be a scratch
 * #ESource with no #GDBusObject.
 *
 * When the operation is finished, @callback will be called.  You can then
 * call e_source_registry_create_sources_finish() to get the result of the
 * operation.
 *
 * Since: 3.6
 **/
void
e_source_registry_create_sources (ESourceRegistry *registry,
                                  GList *list_of_sources,
                                  GCancellable *cancellable,
                                  GAsyncReadyCallback callback,
                                  gpointer user_data)
{
        GSimpleAsyncResult *simple;
        AsyncContext *async_context;
        GList *link;

        g_return_if_fail (E_IS_SOURCE_REGISTRY (registry));

        /* Verify the list elements are all ESources. */
        for (link = list_of_sources; link != NULL; link = g_list_next (link))
                g_return_if_fail (E_IS_SOURCE (link->data));

        async_context = g_slice_new0 (AsyncContext);
        async_context->list_of_sources = g_list_copy (list_of_sources);

        g_list_foreach (
                async_context->list_of_sources,
                (GFunc) g_object_ref, NULL);

        simple = g_simple_async_result_new (
                G_OBJECT (registry), callback, user_data,
                e_source_registry_create_sources);

        g_simple_async_result_set_check_cancellable (simple, cancellable);

        g_simple_async_result_set_op_res_gpointer (
                simple, async_context, (GDestroyNotify) async_context_free);

        g_simple_async_result_run_in_thread (
                simple, source_registry_create_sources_thread,
                G_PRIORITY_DEFAULT, cancellable);

        g_object_unref (simple);
}

/**
 * e_source_registry_create_sources_finish:
 * @registry: an #ESourceRegistry
 * @result: a #GAsyncResult
 * @error: return location for a #GError, or %NULL
 *
 * Finishes the operation started with e_source_registry_create_sources().
 *
 * If an error occurred, the function will set @error and return %FALSE.
 *
 * Returns: %TRUE on success, %FALSE on failure
 *
 * Since: 3.6
 **/
gboolean
e_source_registry_create_sources_finish (ESourceRegistry *registry,
                                         GAsyncResult *result,
                                         GError **error)
{
        GSimpleAsyncResult *simple;

        g_return_val_if_fail (
                g_simple_async_result_is_valid (
                result, G_OBJECT (registry),
                e_source_registry_create_sources), FALSE);

        simple = G_SIMPLE_ASYNC_RESULT (result);

        /* Assume success unless a GError is set. */
        return !g_simple_async_result_propagate_error (simple, error);
}

/**
 * e_source_registry_refresh_backend_sync:
 * @registry: an #ESourceRegistry
 * @source_uid: UID of a collection #ESource whose backend to refresh
 * @cancellable: optional #GCancellable object, or %NULL
 * @error: return location for a #GError, or %NULL
 *
 * Requests the D-Bus service to refresh collection backend for an #ESource
 * with UID @source_uid. The result means that the refresh had been scheduled
 * not whether the refresh itself succeeded. The refresh is not initiated
 * when the collection backend is offline.
 *
 * If an error occurs, the function will set @error and return %FALSE.
 *
 * Returns: Whether succeeded
 *
 * Since: 3.30
 **/
gboolean
e_source_registry_refresh_backend_sync (ESourceRegistry *registry,
                                        const gchar *source_uid,
                                        GCancellable *cancellable,
                                        GError **error)
{
        g_return_val_if_fail (E_IS_SOURCE_REGISTRY (registry), FALSE);
        g_return_val_if_fail (source_uid != NULL, FALSE);

        return e_dbus_source_manager_call_refresh_backend_sync (
                registry->priv->dbus_source_manager,
                source_uid, cancellable, error);
}

static void
e_source_registry_refresh_backend_thread (GTask *task,
                                          gpointer source_object,
                                          gpointer task_data,
                                          GCancellable *cancellable)
{
        gboolean success;
        GError *local_error = NULL;

        success = e_source_registry_refresh_backend_sync (source_object, task_data, cancellable, &local_error);

        if (local_error)
                g_task_return_error (task, local_error);
        else
                g_task_return_boolean (task, success);
}

/**
 * e_source_registry_refresh_backend:
 * @registry: an #ESourceRegistry
 * @source_uid: UID of a collection #ESource whose backend to refresh
 * @cancellable: optional #GCancellable object, or %NULL
 * @callback: (scope async): a #GAsyncReadyCallback to call when the request
 *            is satisfied
 * @user_data: (closure): data to pass to the callback function
 *
 * Asynchronously requests the D-Bus service to refresh collection backend
 * for an #ESource with UID @source_uid. The result means that the refresh
 * had been scheduled not whether the refresh itself succeeded. The refresh
 * is not initiated when the collection backend is offline.
 *
 * When the operation is finished, @callback will be called. You can then
 * call e_source_registry_refresh_backend_finish() to get the result of
 * the operation.
 *
 * Since: 3.30
 **/
void
e_source_registry_refresh_backend (ESourceRegistry *registry,
                                   const gchar *source_uid,
                                   GCancellable *cancellable,
                                   GAsyncReadyCallback callback,
                                   gpointer user_data)
{
        GTask *task;

        g_return_if_fail (E_IS_SOURCE_REGISTRY (registry));
        g_return_if_fail (source_uid != NULL);

        task = g_task_new (registry, cancellable, callback, user_data);
        g_task_set_source_tag (task, e_source_registry_refresh_backend);
        g_task_set_task_data (task, g_strdup (source_uid), g_free);

        g_task_run_in_thread (task, e_source_registry_refresh_backend_thread);

        g_object_unref (task);
}

/**
 * e_source_registry_refresh_backend_finish:
 * @registry: an #ESourceRegistry
 * @result: a #GAsyncResult
 * @error: return location for a #GError, or %NULL
 *
 * Finishes the operation started with e_source_registry_refresh_backend().
 *
 * If an error occurred, the function will set @error and return %FALSE.
 *
 * Returns: Whether succeeded
 *
 * Since: 3.30
 **/
gboolean
e_source_registry_refresh_backend_finish (ESourceRegistry *registry,
                                          GAsyncResult *result,
                                          GError **error)
{
        g_return_val_if_fail (E_IS_SOURCE_REGISTRY (registry), FALSE);
        g_return_val_if_fail (g_task_is_valid (result, registry), FALSE);
        g_return_val_if_fail (g_async_result_is_tagged (result, e_source_registry_refresh_backend), FALSE);

