/*!
 * VisualEditor MediaWiki Initialization ViewPageTarget class.
 *
 * @copyright 2011-2014 VisualEditor Team and others; see AUTHORS.txt
 * @license The MIT License (MIT); see LICENSE.txt
 */

/*global confirm, alert */

/**
 * Initialization MediaWiki view page target.
 *
 * @class
 * @extends ve.init.mw.Target
 *
 * @constructor
 */
ve.init.mw.ViewPageTarget = function VeInitMwViewPageTarget() {
	var prefName,
		prefValue,
		//A workaround, as default URI does not get updated after pushState (bug 72334)
		currentUri = new mw.Uri( document.location.href ),
		conf = mw.config.get( 'wgVisualEditorConfig' );

	// Parent constructor
	ve.init.mw.Target.call(
		this, $( '#content' ),
		mw.config.get( 'wgRelevantPageName' ),
		currentUri.query.oldid
	);

	// Properties
	this.toolbarSaveButton = null;
	this.saveDialog = null;
	this.onBeforeUnloadFallback = null;
	this.onBeforeUnloadHandler = null;
	this.active = false;
	this.activating = false;
	this.deactivating = false;
	this.edited = false;
	// If this is true then #transformPage / #restorePage will not call pushState
	// This is to avoid adding a new history entry for the url we just got from onpopstate
	// (which would mess up with the expected order of Back/Forwards browsing)
	this.actFromPopState = false;
	this.popState = {
		tag: 'visualeditor'
	};
	this.scrollTop = null;
	this.currentUri = currentUri;
	this.section = currentUri.query.vesection;
	this.initialEditSummary = new mw.Uri().query.summary;
	this.namespaceName = mw.config.get( 'wgCanonicalNamespace' );
	this.viewUri = new mw.Uri( mw.util.getUrl( this.pageName ) );
	this.veEditUri = this.viewUri.clone().extend( { veaction: 'edit' } );
	this.isViewPage = (
		mw.config.get( 'wgAction' ) === 'view' &&
		currentUri.query.diff === undefined
	);
	this.originalDocumentTitle = document.title;
	this.tabLayout = mw.config.get( 'wgVisualEditorConfig' ).tabLayout;

	/**
	 * @property {jQuery.Promise|null}
	 */
	this.sanityCheckPromise = null;

	// Add modules specific to desktop (modules shared with mobile go in MWTarget)
	this.modules.push(
		'ext.visualEditor.mwformatting',
		'ext.visualEditor.mwgallery',
		'ext.visualEditor.mwimage',
		'ext.visualEditor.mwmeta'
	);

	// Load preference modules
	for ( prefName in conf.preferenceModules ) {
		prefValue = mw.config.get( 'wgUserName' ) === null ?
			conf.defaultUserOptions[prefName] :
			mw.user.options.get( prefName, conf.defaultUserOptions[prefName] );
		if ( prefValue && prefValue !== '0' ) {
			this.modules.push( conf.preferenceModules[prefName] );
		}
	}

	// Events
	this.connect( this, {
		save: 'onSave',
		saveErrorEmpty: 'onSaveErrorEmpty',
		saveErrorSpamBlacklist: 'onSaveErrorSpamBlacklist',
		saveErrorAbuseFilter: 'onSaveErrorAbuseFilter',
		saveErrorBadToken: 'onSaveErrorBadToken',
		saveErrorNewUser: 'onSaveErrorNewUser',
		saveErrorCaptcha: 'onSaveErrorCaptcha',
		saveErrorUnknown: 'onSaveErrorUnknown',
		loadError: 'onLoadError',
		surfaceReady: 'onSurfaceReady',
		editConflict: 'onEditConflict',
		showChanges: 'onShowChanges',
		showChangesError: 'onShowChangesError',
		noChanges: 'onNoChanges',
		serializeError: 'onSerializeError',
		sanityCheckComplete: 'updateToolbarSaveButtonState'
	} );

	if ( currentUri.query.venotify ) {
		// The following messages can be used here:
		// postedit-confirmation-saved
		// postedit-confirmation-created
		// postedit-confirmation-restored
		mw.hook( 'postEdit' ).fire( {
			message: ve.msg( 'postedit-confirmation-' + currentUri.query.venotify, mw.user )
		} );

		delete currentUri.query.venotify;
	}

	if ( window.history.replaceState ) {
		// This is to stop the back button breaking when it's supposed to take us back out
		// of VE. It used to only be called when venotify is used. FIXME: there should be
		// a much better solution than this.
		window.history.replaceState( this.popState, document.title, currentUri );
	}

	this.setupSkinTabs();

	window.addEventListener( 'popstate', this.onWindowPopState.bind( this ) ) ;
};

/* Inheritance */

OO.inheritClass( ve.init.mw.ViewPageTarget, ve.init.mw.Target );

/* Static Properties */

/**
 * Compatibility map used with jQuery.client to black-list incompatible browsers.
 *
 * @static
 * @property
 */
ve.init.mw.ViewPageTarget.compatibility = {
	// The key is the browser name returned by jQuery.client
	// The value is either null (match all versions) or a list of tuples
	// containing an inequality (<,>,<=,>=) and a version number
	whitelist: {
		firefox: [['>=', 15]],
		iceweasel: [['>=', 10]],
		safari: [['>=', 6]],
		chrome: [['>=', 19]],
		opera: [['>=', 15]]
	}
};

/* Events */

/**
 * @event saveWorkflowBegin
 * Fired when user enters the save workflow
 */

/**
 * @event saveWorkflowEnd
 * Fired when user exits the save workflow
 */

/**
 * @event saveReview
 * Fired when user initiates review changes in save workflow
 */

/**
 * @event saveInitiated
 * Fired when user initiates saving of the document
 */

/* Methods */

/**
 * Verify that a PopStateEvent correlates to a state we created.
 *
 * @param {Mixed} popState From PopStateEvent#state
 * @return {boolean}
 */
ve.init.mw.ViewPageTarget.prototype.verifyPopState = function ( popState ) {
	return popState && popState.tag === 'visualeditor';
};

/**
 * @inheritdoc
 */
ve.init.mw.ViewPageTarget.prototype.setupToolbar = function () {
	var $firstHeading;
	// Parent method
	ve.init.mw.Target.prototype.setupToolbar.call( this );

	// Keep it hidden so that we can slide it down smoothly (avoids sudden
	// offset flash when original content is hidden, and replaced in-place with a
	// similar-looking surface).
	// FIXME: This is not ideal, the parent class creates it and appends
	// to target (visibly), only for us to hide it again 0ms later.
	// Though we can't hide it by default because it needs visible dimensions
	// to compute stuff during setup.
	this.toolbar.$bar.hide();

	this.toolbar.enableFloatable();
	this.toolbar.$element
		.addClass( 've-init-mw-viewPageTarget-toolbar' );

	// Move the toolbar to before #firstHeading if it exists
	$firstHeading = $( '#firstHeading' );
	if ( $firstHeading.length ) {
		this.toolbar.$element.insertBefore( $firstHeading );
	}

	this.toolbar.$bar.slideDown( 'fast', function () {
		// Check the surface wasn't torn down while the toolbar was animating
		if ( this.surface ) {
			this.toolbar.initialize();
			this.surface.getView().emit( 'position' );
			this.surface.getContext().updateDimensions();
		}
	}.bind( this ) );
};

