/*!
 * VisualEditor MediaWiki DesktopArticleTarget init.
 *
 * This file must remain as widely compatible as the base compatibility
 * for MediaWiki itself (see mediawiki/core:/resources/startup.js).
 * Avoid use of: ES5, SVG, HTML5 DOM, ContentEditable etc.
 *
 * @copyright 2011-2015 VisualEditor Team and others; see AUTHORS.txt
 * @license The MIT License (MIT); see LICENSE.txt
 */

/**
 * Platform preparation for the MediaWiki view page. This loads (when user needs it) the
 * actual MediaWiki integration and VisualEditor library.
 *
 * @class mw.libs.ve
 * @alternateClassName ve.init.mw.DesktopArticleTarget.init
 * @singleton
 */
( function () {
	var conf, tabMessages, uri, pageExists, viewUri, veEditUri, isViewPage, isEditPage,
		pageCanLoadVE, init, support, targetPromise, enable, tempdisable, autodisable,
		userPrefEnabled, initialWikitext,
		active = false,
		progressStep = 0,
		progressSteps = [
			[ 30, 3000 ],
			[ 70, 2000 ],
			[ 100, 1000 ]
		],
		plugins = [];

	function showLoading() {
		var $content, contentRect, offsetTop, windowHeight, top, bottom, middle;

		if ( !init.$loading ) {
			init.$loading = $(
				'<div class="ve-init-mw-desktopArticleTarget-loading-overlay">' +
					'<div class="ve-init-mw-desktopArticleTarget-progress">' +
						// Stylesheets might not have processed yet, so manually set starting width to 0
						'<div class="ve-init-mw-desktopArticleTarget-progress-bar" style="width: 0;"></div>' +
					'</div>' +
				'</div>'
			);
		}

		$content = $( '#content' );
		contentRect = $content[ 0 ].getBoundingClientRect();
		offsetTop = $content.offset().top;
		windowHeight = $( window ).height();
		top = Math.max( contentRect.top, 0 );
		bottom = Math.min( contentRect.bottom, windowHeight );
		middle = ( top + bottom ) / 2;

		init.$loading.css( 'top', middle - offsetTop );

		$content.prepend( init.$loading );
	}

	function incrementLoadingProgress() {
		var step = progressSteps[ progressStep ];
		setLoadingProgress( step[ 0 ], step[ 1 ] );
		progressStep++;
	}

	function resetLoadingProgress() {
		progressStep = 0;
		setLoadingProgress( 0, 0 );
	}

	function setLoadingProgress( target, duration ) {
		var $bar = init.$loading.find( '.ve-init-mw-desktopArticleTarget-progress-bar' ).stop();
		$bar.css( 'transition', 'width ' + duration + 'ms ease-in' );
		setTimeout( function () {
			$bar.css( 'width', target + '%' );
		} );
	}

	function hideLoading() {
		if ( init.$loading ) {
			init.$loading.detach();
		}
	}

	/**
	 * Use deferreds to avoid loading and instantiating Target multiple times.
	 *
	 * @private
	 * @return {jQuery.Promise}
	 */
	function getTarget() {
		if ( !targetPromise ) {
			// The TargetLoader module is loaded in the bottom queue, so it should have been
			// requested already but it might not have finished loading yet
			targetPromise = mw.loader.using( 'ext.visualEditor.targetLoader' )
				.then( function () {
					mw.libs.ve.targetLoader.addPlugin( function () {
						// If the user and site modules fail, we still want to continue
						// loading, so convert failure to success

						return mw.loader.using( [ 'user', 'site' ] ).then(
							null,
							function () {
								return $.Deferred().resolve();
							}
						);
					} );
					// Add modules specific to desktop (modules shared between desktop
					// and mobile are already added by TargetLoader)
					// Note: it's safe to use .forEach() (ES5) here, because this code will
					// never be called if the browser doesn't support ES5
					[
						'ext.visualEditor.desktopArticleTarget',
						'ext.visualEditor.mwimage',
						'ext.visualEditor.mwmeta'
					].forEach( mw.libs.ve.targetLoader.addPlugin );
					// Add requested plugins
					plugins.forEach( mw.libs.ve.targetLoader.addPlugin );
					plugins = [];
					return mw.libs.ve.targetLoader.loadModules();
				} )
				.then( function () {
					var target;