        return g_task_propagate_boolean (G_TASK (result), error);
}

/**
 * e_source_registry_ref_source:
 * @registry: an #ESourceRegistry
 * @uid: a unique identifier string
 *
 * Looks up an #ESource in @registry by its unique identifier string.
 *
 * The returned #ESource is referenced for thread-safety and must be
 * unreferenced with g_object_unref() when finished with it.
 *
 * Returns: (transfer full): an #ESource, or %NULL if no match was found
 *
 * Since: 3.6
 **/
ESource *
e_source_registry_ref_source (ESourceRegistry *registry,
                              const gchar *uid)
{
        g_return_val_if_fail (E_IS_SOURCE_REGISTRY (registry), NULL);
        g_return_val_if_fail (uid != NULL, NULL);

        return source_registry_sources_lookup (registry, uid);
}

/**
 * e_source_registry_list_sources:
 * @registry: an #ESourceRegistry
 * @extension_name: (allow-none): an extension name, or %NULL
 *
 * Returns a list of registered sources, sorted by display name.  If
 * @extension_name is given, restrict the list to sources having that
 * extension name.
 *
 * The sources returned in the list are referenced for thread-safety.
 * They must each be unreferenced with g_object_unref() when finished
 * with them.  Free the returned list itself with g_list_free().
 *
 * An easy way to free the list properly in one step is as follows:
 *
 * |[
 *   g_list_free_full (list, g_object_unref);
 * ]|
 *
 * Returns: (element-type ESource) (transfer full): a sorted list of sources
 *
 * Since: 3.6
 **/
GList *
e_source_registry_list_sources (ESourceRegistry *registry,
                                const gchar *extension_name)
{
        GList *list, *link;
        GQueue trash = G_QUEUE_INIT;

        g_return_val_if_fail (E_IS_SOURCE_REGISTRY (registry), NULL);

        list = g_list_sort (
                source_registry_sources_get_values (registry),
                (GCompareFunc) e_source_compare_by_display_name);

        if (extension_name == NULL)
                return list;

        for (link = list; link != NULL; link = g_list_next (link)) {
                ESource *source = E_SOURCE (link->data);

                if (!e_source_has_extension (source, extension_name)) {
                        g_queue_push_tail (&trash, link);
                        g_object_unref (source);
                }
        }

        /* We do want pop_head() here, not pop_head_link(). */
        while ((link = g_queue_pop_head (&trash)) != NULL)
                list = g_list_delete_link (list, link);

        return list;
}

/**
 * e_source_registry_list_enabled:
 * @registry: an #ESourceRegistry
 * @extension_name: (allow-none): an extension name, or %NULL
 *
 * Similar to e_source_registry_list_sources(), but returns only enabled
 * sources according to e_source_registry_check_enabled().
 *
 * The sources returned in the list are referenced for thread-safety.
 * They must each be unreferenced with g_object_unref() when finished
 * with them.  Free the returned list itself with g_list_free().
 *
 * An easy way to free the list properly in one step is as follows:
 *
 * |[
 *   g_list_free_full (list, g_object_unref);
 * ]|
 *
 * Returns: (element-type ESource) (transfer full): a sorted list of sources
 *
 * Since: 3.10
 **/
GList *
e_source_registry_list_enabled (ESourceRegistry *registry,
                                const gchar *extension_name)
{
        GList *list, *link;
        GQueue trash = G_QUEUE_INIT;

        g_return_val_if_fail (E_IS_SOURCE_REGISTRY (registry), NULL);

        list = e_source_registry_list_sources (registry, extension_name);

        for (link = list; link != NULL; link = g_list_next (link)) {
                ESource *source = E_SOURCE (link->data);

                if (!e_source_registry_check_enabled (registry, source)) {
                        g_queue_push_tail (&trash, link);
                        g_object_unref (source);
                }
        }

        /* We do want pop_head() here, not pop_head_link(). */
        while ((link = g_queue_pop_head (&trash)) != NULL)
                list = g_list_delete_link (list, link);

        return list;
}

/**
 * e_source_registry_find_extension:
 * @registry: an #ESourceRegistry
 * @source: an #ESource
 * @extension_name: the extension name to find
 *
 * Examines @source and its ancestors and returns the "deepest" #ESource
 * having an #ESourceExtension with the given @extension_name.  If neither
 * @source nor any of its ancestors have such an extension, the function
 * returns %NULL.
 *
 * This function is useful in cases when an #ESourceExtension is meant to
 * apply to both the #ESource it belongs to and the #ESource's descendants.
 *
 * A common example is the #ESourceCollection extension, where descendants
 * of an #ESource having an #ESourceCollection extension are implied to be
 * members of that collection.  In that example, this function can be used
 * to test whether @source is a member of a collection.
 *
 * The returned #ESource is referenced for thread-safety and must be
 * unreferenced with g_object_unref() when finished with it.
 *
 * Note the function returns the #ESource containing the #ESourceExtension
 * instead of the #ESourceExtension itself because extension instances are
 * not to be referenced directly (see e_source_get_extension()).
 *
 * Returns: (transfer full): an #ESource, or %NULL if no match was found
 *
 * Since: 3.6
 **/
ESource *
e_source_registry_find_extension (ESourceRegistry *registry,
                                  ESource *source,
                                  const gchar *extension_name)
{
        g_return_val_if_fail (E_IS_SOURCE_REGISTRY (registry), NULL);
        g_return_val_if_fail (E_IS_SOURCE (source), NULL);
        g_return_val_if_fail (extension_name != NULL, NULL);

        g_object_ref (source);

        while (!e_source_has_extension (source, extension_name)) {
                gchar *uid;

                uid = e_source_dup_parent (source);

                g_object_unref (source);
                source = NULL;

                if (uid != NULL) {
                        source = e_source_registry_ref_source (registry, uid);
                        g_free (uid);
                }

