Add a way for packagers to override some installation details

[mediawiki.git] / includes / Action.php

<?php
/**
 * Base classes for actions done on pages.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
 *
 * @file
 */

/**
 * @defgroup Actions Action done on pages
 */

/**
 * Actions are things which can be done to pages (edit, delete, rollback, etc).  They
 * are distinct from Special Pages because an action must apply to exactly one page.
 *
 * To add an action in an extension, create a subclass of Action, and add the key to
 * $wgActions.  There is also the deprecated UnknownAction hook
 *
 * Actions generally fall into two groups: the show-a-form-then-do-something-with-the-input
 * format (protect, delete, move, etc), and the just-do-something format (watch, rollback,
 * patrol, etc). The FormAction and FormlessAction classes respresent these two groups.
 */
abstract class Action {

        /**
         * Page on which we're performing the action
         * @var Page $page
         */
        protected $page;

        /**
         * IContextSource if specified; otherwise we'll use the Context from the Page
         * @var IContextSource $context
         */
        protected $context;

        /**
         * The fields used to create the HTMLForm
         * @var Array $fields
         */
        protected $fields;

        /**
         * Get the Action subclass which should be used to handle this action, false if
         * the action is disabled, or null if it's not recognised
         * @param $action String
         * @param $overrides Array
         * @return bool|null|string
         */
        private final static function getClass( $action, array $overrides ) {
                global $wgActions;
                $action = strtolower( $action );

                if ( !isset( $wgActions[$action] ) ) {
                        return null;
                }

                if ( $wgActions[$action] === false ) {
                        return false;
                } elseif ( $wgActions[$action] === true && isset( $overrides[$action] ) ) {
                        return $overrides[$action];
                } elseif ( $wgActions[$action] === true ) {
                        return ucfirst( $action ) . 'Action';
                } else {
                        return $wgActions[$action];
                }
        }

        /**
         * Get an appropriate Action subclass for the given action
         * @param $action String
         * @param $page Page
         * @param $context IContextSource
         * @return Action|bool|null false if the action is disabled, null
         *     if it is not recognised
         */
        public final static function factory( $action, Page $page, IContextSource $context = null ) {
                $class = self::getClass( $action, $page->getActionOverrides() );
                if ( $class ) {
                        $obj = new $class( $page, $context );
                        return $obj;
                }
                return $class;
        }

        /**
         * Get the action that will be executed, not necessarily the one passed
         * passed through the "action" request parameter. Actions disabled in
         * $wgActions will be replaced by "nosuchaction".
         *
         * @since 1.19
         * @param $context IContextSource
         * @return string: action name
         */
        public final static function getActionName( IContextSource $context ) {
                global $wgActions;

                $request = $context->getRequest();
                $actionName = $request->getVal( 'action', 'view' );

                // Check for disabled actions
                if ( isset( $wgActions[$actionName] ) && $wgActions[$actionName] === false ) {
                        $actionName = 'nosuchaction';
                }

                // Workaround for bug #20966: inability of IE to provide an action dependent
                // on which submit button is clicked.
                if ( $actionName === 'historysubmit' ) {
                        if ( $request->getBool( 'revisiondelete' ) ) {
                                $actionName = 'revisiondelete';
                        } else {
                                $actionName = 'view';
                        }
                } elseif ( $actionName == 'editredlink' ) {
                        $actionName = 'edit';
                }

                // Trying to get a WikiPage for NS_SPECIAL etc. will result
                // in WikiPage::factory throwing "Invalid or virtual namespace -1 given."
                // For SpecialPages et al, default to action=view.
                if ( !$context->canUseWikiPage() ) {
                        return 'view';
                }

                $action = Action::factory( $actionName, $context->getWikiPage() );
                if ( $action instanceof Action ) {
                        return $action->getName();
                }

                return 'nosuchaction';
        }

        /**
         * Check if a given action is recognised, even if it's disabled
         *
         * @param $name String: name of an action
         * @return Bool
         */
        public final static function exists( $name ) {
                return self::getClass( $name, array() ) !== null;
        }

        /**
         * Get the IContextSource in use here
         * @return IContextSource
         */
        public final function getContext() {
                if ( $this->context instanceof IContextSource ) {
                        return $this->context;
                }
                return $this->page->getContext();
        }

        /**
         * Get the WebRequest being used for this instance
         *
         * @return WebRequest
         */
        public final function getRequest() {
                return $this->getContext()->getRequest();
        }

        /**
         * Get the OutputPage being used for this instance
         *
         * @return OutputPage
         */
        public final function getOutput() {
                return $this->getContext()->getOutput();
        }

        /**
         * Shortcut to get the User being used for this instance
         *
         * @return User
         */
        public final function getUser() {
                return $this->getContext()->getUser();
        }

        /**
         * Shortcut to get the Skin being used for this instance
         *
         * @return Skin
         */
        public final function getSkin() {
                return $this->getContext()->getSkin();
        }

