/*!
 * VisualEditor MediaWiki Initialization ArticleTarget class.
 *
 * @copyright 2011-2018 VisualEditor Team and others; see AUTHORS.txt
 * @license The MIT License (MIT); see LICENSE.txt
 */

/* global EasyDeflate */

/**
 * Initialization MediaWiki article target.
 *
 * @class
 * @extends ve.init.mw.Target
 *
 * @constructor
 * @param {Object} [config] Configuration options
 */
ve.init.mw.ArticleTarget = function VeInitMwArticleTarget( config ) {
	config = config || {};
	config.toolbarConfig = $.extend( {
		shadow: true,
		actions: true,
		floatable: true
	}, config.toolbarConfig );

	// Parent constructor
	ve.init.mw.ArticleTarget.super.call( this, config );

	// Properties
	this.saveDialog = null;
	this.saveDeferred = null;
	this.captcha = null;
	this.docToSave = null;
	this.originalDmDocPromise = null;
	this.originalHtml = null;
	this.toolbarSaveButton = null;
	this.pageExists = mw.config.get( 'wgRelevantArticleId', 0 ) !== 0;
	this.toolbarScrollOffset = mw.config.get( 'wgVisualEditorToolbarScrollOffset', 0 );
	// A workaround, as default URI does not get updated after pushState (bug 72334)
	this.currentUri = new mw.Uri( location.href );
	this.section = null;
	this.sectionTitle = null;
	this.editSummaryValue = null;
	this.initialEditSummary = null;

	this.$templatesUsed = null;
	this.checkboxFields = null;
	this.checkboxesByName = null;
	this.$saveAccessKeyElements = null;

	// Sometimes we actually don't want to send a useful oldid
	// if we do, PostEdit will give us a 'page restored' message
	this.requestedRevId = mw.config.get( 'wgRevisionId' );
	this.currentRevisionId = mw.config.get( 'wgCurRevisionId' );
	this.revid = this.requestedRevId || this.currentRevisionId;

	this.edited = false;
	this.restoring = !!this.requestedRevId && this.requestedRevId !== this.currentRevisionId;
	this.pageDeletedWarning = false;
	this.submitUrl = ( new mw.Uri( mw.util.getUrl( this.getPageName() ) ) )
		.extend( {
			action: 'submit',
			veswitched: 1
		} );
	this.events = { track: $.noop, trackActivationStart: $.noop, trackActivationComplete: $.noop };

	this.welcomeDialog = null;
	this.welcomeDialogPromise = null;

	this.preparedCacheKeyPromise = null;
	this.clearState();

	// Initialization
	this.$element.addClass( 've-init-mw-articleTarget' );
};

/* Inheritance */

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

/* Events */

/**
 * @event editConflict
 */

/**
 * @event save
 */

/**
 * @event showChanges
 */

/**
 * @event noChanges
 */

/**
 * @event saveErrorEmpty
 * Fired when save API returns no data object
 */

/**
 * @event saveErrorSpamBlacklist
 * Fired when save is considered spam or blacklisted
 */

/**
 * @event saveErrorAbuseFilter
 * Fired when AbuseFilter throws warnings
 */

/**
 * @event saveErrorBadToken
 * @param {boolean} willRetry Whether an automatic retry will occur
 * Fired on save if we have to fetch a new edit token.
 * This is mainly for analytical purposes.
 */

/**
 * @event saveErrorNewUser
 * Fired when user is logged in as a new user
 */

/**
 * @event saveErrorCaptcha
 * Fired when saveError indicates captcha field is required
 */

/**
 * @event saveErrorUnknown
 * @param {string} errorMsg Error message shown to the user
 * Fired for any other type of save error
 */

/**
 * @event saveErrorPageDeleted
 * Fired when user tries to save page that was deleted after opening VE
 */

/**
 * @event saveErrorTitleBlacklist
 * Fired when the user tries to save page in violation of the TitleBlacklist
 */

/**
 * @event saveErrorHookAborted
 * Fired when the user tries to save page in violation of an extension
 */

/**
 * @event saveErrorReadOnly
 * Fired when the user tries to save page but the database is locked
 */

/**
 * @event loadError
 */

/**
 * @event showChangesError
 */

/**
 * @event serializeError
 */

/**
 * @event serializeComplete
 * Fired when serialization is complete
 */

/* Static Properties */

/**
 * @inheritdoc
 */
ve.init.mw.ArticleTarget.static.name = 'article';

/**
 * Tracking name of target class. Used by ArticleTargetEvents to identify which target we are tracking.
 *
 * @static
 * @property {string}
 * @inheritable
 */
ve.init.mw.ArticleTarget.static.trackingName = 'mwTarget';

/**
 * @inheritdoc
 */
ve.init.mw.ArticleTarget.static.integrationType = 'page';

/**
 * @inheritdoc
 */
ve.init.mw.ArticleTarget.static.platformType = 'other';

/**
 * @inheritdoc
 */
ve.init.mw.ArticleTarget.static.documentCommands = ve.init.mw.ArticleTarget.super.static.documentCommands.concat( [
	// Make save commands triggerable from anywhere
	'showSave',
	'showChanges',
	'showPreview',
	'showMinoredit',
	'showWatchthis'
] );

/* Static methods */

/**
 * @inheritdoc
 */
ve.init.mw.ArticleTarget.static.parseDocument = function ( documentString, mode, section ) {
	// Add trailing linebreak to non-empty wikitext documents for consistency
	// with old editor and usability. Will be stripped on save. T156609
	if ( mode === 'source' && documentString ) {
		documentString += '\n';
	}

	// Parent method
	return ve.init.mw.ArticleTarget.super.static.parseDocument.call( this, documentString, mode, section );
};

/**
 * Build DOM for the redirect page subtitle (#redirectsub).
 *
 * @return {jQuery}
 */
ve.init.mw.ArticleTarget.static.buildRedirectSub = function () {
	// Page subtitle
	// Compare: Article::view()
	return $( '<span>' )
		.attr( 'id', 'redirectsub' )
		.append( mw.message( 'redirectpagesub' ).parseDom() );
};

/**
 * Build DOM for the redirect page content header (.redirectMsg).
 *
 * @param {string} title Redirect target
 * @return {jQuery}
 */
ve.init.mw.ArticleTarget.static.buildRedirectMsg = function ( title ) {
	var $link;

	$link = $( '<a>' )
		.attr( {
			href: mw.Title.newFromText( title ).getUrl(),
			title: mw.msg( 'visualeditor-redirect-description', title )
		} )
		.text( title );
	ve.init.platform.linkCache.styleElement( title, $link );

	// Page content header
	// Compare: Article::getRedirectHeaderHtml()
	return $( '<div>' )
		.addClass( 'redirectMsg' )
		// Hack: This is normally inside #mw-content-text, but we may insert it before, so we need this.
		.addClass( 'mw-content-' + mw.config.get( 'wgVisualEditor' ).pageLanguageDir )
		.append(
			$( '<p>' ).text( mw.msg( 'redirectto' ) ),
			$( '<ul>' )
				.addClass( 'redirectText' )
				.append( $( '<li>' ).append( $link ) )
		);
};

/* Methods */

/**
 * @inheritdoc
 */
ve.init.mw.ArticleTarget.prototype.setDefaultMode = function () {
	var oldDefaultMode = this.defaultMode;
	// Parent method
	ve.init.mw.ArticleTarget.super.prototype.setDefaultMode.apply( this, arguments );

	if ( this.defaultMode !== oldDefaultMode ) {
		this.updateTabs( true );
		if ( mw.libs.ve.setEditorPreference ) {
			// only set up by DAT.init
			mw.libs.ve.setEditorPreference( this.defaultMode === 'visual' ? 'visualeditor' : 'wikitext' );
		}
	}
};

/**
 * Update state of editing tabs
 *
 * @param {boolean} editing Whether the editor is loaded.
 */
ve.init.mw.ArticleTarget.prototype.updateTabs = function ( editing ) {
	var $tab;

	// 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' );

	if ( editing ) {
		if ( this.section === 'new' ) {
			$tab = $( '#ca-addsection' );
		} else if ( $( '#ca-ve-edit' ).length ) {
			if ( this.getDefaultMode() === 'visual' ) {
				$tab = $( '#ca-ve-edit' );
			} else {
				$tab = $( '#ca-edit' );
			}
		} else {
			// Single edit tab
			$tab = $( '#ca-edit' );
		}
	} else {
		$tab = $( '#ca-view' );
	}
	$tab.addClass( 'selected' );
};

/**
 * Handle response to a successful load request.
 *
 * This method is called within the context of a target instance. If successful the DOM from the
 * server will be parsed, stored in {this.doc} and then {this.documentReady} will be called.
 *
 * @method
 * @param {Object} response API response data
 * @param {string} status Text status message
 */
ve.init.mw.ArticleTarget.prototype.loadSuccess = function ( response ) {
	var i, len, linkData, aboutDoc, docRevId, docRevIdMatches,
		name, options, accesskey, title, $label, checkbox,
		data = response ? ( response.visualeditor || response.visualeditoredit ) : null;

	if ( !data || typeof data.content !== 'string' ) {
		this.loadFail( 've-api', 'No HTML content in response from server' );
	} else {
		this.track( 'trace.parseResponse.enter' );
		this.originalHtml = data.content;
		this.etag = data.etag;
		this.fromEditedState = data.fromEditedState;
		this.switched = data.switched || 'wteswitched' in new mw.Uri( location.href ).query;
		this.doc = this.constructor.static.parseDocument( this.originalHtml, this.getDefaultMode() );
		this.preloaded = data.preloaded;

		this.remoteNotices = ve.getObjectValues( data.notices );
		this.protectedClasses = data.protectedClasses;

		this.baseTimeStamp = data.basetimestamp;
		this.startTimeStamp = data.starttimestamp;
		this.revid = data.oldid;
		this.recovered = data.recovered;

		this.checkboxesDef = data.checkboxesDef;
		this.checkboxesMessages = data.checkboxesMessages;
		mw.messages.set( data.checkboxesMessages );
		this.$templatesUsed = $( data.templates );
		this.links = data.links;

		this.initialSourceRange = data.initialSourceRange;

		aboutDoc = this.doc.documentElement.getAttribute( 'about' );
		if ( aboutDoc ) {
			docRevIdMatches = aboutDoc.match( /revision\/([0-9]*)$/ );
			if ( docRevIdMatches.length >= 2 ) {
				docRevId = parseInt( docRevIdMatches[ 1 ] );
			}
		}
		if ( docRevId && docRevId !== this.revid ) {
			if ( this.retriedRevIdConflict ) {
				// Retried already, just error the second time.
				this.loadFail(
					've-api',
					'Revision IDs (doc=' + docRevId + ',api=' + this.revid + ') ' +
						'returned by server do not match'
				);
			} else {
				this.retriedRevIdConflict = true;
				// TODO this retries both requests, in RESTbase mode we should only retry
				// the request that gave us the lower revid
				this.loading = false;
				// HACK: Load with explicit revid to hopefully prevent this from happening again
				this.requestedRevId = Math.max( docRevId, this.revid );
				this.load();
			}
			return;
		} else {
			// Set this to false after a successful load, so we don't immediately give up
			// if a subsequent load mismatches again
			this.retriedRevIdConflict = false;
		}