/**
 * Set up notices for things like unknown browsers.
 * Needs to be done on each activation because localNoticeMessages is cleared in clearState
 *
 * @method
 */
ve.init.mw.ViewPageTarget.prototype.setupLocalNoticeMessages = function () {
	if ( mw.config.get( 'wgTranslatePageTranslation' ) === 'source' ) {
		// Warn users if they're on a source of the Page Translation feature
		this.localNoticeMessages.push( 'visualeditor-pagetranslationwarning' );
	}

	if ( !(
		'vewhitelist' in this.currentUri.query ||
		$.client.test( ve.init.mw.ViewPageTarget.compatibility.whitelist, null, true )
	) ) {
		// Show warning in unknown browsers that pass the support test
		// Continue at own risk.
		this.localNoticeMessages.push( 'visualeditor-browserwarning' );
	}
};

/**
 * Switch to edit mode.
 *
 * @method
 * @return {jQuery.Promise}
 */
ve.init.mw.ViewPageTarget.prototype.activate = function () {
	if ( !this.active && !this.activating ) {
		this.activating = true;
		this.activatingDeferred = $.Deferred();

		this.originalEditondbclick = mw.user.options.get( 'editondblclick' );
		mw.user.options.set( 'editondblclick', 0 );

		// User interface changes
		this.transformPage();
		this.hideReadOnlyContent();
		this.mutePageContent();
		this.mutePageTitle();
		this.setupLocalNoticeMessages();

		this.saveScrollPosition();

		this.load( [ 'site', 'user' ] );
	}
	return this.activatingDeferred.promise();
};

/**
 * Determines whether we want to switch to view mode or not (displaying a dialog if necessary)
 * Then, if we do, actually switches to view mode.
 *
 * @method
 */
ve.init.mw.ViewPageTarget.prototype.deactivate = function ( override ) {
	var target = this;
	if ( override || ( this.active && !this.deactivating ) ) {
		if ( override || !this.edited ) {
			this.cancel();
		} else {
			this.surface.dialogs.openWindow( 'cancelconfirm' ).then( function ( opened ) {
				opened.then( function ( closing ) {
					closing.then( function ( data ) {
						if ( data.action === 'discard' ) {
							target.cancel();
						}
					} );
				} );
			} );
		}
	}
};

/**
 * Switch to view mode
 *
 * @method
 */
ve.init.mw.ViewPageTarget.prototype.cancel = function () {
	var promises = [];

	this.deactivating = true;
	// User interface changes
	if ( this.elementsThatHadOurAccessKey ) {
		this.elementsThatHadOurAccessKey.attr( 'accesskey', ve.msg( 'accesskey-save' ) );
	}
	this.restorePage();
	this.showReadOnlyContent();

	mw.user.options.set( 'editondblclick', this.originalEditondbclick );
	this.originalEditondbclick = undefined;

	if ( this.toolbarSaveButton ) {
		// If deactivate is called before a successful load, then the save button has not yet been
		// fully set up so disconnecting it would throw an error when trying call methods on the
		// button property (bug 46456)
		this.toolbarSaveButton.disconnect( this );
		this.toolbarSaveButton.$element.detach();
		this.toolbar.$actions.empty();
	}

	// Check we got as far as setting up the surface
	if ( this.active ) {
		// If we got as far as setting up the surface, tear that down
		promises.push( this.tearDownSurface() );
	}

	$.when.apply( $, promises ).then( function () {
		// Show/restore components that are otherwise handled by tearDownSurface
		this.showPageContent();
		this.restorePageTitle();

		// If there is a load in progress, abort it
		if ( this.loading ) {
			this.loading.abort();
		}

		this.clearState();
		this.docToSave = null;
		this.initialEditSummary = new mw.Uri().query.summary;

		this.deactivating = false;
		this.activatingDeferred.reject();

		mw.hook( 've.deactivationComplete' ).fire( this.edited );
	}.bind( this ) );
};

/**
 * Handle failed DOM load event.
 *
 * @method
 * @param {jqXHR|null} jqXHR jQuery XHR object
 * @param {string} status Text status message
 * @param {Mixed|null} error Thrown exception or HTTP error string
 */
ve.init.mw.ViewPageTarget.prototype.onLoadError = function ( jqXHR, status ) {
	// Don't show an error if the load was manually aborted
	// The response.status check here is to catch aborts triggered by navigation away from the page
	if (
		status !== 'abort' &&
		( !jqXHR || ( jqXHR.status !== 0 && jqXHR.status !== 504 ) ) &&
		confirm( ve.msg( 'visualeditor-loadwarning', status ) )
	) {
		this.load();
	} else if (
		jqXHR && jqXHR.status === 504 &&
		confirm( ve.msg( 'visualeditor-timeout' ) )
	) {
		if ( 'veaction' in this.currentUri.query ) {
			delete this.currentUri.query.veaction;
		}
		this.currentUri.query.action = 'edit';
		window.location.href = this.currentUri.toString();
	} else {
		this.activating = false;
		// User interface changes
		this.deactivate( true );
	}
};

/**
 * Once surface is ready ready, init UI
 *
 * @method
 */
ve.init.mw.ViewPageTarget.prototype.onSurfaceReady = function () {
	this.activating = false;
	this.surface.getModel().connect( this, {
		documentUpdate: function () {
			mw.loader.using( 'mediawiki.notification' ).then( function () {
				this.wikitextWarning = ve.init.mw.ViewPageTarget.static.checkForWikitextWarning(
					this.surface,
					this.wikitextWarning
				);
			}.bind( this ) );
		},
		history: 'updateToolbarSaveButtonState'
	} );
	this.surface.setPasteRules( this.constructor.static.pasteRules );

	// TODO: mwTocWidget should probably live in a ve.ui.MWSurface subclass
	if ( mw.config.get( 'wgVisualEditorConfig' ).enableTocWidget ) {
		this.surface.mwTocWidget = new ve.ui.MWTocWidget( this.surface );
	}

	// Update UI
	this.transformPageTitle();
	this.changeDocumentTitle();
	this.hidePageContent();

	this.surface.getView().focus();

	this.setupToolbarSaveButton();
	this.attachToolbarSaveButton();
	this.restoreScrollPosition();
	this.restoreEditSection();
	this.setupBeforeUnloadHandler();
	this.maybeShowDialogs();
	this.activatingDeferred.resolve();
	mw.hook( 've.activationComplete' ).fire();
};

/**
 * Handle successful DOM save event.
 *
 * @method
 * @param {string} html Rendered page HTML from server
 * @param {string} categoriesHtml Rendered categories HTML from server
 * @param {number} newid New revision id, undefined if unchanged
 * @param {boolean} isRedirect Whether this page is a redirect or not
 * @param {string} displayTitle What HTML to show as the page title
 * @param {Object} lastModified Object containing user-formatted date
    and time strings, or undefined if we made no change.
 */
ve.init.mw.ViewPageTarget.prototype.onSave = function (
	html, categoriesHtml, newid, isRedirect, displayTitle, lastModified, contentSub
) {
	var newUrlParams, watchChecked;
	this.saveDeferred.resolve();
	if ( !this.pageExists || this.restoring ) {
		// This is a page creation or restoration, refresh the page
		this.tearDownBeforeUnloadHandler();
		newUrlParams = newid === undefined ? {} : { venotify: this.restoring ? 'restored' : 'created' };

		if ( isRedirect ) {
			newUrlParams.redirect = 'no';
		}
		window.location.href = this.viewUri.extend( newUrlParams );
	} else {
		// Update watch link to match 'watch checkbox' in save dialog.
		// User logged in if module loaded.
		// Just checking for mw.page.watch is not enough because in Firefox
		// there is Object.prototype.watch...
		if ( mw.page.watch && mw.page.watch.updateWatchLink ) {
			watchChecked = this.saveDialog.$saveOptions
				.find( '.ve-ui-mwSaveDialog-checkboxes' )
					.find( '#wpWatchthis' )
					.prop( 'checked' );
			mw.page.watch.updateWatchLink(
				$( '#ca-watch a, #ca-unwatch a' ),
				watchChecked ? 'unwatch' : 'watch'
			);
		}