                if (source == NULL)
                        break;
        }

        return source;
}

/**
 * e_source_registry_check_enabled:
 * @registry: an #ESourceRegistry
 * @source: an #ESource
 *
 * Determines whether @source is "effectively" enabled by examining its
 * own #ESource:enabled property as well as those of its ancestors in the
 * #ESource hierarchy.  If all examined #ESource:enabled properties are
 * %TRUE, then the function returns %TRUE.  If any are %FALSE, then the
 * function returns %FALSE.
 *
 * Use this function instead of e_source_get_enabled() to determine
 * things like whether to display an #ESource in a user interface or
 * whether to act on the data set described by the #ESource.
 *
 * Returns: whether @source is "effectively" enabled
 *
 * Since: 3.8
 **/
gboolean
e_source_registry_check_enabled (ESourceRegistry *registry,
                                 ESource *source)
{
        gboolean enabled;
        gchar *parent_uid;

        g_return_val_if_fail (E_IS_SOURCE_REGISTRY (registry), FALSE);
        g_return_val_if_fail (E_IS_SOURCE (source), FALSE);

        enabled = e_source_get_enabled (source);
        parent_uid = e_source_dup_parent (source);

        while (enabled && parent_uid != NULL) {
                ESource *parent;

                parent = e_source_registry_ref_source (registry, parent_uid);

                g_free (parent_uid);
                parent_uid = NULL;

                if (parent != NULL) {
                        enabled = e_source_get_enabled (parent);
                        parent_uid = e_source_dup_parent (parent);
                        g_object_unref (parent);
                }
        }

        g_free (parent_uid);

        return enabled;
}

/* Helper for e_source_registry_build_display_tree() */
static gint
source_registry_compare_nodes (GNode *node_a,
                               GNode *node_b)
{
        ESource *source_a = E_SOURCE (node_a->data);
        ESource *source_b = E_SOURCE (node_b->data);
        const gchar *uid_a, *uid_b;

        uid_a = e_source_get_uid (source_a);
        uid_b = e_source_get_uid (source_b);

        /* Sanity check, with runtime warnings. */
        if (uid_a == NULL) {
                g_warn_if_reached ();
                uid_a = "";
        }
        if (uid_b == NULL) {
                g_warn_if_reached ();
                uid_b = "";
        }

        /* The built-in "local-stub" source comes first at depth 1. */

        if (g_strcmp0 (uid_a, "local-stub") == 0)
                return -1;

        if (g_strcmp0 (uid_b, "local-stub") == 0)
                return 1;

        /* The built-in "system-*" sources come first at depth 2. */

        if (g_str_has_prefix (uid_a, "system-"))
                return -1;

        if (g_str_has_prefix (uid_b, "system-"))
                return 1;

        return e_source_compare_by_display_name (source_a, source_b);
}

/* Helper for e_source_registry_build_display_tree() */
static gboolean
source_registry_prune_nodes (GNode *node,
                             const gchar *extension_name)
{
        GQueue queue = G_QUEUE_INIT;
        GNode *child_node;

        /* Unlink all the child nodes and place them in a queue. */
        while ((child_node = g_node_first_child (node)) != NULL) {
                g_node_unlink (child_node);
                g_queue_push_tail (&queue, child_node);
        }

        /* Sort the queue by source name. */
        g_queue_sort (
                &queue, (GCompareDataFunc)
                source_registry_compare_nodes, NULL);

        /* Pop nodes off the head of the queue until the queue is empty.
         * If the node has either its own children or the given extension
         * name, put it back under the parent node (preserving the sorted
         * order).  Otherwise delete the node and its descendants. */
        while ((child_node = g_queue_pop_head (&queue)) != NULL) {
                ESource *child = E_SOURCE (child_node->data);
                gboolean append_child_node = FALSE;

                if (extension_name == NULL)
                        append_child_node = e_source_get_enabled (child);

                else if (e_source_has_extension (child, extension_name))
                        append_child_node = e_source_get_enabled (child);

                else if (g_node_first_child (child_node) != NULL)
                        append_child_node = e_source_get_enabled (child);

                if (append_child_node)
                        g_node_append (node, child_node);
                else
                        e_source_registry_free_display_tree (child_node);
        }

        return FALSE;
}

/**
 * e_source_registry_build_display_tree: (skip)
 * @registry: an #ESourceRegistry
 * @extension_name: (allow-none): an extension name, or %NULL
 *
 * Returns a single #GNode tree of registered sources that can be used to
 * populate a #GtkTreeModel.  (The root #GNode is just an empty placeholder.)
 *
 * Similar to e_source_registry_list_sources(), an @extension_name can be
 * given to restrict the tree to sources having that extension name.  Parents
 * of matched sources are included in the tree regardless of whether they have
 * an extension named @extension_name.
 *
 * Disabled leaf nodes are automatically excluded from the #GNode tree.
 *
 * The sources returned in the tree are referenced for thread-safety.
 * They must each be unreferenced with g_object_unref() when finished
 * with them.  Free the returned tree itself with g_node_destroy().
 * For convenience, e_source_registry_free_display_tree() does all
 * that in one step.
 *
 * Returns: (element-type ESource) (transfer full): a tree of sources,
 *          arranged for display
 *
 * Since: 3.6
 **/
GNode *
e_source_registry_build_display_tree (ESourceRegistry *registry,
                                      const gchar *extension_name)
{
        GNode *root;

        g_return_val_if_fail (E_IS_SOURCE_REGISTRY (registry), NULL);

        /* Assemble all data sources into a tree. */
        root = source_registry_sources_build_tree (registry);

        /* Prune unwanted nodes from the copied source trees.
         * This must be done in "post" order (children first)
         * since it reorders and deletes child nodes. */
        g_node_traverse (
                root, G_POST_ORDER, G_TRAVERSE_ALL, -1,
                (GNodeTraverseFunc) source_registry_prune_nodes,
                (gpointer) extension_name);

        return root;
}

/* Helper for e_source_registry_free_display_tree() */
static void
source_registry_unref_nodes (GNode *node)
{
        while (node != NULL) {
                if (node->children != NULL)
                        source_registry_unref_nodes (node->children);
                if (node->data != NULL)
                        g_object_unref (node->data);
                node = node->next;
        }
}

/**
 * e_source_registry_free_display_tree:
 * @display_tree: a tree of sources, arranged for display
 *
 * Convenience function to free a #GNode tree of registered
 * sources created by e_source_registry_build_display_tree().
 *
 * Since: 3.6
 **/
void
e_source_registry_free_display_tree (GNode *display_tree)
{
        g_return_if_fail (display_tree != NULL);

