/**
 * jQuery makeCollapsible
 * Note: To avoid performance issues such as reflows, several styles are
 * shipped in mediawiki.makeCollapsible.styles to reserve space for the toggle control. Please
 * familiarise yourself with that CSS before making any changes to this code.
 *
 * Dual licensed:
 * - CC BY 3.0 <https://creativecommons.org/licenses/by/3.0>
 * - GPL2 <http://www.gnu.org/licenses/old-licenses/gpl-2.0.html>
 *
 * @class jQuery.plugin.makeCollapsible
 */
( function () {
	/**
	 * Handler for a click on a collapsible toggler.
	 *
	 * @private
	 * @param {jQuery} $collapsible
	 * @param {string} action The action this function will take ('expand' or 'collapse').
	 * @param {jQuery|null} [$defaultToggle]
	 * @param {Object|undefined} [options]
	 */
	function toggleElement( $collapsible, action, $defaultToggle, options ) {
		options = options || {};

		// Validate parameters

		// $collapsible must be an instance of jQuery
		if ( !$collapsible.jquery ) {
			return;
		}
		if ( action !== 'expand' && action !== 'collapse' ) {
			// action must be string with 'expand' or 'collapse'
			return;
		}
		if ( $defaultToggle === undefined ) {
			$defaultToggle = null;
		}

		// Trigger a custom event to allow callers to hook to the collapsing/expanding,
		// allowing the module to be testable, and making it possible to
		// e.g. implement persistence via cookies
		$collapsible.trigger( action === 'expand' ? 'beforeExpand.mw-collapsible' : 'beforeCollapse.mw-collapsible' );
		var hookCallback = function () {
			$collapsible.trigger( action === 'expand' ? 'afterExpand.mw-collapsible' : 'afterCollapse.mw-collapsible' );
		};

		// Handle different kinds of elements
		var $containers;
		if ( !options.plainMode && $collapsible.is( 'table' ) ) {
			// Tables
			// If there is a caption, hide all rows; otherwise, only hide body rows
			if ( $collapsible.find( '> caption' ).length ) {
				$containers = $collapsible.find( '> * > tr' );
			} else {
				$containers = $collapsible.find( '> tbody > tr' );
			}
			if ( $defaultToggle ) {
				// Exclude table row containing togglelink
				$containers = $containers.not( $defaultToggle.closest( 'tr' ) );
			}

		} else if ( !options.plainMode && ( $collapsible.is( 'ul' ) || $collapsible.is( 'ol' ) ) ) {
			// Lists
			$containers = $collapsible.find( '> li' );
			if ( $defaultToggle ) {
				// Exclude list-item containing togglelink
				$containers = $containers.not( $defaultToggle.parent() );
			}
		} else {
			// Everything else: <div>, <p> etc.
			var $collapsibleContent = $collapsible.find( '> .mw-collapsible-content' );

			// If a collapsible-content is defined, act on it
			if ( !options.plainMode && $collapsibleContent.length ) {
				$containers = $collapsibleContent;

			// Otherwise assume this is a customcollapse with a remote toggle
			// .. and there is no collapsible-content because the entire element should be toggled
			} else {
				$containers = $collapsible;
			}
		}

		$containers.toggle( action === 'expand' );
		hookCallback();
	}

	/**
	 * Handle clicking/keypressing on the collapsible element toggle and other
	 * situations where a collapsible element is toggled (e.g. the initial
	 * toggle for collapsed ones).
	 *
	 * @private
	 * @param {jQuery} $toggle the clickable toggle itself
	 * @param {jQuery} $collapsible the collapsible element
	 * @param {jQuery.Event|null} e either the event or null if unavailable
	 * @param {Object|undefined} options
	 */
	function togglingHandler( $toggle, $collapsible, e, options ) {
		options = options || {};

		if ( e ) {
			if (
				e.type === 'click' &&
				e.target.nodeName.toLowerCase() === 'a' &&
				$( e.target ).attr( 'href' )
			) {
				// Don't fire if a link was clicked (for premade togglers)
				return;
			} else if ( e.type === 'keydown' && e.which !== 13 && e.which !== 32 ) {
				// Only handle the "Enter" or "Space" keys
				return;
			} else {
				e.preventDefault();
				e.stopPropagation();
			}
		}