		// If we were explicitly editing an older version, make sure we won't
		// load the same old version again, now that we've saved the next edit
		// will be against the latest version.
		// TODO: What about oldid in the url?
		this.restoring = false;

		if ( newid !== undefined ) {
			mw.config.set( {
				wgCurRevisionId: newid,
				wgRevisionId: newid
			} );
			this.revid = newid;
		}
		this.saveDialog.reset();
		this.replacePageContent(
			html,
			categoriesHtml,
			displayTitle,
			lastModified,
			contentSub
		);
		this.setupSectionEditLinks();
		this.tearDownBeforeUnloadHandler();
		this.deactivate( true );
		if ( newid !== undefined ) {
			mw.hook( 'postEdit' ).fire( {
				message: ve.msg( 'postedit-confirmation-saved', mw.user )
			} );
		}
	}
};

/**
 * Update save dialog message on general error
 *
 * @method
 */
ve.init.mw.ViewPageTarget.prototype.onSaveErrorEmpty = function () {
	this.showSaveError( ve.msg( 'visualeditor-saveerror', 'Empty server response' ), false /* prevents reapply */ );
	this.events.trackSaveError( 'empty' );
};

/**
 * Update save dialog message on spam blacklist error
 *
 * @method
 * @param {Object} editApi
 */
ve.init.mw.ViewPageTarget.prototype.onSaveErrorSpamBlacklist = function ( editApi ) {
	this.showSaveError(
		// TODO: Use mediawiki.language equivalant of Language.php::listToText once it exists
		ve.msg( 'spamprotectiontext' ) + ' ' + ve.msg( 'spamprotectionmatch', editApi.spamblacklist.split( '|' ).join( ', ' ) ),
		false // prevents reapply
	);
	this.events.trackSaveError( 'spamblacklist' );
};

/**
 * Update save dialog message on spam blacklist error
 *
 * @method
 * @param {Object} editApi
 */
ve.init.mw.ViewPageTarget.prototype.onSaveErrorAbuseFilter = function ( editApi ) {
	this.showSaveError( $( $.parseHTML( editApi.warning ) ) );
	// Don't disable the save button. If the action is not disallowed the user may save the
	// edit by pressing Save again. The AbuseFilter API currently has no way to distinguish
	// between filter triggers that are and aren't disallowing the action.
	this.events.trackSaveError( 'abusefilter' );
};

/**
 * Track when there is a bad edit token on save
 *
 * @method
 */
ve.init.mw.ViewPageTarget.prototype.onSaveErrorBadToken = function () {
	this.events.trackSaveError( 'badtoken' );
};

/**
 * Update save dialog when token fetch indicates another user is logged in
 *
 * @method
 * @param {boolean|undefined} isAnon Is newly logged in user anonymous. If
 *  undefined, user is logged in
 */
ve.init.mw.ViewPageTarget.prototype.onSaveErrorNewUser = function ( isAnon ) {
	var badToken, userMsg;
	badToken = document.createTextNode( mw.msg( 'visualeditor-savedialog-error-badtoken' ) + ' ' );
	// mediawiki.jqueryMsg has a bug with [[User:$1|$1]] (bug 51388)
	if ( isAnon ) {
		userMsg = 'visualeditor-savedialog-identify-anon';
	} else {
		userMsg = 'visualeditor-savedialog-identify-user---' + mw.config.get( 'wgUserName' );
	}
	this.showSaveError(
		$( badToken ).add( $.parseHTML( mw.message( userMsg ).parse() ) )
	);
};

/**
 * Update save dialog on captcha error
 *
 * @method
 * @param {Object} editApi
 */
ve.init.mw.ViewPageTarget.prototype.onSaveErrorCaptcha = function ( editApi ) {
	var $captchaDiv = $( '<div>' ), $captchaParagraph = $( '<p>' );

	this.captcha = {
		input: new OO.ui.TextInputWidget(),
		id: editApi.captcha.id
	};
	$captchaDiv.append( $captchaParagraph );
	$captchaParagraph.append(
		$( '<strong>' ).text( mw.msg( 'captcha-label' ) ),
		document.createTextNode( mw.msg( 'colon-separator' ) )
	);
	if ( editApi.captcha.url ) { // FancyCaptcha
		$captchaParagraph.append(
			$( $.parseHTML( mw.message( 'fancycaptcha-edit' ).parse() ) )
				.filter( 'a' ).attr( 'target', '_blank' ).end()
		);
		$captchaDiv.append(
			$( '<img>' ).attr( 'src', editApi.captcha.url )
		);
	} else if ( editApi.captcha.type === 'simple' || editApi.captcha.type === 'math' ) {
		// SimpleCaptcha and MathCaptcha
		$captchaParagraph.append(
			mw.message( 'captcha-edit' ).parse(),
			'<br>',
			document.createTextNode( editApi.captcha.question )
		);
	} else if ( editApi.captcha.type === 'question' ) {
		// QuestyCaptcha
		$captchaParagraph.append(
			mw.message( 'questycaptcha-edit' ).parse(),
			'<br>',
			editApi.captcha.question
		);
	}

	$captchaDiv.append( this.captcha.input.$element );

	// ProcessDialog's error system isn't great for this yet.
	this.saveDialog.clearMessage( 'api-save-error' );
	this.saveDialog.showMessage( 'api-save-error', $captchaDiv );
	this.saveDialog.popPending();

	this.events.trackSaveError( 'captcha' );
};

/**
 * Update save dialog message on unknown error
 *
 * @method
 * @param {Object} editApi
 * @param {Object|null} data API response data
 */
ve.init.mw.ViewPageTarget.prototype.onSaveErrorUnknown = function ( editApi, data ) {
	this.showSaveError(
		$( document.createTextNode(
			( editApi && editApi.info ) ||
			( data.error && data.error.info ) ||
			( editApi && editApi.code ) ||
			( data.error && data.error.code ) ||
			'Unknown error'
		) ),
		false // prevents reapply
	);
	this.events.trackSaveError( 'unknown' );
};

/**
 * Update save dialog api-save-error message
 *
 * @method
 * @param {string|jQuery|Node[]} msg Message content (string of HTML, jQuery object or array of
 *  Node objects)
 * @param {boolean} [allowReapply=true] Whether or not to allow the user to reapply.
 *  Reset when swapping panels. Assumed to be true unless explicitly set to false.
 */
ve.init.mw.ViewPageTarget.prototype.showSaveError = function ( msg, allowReapply ) {
	this.saveDeferred.reject( [ new OO.ui.Error( msg, { recoverable: allowReapply } ) ] );
};