		// Populate link cache
		if ( this.links ) {
			// Format from the API: { missing: [titles], known: 1|[titles] }
			// Format expected by LinkCache: { title: { missing: true|false } }
			linkData = {};
			for ( i = 0, len = this.links.missing.length; i < len; i++ ) {
				linkData[ this.links.missing[ i ] ] = { missing: true };
			}
			if ( this.links.known === 1 ) {
				// Set back to false by surfaceReady()
				ve.init.platform.linkCache.setAssumeExistence( true );
			} else {
				for ( i = 0, len = this.links.known.length; i < len; i++ ) {
					linkData[ this.links.known[ i ] ] = { missing: false };
				}
			}
			ve.init.platform.linkCache.setMissing( linkData );
		}

		this.track( 'trace.parseResponse.exit' );

		// Everything worked, the page was loaded, continue initializing the editor
		this.documentReady( this.doc );
	}

	this.checkboxFields = [];
	this.checkboxesByName = {};
	if ( [ 'edit', 'submit' ].indexOf( mw.util.getParamValue( 'action' ) ) !== -1 ) {
		$( '#firstHeading' ).text(
			mw.Title.newFromText( this.getPageName() ).getPrefixedText()
		);
	}

	if ( this.checkboxesDef ) {
		for ( name in this.checkboxesDef ) {
			options = this.checkboxesDef[ name ];

			accesskey = null;
			title = null;
			if ( options.tooltip ) {
				accesskey = mw.message( 'accesskey-' + options.tooltip ).text();
				title = mw.message( 'tooltip-' + options.tooltip ).text();
			}
			if ( options[ 'title-message' ] ) {
				title = mw.message( options[ 'title-message' ] ).text();
			}
			$label = $( '<span>' ).append( mw.message( options[ 'label-message' ] ).parseDom() );
			ve.targetLinksToNewWindow( $label[ 0 ] );

			checkbox = new OO.ui.CheckboxInputWidget( {
				accessKey: accesskey,
				selected: options.default,
				classes: [ 've-ui-mwSaveDialog-checkbox-' + name ]
			} );

			this.checkboxFields.push(
				new OO.ui.FieldLayout( checkbox, {
					align: 'inline',
					label: $label.contents(),
					title: title
				} )
			);
			this.checkboxesByName[ name ] = checkbox;
		}
	}
};

/**
 * @inheritdoc
 */
ve.init.mw.ArticleTarget.prototype.documentReady = function () {
	// We need to wait until documentReady as local notices may require special messages
	this.editNotices = this.remoteNotices.concat(
		this.localNoticeMessages.map( function ( msgKey ) {
			return '<p>' + ve.init.platform.getParsedMessage( msgKey ) + '</p>';
		} )
	);

	this.loading = false;
	this.edited = this.fromEditedState;

	// Parent method
	ve.init.mw.ArticleTarget.super.prototype.documentReady.apply( this, arguments );
};

/**
 * @inheritdoc
 */
ve.init.mw.ArticleTarget.prototype.surfaceReady = function () {
	var name, i, triggers,
		target = this,
		accessKeyPrefix = $.fn.updateTooltipAccessKeys.getAccessKeyPrefix().replace( /-/g, '+' ),
		accessKeyModifiers = new ve.ui.Trigger( accessKeyPrefix + '-' ).modifiers,
		surfaceModel = this.getSurface().getModel();

	// loadSuccess() may have called setAssumeExistence( true );
	ve.init.platform.linkCache.setAssumeExistence( false );
	surfaceModel.connect( this, {
		history: 'updateToolbarSaveButtonState'
	} );
	this.restoreEditSection();

	// Iterate over the trigger registry and resolve any access key conflicts
	for ( name in ve.ui.triggerRegistry.registry ) {
		triggers = ve.ui.triggerRegistry.registry[ name ];
		for ( i = 0; i < triggers.length; i++ ) {
			if ( ve.compare( triggers[ i ].modifiers, accessKeyModifiers ) ) {
				this.disableAccessKey( triggers[ i ].primary );
			}
		}
	}

	// Auto-save
	if ( this.recovered ) {
		// Restore auto-saved transactions if document state was recovered
		try {
			surfaceModel.restoreChanges();
			mw.notify( ve.msg( 'visualeditor-autosave-recovered-text' ), {
				title: ve.msg( 'visualeditor-autosave-recovered-title' )
			} );
		} catch ( e ) {
			mw.log.warn( e );
			mw.notify( ve.msg( 'visualeditor-autosave-not-recovered-text' ), {
				title: ve.msg( 'visualeditor-autosave-not-recovered-title' ),
				type: 'error'
			} );
		}
	} else {
		// ...otherwise store this document state for later recovery
		if ( this.fromEditedState ) {
			// Store immediately if the document was previously edited
			// (e.g. in a different mode)
			this.storeDocState( this.originalHtml );
		} else {
			// Only store after the first change if this is an unmodified document
			surfaceModel.once( 'undoStackChange', function () {
				// Check the surface hasn't been destroyed
				if ( target.getSurface() ) {
					target.storeDocState( target.originalHtml );
				}
			} );
		}
	}
	// Start auto-saving transactions
	surfaceModel.startStoringChanges();
	// TODO: Listen to autosaveFailed event to notify user

	// Start loading easy-deflate module in the background, so it's
	// already loaded when the save dialog is opened.
	setTimeout( function () {
		mw.loader.load( 'easy-deflate.deflate' );
	}, 500 );

	// Parent method
	ve.init.mw.ArticleTarget.super.prototype.surfaceReady.apply( this, arguments );
};

/**
 * Store a snapshot of the current document state.
 *
 * @param {string} [html] Document HTML, will generate from current state if not provided
 */
ve.init.mw.ArticleTarget.prototype.storeDocState = function ( html ) {
	var mode = this.getSurface().getMode();
	this.getSurface().getModel().storeDocState( {
		request: {
			pageName: this.getPageName(),
			mode: mode,
			// Only source mode fetches data by section
			section: mode === 'source' ? this.section : null
		},
		response: {
			etag: this.etag,
			fromEditedState: this.fromEditedState,
			switched: this.switched,
			preloaded: this.preloaded,
			notices: this.remoteNotices,
			protectedClasses: this.protectedClasses,
			basetimestamp: this.baseTimeStamp,
			starttimestamp: this.startTimeStamp,
			oldid: this.revid,
			checkboxesDef: this.checkboxesDef,
			checkboxesMessages: this.checkboxesMessages,
			// Use $.prop as $templatesUsed may be empty
			templates: this.$templatesUsed.prop( 'outerHTML' ) || '',
			links: this.links
		}
	}, html );
};

/**
 * Disable an access key by removing the attribute from any element containing it
 *
 * @param {string} key Access key
 */
ve.init.mw.ArticleTarget.prototype.disableAccessKey = function ( key ) {
	$( '[accesskey=' + key + ']' ).each( function () {
		var $this = $( this );

		$this
			.attr( 'data-old-accesskey', $this.attr( 'accesskey' ) )
			.removeAttr( 'accesskey' );
	} );
};

/**
 * Re-enable all access keys
 */
ve.init.mw.ArticleTarget.prototype.restoreAccessKeys = function () {
	$( '[data-old-accesskey]' ).each( function () {
		var $this = $( this );

		$this
			.attr( 'accesskey', $this.attr( 'data-old-accesskey' ) )
			.removeAttr( 'data-old-accesskey' );
	} );
};

/**
 * Handle an unsuccessful load request.
 *
 * This method is called within the context of a target instance.
 *
 * @method
 * @param {string} code Error type text from mw.Api
 * @param {Object|string} errorDetails Either an object containing xhr, textStatus and exception keys, or a string.
 * @fires loadError
 */
ve.init.mw.ArticleTarget.prototype.loadFail = function () {
	this.loading = false;
	this.emit( 'loadError' );
};

/**
 * Handle a successful save request.
 *
 * This method is called within the context of a target instance.
 *
 * @method
 * @param {HTMLDocument} doc HTML document we tried to save
 * @param {Object} saveData Options that were used
 * @param {Object} response Response data
 * @param {string} status Text status message
 */
ve.init.mw.ArticleTarget.prototype.saveSuccess = function ( doc, saveData, response ) {
	var data = response.visualeditoredit;
	this.saving = false;
	if ( !data ) {
		this.saveFail( doc, saveData, false, null, 'Invalid response from server', response );
	} else if ( data.result !== 'success' ) {
		// Note, this could be any of db failure, hookabort, badtoken or even a captcha
		this.saveFail( doc, saveData, false, null, 'Save failure', response );
	} else if ( typeof data.content !== 'string' ) {
		this.saveFail( doc, saveData, false, null, 'Invalid HTML content in response from server', response );
	} else {
		this.saveComplete(
			data.content,
			data.categorieshtml,
			data.newrevid,
			data.isRedirect,
			data.displayTitleHtml,
			data.lastModified,
			data.contentSub,
			data.modules,
			data.jsconfigvars
		);
	}
};

/**
 * 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.
 * @param {string} contentSub HTML to show as the content subtitle
 * @param {Array} modules The modules to be loaded on the page
 * @param {Object} jsconfigvars The mw.config values needed on the page
 * @fires save
 */
ve.init.mw.ArticleTarget.prototype.saveComplete = function () {
	this.editSummaryValue = null;
	this.initialEditSummary = null;

	this.saveDeferred.resolve();
	this.emit( 'save' );
};

/**
 * Handle an unsuccessful save request.
 *
 * @method
 * @param {HTMLDocument} doc HTML document we tried to save
 * @param {Object} saveData Options that were used
 * @param {boolean} wasRetry Whether this was a retry after a 'badtoken' error
 * @param {Object} jqXHR
 * @param {string} status Text status message
 * @param {Object|null} data API response data
 */
ve.init.mw.ArticleTarget.prototype.saveFail = function ( doc, saveData, wasRetry, jqXHR, status, data ) {
	var editApi,
		target = this;

	this.saving = false;
	this.pageDeletedWarning = false;

	// Handle empty response
	if ( !data ) {
		this.saveErrorEmpty();
		return;
	}

	editApi = data && data.visualeditoredit && data.visualeditoredit.edit;

