/**
 * jQuery plugin to update the tooltip to show the correct access key
 *
 * @class jQuery.plugin.accessKeyLabel
 */
( function () {

	// Cached access key modifiers for used browser
	var cachedAccessKeyModifiers,

		// Whether to use 'test-' instead of correct prefix (used for testing)
		useTestPrefix = false,

		// tag names which can have a label tag
		// https://developer.mozilla.org/en-US/docs/Web/Guide/HTML/Content_categories#Form-associated_content
		labelable = 'button, input, textarea, keygen, meter, output, progress, select';

	/**
	 * Find the modifier keys that need to be pressed together with the accesskey to trigger the input.
	 *
	 * The result is dependant on the ua paramater or the current platform.
	 * For browsers that support accessKeyLabel, #getAccessKeyLabel never calls here.
	 * Valid key values that are returned can be: ctrl, alt, option, shift, esc
	 *
	 * @private
	 * @param {Object} [ua] An object with a 'userAgent' and 'platform' property.
	 * @return {Array} Array with 1 or more of the string values, in this order: ctrl, option, alt, shift, esc
	 */
	function getAccessKeyModifiers( ua ) {
		var profile, accessKeyModifiers;

		// use cached prefix if possible
		if ( !ua && cachedAccessKeyModifiers ) {
			return cachedAccessKeyModifiers;
		}

		profile = $.client.profile( ua );

		switch ( profile.name ) {
			case 'chrome':
			case 'opera':
				if ( profile.name === 'opera' && profile.versionNumber < 15 ) {
					accessKeyModifiers = [ 'shift', 'esc' ];
				} else if ( profile.platform === 'mac' ) {
					accessKeyModifiers = [ 'ctrl', 'option' ];
				} else {
					// Chrome/Opera on Windows or Linux
					// (both alt- and alt-shift work, but alt with E, D, F etc does not
					// work since they are browser shortcuts)
					accessKeyModifiers = [ 'alt', 'shift' ];
				}
				break;
			case 'firefox':
			case 'iceweasel':
				if ( profile.versionBase < 2 ) {
					// Before v2, Firefox used alt, though it was rebindable in about:config
					accessKeyModifiers = [ 'alt' ];
				} else {
					if ( profile.platform === 'mac' ) {
						if ( profile.versionNumber < 14 ) {
							accessKeyModifiers = [ 'ctrl' ];
						} else {
							accessKeyModifiers = [ 'ctrl', 'option' ];
						}
					} else {
						accessKeyModifiers = [ 'alt', 'shift' ];
					}
				}
				break;
			case 'safari':
			case 'konqueror':
				if ( profile.platform === 'win' ) {
					accessKeyModifiers = [ 'alt' ];
				} else {
					if ( profile.layoutVersion > 526 ) {
						// Non-Windows Safari with webkit_version > 526
						accessKeyModifiers = [ 'ctrl', profile.platform === 'mac' ? 'option' : 'alt' ];
					} else {
						accessKeyModifiers = [ 'ctrl' ];
					}
				}
				break;
			case 'msie':
			case 'edge':
				accessKeyModifiers = [ 'alt' ];
				break;
			default:
				accessKeyModifiers = profile.platform === 'mac' ? [ 'ctrl' ] : [ 'alt' ];
				break;
		}

		// cache modifiers
		if ( !ua ) {
			cachedAccessKeyModifiers = accessKeyModifiers;
		}
		return accessKeyModifiers;
	}

	/**
	 * Get the access key label for an element.
	 *
	 * Will use native accessKeyLabel if available (currently only in Firefox 8+),
	 * falls back to #getAccessKeyModifiers.
	 *
	 * @private
	 * @param {HTMLElement} element Element to get the label for
	 * @return {string} Access key label
	 */
	function getAccessKeyLabel( element ) {
		// abort early if no access key
		if ( !element.accessKey ) {
			return '';
		}
		// use accessKeyLabel if possible
		// https://html.spec.whatwg.org/multipage/interaction.html#dom-accesskeylabel
		if ( !useTestPrefix && element.accessKeyLabel ) {
			return element.accessKeyLabel;
		}
		return ( useTestPrefix ? 'test' : getAccessKeyModifiers().join( '-' ) ) + '-' + element.accessKey;
	}