/**
 * Handle Show changes event.
 *
 * @method
 * @param {string} diffHtml
 */
ve.init.mw.ViewPageTarget.prototype.onShowChanges = function ( diffHtml ) {
	// Invalidate the viewer diff on next change
	this.surface.getModel().getDocument().once( 'transact',
		this.saveDialog.clearDiff.bind( this.saveDialog )
	);
	this.saveDialog.setDiffAndReview( diffHtml );
};

/**
 * Handle failed show changes event.
 *
 * @method
 * @param {Object} jqXHR
 * @param {string} status Text status message
 */
ve.init.mw.ViewPageTarget.prototype.onShowChangesError = function ( jqXHR, status ) {
	alert( ve.msg( 'visualeditor-differror', status ) );
	this.saveDialog.popPending();
};

/**
 * Called if a call to target.serialize() failed.
 *
 * @method
 * @param {jqXHR|null} jqXHR
 * @param {string} status Text status message
 */
ve.init.mw.ViewPageTarget.prototype.onSerializeError = function ( jqXHR, status ) {
	alert( ve.msg( 'visualeditor-serializeerror', status ) );

	// It's possible to get here while the save dialog has never been opened (if the user uses
	// the switch to source mode option)
	if ( this.saveDialog ) {
		this.saveDialog.popPending();
	}
};

/**
 * Handle edit conflict event.
 *
 * @method
 */
ve.init.mw.ViewPageTarget.prototype.onEditConflict = function () {
	this.saveDialog.popPending();
	this.saveDialog.swapPanel( 'conflict' );
};

/**
 * Handle failed show changes event.
 *
 * @method
 */
ve.init.mw.ViewPageTarget.prototype.onNoChanges = function () {
	this.saveDialog.popPending();
	this.saveDialog.swapPanel( 'nochanges' );
	this.saveDialog.getActions().setAbilities( { approve: true } );
};

/**
 * Handle clicks on the view tab.
 *
 * @method
 * @param {jQuery.Event} e Mouse click event
 */
ve.init.mw.ViewPageTarget.prototype.onViewTabClick = function ( e ) {
	if ( ( e.which && e.which !== 1 ) || e.shiftKey || e.altKey || e.ctrlKey || e.metaKey ) {
		return;
	}
	if ( this.active ) {
		this.deactivate();
		// Prevent the edit tab's normal behavior
		e.preventDefault();
	} else if ( this.activating ) {
		this.deactivate( true );
		this.activating = false;
		e.preventDefault();
	}
};

/**
 * Handle clicks on the save button in the toolbar.
 *
 * @method
 * @param {jQuery.Event} e Mouse click event
 */
ve.init.mw.ViewPageTarget.prototype.onToolbarSaveButtonClick = function () {
	if ( this.edited || this.restoring ) {
		this.showSaveDialog();
	}
};

/**
 * Handle clicks on the MwMeta button in the toolbar.
 *
 * @method
 * @param {jQuery.Event} e Mouse click event
 */
ve.init.mw.ViewPageTarget.prototype.onToolbarMetaButtonClick = function () {
	this.surface.getDialogs().openWindow( 'meta' );
};

/**
 * Check if the user is entering wikitext, and show a notification if they are.
 *
 * This check is fairly simplistic: it checks whether the content branch node the selection is in
 * looks like wikitext, so it can trigger if the user types in a paragraph that has pre-existing
 * wikitext-like content.
 *
 * This method is bound to the 'documentUpdate' event on the surface model, and unbinds itself when
 * the wikitext notification is displayed.
 *
 * @param {ve.ui.Surface} surface
 * @param {Object} [wikitextWarning] MediaWiki notification object
 */
ve.init.mw.ViewPageTarget.static.checkForWikitextWarning = function ( surface, wikitextWarning ) {
	var text, node, doc = surface.getView().getDocument(),
		selection = surface.getModel().getSelection(),
		textMatches;

	if ( !( selection instanceof ve.dm.LinearSelection ) ) {
		return;
	}

	node = doc.getBranchNodeFromOffset( selection.getRange().start );
	if ( !( node instanceof ve.ce.ContentBranchNode ) ) {
		return;
	}
	text = ve.ce.getDomText( node.$element[0] );
	textMatches = text.match( /\[\[|\{\{|''|<nowiki|<ref|~~~|^==|^\*|^\#/ );

	if ( textMatches && !wikitextWarning ) {
		wikitextWarning = mw.notification.notify(
			$( $.parseHTML( ve.init.platform.getParsedMessage( 'visualeditor-wikitext-warning' ) ) )
				.filter( 'a' ).attr( 'target', '_blank' ).end(),
			{
				title: ve.msg( 'visualeditor-wikitext-warning-title' ),
				tag: 'visualeditor-wikitext-warning',
				autoHide: false
			}
		);
	} else if ( !textMatches && wikitextWarning ) {
		wikitextWarning.close();
		wikitextWarning = undefined;
	}
	return wikitextWarning;
};

/**
 * Re-evaluate whether the toolbar save button should be disabled or not.
 */
ve.init.mw.ViewPageTarget.prototype.updateToolbarSaveButtonState = function () {
	var isDisabled;

	this.edited = this.surface.getModel().hasBeenModified();
	// Disable the save button if we have no history or if the sanity check is not finished
	isDisabled = ( !this.edited && !this.restoring ) || !this.sanityCheckFinished;
	this.toolbarSaveButton.setDisabled( isDisabled );
	this.toolbarSaveButton.$element.toggleClass( 've-init-mw-viewPageTarget-waiting', !this.sanityCheckFinished );
	mw.hook( 've.toolbarSaveButton.stateChanged' ).fire( isDisabled );
};

/**
 * Handle clicks on the review button in the save dialog.
 *
 * @method
 * @fires saveReview
 */
ve.init.mw.ViewPageTarget.prototype.onSaveDialogReview = function () {
	this.sanityCheckVerified = true;
	this.saveDialog.setSanityCheck( this.sanityCheckVerified );

	if ( !this.saveDialog.$reviewViewer.find( 'table, pre' ).length ) {
		this.emit( 'saveReview' );
		this.saveDialog.getActions().setAbilities( { approve: false } );
		this.saveDialog.pushPending();
		if ( this.pageExists ) {
			// Has no callback, handled via target.onShowChanges
			this.showChanges( this.docToSave );
		} else {
			this.serialize( this.docToSave, this.onSaveDialogReviewComplete.bind( this ) );
		}
	} else {
		this.saveDialog.swapPanel( 'review' );
	}
};

/**
 * Handle completed serialize request for diff views for new page creations.
 *
 * @method
 * @param {string} wikitext
 */
ve.init.mw.ViewPageTarget.prototype.onSaveDialogReviewComplete = function ( wikitext ) {
	// Invalidate the viewer wikitext on next change
	this.surface.getModel().getDocument().once( 'transact',
		this.saveDialog.clearDiff.bind( this.saveDialog )
	);
	this.saveDialog.setDiffAndReview( $( '<pre>' ).text( wikitext ) );
};

/**
 * Try to save the current document.
 * @fires saveInitiated
 * @param {jQuery.Deferred} saveDeferred Deferred object to resolve/reject when the save
 *  succeeds/fails.
 */
ve.init.mw.ViewPageTarget.prototype.saveDocument = function ( saveDeferred ) {
	if ( this.deactivating ) {
		return false;
	}

	var saveOptions = this.getSaveOptions();
	this.emit( 'saveInitiated' );