        /* XXX This would be easier if GLib had something like
         *     g_node_destroy_full() which took a GDestroyNotify.
         *     Then the tree would not have to be traversed twice. */

        source_registry_unref_nodes (display_tree);
        g_node_destroy (display_tree);
}

/**
 * e_source_registry_dup_unique_display_name:
 * @registry: an #ESourceRegistry
 * @source: an #ESource
 * @extension_name: (allow-none): an extension name, or %NULL
 *
 * Compares @source's #ESource:display-name against other sources having
 * an #ESourceExtension named @extension_name, if given, or else against
 * all other sources in the @registry.
 *
 * If @sources's #ESource:display-name is unique among these other sources,
 * the function will return the #ESource:display-name verbatim.  Otherwise
 * the function will construct a string that includes the @sources's own
 * #ESource:display-name as well as those of its ancestors.
 *
 * The function's return value is intended to be used in messages shown to
 * the user to help clarify which source is being referred to.  It assumes
 * @source's #ESource:display-name is at least unique among its siblings.
 *
 * Free the returned string with g_free() when finished with it.
 *
 * Returns: a unique display name for @source
 *
 * Since: 3.8
 **/
gchar *
e_source_registry_dup_unique_display_name (ESourceRegistry *registry,
                                           ESource *source,
                                           const gchar *extension_name)
{
        GString *buffer;
        GList *list, *link;
        gchar *display_name;
        gboolean need_clarification = FALSE;

        g_return_val_if_fail (E_IS_SOURCE_REGISTRY (registry), NULL);
        g_return_val_if_fail (E_IS_SOURCE (source), NULL);

        list = e_source_registry_list_sources (registry, extension_name);

        /* Remove the input source from the list, if present. */
        link = g_list_find (list, source);
        if (link != NULL) {
                g_object_unref (link->data);
                list = g_list_delete_link (list, link);
        }

        /* Now find another source with a matching display name. */
        link = g_list_find_custom (
                list, source, (GCompareFunc)
                e_source_compare_by_display_name);

        need_clarification = (link != NULL);

        g_list_free_full (list, (GDestroyNotify) g_object_unref);
        list = NULL;

        display_name = e_source_dup_display_name (source);
        buffer = g_string_new (display_name);
        g_free (display_name);

        if (need_clarification) {
                /* Build a list of ancestor sources. */

                g_object_ref (source);

                while (source != NULL) {
                        gchar *parent_uid;

                        parent_uid = e_source_dup_parent (source);

                        g_object_unref (source);
                        source = NULL;

                        if (parent_uid != NULL) {
                                source = e_source_registry_ref_source (
                                        registry, parent_uid);
                                g_free (parent_uid);
                        }

                        if (source != NULL) {
                                g_object_ref (source);
                                list = g_list_prepend (list, source);
                        }
                }

                /* Display the ancestor names from the most distant
                 * ancestor to the input source's immediate parent. */

                if (list != NULL)
                        g_string_append (buffer, " (");

                for (link = list; link != NULL; link = g_list_next (link)) {
                        if (link != list)
                                g_string_append (buffer, " / ");

                        source = E_SOURCE (link->data);
                        display_name = e_source_dup_display_name (source);
                        g_string_append (buffer, display_name);
                        g_free (display_name);
                }

                if (list != NULL)
                        g_string_append (buffer, ")");

                g_list_free_full (list, (GDestroyNotify) g_object_unref);
        }

        return g_string_free (buffer, FALSE);
}

/* Helper for e_source_registry_debug_dump() */
static gboolean
source_registry_debug_dump_cb (GNode *node)
{
        guint ii, depth;

        /* Root node is an empty placeholder. */
        if (G_NODE_IS_ROOT (node))
                return FALSE;

        depth = g_node_depth (node);
        for (ii = 2; ii < depth; ii++)
                g_print ("    ");

        if (E_IS_SOURCE (node->data)) {
                ESource *source = E_SOURCE (node->data);
                g_print ("\"%s\" ", e_source_get_display_name (source));
                g_print ("(%s)", e_source_get_uid (source));
        }

        g_print ("\n");

        return FALSE;
}

/**
 * e_source_registry_debug_dump:
 * @registry: an #ESourceRegistry
 * @extension_name: (allow-none): an extension name, or %NULL
 *
 * Handy debugging function that uses e_source_registry_build_display_tree()
 * to print a tree of registered sources to standard output.
 *
 * Since: 3.6
 **/
void
e_source_registry_debug_dump (ESourceRegistry *registry,
                              const gchar *extension_name)
{
        GNode *root;

        g_return_if_fail (E_IS_SOURCE_REGISTRY (registry));

        root = e_source_registry_build_display_tree (registry, extension_name);

        g_node_traverse (
                root, G_PRE_ORDER, G_TRAVERSE_ALL, -1,
                (GNodeTraverseFunc) source_registry_debug_dump_cb, NULL);

        e_source_registry_free_display_tree (root);
}

/**
 * e_source_registry_ref_builtin_address_book:
 * @registry: an #ESourceRegistry
 *
 * Returns the built-in address book #ESource.
 *
 * This #ESource is always present and makes for a safe fallback.
 *
 * The returned #ESource is referenced for thread-safety and must be
 * unreferenced with g_object_unref() when finished with it.
 *
 * Returns: (transfer full): the built-in address book #ESource
 *
 * Since: 3.6
 **/
ESource *
e_source_registry_ref_builtin_address_book (ESourceRegistry *registry)
{
        ESource *source;
        const gchar *uid;

        g_return_val_if_fail (E_IS_SOURCE_REGISTRY (registry), NULL);

        uid = E_SOURCE_BUILTIN_ADDRESS_BOOK_UID;
        source = e_source_registry_ref_source (registry, uid);
        g_return_val_if_fail (source != NULL, NULL);

        return source;
}

/**
 * e_source_registry_ref_builtin_calendar:
 * @registry: an #ESourceRegistry
 *
 * Returns the built-in calendar #ESource.
 *
 * This #ESource is always present and makes for a safe fallback.
 *
 * The returned #ESource is referenced for thread-safety and must be
 * unreferenced with g_object_unref() when finished with it.
 *
 * Returns: (transfer full): the built-in calendar #ESource
 *
 * Since: 3.6
 **/
ESource *
e_source_registry_ref_builtin_calendar (ESourceRegistry *registry)
{
        ESource *source;
        const gchar *uid;