	// Handle spam blacklist error (either from core or from Extension:SpamBlacklist)
	if ( editApi && editApi.spamblacklist ) {
		this.saveErrorSpamBlacklist( editApi );
		return;
	}

	// Handle warnings/errors from Extension:AbuseFilter
	// TODO: Move this to a plugin
	if ( editApi && editApi.info && editApi.info.indexOf( 'Hit AbuseFilter:' ) === 0 && editApi.warning ) {
		this.saveErrorAbuseFilter( editApi );
		return;
	}

	// Handle token errors
	if ( data.error && data.error.code === 'badtoken' ) {
		if ( wasRetry ) {
			this.saveErrorBadToken( null, true );
			return;
		}
		this.refreshEditToken().done( function ( userChanged ) {
			// target.editToken has been refreshed
			if ( userChanged ) {
				target.saveErrorBadToken( mw.user.isAnon() ? null : mw.user.getName(), false );
			} else {
				// New session is the same user still; retry
				target.emit( 'saveErrorBadToken', true );
				target.save( doc, saveData, true );
			}
		} ).fail( function () {
			target.saveErrorBadToken( null, true );
		} );
		return;
	} else if ( data.error && data.error.code === 'editconflict' ) {
		this.editConflict();
		return;
	} else if ( data.error && data.error.code === 'pagedeleted' ) {
		this.saveErrorPageDeleted();
		return;
	} else if ( data.error && data.error.code === 'titleblacklist-forbidden' ) {
		this.saveErrorTitleBlacklist();
		return;
	} else if ( data.error && data.error.code === 'hookaborted' ) {
		this.saveErrorHookAborted();
		return;
	} else if ( data.error && data.error.code === 'readonly' ) {
		this.saveErrorReadOnly();
		return;
	}

	// Handle captcha
	// Captcha "errors" usually aren't errors. We simply don't know about them ahead of time,
	// so we save once, then (if required) we get an error with a captcha back and try again after
	// the user solved the captcha.
	// TODO: ConfirmEdit API is horrible, there is no reliable way to know whether it is a "math",
	// "question" or "fancy" type of captcha. They all expose differently named properties in the
	// API for different things in the UI. At this point we only support the SimpleCaptcha and FancyCaptcha
	// which we very intuitively detect by the presence of a "url" property.
	if ( editApi && editApi.captcha && (
		editApi.captcha.url ||
		editApi.captcha.type === 'simple' ||
		editApi.captcha.type === 'math' ||
		editApi.captcha.type === 'question'
	) ) {
		this.saveErrorCaptcha( editApi );
		return;
	}

	// Handle (other) unknown and/or unrecoverable errors
	this.saveErrorUnknown( editApi, data );
};

/**
 * Show an save process 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.
 * @param {boolean} [warning=false] Whether or not this is a warning.
 */
ve.init.mw.ArticleTarget.prototype.showSaveError = function ( msg, allowReapply, warning ) {
	this.saveDeferred.reject( [ new OO.ui.Error( msg, { recoverable: allowReapply, warning: warning } ) ] );
};

/**
 * Handle general save error
 *
 * @method
 * @fires saveErrorEmpty
 */
ve.init.mw.ArticleTarget.prototype.saveErrorEmpty = function () {
	this.showSaveError( ve.msg( 'visualeditor-saveerror', 'Empty server response' ), false /* prevents reapply */ );
	this.emit( 'saveErrorEmpty' );
};

/**
 * Handle spam blacklist error
 *
 * @method
 * @param {Object} editApi
 * @fires saveErrorSpamBlacklist
 */
ve.init.mw.ArticleTarget.prototype.saveErrorSpamBlacklist = function ( editApi ) {
	this.showSaveError(
		$( $.parseHTML( editApi.sberrorparsed ) ),
		false // prevents reapply
	);
	this.emit( 'saveErrorSpamBlacklist' );
};

/**
 * Handel abuse filter error
 *
 * @method
 * @param {Object} editApi
 * @fires saveErrorAbuseFilter
 */
ve.init.mw.ArticleTarget.prototype.saveErrorAbuseFilter = 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.emit( 'saveErrorAbuseFilter' );
};

/**
 * Handle title blacklist save error
 *
 * @method
 * @fires saveErrorTitleBlacklist
 */
ve.init.mw.ArticleTarget.prototype.saveErrorTitleBlacklist = function () {
	this.showSaveError( mw.msg( 'visualeditor-saveerror-titleblacklist' ) );
	this.emit( 'saveErrorTitleBlacklist' );
};

/**
 * Handle hook abort save error
 *
 * @method
 * @fires saveErrorHookAborted
 */
ve.init.mw.ArticleTarget.prototype.saveErrorHookAborted = function () {
	this.showSaveError( mw.msg( 'visualeditor-saveerror-hookaborted' ) );
	this.emit( 'saveErrorHookAborted' );
};

/**
 * Handle token fetch indicating another user is logged in, and token fetch errors.
 *
 * @method
 * @param {string|null} username Name of newly logged-in user, or null if anonymous
 * @param {boolean} [error=false] Whether there was an error trying to figure out who we're logged in as
 * @fires saveErrorBadToken
 * @fires saveErrorNewUser
 */
ve.init.mw.ArticleTarget.prototype.saveErrorBadToken = function ( username, error ) {
	var userMsg,
		$msg = $( document.createTextNode( mw.msg( 'visualeditor-savedialog-error-badtoken' ) + ' ' ) );

	if ( error ) {
		this.emit( 'saveErrorBadToken', false );
		$msg = $msg.add( document.createTextNode( mw.msg( 'visualeditor-savedialog-identify-trylogin' ) ) );
	} else {
		this.emit( 'saveErrorNewUser' );
		if ( username === null ) {
			userMsg = 'visualeditor-savedialog-identify-anon';
		} else {
			userMsg = 'visualeditor-savedialog-identify-user';
		}
		$msg = $msg.add( mw.message( userMsg, username ).parseDom() );
	}
	this.showSaveError( $msg );
};

/**
 * Handle unknown save error
 *
 * @method
 * @param {Object} editApi
 * @param {Object|null} data API response data
 * @fires saveErrorUnknown
 */
ve.init.mw.ArticleTarget.prototype.saveErrorUnknown = function ( editApi, data ) {
	var errorMsg = ( editApi && editApi.info ) || ( data && data.error && data.error.info ),
		errorCode = ( editApi && editApi.code ) || ( data && data.error && data.error.code ),
		unknown = 'Unknown error';

	if ( data.xhr && data.xhr.status !== 200 ) {
		unknown += ', HTTP status ' + data.xhr.status;
	}

	this.showSaveError(
		$( document.createTextNode( errorMsg || errorCode || unknown ) ),
		false // prevents reapply
	);
	this.emit( 'saveErrorUnknown', errorCode || errorMsg || unknown );
};

/**
 * Handle captcha error
 *
 * @method
 * @param {Object} editApi
 * @fires saveErrorCaptcha
 */
ve.init.mw.ArticleTarget.prototype.saveErrorCaptcha = function ( editApi ) {
	var $captchaImg, msg, question,
		captchaData = editApi.captcha,
		captchaInput = new OO.ui.TextInputWidget( { classes: [ 've-ui-saveDialog-captchaInput' ] } ),
		$captchaDiv = $( '<div>' ),
		$captchaParagraph = $( '<p>' ),
		target = this;

	function onCaptchaLoad() {
		target.saveDialog.updateSize();
		captchaInput.focus();
		captchaInput.scrollElementIntoView();
	}

	// Save when pressing 'Enter' in captcha field as it is single line.
	captchaInput.on( 'enter', function () {
		target.saveDialog.executeAction( 'save' );
	} );

	this.captcha = {
		input: captchaInput,
		id: captchaData.id
	};
	$captchaDiv.append( $captchaParagraph );
	$captchaParagraph.append(
		$( '<strong>' ).text( mw.msg( 'captcha-label' ) ),
		document.createTextNode( mw.msg( 'colon-separator' ) )
	);

	if ( captchaData.url ) {
		// FancyCaptcha
		// Based on FancyCaptcha::getFormInformation() (https://git.io/v6mml) and
		// ext.confirmEdit.fancyCaptcha.js in the ConfirmEdit extension.
		mw.loader.load( 'ext.confirmEdit.fancyCaptcha' );
		$captchaDiv.addClass( 'fancycaptcha-captcha-container' );
		$captchaParagraph.append(
			$( $.parseHTML( mw.message( 'fancycaptcha-edit' ).parse() ) )
				.filter( 'a' ).attr( 'target', '_blank' ).end()
		);
		$captchaImg = $( '<img>' )
			.attr( 'src', captchaData.url )
			.addClass( 'fancycaptcha-image' )
			.on( 'load', onCaptchaLoad );
		$captchaDiv.append(
			$captchaImg,
			' ',
			$( '<a>' ).addClass( 'fancycaptcha-reload' ).text( mw.msg( 'fancycaptcha-reload-text' ) )
		);
	} else {
		if ( captchaData.type === 'simple' || captchaData.type === 'math' ) {
			// SimpleCaptcha and MathCaptcha
			msg = 'captcha-edit';
		} else if ( captchaData.type === 'question' ) {
			// QuestyCaptcha
			msg = 'questycaptcha-edit';
		}

		if ( msg ) {
			switch ( captchaData.mime ) {
				case 'text/html':
					question = $.parseHTML( captchaData.question );
					// TODO: Search for images and wait for them to load
					setTimeout( onCaptchaLoad );
					break;
				case 'text/plain':
					question = document.createTextNode( captchaData.question );
					setTimeout( onCaptchaLoad );
					break;
			}
			$captchaParagraph.append( mw.message( msg ).parse(), '<br>', question );
		}
	}

	$captchaDiv.append( captchaInput.$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.emit( 'saveErrorCaptcha' );
};

/**
 * Handle page deleted error
 *
 * @method
 * @fires saveErrorPageDeleted
 */
ve.init.mw.ArticleTarget.prototype.saveErrorPageDeleted = function () {
	this.pageDeletedWarning = true;
	this.showSaveError( mw.msg( 'visualeditor-recreate', mw.msg( 'ooui-dialog-process-continue' ) ), true, true );
	this.emit( 'saveErrorPageDeleted' );
};

/**
 * Handle read only error
 *
 * @method
 * @fires saveErrorReadOnly
 */
ve.init.mw.ArticleTarget.prototype.saveErrorReadOnly = function () {
	this.showSaveError( $( $.parseHTML( mw.message( 'apierror-readonly' ).parse() ) ), true, true );
	this.emit( 'saveErrorReadOnly' );
};

/**
 * Handle an edit conflict
 *
 * @method
 * @fires editConflict
 */
ve.init.mw.ArticleTarget.prototype.editConflict = function () {
	this.emit( 'editConflict' );
	this.saveDialog.popPending();
	this.saveDialog.swapPanel( 'conflict' );
};