		// This allows the element to be hidden on initial toggle without fiddling with the class
		var wasCollapsed;
		if ( options.wasCollapsed !== undefined ) {
			wasCollapsed = options.wasCollapsed;
		} else {
			// eslint-disable-next-line no-jquery/no-class-state
			wasCollapsed = $collapsible.hasClass( 'mw-collapsed' );
		}

		// Toggle the state of the collapsible element (that is, expand or collapse)
		$collapsible.toggleClass( 'mw-collapsed', !wasCollapsed );

		// Toggle the mw-collapsible-toggle classes, if requested (for default and premade togglers by default)
		if ( options.toggleClasses ) {
			$toggle
				.toggleClass( 'mw-collapsible-toggle-collapsed', !wasCollapsed )
				.toggleClass( 'mw-collapsible-toggle-expanded', wasCollapsed );
		}

		// Toggle `aria-expanded` attribute, if requested (for default and premade togglers by default).
		if ( options.toggleARIA ) {
			$toggle.attr( 'aria-expanded', wasCollapsed ? 'true' : 'false' );
		}

		// Toggle the text ("Show"/"Hide") within elements tagged with mw-collapsible-text
		if ( options.toggleText ) {
			var collapseText = options.toggleText.collapseText;
			var expandText = options.toggleText.expandText;

			var $textContainer = $toggle.find( '.mw-collapsible-text' );
			if ( $textContainer.length ) {
				$textContainer.text( wasCollapsed ? collapseText : expandText );
			}
		}

		// And finally toggle the element state itself
		toggleElement( $collapsible, wasCollapsed ? 'expand' : 'collapse', $toggle, options );
	}

	/**
	 * If the URL contains a hash followed by the fragment identifier of an
	 * element inside collapsed parents, expand them all and scroll to it.
	 *
	 * @private
	 */
	function hashHandler() {
		var fragment = mw.util.getTargetFromFragment();
		if ( !fragment ) {
			// The fragment doesn't exist
			return;
		}

		var $parents = $( fragment ).parents( '.mw-collapsed' );
		if ( !$parents.length ) {
			// The fragment is not in a collapsed element
			return;
		}

		// Expand collapsed parents
		$parents.each( function () {
			var $collapsible = $( this );
			if ( $collapsible.data( 'mw-made-collapsible' ) ) {
				$collapsible.data( 'mw-collapsible' ).expand();
			} else {
				// The collapsible has not been initialized, so just prevent it
				// from being collapsed
				$collapsible.removeClass( 'mw-collapsed' );
			}
		} );

		// Scroll to the fragment
		fragment.scrollIntoView();
	}

	/**
	 * Enable collapsible-functionality on all elements in the collection.
	 *
	 * - Will prevent binding twice to the same element.
	 * - Initial state is expanded by default, this can be overridden by adding class
	 *   "mw-collapsed" to the "mw-collapsible" element.
	 * - Elements made collapsible have jQuery data "mw-made-collapsible" set to true.
	 * - The inner content is wrapped in a "div.mw-collapsible-content" (except for tables and lists).
	 *
	 * @param {Object} [options]
	 * @param {string} [options.collapseText] Text used for the toggler, when clicking it would
	 *   collapse the element. Default: the 'data-collapsetext' attribute of the
	 *   collapsible element or the content of 'collapsible-collapse' message.
	 * @param {string} [options.expandText] Text used for the toggler, when clicking it would
	 *   expand the element. Default: the 'data-expandtext' attribute of the
	 *   collapsible element or the content of 'collapsible-expand' message.
	 * @param {boolean} [options.collapsed] Whether to collapse immediately. By default
	 *   collapse only if the element has the 'mw-collapsed' class.
	 * @param {jQuery} [options.$customTogglers] Elements to be used as togglers
	 *   for this collapsible element. By default, if the collapsible element
	 *   has an id attribute like 'mw-customcollapsible-XXX', elements with a
	 *   **class** of 'mw-customtoggle-XXX' are made togglers for it.
	 * @param {boolean} [options.plainMode=false] Whether to use a "plain mode" when making the
	 *   element collapsible - that is, hide entire tables and lists (instead
	 *   of hiding only all rows but first of tables, and hiding each list
	 *   item separately for lists) and don't wrap other elements in
	 *   div.mw-collapsible-content. May only be used with custom togglers.
	 * @return {jQuery}
	 * @chainable
	 */
	$.fn.makeCollapsible = function ( options ) {
		options = options || {};