        g_return_val_if_fail (E_IS_SOURCE_REGISTRY (registry), NULL);

        uid = E_SOURCE_BUILTIN_CALENDAR_UID;
        source = e_source_registry_ref_source (registry, uid);
        g_return_val_if_fail (source != NULL, NULL);

        return source;
}

/**
 * e_source_registry_ref_builtin_mail_account:
 * @registry: an #ESourceRegistry
 *
 * Returns the built-in mail account #ESource.
 *
 * This #ESource is always present and makes for a safe fallback.
 *
 * The returned #ESource is referenced for thread-safety and must be
 * unreferenced with g_object_unref() when finished with it.
 *
 * Returns: (transfer full): the built-in mail account #ESource
 *
 * Since: 3.6
 **/
ESource *
e_source_registry_ref_builtin_mail_account (ESourceRegistry *registry)
{
        ESource *source;
        const gchar *uid;

        g_return_val_if_fail (E_IS_SOURCE_REGISTRY (registry), NULL);

        uid = E_SOURCE_BUILTIN_MAIL_ACCOUNT_UID;
        source = e_source_registry_ref_source (registry, uid);
        g_return_val_if_fail (source != NULL, NULL);

        return source;
}

/**
 * e_source_registry_ref_builtin_memo_list:
 * @registry: an #ESourceRegistry
 *
 * Returns the built-in memo list #ESource.
 *
 * This #ESource is always present and makes for a safe fallback.
 *
 * The returned #ESource is referenced for thread-safety and must be
 * unreferenced with g_object_unref() when finished with it.
 *
 * Returns: (transfer full): the built-in memo list #ESource
 *
 * Since: 3.6
 **/
ESource *
e_source_registry_ref_builtin_memo_list (ESourceRegistry *registry)
{
        ESource *source;
        const gchar *uid;

        g_return_val_if_fail (E_IS_SOURCE_REGISTRY (registry), NULL);

        uid = E_SOURCE_BUILTIN_MEMO_LIST_UID;
        source = e_source_registry_ref_source (registry, uid);
        g_return_val_if_fail (source != NULL, NULL);

        return source;
}

/**
 * e_source_registry_ref_builtin_proxy:
 * @registry: an #ESourceRegistry
 *
 * Returns the built-in proxy profile #ESource.
 *
 * This #ESource is always present and makes for a safe fallback.
 *
 * The returned #ESource is referenced for thread-safety and must be
 * unreferenced with g_object_unref() when finished with it.
 *
 * Returns: (transfer full): the built-in proxy profile #ESource
 *
 * Since: 3.12
 **/
ESource *
e_source_registry_ref_builtin_proxy (ESourceRegistry *registry)
{
        ESource *source;
        const gchar *uid;

        g_return_val_if_fail (E_IS_SOURCE_REGISTRY (registry), NULL);

        uid = E_SOURCE_BUILTIN_PROXY_UID;
        source = e_source_registry_ref_source (registry, uid);
        g_return_val_if_fail (source != NULL, NULL);

        return source;
}

/**
 * e_source_registry_ref_builtin_task_list:
 * @registry: an #ESourceRegistry
 *
 * Returns the built-in task list #ESource.
 *
 * This #ESource is always present and makes for a safe fallback.
 *
 * The returned #ESource is referenced for thread-safety and must be
 * unreferenced with g_object_unref() when finished with it.
 *
 * Returns: (transfer full): the built-in task list #ESource
 *
 * Since: 3.6
 **/
ESource *
e_source_registry_ref_builtin_task_list (ESourceRegistry *registry)
{
        ESource *source;
        const gchar *uid;

        g_return_val_if_fail (E_IS_SOURCE_REGISTRY (registry), NULL);

        uid = E_SOURCE_BUILTIN_TASK_LIST_UID;
        source = e_source_registry_ref_source (registry, uid);
        g_return_val_if_fail (source != NULL, NULL);

        return source;
}

/**
 * e_source_registry_ref_default_address_book:
 * @registry: an #ESourceRegistry
 *
 * Returns the #ESource most recently passed to
 * e_source_registry_set_default_address_book() either in this session
 * or a previous session, or else falls back to the built-in address book.
 *
 * The returned #ESource is referenced for thread-safety and must be
 * unreferenced with g_object_unref() when finished with it.
 *
 * Returns: (transfer full): the default address book #ESource
 *
 * Since: 3.6
 **/
ESource *
e_source_registry_ref_default_address_book (ESourceRegistry *registry)
{
        const gchar *key;
        ESource *source;
        gchar *uid;

        g_return_val_if_fail (E_IS_SOURCE_REGISTRY (registry), NULL);

        key = E_SETTINGS_DEFAULT_ADDRESS_BOOK_KEY;
        uid = g_settings_get_string (registry->priv->settings, key);
        source = e_source_registry_ref_source (registry, uid);
        g_free (uid);

        /* The built-in source is always present. */
        if (source == NULL)
                source = e_source_registry_ref_builtin_address_book (registry);

        g_return_val_if_fail (E_IS_SOURCE (source), NULL);

        return source;
}

/**
 * e_source_registry_set_default_address_book:
 * @registry: an #ESourceRegistry
 * @default_source: (allow-none): an address book #ESource, or %NULL
 *
 * Sets @default_source as the default address book.  If @default_source
 * is %NULL, the default address book is reset to the built-in address book.
 * This setting will persist across sessions until changed.
 *
 * Since: 3.6
 **/
void
e_source_registry_set_default_address_book (ESourceRegistry *registry,
                                            ESource *default_source)
{
        const gchar *key;
        const gchar *uid;

        g_return_if_fail (E_IS_SOURCE_REGISTRY (registry));

        if (default_source != NULL) {
                g_return_if_fail (E_IS_SOURCE (default_source));
                uid = e_source_get_uid (default_source);
        } else {
                uid = E_SOURCE_BUILTIN_ADDRESS_BOOK_UID;
        }

        key = E_SETTINGS_DEFAULT_ADDRESS_BOOK_KEY;
        g_settings_set_string (registry->priv->settings, key, uid);

        /* The GSettings::changed signal will trigger a "notify" signal
         * from the registry, so no need to call g_object_notify() here. */
}