					// Transfer methods
					ve.init.mw.DesktopArticleTarget.prototype.setupSectionEditLinks = init.setupSectionLinks;

					target = new ve.init.mw.DesktopArticleTarget();
					$( '#content' ).append( target.$element );
					return target;
				}, function ( e ) {
					mw.log.warn( 'VisualEditor failed to load: ' + e );
				} );
		}

		targetPromise.then( function () {
			// Enqueue the loading of deferred modules (that is, modules which provide
			// functionality that is not needed for loading the editor).
			setTimeout( function () {
				mw.loader.load( 'easy-deflate.deflate' );
			}, 500 );
		} );

		return targetPromise;
	}

	function activatePageTarget( modified ) {
		trackActivateStart( { type: 'page', mechanism: 'click' } );

		if ( !active ) {
			if ( $( '#ca-edit a' ).data( 'original-text' ) ) {
				$( '#ca-edit a' ).text( $( '#ca-edit a' ).data( 'original-text' ) );
			}

			if ( uri.query.action !== 'edit' ) {
				if ( history.pushState ) {
					// Replace the current state with one that is tagged as ours, to prevent the
					// back button from breaking when used to exit VE. FIXME: there should be a better
					// way to do this. See also similar code in the DesktopArticleTarget constructor.
					history.replaceState( { tag: 'visualeditor' }, document.title, uri );
					// Set veaction to edit
					history.pushState( { tag: 'visualeditor' }, document.title, veEditUri );
				}

				// Update mw.Uri instance
				uri = veEditUri;
			}

			activateTarget( null, modified );
		}
	}

	/**
	 * Load and activate the target.
	 *
	 * If you need to call methods on the target before activate is called, call getTarget()
	 * yourself, chain your work onto that promise, and pass that chained promise in as targetPromise.
	 * E.g. `activateTarget( getTarget().then( function( target ) { target.doAThing(); } ) );`
	 *
	 * @private
	 * @param {jQuery.Promise} [targetPromise] Promise that will be resolved with a ve.init.mw.DesktopArticleTarget
	 * @param {boolean} [modified] The page was been modified before loading (e.g. in source mode)
	 */
	function activateTarget( targetPromise, modified ) {
		// The TargetLoader module is loaded in the bottom queue, so it should have been
		// requested already but it might not have finished loading yet
		var dataPromise = mw.loader.using( 'ext.visualEditor.targetLoader' )
			.then( function () {
				return mw.libs.ve.targetLoader.requestPageData(
					mw.config.get( 'wgRelevantPageName' ),
					uri.query.oldid || $( 'input[name=parentRevId]' ).val(),
					'mwTarget', // ve.init.mw.DesktopArticleTarget.static.name
					modified
				);
			} )
			.done( function () {
				incrementLoadingProgress();
			} );

		setEditorPreference( 'visualeditor' );

		$( 'html' ).addClass( 've-activated ve-loading' );
		showLoading();
		incrementLoadingProgress();
		active = true;

		targetPromise = targetPromise || getTarget();
		targetPromise
			.then( function ( target ) {
				incrementLoadingProgress();
				target.on( 'deactivate', function () {
					active = false;
				} );
				target.on( 'loadError', function () {
					resetLoadingProgress();
				} );
				return target.activate( dataPromise );
			} )
			.then( function () {
				resetLoadingProgress();
				ve.track( 'mwedit.ready' );
			} )
			.always( hideLoading );
	}

	function trackActivateStart( initData ) {
		ve.track( 'trace.activate.enter' );
		ve.track( 'mwedit.init', initData );
		mw.libs.ve.activationStart = ve.now();
	}

	function setEditorPreference( editor ) {
		if ( editor !== 'visualeditor' && editor !== 'wikitext' ) {
			throw new Error( 'setEditorPreference called with invalid option: ', editor );
		}

