+/**
+ * A content object represents page content, e.g. the text to show on a page.
+ * Content objects have no knowledge about how they relate to wiki pages.
+ *
+ * @since 1.WD
+ */
+interface Content {
+
+ /**
+ * @since WD.1
+ *
+ * @return string A string representing the content in a way useful for
+ * building a full text search index. If no useful representation exists,
+ * this method returns an empty string.
+ *
+ * @todo: test that this actually works
+ * @todo: make sure this also works with LuceneSearch / WikiSearch
+ */
+ public function getTextForSearchIndex( );
+
+ /**
+ * @since WD.1
+ *
+ * @return string The wikitext to include when another page includes this
+ * content, or false if the content is not includable in a wikitext page.
+ *
+ * @TODO: allow native handling, bypassing wikitext representation, like
+ * for includable special pages.
+ * @TODO: allow transclusion into other content models than Wikitext!
+ * @TODO: used in WikiPage and MessageCache to get message text. Not so
+ * nice. What should we use instead?!
+ */
+ public function getWikitextForTransclusion( );
+
+ /**
+ * Returns a textual representation of the content suitable for use in edit
+ * summaries and log messages.
+ *
+ * @since WD.1
+ *
+ * @param $maxlength int Maximum length of the summary text
+ * @return The summary text
+ */
+ public function getTextForSummary( $maxlength = 250 );
+
+ /**
+ * Returns native representation of the data. Interpretation depends on
+ * the data model used, as given by getDataModel().
+ *
+ * @since WD.1
+ *
+ * @return mixed The native representation of the content. Could be a
+ * string, a nested array structure, an object, a binary blob...
+ * anything, really.
+ *
+ * @NOTE: review all calls carefully, caller must be aware of content model!
+ */
+ public function getNativeData( );
+
+ /**
+ * Returns the content's nominal size in bogo-bytes.
+ *
+ * @return int
+ */
+ public function getSize( );
+
+ /**
+ * Returns the ID of the content model used by this Content object.
+ * Corresponds to the CONTENT_MODEL_XXX constants.
+ *
+ * @since WD.1
+ *
+ * @return String The model id
+ */
+ public function getModel();
+
+ /**
+ * Convenience method that returns the ContentHandler singleton for handling
+ * the content model that this Content object uses.
+ *
+ * Shorthand for ContentHandler::getForContent( $this )
+ *
+ * @since WD.1
+ *
+ * @return ContentHandler
+ */
+ public function getContentHandler();
+
+ /**
+ * Convenience method that returns the default serialization format for the
+ * content model that this Content object uses.
+ *
+ * Shorthand for $this->getContentHandler()->getDefaultFormat()
+ *
+ * @since WD.1
+ *
+ * @return String
+ */
+ public function getDefaultFormat();
+
+ /**
+ * Convenience method that returns the list of serialization formats
+ * supported for the content model that this Content object uses.
+ *
+ * Shorthand for $this->getContentHandler()->getSupportedFormats()
+ *
+ * @since WD.1
+ *
+ * @return Array of supported serialization formats
+ */
+ public function getSupportedFormats();
+
+ /**
+ * Returns true if $format is a supported serialization format for this
+ * Content object, false if it isn't.
+ *
+ * Note that this should always return true if $format is null, because null
+ * stands for the default serialization.
+ *
+ * Shorthand for $this->getContentHandler()->isSupportedFormat( $format )
+ *
+ * @since WD.1
+ *
+ * @param $format string The format to check
+ * @return bool Whether the format is supported
+ */
+ public function isSupportedFormat( $format );
+
+ /**
+ * Convenience method for serializing this Content object.
+ *
+ * Shorthand for $this->getContentHandler()->serializeContent( $this, $format )
+ *
+ * @since WD.1
+ *
+ * @param $format null|string The desired serialization format (or null for
+ * the default format).
+ * @return string Serialized form of this Content object
+ */
+ public function serialize( $format = null );
+
+ /**
+ * Returns true if this Content object represents empty content.
+ *
+ * @since WD.1
+ *
+ * @return bool Whether this Content object is empty
+ */
+ public function isEmpty();
+
+ /**
+ * Returns whether the content is valid. This is intended for local validity
+ * checks, not considering global consistency.
+ *
+ * Content needs to be valid before it can be saved.
+ *
+ * This default implementation always returns true.
+ *
+ * @since WD.1
+ *
+ * @return boolean
+ */
+ public function isValid();
+
+ /**
+ * Returns true if this Content objects is conceptually equivalent to the
+ * given Content object.
+ *
+ * Contract:
+ *
+ * - Will return false if $that is null.
+ * - Will return true if $that === $this.
+ * - Will return false if $that->getModelName() != $this->getModel().
+ * - Will return false if $that->getNativeData() is not equal to $this->getNativeData(),
+ * where the meaning of "equal" depends on the actual data model.
+ *
+ * Implementations should be careful to make equals() transitive and reflexive:
+ *
+ * - $a->equals( $b ) <=> $b->equals( $a )
+ * - $a->equals( $b ) && $b->equals( $c ) ==> $a->equals( $c )
+ *
+ * @since WD.1
+ *
+ * @param $that Content The Content object to compare to
+ * @return bool True if this Content object is equal to $that, false otherwise.