/**
 * e_source_registry_ref_default_calendar:
 * @registry: an #ESourceRegistry
 *
 * Returns the #ESource most recently passed to
 * e_source_registry_set_default_calendar() either in this session
 * or a previous session, or else falls back to the built-in calendar.
 *
 * The returned #ESource is referenced for thread-safety and must be
 * unreferenced with g_object_unref() when finished with it.
 *
 * Returns: (transfer full): the default calendar #ESource
 *
 * Since: 3.6
 **/
ESource *
e_source_registry_ref_default_calendar (ESourceRegistry *registry)
{
        const gchar *key;
        ESource *source;
        gchar *uid;

        g_return_val_if_fail (E_IS_SOURCE_REGISTRY (registry), NULL);

        key = E_SETTINGS_DEFAULT_CALENDAR_KEY;
        uid = g_settings_get_string (registry->priv->settings, key);
        source = e_source_registry_ref_source (registry, uid);
        g_free (uid);

        /* The built-in source is always present. */
        if (source == NULL)
                source = e_source_registry_ref_builtin_calendar (registry);

        g_return_val_if_fail (E_IS_SOURCE (source), NULL);

        return source;
}

/**
 * e_source_registry_set_default_calendar:
 * @registry: an #ESourceRegistry
 * @default_source: (allow-none): a calendar #ESource, or %NULL
 *
 * Sets @default_source as the default calendar.  If @default_source
 * is %NULL, the default calendar is reset to the built-in calendar.
 * This setting will persist across sessions until changed.
 *
 * Since: 3.6
 **/
void
e_source_registry_set_default_calendar (ESourceRegistry *registry,
                                        ESource *default_source)
{
        const gchar *key;
        const gchar *uid;

        g_return_if_fail (E_IS_SOURCE_REGISTRY (registry));

        if (default_source != NULL) {
                g_return_if_fail (E_IS_SOURCE (default_source));
                uid = e_source_get_uid (default_source);
        } else {
                uid = E_SOURCE_BUILTIN_CALENDAR_UID;
        }

        key = E_SETTINGS_DEFAULT_CALENDAR_KEY;
        g_settings_set_string (registry->priv->settings, key, uid);

        /* The GSettings::changed signal will trigger a "notify" signal
         * from the registry, so no need to call g_object_notify() here. */
}

/**
 * e_source_registry_ref_default_mail_account:
 * @registry: an #ESourceRegistry
 *
 * Returns the #ESource most recently passed to
 * e_source_registry_set_default_mail_account() either in this session
 * or a previous session, or else falls back to the built-in mail account.
 *
 * The returned #ESource is referenced for thread-safety and must be
 * unreferenced with g_object_unref() when finished with it.
 *
 * Returns: (transfer full): the default mail account #ESource
 *
 * Since: 3.6
 **/
ESource *
e_source_registry_ref_default_mail_account (ESourceRegistry *registry)
{
        const gchar *key;
        ESource *source;
        gchar *uid;

        g_return_val_if_fail (E_IS_SOURCE_REGISTRY (registry), NULL);

        key = E_SETTINGS_DEFAULT_MAIL_ACCOUNT_KEY;
        uid = g_settings_get_string (registry->priv->settings, key);
        source = e_source_registry_ref_source (registry, uid);
        g_free (uid);

        /* The built-in source is always present. */
        if (source == NULL)
                source = e_source_registry_ref_builtin_mail_account (registry);

        g_return_val_if_fail (E_IS_SOURCE (source), NULL);

        return source;
}

/**
 * e_source_registry_set_default_mail_account:
 * @registry: an #ESourceRegistry
 * @default_source: (allow-none): a mail account #ESource, or %NULL
 *
 * Sets @default_source as the default mail account.  If @default_source
 * is %NULL, the default mail account is reset to the built-in mail account.
 * This setting will persist across sessions until changed.
 *
 * Since: 3.6
 **/
void
e_source_registry_set_default_mail_account (ESourceRegistry *registry,
                                            ESource *default_source)
{
        const gchar *key;
        const gchar *uid;

        g_return_if_fail (E_IS_SOURCE_REGISTRY (registry));

        if (default_source != NULL) {
                g_return_if_fail (E_IS_SOURCE (default_source));
                uid = e_source_get_uid (default_source);
        } else {
                uid = E_SOURCE_BUILTIN_MAIL_ACCOUNT_UID;
        }

        key = E_SETTINGS_DEFAULT_MAIL_ACCOUNT_KEY;
        g_settings_set_string (registry->priv->settings, key, uid);

        /* The GSettings::changed signal will trigger a "notify" signal
         * from the registry, so no need to call g_object_notify() here. */
}

/* Helper for e_source_registry_ref_default_mail_identity() */
static ESource *
source_registry_ref_any_mail_identity (ESourceRegistry *registry)
{
        ESource *source;
        GList *list, *link;
        const gchar *extension_name;
        gchar *uid = NULL;

        /* First fallback: Return the mail identity named
         *                 by the default mail account. */

        source = e_source_registry_ref_default_mail_account (registry);

        /* This should never be NULL, but just to be safe. */
        if (source != NULL) {
                ESourceMailAccount *extension;

                extension_name = E_SOURCE_EXTENSION_MAIL_ACCOUNT;
                extension = e_source_get_extension (source, extension_name);
                uid = e_source_mail_account_dup_identity_uid (extension);

                g_object_unref (source);
                source = NULL;
        }

        if (uid != NULL) {
                source = e_source_registry_ref_source (registry, uid);
                g_free (uid);
        }

        if (source != NULL)
                return source;