	// Reset any old captcha data
	if ( this.captcha ) {
		this.saveDialog.clearMessage( 'captcha' );
		delete this.captcha;
	}

	if (
		+mw.user.options.get( 'forceeditsummary' ) &&
		saveOptions.summary === '' &&
		!this.saveDialog.messages.missingsummary
	) {
		this.saveDialog.showMessage(
			'missingsummary',
			// Wrap manually since this core message already includes a bold "Warning:" label
			$( '<p>' ).append( ve.init.platform.getParsedMessage( 'missingsummary' ) ),
			{ wrap: false }
		);
		this.saveDialog.popPending();
	} else {
		this.save( this.docToSave, saveOptions );
		this.saveDeferred = saveDeferred;
	}
};

/**
 * Open the dialog to switch to edit source mode with the current wikitext, or just do it straight
 * away if the document is unmodified. If we open the dialog, the document opacity will be set to
 * half, which can be reset with the resetDocumentOpacity function.
 *
 * @method
 */
ve.init.mw.ViewPageTarget.prototype.editSource = function () {
	if ( !this.surface.getModel().hasBeenModified() ) {
		this.switchToWikitextEditor( true );
		return;
	}

	this.surface.getView().getDocument().getDocumentNode().$element.css( 'opacity', 0.5 );

	this.surface.getDialogs().openWindow( 'wikitextswitchconfirm', { target: this } );
};

/**
 * Handle clicks on the resolve conflict button in the conflict dialog.
 *
 * @method
 */
ve.init.mw.ViewPageTarget.prototype.onSaveDialogResolveConflict = function () {
	// Get Wikitext from the DOM, and set up a submit call when it's done
	this.serialize(
		this.docToSave,
		this.submitWithSaveFields.bind( this, { wpSave: 1 } )
	);
};

/**
 * Get save form fields from the save dialog form.
 * @returns {Object} Form data for submission to the MediaWiki action=edit UI
 */
ve.init.mw.ViewPageTarget.prototype.getSaveFields = function () {
	var fields = {};
	this.$checkboxes
		.each( function () {
			var $this = $( this );
			// We can't just use $this.val() because .val() always returns the value attribute of
			// a checkbox even when it's unchecked
			if ( $this.prop ( 'name' ) && ( $this.prop( 'type' ) !== 'checkbox' || $this.prop( 'checked' ) ) ) {
				fields[$this.prop( 'name' )] = $this.val();
			}
		} );
	ve.extendObject( fields, {
		wpSummary: this.saveDialog ? this.saveDialog.editSummaryInput.getValue() : this.initialEditSummary,
		wpCaptchaId: this.captcha && this.captcha.id,
		wpCaptchaWord: this.captcha && this.captcha.input.getValue()
	} );
	return fields;
};

/**
 * Invoke #submit with the data from #getSaveFields
 * @param {Object} fields Fields to add in addition to those from #getSaveFields
 * @param {string} wikitext Wikitext to submit
 * @returns {boolean} Whether submission was started
 */
ve.init.mw.ViewPageTarget.prototype.submitWithSaveFields = function ( fields, wikitext ) {
	return this.submit( wikitext, $.extend( this.getSaveFields(), fields ) );
};

/**
 * Get edit API options from the save dialog form.
 * @returns {Object} Save options for submission to the MediaWiki API
 */
ve.init.mw.ViewPageTarget.prototype.getSaveOptions = function () {
	var key, options = this.getSaveFields(),
		fieldMap = {
			wpSummary: 'summary',
			wpMinoredit: 'minor',
			wpWatchthis: 'watch',
			wpCaptchaId: 'captchaid',
			wpCaptchaWord: 'captchaword'
		};

	for ( key in fieldMap ) {
		if ( options[key] !== undefined ) {
			options[fieldMap[key]] = options[key];
			delete options[key];
		}
	}

	if ( this.sanityCheckPromise.state() === 'rejected' ) {
		options.needcheck = 1;
	}

	return options;
};

/**
 * Fire off the sanity check. Must be called before the surface is activated.
 *
 * To access the result, check whether #sanityCheckPromise has been resolved or rejected
 * (it's asynchronous, so it may still be pending when you check).
 */
ve.init.mw.ViewPageTarget.prototype.startSanityCheck = function () {
	// We have to get a copy of the data now, before we unlock the surface and let the user edit,
	// but we can defer the actual conversion and comparison
	var viewPage = this,
		doc = viewPage.surface.getModel().getDocument(),
		data = new ve.dm.FlatLinearData( doc.getStore().clone(), ve.copy( doc.getFullData() ) ),
		oldDom = viewPage.doc,
		d = $.Deferred();

	// Reset
	viewPage.sanityCheckFinished = false;
	viewPage.sanityCheckVerified = false;

	setTimeout( function () {
		// We can't compare oldDom.body and newDom.body directly, because the attributes on the
		// <body> were ignored in the conversion. So compare each child separately.
		var i,
			len = oldDom.body.childNodes.length,
			newDoc = new ve.dm.Document( data, oldDom, undefined, doc.getInternalList(), doc.getInnerWhitespace(), doc.getLang(), doc.getDir() ),
			newDom = ve.dm.converter.getDomFromModel( newDoc );

		// Explicitly unlink our full copy of the original version of the document data
		data = undefined;

		if ( len !== newDom.body.childNodes.length ) {
			// Different number of children, so they're definitely different
			d.reject();
			return;
		}
		for ( i = 0; i < len; i++ ) {
			if ( !oldDom.body.childNodes[i].isEqualNode( newDom.body.childNodes[i] ) ) {
				d.reject();
				return;
			}
		}
		d.resolve();
	} );

	viewPage.sanityCheckPromise = d.promise()
		.done( function () {
			// If we detect no roundtrip errors,
			// don't emphasize "review changes" to the user.
			viewPage.sanityCheckVerified = true;
		})
		.always( function () {
			viewPage.sanityCheckFinished = true;
			viewPage.updateToolbarSaveButtonState();
		} );
};

/**
 * Switch to viewing mode.
 *
 * @method
 * @return {jQuery.Promise} Promise resolved when surface is torn down
 */
ve.init.mw.ViewPageTarget.prototype.tearDownSurface = function () {
	var promises = [];

	// Update UI
	this.tearDownToolbar();
	this.tearDownDebugBar();
	this.restoreDocumentTitle();
	if ( this.surface.mwTocWidget ) {
		this.surface.mwTocWidget.teardown();
	}

	if ( this.saveDialog ) {
		// If the save dialog is still open (from saving) close it
		promises.push( this.saveDialog.close() );
		// Release the reference
		this.saveDialog = null;
	}

	return $.when.apply( $, promises ).then( function () {
		// Destroy surface
		if ( this.surface ) {
			this.surface.destroy();
			this.surface = null;
		}
		this.active = false;
	}.bind( this ) );
};

/**
 * Modify tabs in the skin to support in-place editing.
 * Edit tab is bound outside the module in mw.ViewPageTarget.init.
 *
 * @method
 */
ve.init.mw.ViewPageTarget.prototype.setupSkinTabs = function () {
	var viewPageTarget = this;
	if ( this.isViewPage ) {
		// Allow instant switching back to view mode, without refresh
		$( '#ca-view a, #ca-nstab-visualeditor a' )
			.click( this.onViewTabClick.bind( this ) );