+ */
+ public function equals( Content $that = null );
+
+ /**
+ * Return a copy of this Content object. The following must be true for the
+ * object returned:
+ *
+ * if $copy = $original->copy()
+ *
+ * - get_class($original) === get_class($copy)
+ * - $original->getModel() === $copy->getModel()
+ * - $original->equals( $copy )
+ *
+ * If and only if the Content object is immutable, the copy() method can and
+ * should return $this. That is, $copy === $original may be true, but only
+ * for immutable content objects.
+ *
+ * @since WD.1
+ *
+ * @return Content. A copy of this object
+ */
+ public function copy( );
+
+ /**
+ * Returns true if this content is countable as a "real" wiki page, provided
+ * that it's also in a countable location (e.g. a current revision in the
+ * main namespace).
+ *
+ * @since WD.1
+ *
+ * @param $hasLinks Bool: If it is known whether this content contains
+ * links, provide this information here, to avoid redundant parsing to
+ * find out.
+ * @return boolean
+ */
+ public function isCountable( $hasLinks = null ) ;
+
+
+ /**
+ * Parse the Content object and generate a ParserOutput from the result.
+ * $result->getText() can be used to obtain the generated HTML. If no HTML
+ * is needed, $generateHtml can be set to false; in that case,
+ * $result->getText() may return null.
+ *
+ * @param $title Title The page title to use as a context for rendering
+ * @param $revId null|int The revision being rendered (optional)
+ * @param $options null|ParserOptions Any parser options
+ * @param $generateHtml Boolean Whether to generate HTML (default: true). If false,
+ * the result of calling getText() on the ParserOutput object returned by
+ * this method is undefined.
+ *
+ * @since WD.1
+ *
+ * @return ParserOutput
+ */
+ public function getParserOutput( Title $title,
+ $revId = null,
+ ParserOptions $options = null, $generateHtml = true );
+ # TODO: make RenderOutput and RenderOptions base classes
+
+ /**
+ * Returns a list of DataUpdate objects for recording information about this
+ * Content in some secondary data store. If the optional second argument,
+ * $old, is given, the updates may model only the changes that need to be
+ * made to replace information about the old content with information about
+ * the new content.
+ *
+ * This default implementation calls
+ * $this->getParserOutput( $content, $title, null, null, false ),
+ * and then calls getSecondaryDataUpdates( $title, $recursive ) on the
+ * resulting ParserOutput object.
+ *
+ * Subclasses may implement this to determine the necessary updates more
+ * efficiently, or make use of information about the old content.
+ *
+ * @param $title Title The context for determining the necessary updates
+ * @param $old Content|null An optional Content object representing the
+ * previous content, i.e. the content being replaced by this Content
+ * object.
+ * @param $recursive boolean Whether to include recursive updates (default:
+ * false).
+ * @param $parserOutput ParserOutput|null Optional ParserOutput object.
+ * Provide if you have one handy, to avoid re-parsing of the content.
+ *
+ * @return Array. A list of DataUpdate objects for putting information
+ * about this content object somewhere.
+ *
+ * @since WD.1
+ */
+ public function getSecondaryDataUpdates( Title $title,
+ Content $old = null,
+ $recursive = true, ParserOutput $parserOutput = null
+ );
+
+ /**
+ * Construct the redirect destination from this content and return an
+ * array of Titles, or null if this content doesn't represent a redirect.
+ * The last element in the array is the final destination after all redirects
+ * have been resolved (up to $wgMaxRedirects times).
+ *
+ * @since WD.1
+ *
+ * @return Array of Titles, with the destination last
+ */
+ public function getRedirectChain();
+
+ /**
+ * Construct the redirect destination from this content and return a Title,
+ * or null if this content doesn't represent a redirect.
+ * This will only return the immediate redirect target, useful for
+ * the redirect table and other checks that don't need full recursion.
+ *
+ * @since WD.1
+ *
+ * @return Title: The corresponding Title
+ */
+ public function getRedirectTarget();
+
+ /**
+ * Construct the redirect destination from this content and return the
+ * Title, or null if this content doesn't represent a redirect.
+ *
+ * This will recurse down $wgMaxRedirects times or until a non-redirect
+ * target is hit in order to provide (hopefully) the Title of the final
+ * destination instead of another redirect.
+ *
+ * There is usually no need to override the default behaviour, subclasses that
+ * want to implement redirects should override getRedirectTarget().
+ *
+ * @since WD.1
+ *
+ * @return Title
+ */
+ public function getUltimateRedirectTarget();
+
+ /**
+ * Returns whether this Content represents a redirect.
+ * Shorthand for getRedirectTarget() !== null.
+ *
+ * @since WD.1
+ *
+ * @return bool
+ */
+ public function isRedirect();
+
+ /**
+ * If this Content object is a redirect, this method updates the redirect target.
+ * Otherwise, it does nothing.