        /* Second fallback: Pick any available mail identity,
         *                  preferring enabled identities. */

        extension_name = E_SOURCE_EXTENSION_MAIL_IDENTITY;
        list = e_source_registry_list_sources (registry, extension_name);

        for (link = list; link != NULL; link = g_list_next (link)) {
                ESource *candidate = E_SOURCE (link->data);

                if (e_source_registry_check_enabled (registry, candidate)) {
                        source = g_object_ref (candidate);
                        break;
                }
        }

        if (source == NULL && list != NULL)
                source = g_object_ref (list->data);

        g_list_free_full (list, (GDestroyNotify) g_object_unref);

        return source;
}

/**
 * e_source_registry_ref_default_mail_identity:
 * @registry: an #ESourceRegistry
 *
 * Returns the #ESource most recently passed to
 * e_source_registry_set_default_mail_identity() either in this session
 * or a previous session, or else falls back to the mail identity named
 * by the default mail account.  If even that fails it returns any mail
 * identity from @registry, or %NULL if there are none.
 *
 * The returned #ESource is referenced for thread-safety and must be
 * unreferenced with g_object_unref() when finished with it.
 *
 * Returns: (transfer full): the default mail identity #ESource, or %NULL
 *
 * Since: 3.6
 **/
ESource *
e_source_registry_ref_default_mail_identity (ESourceRegistry *registry)
{
        const gchar *key;
        ESource *source;
        gchar *uid;

        g_return_val_if_fail (E_IS_SOURCE_REGISTRY (registry), NULL);

        key = E_SETTINGS_DEFAULT_MAIL_IDENTITY_KEY;
        uid = g_settings_get_string (registry->priv->settings, key);
        source = e_source_registry_ref_source (registry, uid);
        g_free (uid);

        if (source == NULL)
                source = source_registry_ref_any_mail_identity (registry);

        return source;
}

/**
 * e_source_registry_set_default_mail_identity:
 * @registry: an #ESourceRegistry
 * @default_source: (allow-none): a mail identity #ESource, or %NULL
 *
 * Sets @default_source as the default mail identity.  If @default_source
 * is %NULL, the next request for the default mail identity will use the
 * fallbacks described in e_source_registry_ref_default_mail_identity().
 *
 * Since: 3.6
 **/
void
e_source_registry_set_default_mail_identity (ESourceRegistry *registry,
                                             ESource *default_source)
{
        const gchar *key;
        const gchar *uid;

        g_return_if_fail (E_IS_SOURCE_REGISTRY (registry));

        if (default_source != NULL) {
                g_return_if_fail (E_IS_SOURCE (default_source));
                uid = e_source_get_uid (default_source);
        } else {
                uid = "";  /* no built-in mail identity */
        }

        key = E_SETTINGS_DEFAULT_MAIL_IDENTITY_KEY;
        g_settings_set_string (registry->priv->settings, key, uid);

        /* The GSettings::changed signal will trigger a "notify" signal
         * from the registry, so no need to call g_object_notify() here. */
}

/**
 * e_source_registry_ref_default_memo_list:
 * @registry: an #ESourceRegistry
 *
 * Returns the #ESource most recently passed to
 * e_source_registry_set_default_memo_list() either in this session
 * or a previous session, or else falls back to the built-in memo list.
 *
 * The returned #ESource is referenced for thread-safety and must be
 * unreferenced with g_object_unref() when finished with it.
 *
 * Returns: (transfer full): the default memo list #ESource
 *
 * Since: 3.6
 **/
ESource *
e_source_registry_ref_default_memo_list (ESourceRegistry *registry)
{
        const gchar *key;
        ESource *source;
        gchar *uid;

        g_return_val_if_fail (E_IS_SOURCE_REGISTRY (registry), NULL);

        key = E_SETTINGS_DEFAULT_MEMO_LIST_KEY;
        uid = g_settings_get_string (registry->priv->settings, key);
        source = e_source_registry_ref_source (registry, uid);
        g_free (uid);

        /* The built-in source is always present. */
        if (source == NULL)
                source = e_source_registry_ref_builtin_memo_list (registry);

        g_return_val_if_fail (E_IS_SOURCE (source), NULL);

        return source;
}

/**
 * e_source_registry_set_default_memo_list:
 * @registry: an #ESourceRegistry
 * @default_source: (allow-none): a memo list #ESource, or %NULL
 *
 * Sets @default_source as the default memo list.  If @default_source
 * is %NULL, the default memo list is reset to the built-in memo list.
 * This setting will persist across sessions until changed.
 *
 * Since: 3.6
 **/
void
e_source_registry_set_default_memo_list (ESourceRegistry *registry,
                                         ESource *default_source)
{
        const gchar *key;
        const gchar *uid;

        g_return_if_fail (E_IS_SOURCE_REGISTRY (registry));

        if (default_source != NULL) {
                g_return_if_fail (E_IS_SOURCE (default_source));
                uid = e_source_get_uid (default_source);
        } else {
                uid = E_SOURCE_BUILTIN_MEMO_LIST_UID;
        }

        key = E_SETTINGS_DEFAULT_MEMO_LIST_KEY;
        g_settings_set_string (registry->priv->settings, key, uid);

        /* The GSettings::changed signal will trigger a "notify" signal
         * from the registry, so no need to call g_object_notify() here. */
}

/**
 * e_source_registry_ref_default_task_list:
 * @registry: an #ESourceRegistry
 *
 * Returns the #ESource most recently passed to
 * e_source_registry_set_default_task_list() either in this session
 * or a previous session, or else falls back to the built-in task list.
 *
 * The returned #ESource is referenced for thread-safety and must be
 * unreferenced with g_object_unref() when finished with it.
 *
 * Returns: (transfer full): the default task list #ESource
 *
 * Since: 3.6
 **/
ESource *
e_source_registry_ref_default_task_list (ESourceRegistry *registry)
{
        const gchar *key;
        ESource *source;
        gchar *uid;

        g_return_val_if_fail (E_IS_SOURCE_REGISTRY (registry), NULL);

        key = E_SETTINGS_DEFAULT_TASK_LIST_KEY;
        uid = g_settings_get_string (registry->priv->settings, key);
        source = e_source_registry_ref_source (registry, uid);
        g_free (uid);

        /* The built-in source is always present. */
        if (source == NULL)
                source = e_source_registry_ref_builtin_task_list (registry);

        g_return_val_if_fail (E_IS_SOURCE (source), NULL);

        return source;
}

/**
 * e_source_registry_set_default_task_list:
 * @registry: an #ESourceRegistry
 * @default_source: (allow-none): a task list #ESource, or %NULL
 *
 * Sets @default_source as the default task list.  If @default_source
 * is %NULL, the default task list is reset to the built-in task list.
 * This setting will persist across sessions until changed.
 *
 * Since: 3.6
 **/
void
e_source_registry_set_default_task_list (ESourceRegistry *registry,
                                         ESource *default_source)
{
        const gchar *key;
        const gchar *uid;

        g_return_if_fail (E_IS_SOURCE_REGISTRY (registry));

        if (default_source != NULL) {
                g_return_if_fail (E_IS_SOURCE (default_source));
                uid = e_source_get_uid (default_source);
        } else {
                uid = E_SOURCE_BUILTIN_TASK_LIST_UID;
        }

        key = E_SETTINGS_DEFAULT_TASK_LIST_KEY;
        g_settings_set_string (registry->priv->settings, key, uid);