	/**
	 * Update the title for an element (on the element with the access key or it's label) to show
	 * the correct access key label.
	 *
	 * @private
	 * @param {HTMLElement} element Element with the accesskey
	 * @param {HTMLElement} titleElement Element with the title to update (may be the same as `element`)
	 */
	function updateTooltipOnElement( element, titleElement ) {
		var oldTitle, parts, regexp, newTitle, accessKeyLabel,
			separatorMsg = mw.message( 'word-separator' ).plain();

		oldTitle = titleElement.title;
		if ( !oldTitle ) {
			// don't add a title if the element didn't have one before
			return;
		}

		parts = ( separatorMsg + mw.message( 'brackets' ).plain() ).split( '$1' );
		regexp = new RegExp( parts.map( mw.RegExp.escape ).join( '.*?' ) + '$' );
		newTitle = oldTitle.replace( regexp, '' );
		accessKeyLabel = getAccessKeyLabel( element );

		if ( accessKeyLabel ) {
			// Should be build the same as in Linker::titleAttrib
			newTitle += separatorMsg + mw.message( 'brackets', accessKeyLabel ).plain();
		}
		if ( oldTitle !== newTitle ) {
			titleElement.title = newTitle;
		}
	}

	/**
	 * Update the title for an element to show the correct access key label.
	 *
	 * @private
	 * @param {HTMLElement} element Element with the accesskey
	 */
	function updateTooltip( element ) {
		var id, $element, $label, $labelParent;
		updateTooltipOnElement( element, element );

		// update associated label if there is one
		$element = $( element );
		if ( $element.is( labelable ) ) {
			// Search it using 'for' attribute
			id = element.id.replace( /"/g, '\\"' );
			if ( id ) {
				$label = $( 'label[for="' + id + '"]' );
				if ( $label.length === 1 ) {
					updateTooltipOnElement( element, $label[ 0 ] );
				}
			}

			// Search it as parent, because the form control can also be inside the label element itself
			$labelParent = $element.parents( 'label' );
			if ( $labelParent.length === 1 ) {
				updateTooltipOnElement( element, $labelParent[ 0 ] );
			}
		}
	}

	/**
	 * Update the titles for all elements in a jQuery selection.
	 *
	 * @return {jQuery}
	 * @chainable
	 */
	$.fn.updateTooltipAccessKeys = function () {
		return this.each( function () {
			updateTooltip( this );
		} );
	};

	/**
	 * getAccessKeyModifiers
	 *
	 * @method updateTooltipAccessKeys_getAccessKeyModifiers
	 * @inheritdoc #getAccessKeyModifiers
	 */
	$.fn.updateTooltipAccessKeys.getAccessKeyModifiers = getAccessKeyModifiers;

	/**
	 * getAccessKeyLabel
	 *
	 * @method updateTooltipAccessKeys_getAccessKeyLabel
	 * @inheritdoc #getAccessKeyLabel
	 */
	$.fn.updateTooltipAccessKeys.getAccessKeyLabel = getAccessKeyLabel;

	/**
	 * getAccessKeyPrefix
	 *
	 * @method updateTooltipAccessKeys_getAccessKeyPrefix
	 * @deprecated since 1.27 Use #getAccessKeyModifiers
	 * @param {Object} [ua] An object with a 'userAgent' and 'platform' property.
	 * @return {string}
	 */
	$.fn.updateTooltipAccessKeys.getAccessKeyPrefix = function ( ua ) {
		return getAccessKeyModifiers( ua ).join( '-' ) + '-';
	};

	/**
	 * Switch test mode on and off.
	 *
	 * @method updateTooltipAccessKeys_setTestMode
	 * @param {boolean} mode New mode
	 */
	$.fn.updateTooltipAccessKeys.setTestMode = function ( mode ) {
		useTestPrefix = mode;
	};

	/**
	 * @class jQuery
	 * @mixins jQuery.plugin.accessKeyLabel
	 */

}() );
