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[mediawiki.git] / includes / actions / 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 represent these two groups.
 */
abstract class Action {

        /**
         * Page on which we're performing the action
         * @since 1.17
         * @var WikiPage|Article|ImagePage|CategoryPage|Page $page
         */
        protected $page;

        /**
         * IContextSource if specified; otherwise we'll use the Context from the Page
         * @since 1.17
         * @var IContextSource $context
         */
        protected $context;

        /**
         * The fields used to create the HTMLForm
         * @since 1.17
         * @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 string $action
         * @param array $overrides
         * @return bool|null|string|callable
         */
        final private 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
         * @since 1.17
         * @param string $action
         * @param Page $page
         * @param IContextSource $context
         * @return Action|bool|null False if the action is disabled, null
         *     if it is not recognised
         */
        final public static function factory( $action, Page $page, IContextSource $context = null ) {
                $classOrCallable = self::getClass( $action, $page->getActionOverrides() );

                if ( is_string( $classOrCallable ) ) {
                        $obj = new $classOrCallable( $page, $context );
                        return $obj;
                }

                if ( is_callable( $classOrCallable ) ) {
                        return call_user_func_array( $classOrCallable, array( $page, $context ) );
                }

                return $classOrCallable;
        }

        /**
         * 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 IContextSource $context
         * @return string Action name
         */
        final public 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(), $context );
                if ( $action instanceof Action ) {
                        return $action->getName();
                }

                return 'nosuchaction';
        }

        /**
         * Check if a given action is recognised, even if it's disabled
         * @since 1.17
         *
         * @param string $name Name of an action
         * @return bool
         */
        final public static function exists( $name ) {
                return self::getClass( $name, array() ) !== null;
        }

        /**
         * Get the IContextSource in use here
         * @since 1.17
         * @return IContextSource
         */
        final public function getContext() {
                if ( $this->context instanceof IContextSource ) {
                        return $this->context;
                } elseif ( $this->page instanceof Article ) {
                        // NOTE: $this->page can be a WikiPage, which does not have a context.
                        wfDebug( __METHOD__ . ": no context known, falling back to Article's context.\n" );
                        return $this->page->getContext();
                }

                wfWarn( __METHOD__ . ': no context known, falling back to RequestContext::getMain().' );
                return RequestContext::getMain();
        }

        /**
         * Get the WebRequest being used for this instance
         * @since 1.17
         *
         * @return WebRequest
         */
        final public function getRequest() {
                return $this->getContext()->getRequest();
        }

        /**
         * Get the OutputPage being used for this instance
         * @since 1.17
         *
         * @return OutputPage
         */
        final public function getOutput() {
                return $this->getContext()->getOutput();
        }

        /**
         * Shortcut to get the User being used for this instance
         * @since 1.17
         *
         * @return User
         */
        final public function getUser() {
                return $this->getContext()->getUser();
        }

        /**
         * Shortcut to get the Skin being used for this instance
         * @since 1.17
         *
         * @return Skin
         */
        final public function getSkin() {
                return $this->getContext()->getSkin();
        }

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

        /**
         * Shortcut to get the Title object from the page
         * @since 1.17
         *
         * @return Title
         */
        final public function getTitle() {
                return $this->page->getTitle();
        }

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

        /**
         * Constructor.
         *
         * Only public since 1.21
         *
         * @param Page $page
         * @param IContextSource $context
         */
        public function __construct( Page $page, IContextSource $context = null ) {
                if ( $context === null ) {
                        wfWarn( __METHOD__ . ' called without providing a Context object.' );
                        // NOTE: We could try to initialize $context using $page->getContext(),
                        //      if $page is an Article. That however seems to not work seamlessly.
                }

                $this->page = $page;
                $this->context = $context;
        }

        /**
         * Return the name of the action this object responds to
         * @since 1.17
         *
         * @return string Lowercase name
         */
        abstract public function getName();

        /**
         * Get the permission required to perform this action.  Often, but not always,
         * the same as the action name
         * @since 1.17
         *
         * @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
         * @since 1.17
         *
         * @param User $user The user to check, or null to use the context user
         * @throws UserBlockedError|ReadOnlyError|PermissionsError
         */
        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();
                }
        }

        /**
         * Whether this action requires the wiki not to be locked
         * @since 1.17
         *
         * @return bool
         */
        public function requiresWrite() {
                return true;
        }

        /**
         * Whether this action can still be executed by a blocked user
         * @since 1.17
         *
         * @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.
         * @since 1.17
         */
        protected function setHeaders() {
                $out = $this->getOutput();
                $out->setRobotPolicy( "noindex,nofollow" );
                $out->setPageTitle( $this->getPageTitle() );
                $out->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
         * @since 1.17
         *
         * @return string
         */
        protected function getDescription() {
                return $this->msg( strtolower( $this->getName() ) )->escaped();
        }

        /**
         * 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.
         * @since 1.17
         *
         * @throws ErrorPageError
         */
        abstract public function show();
}