		$( '#ca-viewsource, #ca-edit' ).click( function ( e ) {
			if ( viewPageTarget.surface && !viewPageTarget.deactivating ) {
				viewPageTarget.editSource();

				if ( viewPageTarget.surface.getModel().hasBeenModified() ) {
					e.preventDefault();
				}
			}
		} );
	}

	mw.hook( 've.skinTabSetupComplete' ).fire();
};

/**
 * Modify page content to make section edit links activate the editor.
 * Dummy replaced by init.js so that we can call it again from #onSave after
 * replacing the page contents with the new html.
 */
ve.init.mw.ViewPageTarget.prototype.setupSectionEditLinks = null;

/**
 * Add content and event bindings to toolbar save button.
 *
 * @method
 */
ve.init.mw.ViewPageTarget.prototype.setupToolbarSaveButton = function () {
	this.toolbarSaveButton = new OO.ui.ButtonWidget( {
		label: ve.msg( 'visualeditor-toolbar-savedialog' ),
		flags: ['constructive'],
		disabled: !this.restoring
	} );

	// NOTE (phuedx, 2014-08-20): This class is used by the firsteditve guided
	// tour to attach a guider to the "Save page" button.
	this.toolbarSaveButton.$element.addClass( 've-ui-toolbar-saveButton' );

	if ( ve.msg( 'accesskey-save' ) !== '-' && ve.msg( 'accesskey-save' ) !== '' ) {
		// FlaggedRevs tries to use this - it's useless on VE pages because all that stuff gets hidden, but it will still conflict so get rid of it
		this.elementsThatHadOurAccessKey = $( '[accesskey="' + ve.msg( 'accesskey-save' ) + '"]' ).removeAttr( 'accesskey' );
		this.toolbarSaveButton.$button.attr( 'accesskey', ve.msg( 'accesskey-save' ) );
	}

	this.updateToolbarSaveButtonState();

	this.toolbarSaveButton.connect( this, { click: 'onToolbarSaveButtonClick' } );
};

/**
 * Add the save button to the user interface.
 *
 * @method
 */
ve.init.mw.ViewPageTarget.prototype.attachToolbarSaveButton = function () {
	var $actionTools = $( '<div>' ),
		$pushButtons = $( '<div>' ),
		actions = new ve.ui.TargetToolbar( this, this.surface );

	actions.setup( [
		{ include: [ 'help', 'notices' ] },
		{
			type: 'list',
			icon: 'menu',
			title: ve.msg( 'visualeditor-pagemenu-tooltip' ),
			include: [ 'meta', 'settings', 'advancedSettings', 'categories', 'languages', 'editModeSource' ]
		}
	] );

	$actionTools
		.addClass( 've-init-mw-viewPageTarget-toolbar-utilites' )
		.append( actions.$element );

	$pushButtons
		.addClass( 've-init-mw-viewPageTarget-toolbar-actions' )
		.append( this.toolbarSaveButton.$element );

	this.toolbar.$actions.append( $actionTools, $pushButtons );
};

/**
 * Show the save dialog.
 *
 * @method
 * @fires saveWorkflowBegin
 */
ve.init.mw.ViewPageTarget.prototype.showSaveDialog = function () {
	this.surface.getDialogs().getWindow( 'mwSave' ).then( function ( win ) {
		var currentWindow = this.surface.getContext().getInspectors().getCurrentWindow(),
			target = this;
		this.origSelection = this.surface.getModel().getSelection();

		// Make sure any open inspectors are closed
		if ( currentWindow ) {
			currentWindow.close();
		}

		// Preload the serialization
		if ( !this.docToSave ) {
			this.docToSave = ve.dm.converter.getDomFromModel( this.surface.getModel().getDocument() );
		}
		this.prepareCacheKey( this.docToSave );

		if ( !this.saveDialog ) {
			this.saveDialog = win;

			// Connect to save dialog
			this.saveDialog.connect( this, {
				save: 'saveDocument',
				review: 'onSaveDialogReview',
				resolve: 'onSaveDialogResolveConflict'
			} );
			// Setup edit summary and checkboxes
			this.saveDialog.setEditSummary( this.initialEditSummary );
			this.saveDialog.setupCheckboxes( this.$checkboxes );
		}

		this.saveDialog.setSanityCheck( this.sanityCheckVerified );
		this.surface.getDialogs().openWindow(
			this.saveDialog,
			{ dir: this.surface.getModel().getDocument().getLang() }
		)
			// Call onSaveDialogClose() when the save dialog starts closing
			.always( function ( opened ) {
				opened.always( target.onSaveDialogClose.bind( target ) );
			} );
		this.emit( 'saveWorkflowBegin' );
	}.bind( this ) );
};

/**
 * Handle dialog close events.
 *
 * @fires saveWorkflowEnd
 */
ve.init.mw.ViewPageTarget.prototype.onSaveDialogClose = function () {
	// Clear the cached HTML and cache key once the document changes
	var clear = function () {
		this.docToSave = null;
		this.clearPreparedCacheKey();
	}.bind( this );
	if ( this.surface ) {
		this.surface.getModel().getDocument().once( 'transact', clear );
	} else {
		clear();
	}
	this.surface.getModel().setSelection( this.origSelection );
	this.emit( 'saveWorkflowEnd' );
};

/**
 * Remember the window's scroll position.
 *
 * @method
 */
ve.init.mw.ViewPageTarget.prototype.saveScrollPosition = function () {
	this.scrollTop = $( window ).scrollTop();
};

/**
 * Restore the window's scroll position.
 *
 * @method
 */
ve.init.mw.ViewPageTarget.prototype.restoreScrollPosition = function () {
	if ( this.scrollTop ) {
		$( window ).scrollTop( this.scrollTop );
		this.scrollTop = null;
	}
};

/**
 * Show the page content.
 *
 * @method
 */
ve.init.mw.ViewPageTarget.prototype.showPageContent = function () {
	$( '#bodyContent > .ve-init-mw-viewPageTarget-content' )
		.removeClass( 've-init-mw-viewPageTarget-content' )
		.show()
		.fadeTo( 0, 1 );
	$( '#t-print, #t-permalink, #p-coll-print_export, #t-cite' ).show();
};

/**
 * Mute the page content.
 *
 * @method
 */
ve.init.mw.ViewPageTarget.prototype.mutePageContent = function () {
	$( '#bodyContent > :visible:not(#siteSub)' )
		.addClass( 've-init-mw-viewPageTarget-content' )
		.fadeTo( 'fast', 0.6 );
};

/**
 * Hide the page content.
 *
 * @method
 */
ve.init.mw.ViewPageTarget.prototype.hidePageContent = function () {
	$( '#bodyContent > :visible:not(#siteSub,.ve-ui-mwTocWidget)' )
		.addClass( 've-init-mw-viewPageTarget-content' )
		.hide();
	$( '#t-print, #t-permalink, #p-coll-print_export, #t-cite' ).hide();
};

/**
 * Show elements that didn't have a counter-part in the edit view.
 */
ve.init.mw.ViewPageTarget.prototype.showReadOnlyContent = function () {
	var $toc = $( '#toc' ),
		$wrap = $toc.parent();
	if ( $wrap.data( 've.hideTableOfContents' ) ) {
		$wrap.show( function () {
			$toc.unwrap();
		} );
	}

	$( '#contentSub' ).show();
};