		$.cookie( 'VEE', editor, { path: '/', expires: 30 } );
		new mw.Api().saveOption( 'visualeditor-editor', editor );
		mw.user.options.set( 'visualeditor-editor', editor );
	}

	function getLastEditor() {
		var editor = $.cookie( 'VEE' );
		if ( !mw.user.isAnon() || !editor ) {
			editor = mw.user.options.get( 'visualeditor-editor' );
		}
		return editor;
	}

	conf = mw.config.get( 'wgVisualEditorConfig' );
	tabMessages = conf.tabMessages;
	uri = new mw.Uri();
	pageExists = !!mw.config.get( 'wgRelevantArticleId' );
	viewUri = new mw.Uri( mw.util.getUrl( mw.config.get( 'wgRelevantPageName' ) ) );
	isViewPage = mw.config.get( 'wgIsArticle' ) && !( 'diff' in uri.query );
	pageCanLoadVE = (
		isViewPage ||
		mw.config.get( 'wgAction' ) === 'edit' ||
		mw.config.get( 'wgAction' ) === 'submit'
	);
	isEditPage = conf.singleEditTab && (
		uri.query.action === 'edit' ||
		uri.query.action === 'submit'
	);
	// On a view page, extend the current URI so parameters like oldid are carried over
	// On a non-view page, use viewUri
	if ( conf.singleEditTab ) {
		veEditUri = viewUri.clone().extend( { action: 'edit' } );
		delete veEditUri.query.veaction;
	} else {
		veEditUri = ( pageCanLoadVE ? uri : viewUri ).clone().extend( { veaction: 'edit' } );
		delete veEditUri.query.action;
	}

	support = {
		es5: !!(
			// It would be much easier to do a quick inline function that asserts "use strict"
			// works, but since IE9 doesn't support strict mode (and we don't use strict mode) we
			// have to instead list all the ES5 features we do use.
			Array.isArray &&
			Array.prototype.filter &&
			Array.prototype.indexOf &&
			Array.prototype.map &&
			Date.now &&
			Date.prototype.toJSON &&
			Object.create &&
			Object.keys &&
			String.prototype.trim &&
			window.JSON &&
			JSON.parse &&
			JSON.stringify &&
			Function.prototype.bind
		),
		contentEditable: 'contentEditable' in document.createElement( 'div' ),
		svg: !!(
			document.createElementNS &&
			document.createElementNS( 'http://www.w3.org/2000/svg', 'svg' ).createSVGRect
		)
	};

	init = {

		support: support,

		blacklist: conf.blacklist,

		/**
		 * Add a plugin module or function.
		 *
		 * Plugins are run after VisualEditor is loaded, but before it is initialized. This allows
		 * plugins to add classes and register them with the factories and registries.
		 *
		 * The parameter to this function can be a ResourceLoader module name or a function.
		 *
		 * If it's a module name, it will be loaded together with the VisualEditor core modules when
		 * VE is loaded. No special care is taken to ensure that the module runs after the VE
		 * classes are loaded, so if this is desired, the module should depend on
		 * ext.visualEditor.core .
		 *
		 * If it's a function, it will be invoked once the VisualEditor core modules and any
		 * plugin modules registered through this function have been loaded, but before the editor
		 * is intialized. The function can optionally return a jQuery.Promise . VisualEditor will
		 * only be initialized once all promises returned by plugin functions have been resolved.
		 *
		 *     // Register ResourceLoader module
		 *     mw.libs.ve.addPlugin( 'ext.gadget.foobar' );
		 *
		 *     // Register a callback
		 *     mw.libs.ve.addPlugin( function ( target ) {
		 *         ve.dm.Foobar = .....
		 *     } );
		 *
		 *     // Register a callback that loads another script
		 *     mw.libs.ve.addPlugin( function () {
		 *         return $.getScript( 'http://example.com/foobar.js' );
		 *     } );
		 *
		 * @param {string|Function} plugin Module name or callback that optionally returns a promise
		 */
		addPlugin: function ( plugin ) {
			plugins.push( plugin );
		},