        /**
         * Shortcut to get the user Language being used for this instance
         *
         * @return Language
         */
        public final function getLanguage() {
                return $this->getContext()->getLanguage();
        }

        /**
         * Shortcut to get the user Language being used for this instance
         *
         * @deprecated 1.19 Use getLanguage instead
         * @return Language
         */
        public final function getLang() {
                wfDeprecated( __METHOD__, '1.19' );
                return $this->getLanguage();
        }

        /**
         * Shortcut to get the Title object from the page
         * @return Title
         */
        public final function getTitle() {
                return $this->page->getTitle();
        }

        /**
         * Get a Message object with context set
         * Parameters are the same as wfMessage()
         *
         * @return Message object
         */
        public final function msg() {
                $params = func_get_args();
                return call_user_func_array( array( $this->getContext(), 'msg' ), $params );
        }

        /**
         * Protected constructor: use Action::factory( $action, $page ) to actually build
         * these things in the real world
         * @param $page Page
         * @param $context IContextSource
         */
        protected function __construct( Page $page, IContextSource $context = null ) {
                $this->page = $page;
                $this->context = $context;
        }

        /**
         * Return the name of the action this object responds to
         * @return String lowercase
         */
        public abstract function getName();

        /**
         * Get the permission required to perform this action.  Often, but not always,
         * the same as the action name
         * @return String|null
         */
        public function getRestriction() {
                return null;
        }

        /**
         * Checks if the given user (identified by an object) can perform this action.  Can be
         * overridden by sub-classes with more complicated permissions schemes.  Failures here
         * must throw subclasses of ErrorPageError
         *
         * @param $user User: the user to check, or null to use the context user
         * @throws ErrorPageError
         * @return bool True on success
         */
        protected function checkCanExecute( User $user ) {
                $right = $this->getRestriction();
                if ( $right !== null ) {
                        $errors = $this->getTitle()->getUserPermissionsErrors( $right, $user );
                        if ( count( $errors ) ) {
                                throw new PermissionsError( $right, $errors );
                        }
                }

                if ( $this->requiresUnblock() && $user->isBlocked() ) {
                        $block = $user->getBlock();
                        throw new UserBlockedError( $block );
                }

                // This should be checked at the end so that the user won't think the
                // error is only temporary when he also don't have the rights to execute
                // this action
                if ( $this->requiresWrite() && wfReadOnly() ) {
                        throw new ReadOnlyError();
                }
                return true;
        }

        /**
         * Whether this action requires the wiki not to be locked
         * @return Bool
         */
        public function requiresWrite() {
                return true;
        }

        /**
         * Whether this action can still be executed by a blocked user
         * @return Bool
         */
        public function requiresUnblock() {
                return true;
        }

        /**
         * Set output headers for noindexing etc.  This function will not be called through
         * the execute() entry point, so only put UI-related stuff in here.
         */
        protected function setHeaders() {
                $out = $this->getOutput();
                $out->setRobotPolicy( "noindex,nofollow" );
                $out->setPageTitle( $this->getPageTitle() );
                $this->getOutput()->setSubtitle( $this->getDescription() );
                $out->setArticleRelated( true );
        }

        /**
         * Returns the name that goes in the \<h1\> page title
         *
         * @return String
         */
        protected function getPageTitle() {
                return $this->getTitle()->getPrefixedText();
        }

        /**
         * Returns the description that goes below the \<h1\> tag
         *
         * @return String
         */
        protected function getDescription() {
                return wfMsgHtml( strtolower( $this->getName() ) );
        }

        /**
         * The main action entry point.  Do all output for display and send it to the context
         * output.  Do not use globals $wgOut, $wgRequest, etc, in implementations; use
         * $this->getOutput(), etc.
         * @throws ErrorPageError
         */
        public abstract function show();

        /**
         * Execute the action in a silent fashion: do not display anything or release any errors.
         * @return Bool whether execution was successful
         */
        public abstract function execute();
}

/**
 * An action which shows a form and does something based on the input from the form
 */
abstract class FormAction extends Action {

        /**
         * Get an HTMLForm descriptor array
         * @return Array
         */
        protected abstract function getFormFields();

        /**
         * Add pre- or post-text to the form
         * @return String HTML which will be sent to $form->addPreText()
         */
        protected function preText() { return ''; }

        /**
         * @return string
         */
        protected function postText() { return ''; }

        /**
         * Play with the HTMLForm if you need to more substantially
         * @param $form HTMLForm
         */
        protected function alterForm( HTMLForm $form ) {}

        /**
         * Get the HTMLForm to control behaviour
         * @return HTMLForm|null
         */
        protected function getForm() {
                $this->fields = $this->getFormFields();

                // Give hooks a chance to alter the form, adding extra fields or text etc
                wfRunHooks( 'ActionModifyFormFields', array( $this->getName(), &$this->fields, $this->page ) );