/**
 * Handle a successful serialize request.
 *
 * This method is called within the context of a target instance.
 *
 * @static
 * @method
 * @param {Object} response API response data
 * @param {string} status Text status message
 * @fires serializeComplete
 */
ve.init.mw.ArticleTarget.prototype.serializeSuccess = function ( response ) {
	var data = response.visualeditoredit;
	this.serializing = false;
	if ( !data && !response.error ) {
		this.serializeFail( null, 'Invalid response from server', null );
	} else if ( response.error ) {
		this.serializeFail(
			null, 'Unsuccessful request: ' + response.error.info, null
		);
	} else if ( data.result === 'error' ) {
		this.serializeFail( null, 'Server error', null );
	} else if ( typeof data.content !== 'string' ) {
		this.serializeFail(
			null, 'No Wikitext content in response from server', null
		);
	} else {
		if ( typeof this.serializeCallback === 'function' ) {
			this.serializeCallback( data.content );
			this.emit( 'serializeComplete' );
			delete this.serializeCallback;
		}
	}
};

/**
 * Handle an unsuccessful serialize request.
 *
 * This method is called within the context of a target instance.
 *
 * @method
 * @param {jqXHR|null} jqXHR
 * @param {string} status Text status message
 * @param {Mixed|null} error HTTP status text
 * @fires serializeError
 */
ve.init.mw.ArticleTarget.prototype.serializeFail = function () {
	this.serializing = false;
	this.emit( 'serializeError' );
};

/**
 * Handle clicks on the review button in the save dialog.
 *
 * @method
 * @fires saveReview
 */
ve.init.mw.ArticleTarget.prototype.onSaveDialogReview = function () {
	if ( !this.saveDialog.hasDiff ) {
		this.emit( 'saveReview' );
		this.saveDialog.pushPending();
		if ( this.pageExists ) {
			// Has no callback, handled via target.showChangesDiff
			this.showChanges( this.getDocToSave() );
		} else {
			this.serialize( this.getDocToSave(), this.onSaveDialogReviewComplete.bind( this ) );
		}
	} else {
		this.saveDialog.swapPanel( 'review' );
	}
};

/**
 * Handle clicks on the show preview button in the save dialog.
 *
 * @method
 * @fires savePreview
 */
ve.init.mw.ArticleTarget.prototype.onSaveDialogPreview = function () {
	var wikitext,
		target = this;

	if ( !this.saveDialog.$previewViewer.children().length ) {
		this.emit( 'savePreview' );
		this.saveDialog.pushPending();

		wikitext = this.getDocToSave();
		if ( this.sectionTitle && this.sectionTitle.getValue() ) {
			wikitext = '== ' + this.sectionTitle.getValue() + ' ==\n\n' + wikitext;
		}

		this.getContentApi().post( {
			action: 'visualeditor',
			paction: 'parsedoc',
			page: this.getPageName(),
			wikitext: wikitext,
			pst: true
		} ).always( function ( response, details ) {
			var doc,
				baseDoc = target.getSurface().getModel().getDocument().getHtmlDocument();

			if ( ve.getProp( response, 'visualeditor', 'result' ) === 'success' ) {
				doc = target.constructor.static.parseDocument( response.visualeditor.content, 'visual' );
				target.saveDialog.showPreview( doc, baseDoc );

			} else {
				target.saveDialog.showPreview(
					ve.msg(
						'visualeditor-loaderror-message',
						ve.getProp( details, 'error', 'info' ) || 'Failed to connect'
					)
				);
			}
			target.bindSaveDialogClearDiff();
		} );
	} else {
		this.saveDialog.swapPanel( 'preview' );
	}
};

/**
 * Clear the save dialog's diff cache when the document changes
 */
ve.init.mw.ArticleTarget.prototype.bindSaveDialogClearDiff = function () {
	// Invalidate the viewer wikitext on next change
	this.getSurface().getModel().getDocument().once( 'transact',
		this.saveDialog.clearDiff.bind( this.saveDialog )
	);
	if ( this.sectionTitle ) {
		this.sectionTitle.once( 'change', this.saveDialog.clearDiff.bind( this.saveDialog ) );
	}
};

/**
 * Handle completed serialize request for diff views for new page creations.
 *
 * @method
 * @param {string} wikitext
 */
ve.init.mw.ArticleTarget.prototype.onSaveDialogReviewComplete = function ( wikitext ) {
	this.bindSaveDialogClearDiff();
	this.saveDialog.setDiffAndReview(
		$.Deferred().resolve( $( '<pre>' ).text( wikitext ) ).promise(),
		this.getVisualDiffGeneratorPromise(),
		this.getSurface().getModel().getDocument().getHtmlDocument()
	);
};

/**
 * Get a visual diff object for the current document state
 *
 * @return {jQuery.Promise} Promise resolving with a generator for a ve.dm.VisualDiff visual diff
 */
ve.init.mw.ArticleTarget.prototype.getVisualDiffGeneratorPromise = function () {
	var target = this;

	return mw.loader.using( 'ext.visualEditor.diffLoader' ).then( function () {
		var newRevPromise;

		if ( !target.originalDmDocPromise ) {
			if ( !target.fromEditedState && target.getSurface().getMode() === 'visual' ) {
				// If this.doc was loaded from an un-edited state and in visual mode,
				// then just parse it to get originalDmDoc, otherwise we need to
				// re-fetch the HTML
				target.originalDmDocPromise = $.Deferred().resolve( target.constructor.static.createModelFromDom( target.doc, 'visual' ) ).promise();
			} else {
				target.originalDmDocPromise = mw.libs.ve.diffLoader.fetchRevision( target.revid, target.getPageName(), undefined, target.section !== null ? target.section : undefined );
			}
		}

		if ( target.getSurface().getMode() === 'source' ) {
			newRevPromise = mw.libs.ve.targetLoader.requestParsoidData(
				mw.config.get( 'wgRelevantPageName' ),
				{
					oldId: target.revid,
					targetName: 'diff',
					modified: true,
					wikitext: ve.init.target.getSurface().getDom()
				}
			).then( mw.libs.ve.diffLoader.getModelFromResponse );

			return mw.libs.ve.diffLoader.getVisualDiffGeneratorPromise( target.originalDmDocPromise, newRevPromise );
		} else {
			return target.originalDmDocPromise.then( function ( originalDmDoc ) {
				return function () {
					return new ve.dm.VisualDiff( originalDmDoc, target.getSurface().getModel().getDocument() );
				};
			} );
		}
	} );
};

/**
 * Handle clicks on the resolve conflict button in the conflict dialog.
 *
 * @method
 */
ve.init.mw.ArticleTarget.prototype.onSaveDialogResolveConflict = function () {
	var fields = { wpSave: 1 };

	if ( this.getSurface().getMode() === 'source' && this.section !== null ) {
		fields.section = this.section;
	}
	// Get Wikitext from the DOM, and set up a submit call when it's done
	this.serialize(
		this.getDocToSave(),
		this.submitWithSaveFields.bind( this, fields )
	);
};

/**
 * Handle dialog retry events
 * So we can handle trying to save again after page deletion warnings
 */
ve.init.mw.ArticleTarget.prototype.onSaveDialogRetry = function () {
	if ( this.pageDeletedWarning ) {
		this.recreating = true;
		this.pageExists = false;
	}
};

/**
 * Handle dialog close events.
 *
 * @fires saveWorkflowEnd
 */
ve.init.mw.ArticleTarget.prototype.onSaveDialogClose = function () {
	this.emit( 'saveWorkflowEnd' );
};

/**
 * Get deflated HTML. This function is async because easy-deflate may not have finished loading yet.
 *
 * @param {HTMLDocument} newDoc Document to get HTML for
 * @return {jQuery.Promise} Promise resolved with deflated HTML
 * @see #getHtml
 */
ve.init.mw.ArticleTarget.prototype.deflateHtml = function ( newDoc ) {
	var html = this.getHtml( newDoc, this.doc );
	return mw.loader.using( 'easy-deflate.deflate' )
		.then( function () {
			return EasyDeflate.deflate( html );
		} );
};

/**
 * Load the editor.
 *
 * This method initiates an API request for the page data unless dataPromise is passed in,
 * in which case it waits for that promise instead.
 *
 * @param {jQuery.Promise} [dataPromise] Promise for pending request, if any
 * @return {boolean} Loading has been started
*/
ve.init.mw.ArticleTarget.prototype.load = function ( dataPromise ) {
	// Prevent duplicate requests
	if ( this.loading ) {
		return false;
	}
	this.events.trackActivationStart( mw.libs.ve.activationStart );
	mw.libs.ve.activationStart = null;

	this.loading = dataPromise || mw.libs.ve.targetLoader.requestPageData( this.getDefaultMode(), this.getPageName(), {
		sessionStore: true,
		section: this.section,
		oldId: this.requestedRevId,
		targetName: this.constructor.static.trackingName
	} );
	this.loading
		.done( this.loadSuccess.bind( this ) )
		.fail( this.loadFail.bind( this ) );

	return true;
};

/**
 * Clear the state of this target, preparing it to be reactivated later.
 */
ve.init.mw.ArticleTarget.prototype.clearState = function () {
	this.restoreAccessKeys();
	this.clearPreparedCacheKey();
	this.loading = false;
	this.saving = false;
	this.clearDiff();
	this.serializing = false;
	this.submitting = false;
	this.baseTimeStamp = null;
	this.startTimeStamp = null;
	this.checkboxes = null;
	this.initialSourceRange = null;
	this.doc = null;
	this.originalDmDocPromise = null;
	this.originalHtml = null;
	this.toolbarSaveButton = null;
	this.section = null;
	this.editNotices = [];
	this.remoteNotices = [];
	this.localNoticeMessages = [];
	this.recovered = false;
};

/**
 * Switch to edit source mode
 *
 * @abstract
 * @method
 */
ve.init.mw.ArticleTarget.prototype.editSource = null;

/**
 * Get a document to save, cached until the surface is modified
 *
 * The default implementation returns an HTMLDocument, but other targets
 * may use a different document model (e.g. plain text for source mode).
 *
 * @return {Object} Document to save
 */
ve.init.mw.ArticleTarget.prototype.getDocToSave = function () {
	var surface;
	if ( !this.docToSave ) {
		this.docToSave = this.createDocToSave();
		// Cache clearing events
		surface = this.getSurface();
		surface.getModel().getDocument().once( 'transact', this.clearDocToSave.bind( this ) );
		surface.once( 'destroy', this.clearDocToSave.bind( this ) );
	}
	return this.docToSave;
};

/**
 * Create a document to save
 *
 * @return {Object} Document to save
 */
ve.init.mw.ArticleTarget.prototype.createDocToSave = function () {
	return this.getSurface().getDom();
};