		setupSkin: function () {
			init.setupTabs();
			init.setupSectionLinks();
		},

		setupTabs: function () {
			var caVeEdit,
				action = pageExists ? 'edit' : 'create',
				pTabsId = $( '#p-views' ).length ? 'p-views' : 'p-cactions',
				$caSource = $( '#ca-viewsource' ),
				$caEdit = $( '#ca-edit' ),
				$caVeEdit = $( '#ca-ve-edit' ),
				$caEditLink = $caEdit.find( 'a' ),
				$caVeEditLink = $caVeEdit.find( 'a' ),
				reverseTabOrder = $( 'body' ).hasClass( 'rtl' ) && pTabsId === 'p-views',
				/*jshint bitwise:false */
				caVeEditNextnode =
					( reverseTabOrder ^ conf.tabPosition === 'before' ) ?
						/*jshint bitwise:true */
						$caEdit.get( 0 ) :
						$caEdit.next().get( 0 );

			// HACK: Remove this when the Education Program offers a proper way to detect and disable.
			if (
				// HACK: Work around jscs.requireCamelCaseOrUpperCaseIdentifiers
				mw.config.get( 'wgNamespaceIds' )[ true && 'education_program' ] === mw.config.get( 'wgNamespaceNumber' )
			) {
				return;
			}

			if ( !$caVeEdit.length ) {
				// The below duplicates the functionality of VisualEditorHooks::onSkinTemplateNavigation()
				// in case we're running on a cached page that doesn't have these tabs yet.

				// If there is no edit tab or a view-source tab,
				// the user doesn't have permission to edit.
				if ( $caEdit.length && !$caSource.length ) {
					// Add the VisualEditor tab (#ca-ve-edit)
					caVeEdit = mw.util.addPortletLink(
						pTabsId,
						// Use url instead of '#'.
						// So that 1) one can always open it in a new tab, even when
						// onEditTabClick is bound.
						// 2) when onEditTabClick is not bound (!pageCanLoadVE) it will
						// just work.
						veEditUri,
						tabMessages[ action ] !== null ? mw.msg( tabMessages[ action ] ) : $caEditLink.text(),
						'ca-ve-edit',
						mw.msg( 'tooltip-ca-ve-edit' ),
						mw.msg( 'accesskey-ca-ve-edit' ),
						caVeEditNextnode
					);

					$caVeEdit = $( caVeEdit );
					$caVeEditLink = $caVeEdit.find( 'a' );
				}
			} else if ( $caEdit.length && $caVeEdit.length ) {
				// Make the state of the page consistent with the config if needed
				/*jshint bitwise:false */
				if ( reverseTabOrder ^ conf.tabPosition === 'before' ) {
					if ( $caEdit[ 0 ].nextSibling === $caVeEdit[ 0 ] ) {
						$caVeEdit.after( $caEdit );
					}
				} else {
					if ( $caVeEdit[ 0 ].nextSibling === $caEdit[ 0 ] ) {
						$caEdit.after( $caVeEdit );
					}
				}
				if ( tabMessages[ action ] !== null ) {
					$caVeEditLink.text( mw.msg( tabMessages[ action ] ) );
				}
			}

			// If the edit tab is hidden, remove it.
			if ( !( init.isAvailable && userPrefEnabled ) ) {
				$caVeEdit.remove();
			} else if ( pageCanLoadVE ) {
				// Allow instant switching to edit mode, without refresh
				$caVeEdit.on( 'click', init.onEditTabClick );
			}