		this.each( function () {
			// Ensure class "mw-collapsible" is present in case .makeCollapsible()
			// is called on element(s) that don't have it yet.
			var $collapsible = $( this ).addClass( 'mw-collapsible' );

			// Return if it has been enabled already.
			if ( $collapsible.data( 'mw-made-collapsible' ) ) {
				return;
			} else {
				// Let CSS know that it no longer needs to worry about flash of unstyled content.
				// This will allow mediawiki.makeCollapsible.styles to disable temporary pseudo elements, that
				// are needed to avoid a flash of unstyled content.
				$collapsible.addClass( 'mw-made-collapsible' )
					.data( 'mw-made-collapsible', true );
			}

			// Use custom text or default?
			var collapseText = options.collapseText || $collapsible.attr( 'data-collapsetext' ) || mw.msg( 'collapsible-collapse' );
			var expandText = options.expandText || $collapsible.attr( 'data-expandtext' ) || mw.msg( 'collapsible-expand' );

			// Default click/keydown handler and toggle link to use when none is present
			var actionHandler = function ( e, opts ) {
				var defaultOpts = {
					toggleClasses: true,
					toggleARIA: true,
					toggleText: { collapseText: collapseText, expandText: expandText }
				};
				opts = $.extend( defaultOpts, options, opts );
				togglingHandler( $( this ), $collapsible, e, opts );
			};

			// Default toggle link. Only build it when needed to avoid jQuery memory leaks (event data).
			var buildDefaultToggleLink = function () {
				return $( '<span>' )
					.addClass( 'mw-collapsible-text' )
					.text( collapseText )
					.wrap( '<button type="button" class="mw-collapsible-toggle mw-collapsible-toggle-default"></button>' )
					.parent();
			};

			// Check if this element has a custom position for the toggle link
			// (ie. outside the container or deeper inside the tree)
			var $customTogglers;
			if ( options.$customTogglers ) {
				$customTogglers = $( options.$customTogglers );
			} else {
				var collapsibleId = $collapsible.attr( 'id' ) || '';
				if ( collapsibleId.indexOf( 'mw-customcollapsible-' ) === 0 ) {
					collapsibleId = $.escapeSelector( collapsibleId );
					$customTogglers = $( '.' + collapsibleId.replace( 'mw-customcollapsible', 'mw-customtoggle' ) )
						.addClass( 'mw-customtoggle' );
				}
			}

			// Add event handlers to custom togglers or create our own ones
			var $toggle;
			if ( $customTogglers && $customTogglers.length ) {
				actionHandler = function ( e, opts ) {
					var defaultOpts = {};
					opts = $.extend( defaultOpts, options, opts );
					togglingHandler( $( this ), $collapsible, e, opts );
				};

				$toggle = $customTogglers;

			} else {
				// If this is not a custom case, do the default: wrap the
				// contents and add the toggle link. Different elements are
				// treated differently.

				var $firstItem;
				if ( $collapsible.is( 'table' ) ) {

					// If the table has a caption, collapse to the caption
					// as opposed to the first row
					var $caption = $collapsible.find( '> caption' );
					if ( $caption.length ) {
						$toggle = $caption.find( '> .mw-collapsible-toggle, .mw-collapsible-toggle-placeholder' ).first();

						// If there is no toggle link, add it to the end of the caption
						if ( !$toggle.length ) {
							$toggle = buildDefaultToggleLink().appendTo( $caption );
						}
					} else {
						// The toggle-link will be in one of the cells (td or th) of the first row
						$firstItem = $collapsible.find( 'tr' ).first().find( 'th, td' );
						$toggle = $firstItem.find( '> .mw-collapsible-toggle, .mw-collapsible-toggle-placeholder' ).first();