/**
 * Hide elements that don't have a counter-part in the edit view.
 *
 * Call this when puting the page content, so that when we replace the
 * muted content with the edit surface, everything aligns in the same
 * place. If things like contentSub and TOC remain visible in mute mode,
 * there is an additional visual shift that is unpleasant to the user.
 */
ve.init.mw.ViewPageTarget.prototype.hideReadOnlyContent = function () {
	$( '#toc' )
		.wrap( '<div>' )
		.parent()
			.data( 've.hideTableOfContents', true )
			.hide();

	$( '#contentSub' ).hide();
};

/**
 * Hide the toolbar.
 *
 * @method
 */
ve.init.mw.ViewPageTarget.prototype.tearDownToolbar = function () {
	this.toolbar.$bar.slideUp( 'fast', function () {
		this.toolbar.destroy();
		this.toolbar = null;
	}.bind( this ) );
};

/**
 * Hide the debug bar.
 *
 * @method
 */
ve.init.mw.ViewPageTarget.prototype.tearDownDebugBar = function () {
	if ( this.debugBar ) {
		this.debugBar.$element.slideUp( 'fast', function () {
			this.debugBar.$element.remove();
			this.debugBar = null;
		}.bind( this ) );
	}
};

/**
 * Transform the page title into a VE-style title.
 *
 * @method
 */
ve.init.mw.ViewPageTarget.prototype.transformPageTitle = function () {
	$( '#firstHeading' ).addClass( 've-init-mw-viewPageTarget-pageTitle' );
};

/**
 * Fade the page title to indicate it is not editable.
 *
 * @method
 */
ve.init.mw.ViewPageTarget.prototype.mutePageTitle = function () {
	$( '#firstHeading, #siteSub' )
		.addClass( 've-init-mw-viewPageTarget-transform ve-init-mw-viewPageTarget-transform-muted' );
};

/**
 * Restore the page title to its original style.
 *
 * @method
 */
ve.init.mw.ViewPageTarget.prototype.restorePageTitle = function () {
	var $els = $( '#firstHeading, #siteSub' )
		.removeClass( 've-init-mw-viewPageTarget-transform-muted' );

	setTimeout( function () {
		$els.removeClass( 've-init-mw-viewPageTarget-transform' );
		$( '#firstHeading' ).removeClass( 've-init-mw-viewPageTarget-pageTitle' );
	}, 1000 );
};

/**
 * Change the document title to state that we are now editing.
 *
 * @method
 */
ve.init.mw.ViewPageTarget.prototype.changeDocumentTitle = function () {
	document.title = ve.msg(
		this.pageExists ? 'editing' : 'creating',
		mw.config.get( 'wgTitle' )
	) + ' - ' + mw.config.get( 'wgSiteName' );
};

/**
 * Restore the original document title.
 *
 * @method
 */
ve.init.mw.ViewPageTarget.prototype.restoreDocumentTitle = function () {
	document.title = this.originalDocumentTitle;
};

/**
 * Page modifications for switching to edit mode.
 */
ve.init.mw.ViewPageTarget.prototype.transformPage = function () {
	var uri;

	// Deselect current mode (e.g. "view" or "history"). In skins like monobook that don't have
	// separate tab sections for content actions and namespaces the below is a no-op.
	$( '#p-views' ).find( 'li.selected' ).removeClass( 'selected' );
	$( '#ca-ve-edit' ).addClass( 'selected' );

	mw.hook( 've.activate' ).fire();

	// Hide site notice (if present)
	$( '#siteNotice:visible' )
		.addClass( 've-hide' )
		.slideUp( 'fast' );
	// Hide page status indicators (if present)
	$( '.mw-indicators' )
		.addClass( 've-hide' )
		.fadeOut( 'fast' );

	// Add class to document
	$( 'html' ).addClass( 've-activated' );

	// Push veaction=edit url in history (if not already. If we got here by a veaction=edit
	// permalink then it will be there already and the constructor called #activate)
	if ( !this.actFromPopState && window.history.pushState && this.currentUri.query.veaction !== 'edit' ) {
		// Set the current URL
		uri = this.currentUri;
		uri.query.veaction = 'edit';

		window.history.pushState( this.popState, document.title, uri );
	}
	this.actFromPopState = false;
};

/**
 * Page modifications for switching back to view mode.
 */
ve.init.mw.ViewPageTarget.prototype.restorePage = function () {
	var uri;

	// Skins like monobook don't have a tab for view mode and instead just have the namespace tab
	// selected. We didn't deselect the namespace tab, so we're ready after deselecting #ca-ve-edit.
	// In skins having #ca-view (like Vector), select that.
	$( '#ca-ve-edit' ).removeClass( 'selected' );
	$( '#ca-view' ).addClass( 'selected' );

	mw.hook( 've.deactivate' ).fire();

	// Make site notice visible again (if present)
	$( '#siteNotice.ve-hide' )
		.slideDown( 'fast' );
	// Make page status indicators visible again (if present)
	$( '.mw-indicators.ve-hide' )
		.fadeIn( 'fast' );

	// Remove class from document
	$( 'html' ).removeClass( 've-activated' );

	// Push non-veaction=edit url in history
	if ( !this.actFromPopState && window.history.pushState ) {
		// Remove the veaction query parameter
		uri = this.currentUri;
		if ( 'veaction' in uri.query ) {
			delete uri.query.veaction;
		}
		if ( 'vesection' in uri.query ) {
			delete uri.query.vesection;
		}

		// If there are other query parameters, set the url to the current url (with veaction removed).
		// Otherwise use the canonical style view url (bug 42553).
		if ( ve.getObjectValues( uri.query ).length ) {
			window.history.pushState( this.popState, document.title, uri );
		} else {
			window.history.pushState( this.popState, document.title, this.viewUri );
		}
	}
	this.actFromPopState = false;
};

/**
 * @param {Event} e Native event object
 */
ve.init.mw.ViewPageTarget.prototype.onWindowPopState = function ( e ) {
	var newUri;

	if ( !this.verifyPopState( e.state ) ) {
		// Ignore popstate events fired for states not created by us
		// This also filters out the initial fire in Chrome (bug 57901).
		return;
	}

	newUri = this.currentUri = new mw.Uri( document.location.href );

	if ( !this.active && newUri.query.veaction === 'edit' ) {
		this.actFromPopState = true;
		this.activate();
	}
	if ( this.active && newUri.query.veaction !== 'edit' ) {
		this.actFromPopState = true;
		this.deactivate();
	}
};

/**
 * Replace the page content with new HTML.
 *
 * @method
 * @param {string} html Rendered HTML from server
 * @param {string} categoriesHtml Rendered categories HTML from server
 * @param {string} displayTitle What HTML to show as the page title
 * @param {Object} lastModified Object containing user-formatted date
    and time strings, or undefined if we made no change.
 * @param {string} contentSub What HTML to show as the content subtitle
 */
ve.init.mw.ViewPageTarget.prototype.replacePageContent = function (
	html, categoriesHtml, displayTitle, lastModified, contentSub
) {
	var $content = $( $.parseHTML( html ) ), $editableContent;

	if ( lastModified ) {
		// If we were not viewing the most recent revision before (a requirement
		// for lastmod to have been added by MediaWiki), we will be now.
		if ( !$( '#footer-info-lastmod' ).length ) {
			$( '#footer-info' ).prepend(
				$( '<li>' ).attr( 'id', 'footer-info-lastmod' )
			);
		}