			// Alter the edit tab (#ca-edit)
			if ( $( '#ca-view-foreign' ).length ) {
				if ( tabMessages[ action + 'localdescriptionsource' ] !== null ) {
					$caEditLink.text( mw.msg( tabMessages[ action + 'localdescriptionsource' ] ) );
				}
			} else {
				if ( tabMessages[ action + 'source' ] !== null ) {
					$caEditLink.text( mw.msg( tabMessages[ action + 'source' ] ) );
				}
			}

			if ( init.isAvailable ) {
				if ( conf.tabPosition === 'before' ) {
					$caEdit.addClass( 'collapsible' );
				} else {
					$caVeEdit.addClass( 'collapsible' );
				}
			}

			// Process appendix messages
			if ( tabMessages[ action + 'appendix' ] !== null ) {
				$caVeEditLink.append(
					$( '<span>' )
						.addClass( 've-tabmessage-appendix' )
						.text( mw.msg( tabMessages[ action + 'appendix' ] ) )
				);
			}
			if ( tabMessages[ action + 'sourceappendix' ] !== null ) {
				$caEditLink.append(
					$( '<span>' )
						.addClass( 've-tabmessage-appendix' )
						.text( mw.msg( tabMessages[ action + 'sourceappendix' ] ) )
				);
			}
		},

		setupSectionLinks: function () {
			var $editsections = $( '#mw-content-text .mw-editsection' ),
				bodyDir = $( 'body' ).css( 'direction' );

			// Match direction of the user interface
			// TODO: Why is this needed? It seems to work fine without.
			if ( $editsections.css( 'direction' ) !== bodyDir ) {
				// Avoid creating inline style attributes if the inherited value is already correct
				$editsections.css( 'direction', bodyDir );
			}

			// The "visibility" css construct ensures we always occupy the same space in the layout.
			// This prevents the heading from changing its wrap when the user toggles editSourceLink.
			if ( $editsections.find( '.mw-editsection-visualeditor' ).length === 0 ) {
				// If PHP didn't build the section edit links (because of caching), build them
				$editsections.each( function () {
					var $editsection = $( this ),
						$editSourceLink = $editsection.find( 'a' ).eq( 0 ),
						$editLink = $editSourceLink.clone(),
						$divider = $( '<span>' ),
						dividerText = mw.msg( 'pipe-separator' );

					if ( tabMessages.editsectionsource !== null ) {
						$editSourceLink.text( mw.msg( tabMessages.editsectionsource ) );
					}
					if ( tabMessages.editsection !== null ) {
						$editLink.text( mw.msg( tabMessages.editsection ) );
					}
					$divider
						.addClass( 'mw-editsection-divider' )
						.text( dividerText );
					// Don't mess with section edit links on foreign file description pages
					// (bug 54259)
					if ( !$( '#ca-view-foreign' ).length ) {
						$editLink
							.attr( 'href', function ( i, val ) {
								return new mw.Uri( veEditUri ).extend( {
									vesection: new mw.Uri( val ).query.section
								} );
							} )
							.addClass( 'mw-editsection-visualeditor' );
						if ( conf.tabPosition === 'before' ) {
							$editSourceLink.before( $editLink, $divider );
						} else {
							$editSourceLink.after( $divider, $editLink );
						}
					}
				} );
			}