						// If theres no toggle link, add it to the last cell
						if ( !$toggle.length ) {
							$toggle = buildDefaultToggleLink().prependTo( $firstItem.eq( -1 ) );
						}
					}

				} else if ( $collapsible.parent().is( 'li' ) &&
					$collapsible.parent().children( '.mw-collapsible' ).length === 1 &&
					$collapsible.find( '> .mw-collapsible-toggle, .mw-collapsible-toggle-placeholder' ).length === 0
				) {
					// special case of one collapsible in <li> tag
					$toggle = buildDefaultToggleLink();
					$collapsible.before( $toggle );
				} else if ( $collapsible.is( 'ul' ) || $collapsible.is( 'ol' ) ) {
					// The toggle-link will be in the first list-item
					$firstItem = $collapsible.find( 'li' ).first();
					$toggle = $firstItem.find( '> .mw-collapsible-toggle, .mw-collapsible-toggle-placeholder' ).first();

					// If theres no toggle link, add it
					if ( !$toggle.length ) {
						// Make sure the numeral order doesn't get messed up, force the first (soon to be second) item
						// to be "1". Except if the value-attribute is already used.
						// If no value was set WebKit returns "", Mozilla returns '-1', others return 0, null or undefined.
						var firstval = $firstItem.prop( 'value' );
						if ( firstval === undefined || !firstval || firstval === '-1' || firstval === -1 ) {
							$firstItem.prop( 'value', '1' );
						}
						$toggle = buildDefaultToggleLink();
						$toggle.wrap( '<li class="mw-collapsible-toggle-li"></li>' ).parent().prependTo( $collapsible );
					}

				} else { // <div>, <p> etc.

					// The toggle-link will be the first child of the element
					$toggle = $collapsible.find( '> .mw-collapsible-toggle, .mw-collapsible-toggle-placeholder' ).first();

					// If a direct child .content-wrapper does not exists, create it
					if ( !$collapsible.find( '> .mw-collapsible-content' ).length ) {
						$collapsible.wrapInner( '<div class="mw-collapsible-content"></div>' );
					}

					// If theres no toggle link, add it
					if ( !$toggle.length ) {
						$toggle = buildDefaultToggleLink().prependTo( $collapsible );
					}
				}
			}

			// If the toggle is just a placeholder, replace it with a real one
			// eslint-disable-next-line no-jquery/no-class-state
			if ( $toggle.hasClass( 'mw-collapsible-toggle-placeholder' ) ) {
				var $realToggle = buildDefaultToggleLink();
				$toggle.replaceWith( $realToggle );
				$toggle = $realToggle;
			}

			// Attach event handlers to togglelink
			$toggle.on( 'click.mw-collapsible keydown.mw-collapsible', actionHandler )
				.attr( 'aria-expanded', 'true' )
				.prop( 'tabIndex', 0 );

			$( this ).data( 'mw-collapsible', {
				collapse: function () {
					actionHandler.call( $toggle.get( 0 ), null, { wasCollapsed: false } );
				},
				expand: function () {
					actionHandler.call( $toggle.get( 0 ), null, { wasCollapsed: true } );
				},
				toggle: function () {
					actionHandler.call( $toggle.get( 0 ), null, null );
				}
			} );

			// Initial state
			// eslint-disable-next-line no-jquery/no-class-state
			if ( options.collapsed || $collapsible.hasClass( 'mw-collapsed' ) ) {
				// One toggler can hook to multiple elements, and one element can have
				// multiple togglers. This is the best way to handle that.
				actionHandler.call( $toggle.get( 0 ), null, { wasCollapsed: false } );
			}

		} );

		// Attach hash handler
		window.addEventListener( 'hashchange', hashHandler );

		/**
		 * Fired after collapsible content has been initialized
		 *
		 * This gives an option to modify the collapsible behavior.
		 *
		 * @event wikipage_collapsibleContent
		 * @member mw.hook
		 * @param {jQuery} $content All the elements that have been made collapsible
		 */
		mw.hook( 'wikipage.collapsibleContent' ).fire( this );

		return this;
	};

	// Run hash handler right now in case the URL already has a hash
	hashHandler();

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

}() );