/**
 * Clear the document to save from the cache
 */
ve.init.mw.ArticleTarget.prototype.clearDocToSave = function () {
	this.docToSave = null;
	this.clearPreparedCacheKey();
};

/**
 * Serialize the current document and store the result in the serialization cache on the server.
 *
 * This function returns a promise that is resolved once serialization is complete, with the
 * cache key passed as the first parameter.
 *
 * If there's already a request pending for the same (reference-identical) HTMLDocument, this
 * function will not initiate a new request but will return the promise for the pending request.
 * If a request for the same document has already been completed, this function will keep returning
 * the same promise (which will already have been resolved) until clearPreparedCacheKey() is called.
 *
 * @param {HTMLDocument} doc Document to serialize
 */
ve.init.mw.ArticleTarget.prototype.prepareCacheKey = function ( doc ) {
	var xhr, deflated,
		aborted = false,
		start = ve.now(),
		target = this;

	if ( this.getSurface().getMode() === 'source' ) {
		return;
	}

	if ( this.preparedCacheKeyPromise && this.preparedCacheKeyPromise.doc === doc ) {
		return this.preparedCacheKeyPromise;
	}
	this.clearPreparedCacheKey();

	this.preparedCacheKeyPromise = this.deflateHtml( doc )
		.then( function ( deflatedHtml ) {
			deflated = deflatedHtml;
			if ( aborted ) {
				return $.Deferred().reject();
			}
			xhr = target.getContentApi().postWithToken( 'csrf',
				{
					action: 'visualeditoredit',
					paction: 'serializeforcache',
					html: deflatedHtml,
					page: target.getPageName(),
					oldid: target.revid,
					etag: target.etag
				},
				{ contentType: 'multipart/form-data' }
			);
			return xhr.then(
				function ( response ) {
					var trackData = { duration: ve.now() - start };
					if ( response.visualeditoredit && typeof response.visualeditoredit.cachekey === 'string' ) {
						target.events.track( 'performance.system.serializeforcache', trackData );
						return response.visualeditoredit.cachekey;
					} else {
						target.events.track( 'performance.system.serializeforcache.nocachekey', trackData );
						return $.Deferred().reject();
					}
				},
				function () {
					target.events.track( 'performance.system.serializeforcache.fail', { duration: ve.now() - start } );
				}
			);
		} )
		.promise( {
			abort: function () {
				if ( xhr ) {
					xhr.abort();
				}
				aborted = true;
			},
			getDeflatedHtml: function () {
				return deflated;
			},
			doc: doc
		} );
};

/**
 * Get the prepared wikitext, if any. Same as prepareWikitext() but does not initiate a request
 * if one isn't already pending or finished. Instead, it returns a rejected promise in that case.
 *
 * @param {HTMLDocument} doc Document to serialize
 * @return {jQuery.Promise} Abortable promise, resolved with the cache key.
 */
ve.init.mw.ArticleTarget.prototype.getPreparedCacheKey = function ( doc ) {
	var deferred;
	if ( this.preparedCacheKeyPromise && this.preparedCacheKeyPromise.doc === doc ) {
		return this.preparedCacheKeyPromise;
	}
	deferred = $.Deferred();
	deferred.reject();
	return deferred.promise();
};

/**
 * Clear the promise for the prepared wikitext cache key, and abort it if it's still in progress.
 */
ve.init.mw.ArticleTarget.prototype.clearPreparedCacheKey = function () {
	if ( this.preparedCacheKeyPromise ) {
		this.preparedCacheKeyPromise.abort();
		this.preparedCacheKeyPromise = null;
	}
};

/**
 * Try submitting an API request with a cache key for prepared wikitext, falling back to submitting
 * HTML directly if there is no cache key present or pending, or if the request for the cache key
 * fails, or if using the cache key fails with a badcachekey error.
 *
 * If options.token is set, this function will use mw.Api#post and let the caller handle badtoken
 * errors. If options.token is not set, this function will use mw.Api#postWithToken which retries
 * automatically when encountering a badtoken error. If you do not want the automatic retry behavior
 * and want to control badtoken retries, you have to set options.token.
 *
 * @param {HTMLDocument|string} doc Document to submit or string in source mode
 * @param {Object} options POST parameters to send. Do not include 'html', 'cachekey' or 'format'.
 * @param {string} [eventName] If set, log an event when the request completes successfully. The
 *  full event name used will be 'performance.system.{eventName}.withCacheKey' or .withoutCacheKey
 *  depending on whether or not a cache key was used.
 * @return {jQuery.Promise}
 */
ve.init.mw.ArticleTarget.prototype.tryWithPreparedCacheKey = function ( doc, options, eventName ) {
	var data, postData, preparedCacheKey, api,
		target = this;

	if ( this.getSurface().getMode() === 'source' ) {
		data = {
			wikitext: doc,
			format: 'json'
		};
		postData = ve.extendObject( {}, options, data );
		if ( this.section !== null ) {
			postData.section = this.section;
		}
		if ( this.sectionTitle ) {
			postData.sectiontitle = this.sectionTitle.getValue();
			postData.summary = undefined;
		}
		api = this.getContentApi();
		if ( postData.token ) {
			return api.post( postData, { contentType: 'multipart/form-data' } );
		}
		return api.postWithToken( 'csrf', postData, { contentType: 'multipart/form-data' } );
	}

	preparedCacheKey = this.getPreparedCacheKey( doc );
	data = ve.extendObject( {}, options, { format: 'json' } );

	function ajaxRequest( cachekey, isRetried ) {
		var fullEventName,
			start = ve.now(),
			deflatePromise = $.Deferred().resolve().promise();

		if ( typeof cachekey === 'string' ) {
			data.cachekey = cachekey;
		} else {
			// Getting a cache key failed, fall back to sending the HTML
			data.html = preparedCacheKey && preparedCacheKey.getDeflatedHtml && preparedCacheKey.getDeflatedHtml();
			if ( !data.html ) {
				deflatePromise = target.deflateHtml( doc ).then( function ( deflatedHtml ) {
					data.html = deflatedHtml;
				} );
			}
			// If using the cache key fails, we'll come back here with cachekey still set
			delete data.cachekey;
		}
		return deflatePromise
			.then( function () {
				var api = target.getContentApi();
				if ( data.token ) {
					return api.post( data, { contentType: 'multipart/form-data' } );
				}
				return api.postWithToken( 'csrf', data, { contentType: 'multipart/form-data' } );
			} )
			.then(
				function ( response, jqxhr ) {
					var eventData = {
						bytes: require( 'mediawiki.String' ).byteLength( jqxhr.responseText ),
						duration: ve.now() - start
					};

					// Log data about the request if eventName was set
					if ( eventName ) {
						fullEventName = 'performance.system.' + eventName +
							( typeof cachekey === 'string' ? '.withCacheKey' : '.withoutCacheKey' );
						target.events.track( fullEventName, eventData );
					}
					return jqxhr;
				},
				function ( errorName, errorObject ) {
					var responseText = ve.getProp( errorObject, 'xhr', 'responseText' ),
						eventData;
					if ( responseText ) {
						eventData = {
							bytes: require( 'mediawiki.String' ).byteLength( responseText ),
							duration: ve.now() - start
						};

						if ( eventName ) {
							if ( errorName === 'badcachekey' ) {
								fullEventName = 'performance.system.' + eventName + '.badCacheKey';
							} else {
								fullEventName = 'performance.system.' + eventName + '.withoutCacheKey';
							}
							target.events.track( fullEventName, eventData );
						}
					}
					// This cache key is evidently bad, clear it
					target.clearPreparedCacheKey();
					if ( !isRetried && errorName === 'badcachekey' ) {
						// Try again without a cache key
						return ajaxRequest( null, true );
					} else {
						// Failed twice in a row, must be some other error - let caller handle it.
						// FIXME Can't just `return this` because all callers are broken.
						return $.Deferred().reject( null, errorName, errorObject ).promise();
					}
				}
			);
	}

	// If we successfully get prepared wikitext, then invoke ajaxRequest() with the cache key,
	// otherwise invoke it without.
	return preparedCacheKey.then( ajaxRequest, ajaxRequest );
};

/**
 * Handle the save dialog's save event
 *
 * Validates the inputs then starts the save process
 *
 * @param {jQuery.Deferred} saveDeferred Deferred object to resolve/reject when the save
 *  succeeds/fails.
 * @fires saveInitiated
 */
ve.init.mw.ArticleTarget.prototype.onSaveDialogSave = function ( saveDeferred ) {
	var saveOptions;

	if ( this.deactivating ) {
		return;
	}

	saveOptions = this.getSaveOptions();

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

	if (
		+mw.user.options.get( 'forceeditsummary' ) &&
		( saveOptions.summary === '' || saveOptions.summary === this.initialEditSummary ) &&
		!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.emit( 'saveInitiated' );
		this.startSave( saveOptions );
		this.saveDeferred = saveDeferred;
	}
};

/**
 * Start the save process
 *
 * @param {Object} saveOptions Save options
 */
ve.init.mw.ArticleTarget.prototype.startSave = function ( saveOptions ) {
	this.save( this.getDocToSave(), saveOptions );
};

/**
 * Get save form fields from the save dialog form.
 *
 * @return {Object} Form data for submission to the MediaWiki action=edit UI
 */
ve.init.mw.ArticleTarget.prototype.getSaveFields = function () {
	var name,
		fields = {
			wpSummary: this.saveDialog ? this.saveDialog.editSummaryInput.getValue() : ( this.editSummaryValue || this.initialEditSummary ),
			wpCaptchaId: this.captcha && this.captcha.id,
			wpCaptchaWord: this.captcha && this.captcha.input.getValue()
		};
	if ( this.recreating ) {
		fields.wpRecreate = true;
	}

	for ( name in this.checkboxesByName ) {
		if ( this.checkboxesByName[ name ].isSelected() ) {
			fields[ name ] = this.checkboxesByName[ name ].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
 * @return {boolean} Whether submission was started
 */
ve.init.mw.ArticleTarget.prototype.submitWithSaveFields = function ( fields, wikitext ) {
	return this.submit( wikitext, $.extend( this.getSaveFields(), fields ) );
};

/**
 * Get edit API options from the save dialog form.
 *
 * @return {Object} Save options for submission to the MediaWiki API
 */
ve.init.mw.ArticleTarget.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 ];
		}
	}

	return options;
};