			// Process appendix messages
			if ( tabMessages.editsectionappendix ) {
				$editsections.find( '.mw-editsection-visualeditor' )
					.append(
						$( '<span>' )
							.addClass( 've-tabmessage-appendix' )
							.text( mw.msg( tabMessages.editsectionappendix ) )
					);
			}
			if ( tabMessages.editsectionsourceappendix ) {
				$editsections.find( 'a:not(.mw-editsection-visualeditor)' )
					.append(
						$( '<span>' )
							.addClass( 've-tabmessage-appendix' )
							.text( mw.msg( tabMessages.editsectionsourceappendix ) )
					);
			}

			if ( pageCanLoadVE ) {
				// Only init without refresh if we're on a view page. Though section edit links
				// are rarely shown on non-view pages, they appear in one other case, namely
				// when on a diff against the latest version of a page. In that case we mustn't
				// init without refresh as that'd initialise for the wrong rev id (bug 50925)
				// and would preserve the wrong DOM with a diff on top.
				$editsections
					.find( '.mw-editsection-visualeditor' )
						.on( 'click', init.onEditSectionLinkClick )
				;
			}
		},

		onEditTabClick: function ( e ) {
			// Default mouse button is normalised by jQuery to key code 1.
			// Only do our handling if no keys are pressed, mouse button is 1
			// (e.g. not middle click or right click) and no modifier keys
			// (e.g. cmd-click to open in new tab).
			if ( ( e.which && e.which !== 1 ) || e.shiftKey || e.altKey || e.ctrlKey || e.metaKey ) {
				return;
			}
			e.preventDefault();
			init.activateVe();
		},

		activateVe: function () {
			var wikitext = $( '#wpTextbox1' ).val(),
				wikitextModified = wikitext !== initialWikitext;

			// Close any open jQuery.UI dialogs (e.g. WikiEditor's find and replace)
			if ( $.fn.dialog ) {
				$( '.ui-dialog-content' ).dialog( 'close' );
			}

			if (
				mw.config.get( 'wgAction' ) === 'submit' ||
				( mw.config.get( 'wgAction' ) === 'edit' && wikitextModified ) ||
				// switching from section editing must prompt because we can't
				// keep changes from that (yet?)
				$( 'input[name=wpSection]' ).val()
			) {
				mw.loader.using( 'ext.visualEditor.switching' ).done( function () {
					var windowManager = new OO.ui.WindowManager(),
						switchWindow = new mw.libs.ve.SwitchConfirmDialog();
					// Prompt if either we're on action=submit (the user has previewed) or
					// the wikitext hash is different to the value observed upon page load.

					$( 'body' ).append( windowManager.$element );
					windowManager.addWindows( [ switchWindow ] );
					windowManager.openWindow( switchWindow )
						.then( function ( opened ) { return opened; } )
						.then( function ( closing ) { return closing; } )
						.then( function ( data ) {
							if ( data && data.action === 'keep' ) {
								activatePageTarget( true );
							} else if ( data && data.action === 'discard' ) {
								setEditorPreference( 'visualeditor' );
								location.href = veEditUri;
							}
						} );
				} );
			} else if ( isViewPage || wikitext ) {
				activatePageTarget( false );
			} else {
				setEditorPreference( 'visualeditor' );
				location.href = veEditUri;
			}
		},

		onEditSectionLinkClick: function ( e ) {
			var targetPromise;
			if ( ( e.which && e.which !== 1 ) || e.shiftKey || e.altKey || e.ctrlKey || e.metaKey ) {
				return;
			}

			trackActivateStart( { type: 'section', mechanism: 'click' } );

			if ( history.pushState && uri.query.veaction !== 'edit' ) {
				// Replace the current state with one that is tagged as ours, to prevent the
				// back button from breaking when used to exit VE. FIXME: there should be a better
				// way to do this. See also similar code in the DesktopArticleTarget constructor.
				history.replaceState( { tag: 'visualeditor' }, document.title, uri );
				// Change the state to the href of the section link that was clicked. This saves
				// us from having to figure out the section number again.
				history.pushState( { tag: 'visualeditor' }, document.title, this.href );
			}

			e.preventDefault();

			targetPromise = getTarget().then( function ( target ) {
				target.saveEditSection( $( e.target ).closest( 'h1, h2, h3, h4, h5, h6' ).get( 0 ) );
				return target;
			} );
			activateTarget( targetPromise );
		}
	};

	support.visualEditor = support.es5 &&
		support.contentEditable &&
		support.svg &&
		( ( 'vewhitelist' in uri.query ) || !$.client.test( init.blacklist, null, true ) );