                $form = new HTMLForm( $this->fields, $this->getContext() );
                $form->setSubmitCallback( array( $this, 'onSubmit' ) );

                // Retain query parameters (uselang etc)
                $form->addHiddenField( 'action', $this->getName() ); // Might not be the same as the query string
                $params = array_diff_key(
                        $this->getRequest()->getQueryValues(),
                        array( 'action' => null, 'title' => null )
                );
                $form->addHiddenField( 'redirectparams', wfArrayToCGI( $params ) );

                $form->addPreText( $this->preText() );
                $form->addPostText( $this->postText() );
                $this->alterForm( $form );

                // Give hooks a chance to alter the form, adding extra fields or text etc
                wfRunHooks( 'ActionBeforeFormDisplay', array( $this->getName(), &$form, $this->page ) );

                return $form;
        }

        /**
         * Process the form on POST submission.  If you return false from getFormFields(),
         * this will obviously never be reached.  If you don't want to do anything with the
         * form, just return false here
         * @param  $data Array
         * @return Bool|Array true for success, false for didn't-try, array of errors on failure
         */
        public abstract function onSubmit( $data );

        /**
         * Do something exciting on successful processing of the form.  This might be to show
         * a confirmation message (watch, rollback, etc) or to redirect somewhere else (edit,
         * protect, etc).
         */
        public abstract function onSuccess();

        /**
         * The basic pattern for actions is to display some sort of HTMLForm UI, maybe with
         * some stuff underneath (history etc); to do some processing on submission of that
         * form (delete, protect, etc) and to do something exciting on 'success', be that
         * display something new or redirect to somewhere.  Some actions have more exotic
         * behaviour, but that's what subclassing is for :D
         */
        public function show() {
                $this->setHeaders();

                // This will throw exceptions if there's a problem
                $this->checkCanExecute( $this->getUser() );

                $form = $this->getForm();
                if ( $form->show() ) {
                        $this->onSuccess();
                }
        }

        /**
         * @see Action::execute()
         * @throws ErrorPageError
         * @param $data array|null
         * @param $captureErrors bool
         * @return bool
         */
        public function execute( array $data = null, $captureErrors = true ) {
                try {
                        // Set a new context so output doesn't leak.
                        $this->context = clone $this->page->getContext();

                        // This will throw exceptions if there's a problem
                        $this->checkCanExecute( $this->getUser() );

                        $fields = array();
                        foreach ( $this->fields as $key => $params ) {
                                if ( isset( $data[$key] ) ) {
                                        $fields[$key] = $data[$key];
                                } elseif ( isset( $params['default'] ) ) {
                                        $fields[$key] = $params['default'];
                                } else {
                                        $fields[$key] = null;
                                }
                        }
                        $status = $this->onSubmit( $fields );
                        if ( $status === true ) {
                                // This might do permanent stuff
                                $this->onSuccess();
                                return true;
                        } else {
                                return false;
                        }
                }
                catch ( ErrorPageError $e ) {
                        if ( $captureErrors ) {
                                return false;
                        } else {
                                throw $e;
                        }
                }
        }
}

/**
 * An action which just does something, without showing a form first.
 */
abstract class FormlessAction extends Action {

        /**
         * Show something on GET request.
         * @return String|null will be added to the HTMLForm if present, or just added to the
         *     output if not.  Return null to not add anything
         */
        public abstract function onView();

        /**
         * We don't want an HTMLForm
         * @return bool
         */
        protected function getFormFields() {
                return false;
        }

        /**
         * @param $data Array
         * @return bool
         */
        public function onSubmit( $data ) {
                return false;
        }

        /**
         * @return bool
         */
        public function onSuccess() {
                return false;
        }

        public function show() {
                $this->setHeaders();

                // This will throw exceptions if there's a problem
                $this->checkCanExecute( $this->getUser() );

                $this->getOutput()->addHTML( $this->onView() );
        }

        /**
         * Execute the action silently, not giving any output.  Since these actions don't have
         * forms, they probably won't have any data, but some (eg rollback) may do
         * @param $data Array values that would normally be in the GET request
         * @param $captureErrors Bool whether to catch exceptions and just return false
         * @return Bool whether execution was successful
         */
        public function execute( array $data = null, $captureErrors = true ) {
                try {
                        // Set a new context so output doesn't leak.
                        $this->context = clone $this->page->getContext();
                        if ( is_array( $data ) ) {
                                $this->context->setRequest( new FauxRequest( $data, false ) );
                        }

                        // This will throw exceptions if there's a problem
                        $this->checkCanExecute( $this->getUser() );

                        $this->onView();
                        return true;
                }
                catch ( ErrorPageError $e ) {
                        if ( $captureErrors ) {
                                return false;
                        } else {
                                throw $e;
                        }
                }
        }
}