/**
 * Post DOM data to the Parsoid API.
 *
 * This method performs an asynchronous action and uses a callback function to handle the result.
 *
 *     target.save( dom, { summary: 'test', minor: true, watch: false } );
 *
 * @method
 * @param {HTMLDocument} doc Document to save
 * @param {Object} options Saving options. All keys are passed through, including unrecognized ones.
 *  - {string} summary Edit summary
 *  - {boolean} minor Edit is a minor edit
 *  - {boolean} watch Watch the page
 * @param {boolean} [isRetry=false] Whether this is a retry after a 'badtoken' error
 * @return {boolean} Saving has been started
*/
ve.init.mw.ArticleTarget.prototype.save = function ( doc, options, isRetry ) {
	var data;
	// Prevent duplicate requests
	if ( this.saving ) {
		return false;
	}

	data = ve.extendObject( {}, options, {
		action: 'visualeditoredit',
		paction: 'save',
		page: this.getPageName(),
		oldid: this.revid,
		basetimestamp: this.baseTimeStamp,
		starttimestamp: this.startTimeStamp,
		etag: this.etag,
		// Pass in token to prevent automatic badtoken retries
		token: this.editToken
	} );

	this.saving = this.tryWithPreparedCacheKey( doc, data, 'save' )
		.done( this.saveSuccess.bind( this, doc, data ) )
		.fail( this.saveFail.bind( this, doc, data, !!isRetry ) );

	return true;
};

/**
 * Show changes in the save dialog
 *
 * @param {Object} doc Document
 */
ve.init.mw.ArticleTarget.prototype.showChanges = function ( doc ) {
	var target = this;
	// Invalidate the viewer diff on next change
	this.getSurface().getModel().getDocument().once( 'transact', function () {
		target.clearDiff();
	} );
	this.saveDialog.setDiffAndReview(
		this.getWikitextDiffPromise( doc ),
		this.getVisualDiffGeneratorPromise(),
		this.getSurface().getModel().getDocument().getHtmlDocument()
	);
};

/**
 * Clear all state associated with the diff
 */
ve.init.mw.ArticleTarget.prototype.clearDiff = function () {
	if ( this.saveDialog ) {
		this.saveDialog.clearDiff();
	}
	this.wikitextDiffPromise = null;
};

/**
 * Post DOM data to the Parsoid API to retrieve wikitext diff.
 *
 * @method
 * @param {HTMLDocument} doc Document to compare against (via wikitext)
 * @return {jQuery.Promise} Promise which resolves with the wikitext diff, or rejects with an error
 * @fires showChanges
 * @fires showChangesError
*/
ve.init.mw.ArticleTarget.prototype.getWikitextDiffPromise = function ( doc ) {
	var target = this;
	if ( !this.wikitextDiffPromise ) {
		this.wikitextDiffPromise = this.tryWithPreparedCacheKey( doc, {
			action: 'visualeditoredit',
			paction: 'diff',
			page: this.getPageName(),
			oldid: this.revid,
			etag: this.etag
		}, 'diff' ).then( function ( response ) {
			var data = response.visualeditoredit;
			if ( !data && !response.error ) {
				return $.Deferred().reject( 'Invalid response from server' ).promise();
			} else if ( response.error ) {
				return $.Deferred().reject( response.error.info ).promise();
			} else if ( data.result === 'nochanges' ) {
				target.emit( 'noChanges' );
				return null;
			} else if ( data.result !== 'success' ) {
				return $.Deferred().reject( 'Failed request: ' + data.result ).promise();
			} else if ( typeof data.diff !== 'string' ) {
				return $.Deferred().reject( 'Invalid HTML content in response from server' ).promise();
			} else {
				return data.diff;
			}
		} );
		this.wikitextDiffPromise
			.done( this.emit.bind( this, 'showChanges' ) )
			.fail( this.emit.bind( this, 'showChangesError' ) );
	}
	return this.wikitextDiffPromise;
};

/**
 * Post wikitext to MediaWiki.
 *
 * This method performs a synchronous action and will take the user to a new page when complete.
 *
 *     target.submit( wikitext, { wpSummary: 'test', wpMinorEdit: 1, wpSave: 1 } );
 *
 * @method
 * @param {string} wikitext Wikitext to submit
 * @param {Object} fields Other form fields to add (e.g. wpSummary, wpWatchthis, etc.). To actually
 *  save the wikitext, add { wpSave: 1 }. To go to the diff view, add { wpDiff: 1 }.
 * @return {boolean} Submitting has been started
*/
ve.init.mw.ArticleTarget.prototype.submit = function ( wikitext, fields ) {
	var key, $form, params;

	// Prevent duplicate requests
	if ( this.submitting ) {
		return false;
	}
	// Save DOM
	this.submitting = true;
	$form = $( '<form>' ).attr( { method: 'post', enctype: 'multipart/form-data' } ).addClass( 'oo-ui-element-hidden' );
	params = ve.extendObject( {
		format: 'text/x-wiki',
		model: 'wikitext',
		oldid: this.requestedRevId,
		wpStarttime: this.startTimeStamp,
		wpEdittime: this.baseTimeStamp,
		wpTextbox1: wikitext,
		wpUnicodeCheck: 'ℳ𝒲♥𝓊𝓃𝒾𝒸ℴ𝒹ℯ',
		wpEditToken: this.editToken
	}, fields );
	// Add params as hidden fields
	for ( key in params ) {
		$form.append( $( '<input>' ).attr( { type: 'hidden', name: key, value: params[ key ] } ) );
	}
	// Submit the form, mimicking a traditional edit
	// Firefox requires the form to be attached
	$form.attr( 'action', this.submitUrl ).appendTo( 'body' ).submit();
	return true;
};

/**
 * Get Wikitext data from the Parsoid API.
 *
 * This method performs an asynchronous action and uses a callback function to handle the result.
 *
 *     target.serialize(
 *         dom,
 *         function ( wikitext ) {
 *             // Do something with the loaded DOM
 *         }
 *     );
 *
 * @method
 * @param {HTMLDocument} doc Document to serialize
 * @param {Function} callback Function to call when complete, accepts error and wikitext arguments
 * @return {boolean} Serializing has been started
*/
ve.init.mw.ArticleTarget.prototype.serialize = function ( doc, callback ) {
	// Prevent duplicate requests
	if ( this.serializing ) {
		return false;
	}
	this.serializeCallback = callback;
	this.serializing = this.tryWithPreparedCacheKey( doc, {
		action: 'visualeditoredit',
		paction: 'serialize',
		page: this.getPageName(),
		oldid: this.revid,
		etag: this.etag
	}, 'serialize' )
		.done( this.serializeSuccess.bind( this ) )
		.fail( this.serializeFail.bind( this ) );
	return true;
};

/**
 * Get list of edit notices.
 *
 * @return {Array} List of edit notices
 */
ve.init.mw.ArticleTarget.prototype.getEditNotices = function () {
	return this.editNotices;
};

// FIXME: split out view specific functionality, emit to subclass

/**
 * @inheritdoc
 */
ve.init.mw.ArticleTarget.prototype.track = function ( name ) {
	var mode = this.surface ? this.surface.getMode() : this.getDefaultMode();
	ve.track( name, { mode: mode } );
};

/**
 * @inheritdoc
 */
ve.init.mw.ArticleTarget.prototype.createSurface = function () {
	// Parent method
	var surface = ve.init.mw.ArticleTarget.super.prototype.createSurface.apply( this, arguments );

	surface.$element.addClass( this.protectedClasses );

	return surface;
};

/**
 * @inheritdoc
 */
ve.init.mw.ArticleTarget.prototype.teardown = function () {
	var surface = this.getSurface();
	// Restore access keys
	if ( this.$saveAccessKeyElements ) {
		this.$saveAccessKeyElements.attr( 'accesskey', ve.msg( 'accesskey-save' ) );
		this.$saveAccessKeyElements = null;
	}
	if ( surface ) {
		// If target is closed cleanly (after save or deliberate close) then remove autosave state
		surface.getModel().removeDocStateAndChanges();
		// Disconnect history listener
		surface.getModel().disconnect( this );
	}
	return ve.init.mw.ArticleTarget.super.prototype.teardown.call( this );
};

/**
 * Try to tear down the target, but leave ready for re-activation later
 *
 * Will first prompt the user if required, then call #teardown.
 *
 * @param {boolean} [noPrompt] Do not display a prompt to the user
 * @param {string} [trackMechanism] Abort mechanism; used for event tracking if present
 * @return {jQuery.Promise} Promise which resolves when the target has been torn down
 */
ve.init.mw.ArticleTarget.prototype.tryTeardown = function ( noPrompt, trackMechanism ) {
	var target = this;

	if ( noPrompt || !this.edited ) {
		return this.teardown( trackMechanism );
	} else {
		return this.getSurface().dialogs.openWindow( 'cancelconfirm' )
			.closed.then( function ( data ) {
				if ( data && data.action === 'discard' ) {
					return target.teardown( trackMechanism );
				}
				return $.Deferred().reject().promise();
			} );
	}
};

/**
 * @inheritdoc
 */
ve.init.mw.ArticleTarget.prototype.setupToolbar = function () {
	// Parent method
	ve.init.mw.ArticleTarget.super.prototype.setupToolbar.apply( this, arguments );

	this.setupToolbarSaveButton();
	this.attachToolbarSaveButton();

	if ( this.saveDialog ) {
		this.editSummaryValue = this.saveDialog.editSummaryInput.getValue();
		this.saveDialog.disconnect( this );
		this.saveDialog = null;
	}
};

/**
 * Getting the message for the toolbar / save dialog save / publish button
 *
 * @param {boolean} [startProcess] Use version of the label for starting that process, i.e. with an ellipsis after it
 * @return {Function|string} An i18n message or resolveable function
 */
ve.init.mw.ArticleTarget.prototype.getSaveButtonLabel = function ( startProcess ) {
	var suffix = startProcess ? '-start' : '';
	// The following messages can be used here
	// * publishpage
	// * pubishhpage-start
	// * publishchanges
	// * pubishhchanges-start
	// * savearticle
	// * savearticle-start
	// * savechanges
	// * savechanges-start
	if ( mw.config.get( 'wgEditSubmitButtonLabelPublish' ) ) {
		return OO.ui.deferMsg( ( !this.pageExists ? 'publishpage' : 'publishchanges' ) + suffix );
	}

	return OO.ui.deferMsg( ( !this.pageExists ? 'savearticle' : 'savechanges' ) + suffix );
};

/**
 * Add content and event bindings to toolbar save button.
 *
 * @param {Object} [config] Configuration options for the button
 */
ve.init.mw.ArticleTarget.prototype.setupToolbarSaveButton = function ( config ) {
	if ( !this.toolbarSaveButton ) {
		this.toolbarSaveButton = new OO.ui.ButtonWidget( ve.extendObject( {
			label: this.getSaveButtonLabel( true ),
			flags: [ 'progressive', 'primary' ],
			disabled: !this.restoring
		}, config ) );