	// Cast "0" (T89513)
	enable = Number( mw.user.options.get( 'visualeditor-enable' ) );
	tempdisable = Number( mw.user.options.get( 'visualeditor-betatempdisable' ) );
	autodisable = Number( mw.user.options.get( 'visualeditor-autodisable' ) );

	userPrefEnabled = (
		// Allow disabling for anonymous users separately from changing the
		// default preference (bug 50000)
		!( conf.disableForAnons && mw.config.get( 'wgUserName' ) === null ) &&

		// User has 'visualeditor-enable' preference enabled (for alpha opt-in)
		// User has 'visualeditor-betatempdisable' preference disabled
		// User has 'visualeditor-autodisable' preference disabled
		enable && !tempdisable && !autodisable
	);

	// Whether VisualEditor should be available for the current user, page, wiki, mediawiki skin,
	// browser etc.
	init.isAvailable = (
		support.visualEditor &&

		// Only in supported skins
		$.inArray( mw.config.get( 'skin' ), conf.skins ) !== -1 &&

		// Only in enabled namespaces
		$.inArray(
			new mw.Title( mw.config.get( 'wgRelevantPageName' ) ).getNamespaceId(),
			conf.namespaces
		) !== -1 &&

		// Not on pages like Special:RevisionDelete
		mw.config.get( 'wgNamespaceNumber' ) !== -1 &&

		// Not on pages which are outputs of the Page Translation feature
		mw.config.get( 'wgTranslatePageTranslation' ) !== 'translation' &&

		// Only for pages with a wikitext content model
		mw.config.get( 'wgPageContentModel' ) === 'wikitext'
	);

	// FIXME: We should do this more elegantly
	init.setEditorPreference = setEditorPreference;

	// Note: Though VisualEditor itself only needs this exposure for a very small reason
	// (namely to access init.blacklist from the unit tests...) this has become one of the nicest
	// ways to easily detect whether the VisualEditor initialisation code is present.
	//
	// The VE global was once available always, but now that platform integration initialisation
	// is properly separated, it doesn't exist until the platform loads VisualEditor core.
	//
	// Most of mw.libs.ve is considered subject to change and private.  The exception is that
	// mw.libs.ve.isAvailable is public, and indicates whether the VE editor itself can be loaded
	// on this page. See above for why it may be false.
	mw.libs.ve = $.extend( mw.libs.ve || {}, init );

	if ( init.isAvailable && userPrefEnabled ) {
		$( 'html' ).addClass( 've-available' );
	} else {
		$( 'html' ).addClass( 've-not-available' );
		// Don't return here because we do want the skin setup to consistently happen
		// for e.g. "Edit" > "Edit source" even when VE is not available.
	}

	$( function () {
		var key, loadVEInPage;
		if ( uri.query.action === 'edit' && $( '#wpTextbox1' ).length ) {
			initialWikitext = $( '#wpTextbox1' ).val();
		}

		if ( init.isAvailable ) {
			if (
				(
					( isViewPage && uri.query.veaction === 'edit' ) ||
					(
						isEditPage &&
						mw.user.options.get( 'visualeditor-tabs' ) !== 'prefer-wt' &&
						mw.user.options.get( 'visualeditor-tabs' ) !== 'multi-tab' &&
						(
							(
								mw.user.options.get( 'visualeditor-tabs' ) === 'prefer-ve' &&
								mw.config.get( 'wgAction' ) !== 'submit'
							) || getLastEditor() !== 'wikitext'
						)
					)
				) &&
				uri.query.veswitched === undefined &&
				uri.query.undo === undefined &&
				uri.query.undoafter === undefined &&
				uri.query.editintro === undefined &&
				uri.query.preload === undefined &&
				uri.query.preloadtitle === undefined &&
				uri.query.preloadparams === undefined
				// TODO: other params too? See identical list in VisualEditor.hooks.php
			) {
				trackActivateStart( {
					type: uri.query.vesection === undefined ? 'page' : 'section',
					mechanism: 'url'
				} );
				activateTarget();
			}