        /* The GSettings::changed signal will trigger a "notify" signal
         * from the registry, so no need to call g_object_notify() here. */
}

/**
 * e_source_registry_ref_default_for_extension_name:
 * @registry: an #ESourceRegistry
 * @extension_name: an extension_name
 *
 * This is a convenience function to return a default #ESource based on
 * @extension_name.  This only works with a subset of extension names.
 *
 * If @extension_name is #E_SOURCE_EXTENSION_ADDRESS_BOOK, the function
 * returns the current default address book, or else falls back to the
 * built-in address book.
 *
 * If @extension_name is #E_SOURCE_EXTENSION_CALENDAR, the function returns
 * the current default calendar, or else falls back to the built-in calendar.
 *
 * If @extension_name is #E_SOURCE_EXTENSION_MAIL_ACCOUNT, the function
 * returns the current default mail account, or else falls back to the
 * built-in mail account.
 *
 * If @extension_name is #E_SOURCE_EXTENSION_MAIL_IDENTITY, the function
 * returns the current default mail identity, or else falls back to the
 * mail identity named by the current default mail account.
 *
 * If @extension_name is #E_SOURCE_EXTENSION_MEMO_LIST, the function returns
 * the current default memo list, or else falls back to the built-in memo list.
 *
 * If @extension_name is #E_SOURCE_EXTENSION_TASK_LIST, the function returns
 * the current default task list, or else falls back to the built-in task list.
 *
 * For all other values of @extension_name, the function returns %NULL.
 *
 * The returned #ESource is referenced for thread-safety and must be
 * unreferenced with g_object_unref() when finished with it.
 *
 * Returns: (transfer full): the default #ESource based on @extension_name
 *
 * Since: 3.6
 **/
ESource *
e_source_registry_ref_default_for_extension_name (ESourceRegistry *registry,
                                                  const gchar *extension_name)
{
        g_return_val_if_fail (E_IS_SOURCE_REGISTRY (registry), NULL);
        g_return_val_if_fail (extension_name != NULL, NULL);

        if (strcmp (extension_name, E_SOURCE_EXTENSION_ADDRESS_BOOK) == 0)
                return e_source_registry_ref_default_address_book (registry);

        if (strcmp (extension_name, E_SOURCE_EXTENSION_CALENDAR) == 0)
                return e_source_registry_ref_default_calendar (registry);

        if (strcmp (extension_name, E_SOURCE_EXTENSION_MAIL_ACCOUNT) == 0)
                return e_source_registry_ref_default_mail_account (registry);

        if (strcmp (extension_name, E_SOURCE_EXTENSION_MAIL_IDENTITY) == 0)
                return e_source_registry_ref_default_mail_identity (registry);

        if (strcmp (extension_name, E_SOURCE_EXTENSION_MEMO_LIST) == 0)
                return e_source_registry_ref_default_memo_list (registry);

        if (strcmp (extension_name, E_SOURCE_EXTENSION_TASK_LIST) == 0)
                return e_source_registry_ref_default_task_list (registry);

        return NULL;
}

/**
 * e_source_registry_set_default_for_extension_name:
 * @registry: an #ESourceRegistry
 * @extension_name: an extension name
 * @default_source: (allow-none): an #ESource, or %NULL
 *
 * This is a convenience function to set a default #ESource based on
 * @extension_name.  This only works with a subset of extension names.
 *
 * If @extension_name is #E_SOURCE_EXTENSION_ADDRESS_BOOK, the function
 * sets @default_source as the default address book.  If @default_source
 * is %NULL, the default address book is reset to the built-in address book.
 *
 * If @extension_name is #E_SOURCE_EXTENSION_CALENDAR, the function sets
 * @default_source as the default calendar.  If @default_source is %NULL,
 * the default calendar is reset to the built-in calendar.
 *
 * If @extension_name is #E_SOURCE_EXTENSION_MAIL_ACCOUNT, the function
 * sets @default_source as the default mail account.  If @default_source
 * is %NULL, the default mail account is reset to the built-in mail account.
 *
 * If @extension_name is #E_SOURCE_EXTENSION_MAIL_IDENTITY, the function
 * sets @default_source as the default mail identity.  If @default_source
 * is %NULL, the next request for the default mail identity will return
 * the mail identity named by the default mail account.
 *
 * If @extension_name is #E_SOURCE_EXTENSION_MEMO_LIST, the function sets
 * @default_source as the default memo list.  If @default_source is %NULL,
 * the default memo list is reset to the built-in memo list.
 *
 * If @extension_name is #E_SOURCE_EXTENSION_TASK_LIST, the function sets
 * @default_source as the default task list.  If @default_source is %NULL,
 * the default task list is reset to the built-in task list.
 *
 * For all other values of @extension_name, the function does nothing.
 *
 * Since: 3.6
 **/
void
e_source_registry_set_default_for_extension_name (ESourceRegistry *registry,
                                                  const gchar *extension_name,
                                                  ESource *default_source)
{
        g_return_if_fail (E_IS_SOURCE_REGISTRY (registry));
        g_return_if_fail (extension_name != NULL);

        if (strcmp (extension_name, E_SOURCE_EXTENSION_ADDRESS_BOOK) == 0)
                e_source_registry_set_default_address_book (
                        registry, default_source);

        if (strcmp (extension_name, E_SOURCE_EXTENSION_CALENDAR) == 0)
                e_source_registry_set_default_calendar (
                        registry, default_source);

        if (strcmp (extension_name, E_SOURCE_EXTENSION_MAIL_ACCOUNT) == 0)
                e_source_registry_set_default_mail_account (
                        registry, default_source);

        if (strcmp (extension_name, E_SOURCE_EXTENSION_MAIL_IDENTITY) == 0)
                e_source_registry_set_default_mail_identity (
                        registry, default_source);

        if (strcmp (extension_name, E_SOURCE_EXTENSION_MEMO_LIST) == 0)
                e_source_registry_set_default_memo_list (
                        registry, default_source);

        if (strcmp (extension_name, E_SOURCE_EXTENSION_TASK_LIST) == 0)
                e_source_registry_set_default_task_list (
                        registry, default_source);
}