		// 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.$saveAccessKeyElements = $( '[accesskey="' + ve.msg( 'accesskey-save' ) + '"]' ).removeAttr( 'accesskey' );
			this.toolbarSaveButton.$button.attr( 'accesskey', ve.msg( 'accesskey-save' ) );
		}

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

/**
 * Add the save button to the user interface.
 */
ve.init.mw.ArticleTarget.prototype.attachToolbarSaveButton = function () {
	this.toolbar.$actions.append( this.toolbarSaveButton.$element );
};

/**
 * Re-evaluate whether the article can be saved
 *
 * @return {boolean} The article can be saved
 */
ve.init.mw.ArticleTarget.prototype.isSaveable = function () {
	var surface = this.getSurface();
	if ( !surface ) {
		// Called before we're attached, so meaningless; abandon for now
		return false;
	}

	this.edited =
		// Document was edited before loading
		this.fromEditedState || this.preloaded ||
		// Document was edited
		surface.getModel().hasBeenModified() ||
		// Section title (if it exists) was edited
		( this.sectionTitle && this.sectionTitle.getValue() !== '' );

	return this.edited || this.restoring;
};

/**
 * Update the toolbar save button to reflect if the article can be saved
 */
ve.init.mw.ArticleTarget.prototype.updateToolbarSaveButtonState = function () {
	// Disable the save button if we can't save
	var wasDisabled = this.toolbarSaveButton.isDisabled(),
		isDisabled = !this.isSaveable();
	if ( wasDisabled !== isDisabled ) {
		this.toolbarSaveButton.setDisabled( isDisabled );
		mw.hook( 've.toolbarSaveButton.stateChanged' ).fire( isDisabled );
	}
};

/**
 * Handle clicks on the save button in the toolbar.
 */
ve.init.mw.ArticleTarget.prototype.onToolbarSaveButtonClick = function () {
	this.showSaveDialog();
};

/**
 * Show a save dialog
 *
 * @param {string} [action] Window action to trigger after opening
 * @param {string} [checkboxName] Checkbox to toggle after opening
 *
 * @fires saveWorkflowBegin
 */
ve.init.mw.ArticleTarget.prototype.showSaveDialog = function ( action, checkboxName ) {
	var checkbox, currentWindow,
		target = this;

	if ( !this.isSaveable() ) {
		return;
	}

	currentWindow = this.getSurface().getDialogs().getCurrentWindow();
	if ( currentWindow && currentWindow.constructor.static.name === 'mwSave' && ( action === 'save' || action === null ) ) {
		// The current window is the save dialog, and we've gotten here via
		// the save action. Trigger a save. We're doing this here instead of
		// relying on an accesskey on the save button, because that has some
		// cross-browser issues that makes it not work in Firefox.
		currentWindow.executeAction( 'save' );
		return;
	}

	this.emit( 'saveWorkflowBegin' );

	// Preload the serialization
	this.prepareCacheKey( this.getDocToSave() );

	// Get the save dialog
	this.getSurface().getDialogs().getWindow( 'mwSave' ).done( function ( win ) {
		var data, checked,
			windowAction = ve.ui.actionFactory.create( 'window', target.getSurface() );

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

			// Connect to save dialog
			target.saveDialog.connect( target, {
				save: 'onSaveDialogSave',
				review: 'onSaveDialogReview',
				preview: 'onSaveDialogPreview',
				resolve: 'onSaveDialogResolveConflict',
				retry: 'onSaveDialogRetry',
				close: 'onSaveDialogClose'
			} );
		}

		data = target.getSaveDialogOpeningData();

		if (
			( action === 'review' && !data.canReview ) ||
			( action === 'preview' && !data.canPreview )
		) {
			return;
		}

		if ( checkboxName && ( checkbox = target.checkboxesByName[ checkboxName ] ) ) {
			checked = !checkbox.isSelected();
			// Wait for native access key change to happen
			setTimeout( function () {
				checkbox.setSelected( checked );
			} );
		}

		// When calling review/preview action, switch to those panels immediately
		if ( action === 'review' || action === 'preview' ) {
			data.initialPanel = action;
		}

		// Open the dialog
		windowAction.open( 'mwSave', data, action );
	} );
};

/**
 * Get opening data to pass to the save dialog
 */
ve.init.mw.ArticleTarget.prototype.getSaveDialogOpeningData = function () {
	var mode = this.getSurface().getMode();
	return {
		canPreview: mode === 'source',
		canReview: !( mode === 'source' && this.section === 'new' ),
		sectionTitle: this.sectionTitle && this.sectionTitle.getValue(),
		saveButtonLabel: this.getSaveButtonLabel(),
		checkboxFields: this.checkboxFields,
		checkboxesByName: this.checkboxesByName
	};
};

/**
 * Move the cursor in the editor to section specified by this.section.
 * Do nothing if this.section is undefined.
 *
 * @method
 */
ve.init.mw.ArticleTarget.prototype.restoreEditSection = function () {
	var headingText,
		section,
		surface = this.getSurface(),
		mode = surface.getMode(),
		surfaceView, $documentNode, $section, headingNode;

	if ( this.section !== null && this.section !== 'new' && this.section !== 0 && this.section !== 'T-0' ) {
		if ( mode === 'visual' ) {
			// Get numerical part of section (strip 'T-'' if present)
			section = this.section.toString().indexOf( 'T-' ) === 0 ? +this.section.slice( 2 ) : this.section;
			surfaceView = surface.getView();
			$documentNode = surfaceView.getDocument().getDocumentNode().$element;
			// Find all headings including those inside templates, not just HeadingNodes
			$section = $documentNode.find( 'h1, h2, h3, h4, h5, h6' )
				// Ignore headings inside TOC
				.filter( function () {
					return $( this ).closest( '.ve-ui-mwTocWidget' ).length === 0;
				} )
				.eq( section - 1 );
			headingNode = $section.data( 'view' );

			if ( $section.length && new mw.Uri().query.summary === undefined ) {
				// Due to interactions with Translate, strip out mw-
				// editsection from the heading.
				headingText = $section.clone().find( 'span.mw-editsection' ).remove().end().text();
			}

			if ( headingNode ) {
				this.goToHeading( headingNode );
			}
		} else if ( mode === 'source' ) {
			// With elements of extractSectionTitle + stripSectionName TODO:
			// Arguably, we should just throw this through the API and then do
			// the same extract-text pass we do in visual mode. Would save us
			// having to think about wikitext here.
			headingText = surface.getModel().getDocument().data.getText(
				false,
				surface.getModel().getDocument().getDocumentNode().children[ 0 ].getRange()
			)
				// Extract the title
				.replace( /^\s*=+\s*(.*?)\s*=+\s*$/, '$1' )
				// Remove links
				.replace( /\[\[:?([^[|]+)\|([^[]+)\]\]/, '$2' )
				.replace( /\[\[:?([^[]+)\|?\]\]/, '$1' )
				.replace( new RegExp( '\\[(?:' + ve.init.platform.getUnanchoredExternalLinkUrlProtocolsRegExp().source + ')([^ ]+?) ([^\\[]+)\\]', 'i' ), '$3' )
				// Cheap HTML removal
				.replace( /<[^>]+?>/g, '' )
			;
		}
		if ( headingText ) {
			this.initialEditSummary =
				'/* ' +
				ve.graphemeSafeSubstring( headingText, 0, 244 ) +
				' */ ';
		}
	}
};

/**
 * Move the cursor to a given heading and scroll to it.
 *
 * @method
 * @param {ve.ce.HeadingNode} headingNode Heading node to scroll to
 */
ve.init.mw.ArticleTarget.prototype.goToHeading = function ( headingNode ) {
	var nextNode, offset,
		target = this,
		offsetNode = headingNode,
		surface = this.getSurface(),
		surfaceModel = surface.getModel(),
		surfaceView = surface.getView(),
		lastHeadingLevel = -1;

	// Find next sibling which isn't a heading
	while ( offsetNode instanceof ve.ce.HeadingNode && offsetNode.getModel().getAttribute( 'level' ) > lastHeadingLevel ) {
		lastHeadingLevel = offsetNode.getModel().getAttribute( 'level' );
		// Next sibling
		nextNode = offsetNode.parent.children[ offsetNode.parent.children.indexOf( offsetNode ) + 1 ];
		if ( !nextNode ) {
			break;
		}
		offsetNode = nextNode;
	}
	offset = surfaceModel.getDocument().data.getNearestContentOffset(
		offsetNode.getModel().getOffset(), 1
	);

	function scrollAndSetSelection() {
		surfaceModel.setLinearSelection( new ve.Range( offset ) );
		// Focussing the document triggers showSelection which calls scrollIntoView
		// which uses a jQuery animation, so make sure this is aborted.
		$( OO.ui.Element.static.getClosestScrollableContainer( surfaceView.$element[ 0 ] ) ).stop( true );
		target.scrollToHeading( headingNode );
	}

	if ( surfaceView.isFocused() ) {
		scrollAndSetSelection();
	} else {
		// onDocumentFocus is debounced, so wait for that to happen before setting
		// the model selection, otherwise it will get reset
		surfaceView.once( 'focus', scrollAndSetSelection );
	}
};

/**
 * Scroll to a given heading in the document.
 *
 * @method
 * @param {ve.ce.HeadingNode} headingNode Heading node to scroll to
 */
ve.init.mw.ArticleTarget.prototype.scrollToHeading = function ( headingNode ) {
	var $window = $( OO.ui.Element.static.getWindow( this.$element ) );

	$window.scrollTop( headingNode.$element.offset().top - this.getToolbar().$element.height() );
};

/**
 * Show the beta dialog as needed
 */
ve.init.mw.ArticleTarget.prototype.maybeShowWelcomeDialog = function () {
	var usePrefs, prefSaysShow, urlSaysHide,
		windowManager = this.getSurface().dialogs,
		target = this;

	this.welcomeDialogPromise = $.Deferred();

	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 new mw.Uri( location.href ).query;

		if (
			!urlSaysHide &&
			(
				prefSaysShow ||
				(
					!usePrefs &&
					mw.storage.get( 've-beta-welcome-dialog' ) === null &&
					$.cookie( 've-beta-welcome-dialog' ) === null
				)
			)
		) {
			this.welcomeDialog = new mw.libs.ve.WelcomeDialog();
			windowManager.addWindows( [ this.welcomeDialog ] );
			windowManager.openWindow(
				this.welcomeDialog,
				{
					switchable: this.constructor.static.trackingName !== 'mobile',
					editor: this.getDefaultMode()
				}
			)
				.closed.then( function ( data ) {
					target.welcomeDialogPromise.resolve();
					target.welcomeDialog = null;
					// switchToWikitextEditor and switchToVisualEditor are actually
					// only defined in subclasses :/
					if ( data && data.action === 'switch-wte' ) {
						// TODO: Make this work on mobile - right now we can only
						// get away with it because the button which triggers this
						// action is hidden on mobile
						target.switchToWikitextEditor( true, true );
					} else if ( data && data.action === 'switch-ve' ) {
						target.switchToVisualEditor();
					}
				} );
		} else {
			this.welcomeDialogPromise.resolve();
		}

		if ( prefSaysShow ) {
			ve.init.target.getLocalApi().saveOption( 'visualeditor-hidebetawelcome', '1' );
			mw.user.options.set( 'visualeditor-hidebetawelcome', '1' );