			if ( [ 'edit', 'submit' ].indexOf( mw.config.get( 'wgAction' ) ) !== -1 ) {
				mw.loader.load( 'ext.visualEditor.switching' );
				$( '#wpTextbox1' ).on( 'wikiEditor-toolbar-doneInitialSections', function () {
					mw.loader.using( 'ext.visualEditor.switching' ).done( function () {
						var windowManager, editingTabDialog;
						$( '.wikiEditor-ui-toolbar' ).prepend(
							new OO.ui.ButtonWidget( {
								framed: false,
								icon: 'edit',
								title: mw.msg( 'visualeditor-mweditmodeve-tool' ),
								classes: [ 've-init-mw-desktopArticleTarget-editSwitch' ]
							} ).on( 'click', init.activateVe ).$element
						);

						// Duplicate of this code in ve.init.mw.DesktopArticleTarget.js
						if ( $( '#ca-edit' ).hasClass( 'visualeditor-showtabdialog' ) ) {
							// Set up a temporary window manager
							windowManager = new OO.ui.WindowManager();
							$( 'body' ).append( windowManager.$element );
							editingTabDialog = new mw.libs.ve.EditingTabDialog();
							windowManager.addWindows( [ editingTabDialog ] );
							windowManager.openWindow( editingTabDialog, { message: mw.msg(
								'visualeditor-editingtabdialog-body',
								$( '#ca-edit' ).text()
							) } )
								.then( function ( opened ) { return opened; } )
								.then( function ( closing ) { return closing; } )
								.then( function ( data ) {
									// Detach the temporary window manager
									windowManager.destroy();

									if ( data && data.action === 'prefer-ve' ) {
										location.href = veEditUri;
									}
								} );
						}
					} );
				} );
			}
			if (
				conf.singleEditTab &&
				mw.user.options.get( 'visualeditor-tabs' ) !== 'multi-tab' &&
				userPrefEnabled
			) {
				loadVEInPage = mw.user.options.get( 'visualeditor-tabs' ) === 'prefer-ve' ||
					(
						getLastEditor() !== 'wikitext' &&
						mw.user.options.get( 'visualeditor-tabs' ) !== 'prefer-wt'
					);
				// Handle section edit link clicks
				$( '.mw-editsection a' ).on( 'click', function ( e ) {
					if ( loadVEInPage ) {
						init.onEditSectionLinkClick( e );
					}
				} );
				// Allow instant switching to edit mode, without refresh
				$( '#ca-edit' ).on( 'click', function ( e ) {
					if ( loadVEInPage ) {
						trackActivateStart( { type: 'page', mechanism: 'click' } );
						activateTarget();
						e.preventDefault();
					}
				} );
			} else if ( userPrefEnabled ) {
				init.setupSkin();
			}
		}

		if (
			conf.singleEditTab &&
			mw.user.options.get( 'visualeditor-tabs' ) === 'multi-tab' &&
			userPrefEnabled &&
			(
				init.isAvailable &&
				!mw.user.isAnon() &&
				getLastEditor() === 'wikitext'
			) || (
				!init.isAvailable &&
				mw.user.options.get( 'visualeditor-tabs' ) === 'prefer-ve'
			)
		) {
			key = pageExists ? 'edit' : 'create';
			if ( $( '#ca-view-foreign' ).length ) {
				key += 'localdescription';
			}
			key += 'source';
			if ( tabMessages[ key ] !== null ) {
				$( '#ca-edit a' )
					.data( 'original-text', $( '#ca-edit a' ).text() )
					.text( mw.msg( tabMessages[ key ] ) );
			}
		}

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

			delete uri.query.venotify;
		}
	} );
}() );