		$( '#footer-info-lastmod' ).text( ' ' + mw.msg(
			'lastmodifiedat',
			lastModified.date,
			lastModified.time
		) );
	}

	if ( $( '#mw-imagepage-content' ).length ) {
		// On file pages, we only want to replace the (local) description.
		$editableContent = $( '#mw-imagepage-content' );
	} else if ( $( '#mw-pages' ).length ) {
		// It would be nice if MW core did this for us...
		if ( !$( '#ve-cat-description' ).length ) {
			$( '#mw-content-text > :not(div:has(#mw-pages))' ).wrapAll(
				$( '<div>' )
					.attr( 'id', 've-cat-description' )
			);
		}
		$editableContent = $( '#ve-cat-description' );
	} else {
		$editableContent = $( '#mw-content-text' );
	}

	mw.hook( 'wikipage.content' ).fire( $editableContent.empty().append( $content ) );
	if ( displayTitle ) {
		$( '#content > #firstHeading > span:first' ).html( displayTitle );
	}
	$( '#catlinks' ).replaceWith( categoriesHtml );
	$( '#contentSub' ).html( contentSub );
};

/**
 * Get the numeric index of a section in the page.
 *
 * @method
 * @param {HTMLElement} heading Heading element of section
 */
ve.init.mw.ViewPageTarget.prototype.getEditSection = function ( heading ) {
	var $page = $( '#mw-content-text' ),
		section = 0;
	$page.find( 'h1, h2, h3, h4, h5, h6' ).not( '#toc h2' ).each( function () {
		section++;
		if ( this === heading ) {
			return false;
		}
	} );
	return section;
};

/**
 * Store the section for which the edit link has been triggered.
 *
 * @method
 * @param {HTMLElement} heading Heading element of section
 */
ve.init.mw.ViewPageTarget.prototype.saveEditSection = function ( heading ) {
	this.section = this.getEditSection( heading );
};

/**
 * Add onbeforeunload handler.
 *
 * @method
 */
ve.init.mw.ViewPageTarget.prototype.setupBeforeUnloadHandler = function () {
	// Remember any already set on before unload handler
	this.onBeforeUnloadFallback = window.onbeforeunload;
	// Attach before unload handler
	window.onbeforeunload = this.onBeforeUnloadHandler = this.onBeforeUnload.bind( this );
	// Attach page show handlers
	if ( window.addEventListener ) {
		window.addEventListener( 'pageshow', this.onPageShow.bind( this ), false );
	} else if ( window.attachEvent ) {
		window.attachEvent( 'pageshow', this.onPageShow.bind( this ) );
	}
};

/**
 * Remove onbeforunload handler.
 *
 * @method
 */
ve.init.mw.ViewPageTarget.prototype.tearDownBeforeUnloadHandler = function () {
	// Restore whatever previous onbeforeload hook existed
	window.onbeforeunload = this.onBeforeUnloadFallback;
};

/**
 * Show dialogs as needed on load.
 */
ve.init.mw.ViewPageTarget.prototype.maybeShowDialogs = function () {
	var usePrefs, prefSaysShow, urlSaysHide;
	if ( mw.config.get( 'wgVisualEditorConfig' ).showBetaWelcome ) {

		// Only use the preference value if the user is logged-in.
		// If the user is anonymous, we can't save the preference
		// after showing the dialog. And we don't intend to use this
		// preference to influence anonymous users (use the config
		// variable for that; besides the pref value would be stale if
		// the wiki uses static html caching).
		usePrefs = !mw.user.isAnon();
		prefSaysShow = usePrefs && !mw.user.options.get( 'visualeditor-hidebetawelcome' );
		urlSaysHide = 'vehidebetadialog' in this.currentUri.query;

		if (
				!urlSaysHide &&
				(
					prefSaysShow ||
					( !usePrefs && $.cookie( 've-beta-welcome-dialog' ) === null )
				)
			) {
			this.surface.getDialogs().openWindow( 'betaWelcome' );
		}

		if ( prefSaysShow ) {
			ve.init.target.constructor.static.apiRequest( {
				action: 'options',
				token: mw.user.tokens.get( 'editToken' ),
				change: 'visualeditor-hidebetawelcome=1'
			}, { type: 'POST' } );

		// No need to set a cookie every time for logged-in users that have already
		// set the hidebetawelcome=1 preference, but only if this isn't a one-off
		// view of the page via the hiding GET parameter.
		} else if ( !usePrefs && !urlSaysHide ) {
			$.cookie( 've-beta-welcome-dialog', 1, { path: '/', expires: 30 } );
		}
	}

	if ( this.surface.getModel().metaList.getItemsInGroup( 'mwRedirect' ).length ) {
		this.surface.getDialogs().openWindow( 'meta', {
			page: 'settings',
			fragment: this.surface.getModel().getFragment()
		} );
	}
};

/**
 * Handle page show event.
 *
 * @method
 */
ve.init.mw.ViewPageTarget.prototype.onPageShow = function () {
	// Re-add onbeforeunload handler
	window.onbeforeunload = this.onBeforeUnloadHandler;
};

/**
 * Handle before unload event.
 *
 * @method
 */
ve.init.mw.ViewPageTarget.prototype.onBeforeUnload = function () {
	var fallbackResult,
		message,
		onBeforeUnloadHandler = this.onBeforeUnloadHandler;
	// Check if someone already set on onbeforeunload hook
	if ( this.onBeforeUnloadFallback ) {
		// Get the result of their onbeforeunload hook
		fallbackResult = this.onBeforeUnloadFallback();
	}
	// Check if their onbeforeunload hook returned something
	if ( fallbackResult !== undefined ) {
		// Exit here, returning their message
		message = fallbackResult;
	} else {
		// Override if submitting
		if ( this.submitting ) {
			return undefined;
		}
		// Check if there's been an edit
		if ( this.surface && this.edited && mw.user.options.get( 'useeditwarning' ) ) {
			// Return our message
			message = ve.msg( 'visualeditor-viewpage-savewarning' );
		}
	}
	// Unset the onbeforeunload handler so we don't break page caching in Firefox
	window.onbeforeunload = null;
	if ( message !== undefined ) {
		// ...but if the user chooses not to leave the page, we need to rebind it
		setTimeout( function () {
			window.onbeforeunload = onBeforeUnloadHandler;
		} );
		return message;
	}
};

/**
 * Switches to the wikitext editor, either keeping (default) or discarding changes.
 *
 * @param {boolean} [discardChanges] Whether to discard changes or not.
 */
ve.init.mw.ViewPageTarget.prototype.switchToWikitextEditor = function ( discardChanges ) {
	if ( discardChanges ) {
		this.submitting = true;
		window.location.href = this.viewUri.clone().extend( {
			action: 'edit',
			veswitched: 1
		} ).toString();
	} else {
		this.serialize(
			this.docToSave || ve.dm.converter.getDomFromModel( this.surface.getModel().getDocument() ),
			this.submitWithSaveFields.bind( this, { wpDiff: 1, veswitched: 1 } )
		);
	}
};

/**
 * Resets the document opacity when we've decided to cancel switching to the wikitext editor.
 */
ve.init.mw.ViewPageTarget.prototype.resetDocumentOpacity = function () {
	this.surface.getView().getDocument().getDocumentNode().$element.css( 'opacity', 1 );
};