			// 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 ) {
			if ( !mw.storage.set( 've-beta-welcome-dialog', 1 ) ) {
				$.cookie( 've-beta-welcome-dialog', 1, { path: '/', expires: 30 } );
			}
		}
	} else {
		this.welcomeDialogPromise.reject();
	}
};

/**
 * Switches to the wikitext editor, either keeping (default) or discarding changes.
 *
 * @param {boolean} [discardChanges] Whether to discard changes or not.
 * @param {boolean} [modified] Whether there were any changes at all.
 * @param {boolean} [leaveVE] Leave VE, even if source mode is available
 */
ve.init.mw.ArticleTarget.prototype.switchToWikitextEditor = function ( discardChanges, modified, leaveVE ) {
	var dataPromise,
		target = this;

	// We may have this.section but VE is always full page at the moment
	this.section = null;

	if ( ve.init.target.isModeAvailable( 'source' ) && !leaveVE ) {
		if ( discardChanges ) {
			dataPromise = mw.libs.ve.targetLoader.requestPageData( 'source', this.getPageName(), {
				sessionStore: true,
				section: this.section,
				oldId: this.requestedRevId,
				targetName: this.constructor.static.trackingName
			} ).then(
				function ( response ) { return response; },
				function () {
					// TODO: Some sort of progress bar?
					target.switchToWikitextEditor( discardChanges, modified, true );
					// Keep everything else waiting so our error handler can do its business
					return $.Deferred().promise();
				}
			);
		} else {
			this.serialize( this.getDocToSave() );
			dataPromise = this.serializing.then( function ( response ) {
				// HACK - add parameters the API doesn't provide for a VE->WT switch
				var data = response.visualeditoredit;
				data.etag = target.etag;
				data.fromEditedState = modified;
				data.notices = target.remoteNotices;
				data.protectedClasses = target.protectedClasses;
				data.basetimestamp = target.baseTimeStamp;
				data.starttimestamp = target.startTimeStamp;
				data.oldid = target.revid;
				data.checkboxesDef = target.checkboxesDef;
				return response;
			} );
		}
		this.reloadSurface( 'source', dataPromise );
	} else {
		this.switchToFallbackWikitextEditor( discardChanges, modified );
	}
};

/**
 * Switches to the fallback wikitext editor, either keeping (default) or discarding changes.
 *
 * @param {boolean} [discardChanges] Whether to discard changes or not.
 * @param {boolean} [modified] Whether there were any changes at all.
 */
ve.init.mw.ArticleTarget.prototype.switchToFallbackWikitextEditor = function () {
	// Assume the fallback editor won't support VE auto-save. Changes need to
	// be wiped in case the user makes changes in the other editor then comes
	// back to VE.
	this.getSurface().getModel().removeDocStateAndChanges();
};

/**
 * Switch to the visual editor.
 */
ve.init.mw.ArticleTarget.prototype.switchToVisualEditor = function () {
	var dataPromise, windowManager, switchWindow,
		target = this;

	// Show a discard-only confirm dialog, and then reload the whole page, if:
	if (
		// * section editing in WT, as WT -> VE is not yet supported, or
		this.section !== null ||
		// * the server can't switch for us because that's not supported.
		!mw.config.get( 'wgVisualEditorConfig' ).fullRestbaseUrl
	) {
		windowManager = new OO.ui.WindowManager();
		switchWindow = new mw.libs.ve.SwitchConfirmDialog();
		$( 'body' ).append( windowManager.$element );
		windowManager.addWindows( [ switchWindow ] );
		windowManager.openWindow( switchWindow, { mode: 'simple' } )
			.closed.then( function ( data ) {
				if ( data && data.action === 'discard' ) {
					target.section = null;
					target.reloadSurface( 'visual' );
				}
				windowManager.destroy();
			} );
	} else {
		dataPromise = mw.libs.ve.targetLoader.requestParsoidData( this.getPageName(), {
			oldId: this.revid,
			targetName: this.constructor.static.trackingName,
			modified: this.edited,
			wikitext: this.getDocToSave()
		} );

		this.reloadSurface( 'visual', dataPromise );
	}
};

/**
 * Switch to a different wikitext section
 *
 * @param {number|string|null} section New section, number, 'new' or null (whole document)
 * @param {boolean} noConfirm Swtich without prompting (changes will be lost either way)
 */
ve.init.mw.ArticleTarget.prototype.switchToWikitextSection = function ( section, noConfirm ) {
	var promise,
		target = this;
	if ( section === this.section ) {
		return;
	}
	if ( !noConfirm && this.edited && mw.user.options.get( 'useeditwarning' ) ) {
		promise = OO.ui.confirm( mw.msg( 'visualeditor-viewpage-savewarning' ) );
	} else {
		promise = $.Deferred().resolve( true ).promise();
	}
	promise.then( function ( confirmed ) {
		if ( confirmed ) {
			target.section = section;
			target.reloadSurface( 'source' );
			target.updateTabs( true );
		}
	} );
};

/**
 * Reload the target surface in the new editor mode
 *
 * @param {string} newMode New mode
 * @param {jQuery.Promise} [dataPromise] Data promise, if any
 */
ve.init.mw.ArticleTarget.prototype.reloadSurface = function ( newMode, dataPromise ) {
	this.setDefaultMode( newMode );
	this.clearDiff();
	// Create progress - will be discarded when surface is destroyed.
	this.getSurface().createProgress(
		$.Deferred().promise(),
		ve.msg( newMode === 'source' ? 'visualeditor-mweditmodesource-progress' : 'visualeditor-mweditmodeve-progress' ),
		true /* non-cancellable */
	);
	this.load( dataPromise );
};

/**
 * Display the given redirect subtitle and redirect page content header on the page.
 *
 * @param {jQuery} $sub Redirect subtitle, see #buildRedirectSub
 * @param {jQuery} $msg Redirect page content header, see #buildRedirectMsg
 */
ve.init.mw.ArticleTarget.prototype.updateRedirectInterface = function ( $sub, $msg ) {
	var $currentSub, $currentMsg, $subtitle,
		target = this;

	// For the subtitle, replace the real one with ours.
	// This is more complicated than it should be because we have to fiddle with the <br>.
	$currentSub = $( '#redirectsub' );
	if ( $currentSub.length ) {
		if ( $sub.length ) {
			$currentSub.replaceWith( $sub );
		} else {
			$currentSub.prev().filter( 'br' ).remove();
			$currentSub.remove();
		}
	} else {
		$subtitle = $( '#contentSub' );
		if ( $sub.length ) {
			if ( $subtitle.children().length ) {
				$subtitle.append( $( '<br>' ) );
			}
			$subtitle.append( $sub );
		}
	}

	if ( $msg.length ) {
		$msg
			// We need to be able to tell apart the real one and our fake one
			.addClass( 've-redirect-header' )
			.on( 'click', function ( e ) {
				var windowAction = ve.ui.actionFactory.create( 'window', target.getSurface() );
				windowAction.open( 'meta', { page: 'settings' } );
				e.preventDefault();
			} );
	}
	// For the content header, the real one is hidden, insert ours before it.
	$currentMsg = $( '.ve-redirect-header' );
	if ( $currentMsg.length ) {
		$currentMsg.replaceWith( $msg );
	} else {
		// Hack: This is normally inside #mw-content-text, but that's hidden while editing.
		$( '#mw-content-text' ).before( $msg );
	}
};

/**
 * Render a list of categories
 *
 * @param {ve.dm.MetaItem[]} categoryItems Array of category metaitems to display
 * @return {jQuery.Promise} A promise which will be resolved with the rendered categories
 */
ve.init.mw.ArticleTarget.prototype.renderCategories = function ( categoryItems ) {
	var $normal, $hidden,
		promises = [],
		categories = { hidden: [], normal: [] };
	categoryItems.forEach( function ( categoryItem ) {
		var attributes = ve.cloneObject( ve.getProp( categoryItem, 'element', 'attributes' ) );
		promises.push( ve.init.platform.linkCache.get( attributes.category ).done( function ( result ) {
			if ( result.hidden ) {
				categories.hidden.push( attributes );
			} else {
				categories.normal.push( attributes );
			}
		} ) );
	} );
	return $.when.apply( $, promises ).then( function () {
		var $output = $( '<div class="catlinks" />' );
		function renderPageLink( page ) {
			var title = mw.Title.newFromText( page.category || page );
			return $( '<a>' ).attr( 'rel', 'mw:WikiLink' ).attr( 'href', title.getUrl() ).text( title.getMainText() );
		}
		function renderPageLinks( pages ) {
			var i, $list = $( '<ul />' );
			for ( i = 0; i < pages.length; i++ ) {
				$list.append( $( '<li />' ).append( renderPageLink( pages[ i ] ) ) );
			}
			return $list;
		}
		function categorySort( a, b ) {
			var sortA = a.sortkey || a.category,
				sortB = b.sortkey || b.category;
			if ( sortA < sortB ) {
				return -1;
			}
			if ( sortA > sortB ) {
				return 1;
			}
			return 0;
		}
		if ( categories.normal.length ) {
			categories.normal.sort( categorySort );
			$normal = $( '<div class="mw-normal-catlinks" />' );
			$normal.append(
				renderPageLink( ve.msg( 'pagecategorieslink' ) ).text( ve.msg( 'pagecategories', categories.normal.length ) ),
				ve.msg( 'colon-separator' ),
				renderPageLinks( categories.normal )
			);
			$output.append( $normal );
		}
		if ( categories.hidden.length ) {
			categories.hidden.sort( categorySort );
			$hidden = $( '<div class="mw-hidden-catlinks" />' );
			if ( mw.user.options.get( 'showhiddencats' ) ) {
				$hidden.addClass( 'mw-hidden-cats-user-shown' );
			} else if ( mw.config.get( 'wgNamespaceIds' ).category === mw.config.get( 'wgNamespaceNumber' ) ) {
				$hidden.addClass( 'mw-hidden-cats-ns-shown' );
			} else {
				$hidden.addClass( 'mw-hidden-cats-hidden' );
			}
			$hidden.append(
				ve.msg( 'hidden-categories', categories.hidden.length ),
				ve.msg( 'colon-separator' ),
				renderPageLinks( categories.hidden )
			);
			$output.append( $hidden );
		}
		return $output;
	} );
};