+ *
+ * @since WD.1
+ *
+ * @param Title $target the new redirect target
+ *
+ * @return Content a new Content object with the updated redirect (or $this if this Content object isn't a redirect)
+ */
+ public function updateRedirect( Title $target );
+
+ /**
+ * Returns the section with the given ID.
+ *
+ * @since WD.1
+ *
+ * @param $sectionId string The section's ID, given as a numeric string.
+ * The ID "0" retrieves the section before the first heading, "1" the
+ * text between the first heading (included) and the second heading
+ * (excluded), etc.
+ * @return Content|Boolean|null The section, or false if no such section
+ * exist, or null if sections are not supported.
+ */
+ public function getSection( $sectionId );
+
+ /**
+ * Replaces a section of the content and returns a Content object with the
+ * section replaced.
+ *
+ * @since WD.1
+ *
+ * @param $section Empty/null/false or a section number (0, 1, 2, T1, T2...), or "new"
+ * @param $with Content: new content of the section
+ * @param $sectionTitle String: new section's subject, only if $section is 'new'
+ * @return string Complete article text, or null if error
+ */
+ public function replaceSection( $section, Content $with, $sectionTitle = '' );
+
+ /**
+ * Returns a Content object with pre-save transformations applied (or this
+ * object if no transformations apply).
+ *
+ * @since WD.1
+ *
+ * @param $title Title
+ * @param $user User
+ * @param $popts null|ParserOptions
+ * @return Content
+ */
+ public function preSaveTransform( Title $title, User $user, ParserOptions $popts );
+
+ /**
+ * Returns a new WikitextContent object with the given section heading
+ * prepended, if supported. The default implementation just returns this
+ * Content object unmodified, ignoring the section header.
+ *
+ * @since WD.1
+ *
+ * @param $header string
+ * @return Content
+ */
+ public function addSectionHeader( $header );
+
+ /**
+ * Returns a Content object with preload transformations applied (or this
+ * object if no transformations apply).
+ *
+ * @since WD.1
+ *
+ * @param $title Title
+ * @param $popts null|ParserOptions
+ * @return Content
+ */
+ public function preloadTransform( Title $title, ParserOptions $popts );
+
+ /**
+ * Prepare Content for saving. Called before Content is saved by WikiPage::doEditContent() and in
+ * similar places.
+ *
+ * This may be used to check the content's consistency with global state. This function should
+ * NOT write any information to the database.
+ *
+ * Note that this method will usually be called inside the same transaction bracket that will be used
+ * to save the new revision.
+ *
+ * Note that this method is called before any update to the page table is performed. This means that
+ * $page may not yet know a page ID.
+ *
+ * @param WikiPage $page The page to be saved.
+ * @param int $flags bitfield for use with EDIT_XXX constants, see WikiPage::doEditContent()
+ * @param int $baseRevId the ID of the current revision
+ * @param User $user
+ *
+ * @return Status A status object indicating whether the content was successfully prepared for saving.
+ * If the returned status indicates an error, a rollback will be performed and the
+ * transaction aborted.
+ *
+ * @see see WikiPage::doEditContent()
+ */
+ public function prepareSave( WikiPage $page, $flags, $baseRevId, User $user );
+
+ /**
+ * Returns a list of updates to perform when this content is deleted.
+ * The necessary updates may be taken from the Content object, or depend on
+ * the current state of the database.
+ *
+ * @since WD.1
+ *
+ * @param $page \WikiPage the deleted page
+ * @param $parserOutput null|\ParserOutput optional parser output object
+ * for efficient access to meta-information about the content object.
+ * Provide if you have one handy.
+ *
+ * @return array A list of DataUpdate instances that will clean up the
+ * database after deletion.
+ */
+ public function getDeletionUpdates( WikiPage $page,
+ ParserOutput $parserOutput = null );
+
+ /**
+ * Returns true if this Content object matches the given magic word.
+ *
+ * @param MagicWord $word the magic word to match
+ *
+ * @return bool whether this Content object matches the given magic word.
+ */
+ public function matchMagicWord( MagicWord $word );
+
+ # TODO: handle ImagePage and CategoryPage
+ # TODO: make sure we cover lucene search / wikisearch.
+ # TODO: make sure ReplaceTemplates still works
+ # FUTURE: nice&sane integration of GeSHi syntax highlighting
+ # [11:59] <vvv> Hooks are ugly; make CodeHighlighter interface and a
+ # config to set the class which handles syntax highlighting
+ # [12:00] <vvv> And default it to a DummyHighlighter
+
+ # TODO: make sure we cover the external editor interface (does anyone actually use that?!)
+
+ # TODO: tie into API to provide contentModel for Revisions
+ # TODO: tie into API to provide serialized version and contentFormat for Revisions
+ # TODO: tie into API edit interface
+ # FUTURE: make EditForm plugin for EditPage
+
+ # FUTURE: special type for redirects?!
+ # FUTURE: MultipartMultipart < WikipageContent (Main + Links + X)
+ # FUTURE: LinksContent < LanguageLinksContent, CategoriesContent
+}
+