(function ( window, document ) {

	'use strict';

	var supportedBrowser = ( document.querySelector && window.addEventListener ),

		loaded = false,

		secret,

		secretTimeout,

		resizing;

	function sendEmbedMessage( message, value ) {

		window.parent.postMessage( {

			message: message,

			value: value,

			secret: secret

		}, '*' );

	}

	function onLoad() {

		if ( loaded ) {

			return;

		}

		loaded = true;

		var share_dialog = document.querySelector( '.wp-embed-share-dialog' ),

			share_dialog_open = document.querySelector( '.wp-embed-share-dialog-open' ),

			share_dialog_close = document.querySelector( '.wp-embed-share-dialog-close' ),

			share_input = document.querySelectorAll( '.wp-embed-share-input' ),

			share_dialog_tabs = document.querySelectorAll( '.wp-embed-share-tab-button button' ),

			featured_image = document.querySelector( '.wp-embed-featured-image img' ),

			i;

		if ( share_input ) {

			for ( i = 0; i < share_input.length; i++ ) {

				share_input[ i ].addEventListener( 'click', function ( e ) {

					e.target.select();

				} );

			}

		}

		function openSharingDialog() {

			share_dialog.className = share_dialog.className.replace( 'hidden', '' );

			// Initial focus should go on the currently selected tab in the dialog.

			document.querySelector( '.wp-embed-share-tab-button [aria-selected="true"]' ).focus();

		}

		function closeSharingDialog() {

			share_dialog.className += ' hidden';

			document.querySelector( '.wp-embed-share-dialog-open' ).focus();

		}

		if ( share_dialog_open ) {

			share_dialog_open.addEventListener( 'click', function () {

				openSharingDialog();

			} );

		}

		if ( share_dialog_close ) {

			share_dialog_close.addEventListener( 'click', function () {

				closeSharingDialog();

			} );

		}

		function shareClickHandler( e ) {

			var currentTab = document.querySelector( '.wp-embed-share-tab-button [aria-selected="true"]' );

			currentTab.setAttribute( 'aria-selected', 'false' );

			document.querySelector( '#' + currentTab.getAttribute( 'aria-controls' ) ).setAttribute( 'aria-hidden', 'true' );

			e.target.setAttribute( 'aria-selected', 'true' );

			document.querySelector( '#' + e.target.getAttribute( 'aria-controls' ) ).setAttribute( 'aria-hidden', 'false' );

		}

		function shareKeyHandler( e ) {

			var target = e.target,

				previousSibling = target.parentElement.previousElementSibling,

				nextSibling = target.parentElement.nextElementSibling,

				newTab, newTabChild;

			if ( 37 === e.keyCode ) {

				newTab = previousSibling;

			} else if ( 39 === e.keyCode ) {

				newTab = nextSibling;

			} else {

				return false;

			}

			if ( 'rtl' === document.documentElement.getAttribute( 'dir' ) ) {

				newTab = ( newTab === previousSibling ) ? nextSibling : previousSibling;

			}

			if ( newTab ) {

				newTabChild = newTab.firstElementChild;

				target.setAttribute( 'tabindex', '-1' );

				target.setAttribute( 'aria-selected', false );

				document.querySelector( '#' + target.getAttribute( 'aria-controls' ) ).setAttribute( 'aria-hidden', 'true' );

				newTabChild.setAttribute( 'tabindex', '0' );

				newTabChild.setAttribute( 'aria-selected', 'true' );

				newTabChild.focus();

				document.querySelector( '#' + newTabChild.getAttribute( 'aria-controls' ) ).setAttribute( 'aria-hidden', 'false' );

			}

		}

		if ( share_dialog_tabs ) {

			for ( i = 0; i < share_dialog_tabs.length; i++ ) {

				share_dialog_tabs[ i ].addEventListener( 'click', shareClickHandler );

				share_dialog_tabs[ i ].addEventListener( 'keydown', shareKeyHandler );

			}

		}

		document.addEventListener( 'keydown', function ( e ) {

			if ( 27 === e.keyCode && -1 === share_dialog.className.indexOf( 'hidden' ) ) {

				closeSharingDialog();

			} else if ( 9 === e.keyCode ) {

				constrainTabbing( e );

			}

		}, false );

		function constrainTabbing( e ) {

			// Need to re-get the selected tab each time.

			var firstFocusable = document.querySelector( '.wp-embed-share-tab-button [aria-selected="true"]' );

			if ( share_dialog_close === e.target && ! e.shiftKey ) {

				firstFocusable.focus();

				e.preventDefault();

			} else if ( firstFocusable === e.target && e.shiftKey ) {

				share_dialog_close.focus();

				e.preventDefault();

			}

		}

		if ( window.self === window.top ) {

			return;

		}

		/**

		 * Send this document's height to the parent (embedding) site.

		 */

		sendEmbedMessage( 'height', Math.ceil( document.body.getBoundingClientRect().height ) );

		// Send the document's height again after the featured image has been loaded.

		if ( featured_image ) {

			featured_image.addEventListener( 'load', function() {

				sendEmbedMessage( 'height', Math.ceil( document.body.getBoundingClientRect().height ) );

			} );

		}

		/**

		 * Detect clicks to external (_top) links.

		 */

		function linkClickHandler( e ) {

			var target = e.target,

				href;

			if ( target.hasAttribute( 'href' ) ) {

				href = target.getAttribute( 'href' );

			} else {

				href = target.parentElement.getAttribute( 'href' );

			}

			/**

			 * Send link target to the parent (embedding) site.

			 */

			if ( href ) {

				sendEmbedMessage( 'link', href );

				e.preventDefault();

			}

		}

		document.addEventListener( 'click', linkClickHandler );

	}

	/**

	 * Iframe resize handler.

	 */

	function onResize() {

		if ( window.self === window.top ) {

			return;

		}

		clearTimeout( resizing );

		resizing = setTimeout( function () {

			sendEmbedMessage( 'height', Math.ceil( document.body.getBoundingClientRect().height ) );

		}, 100 );

	}

	/**

	 * Re-get the secret when it was added later on.

	 */

	function getSecret() {

		if ( window.self === window.top || !!secret ) {

			return;

		}

		secret = window.location.hash.replace( /.*secret=([\d\w]{10}).*/, '$1' );

		clearTimeout( secretTimeout );

		secretTimeout = setTimeout( function () {

			getSecret();

		}, 100 );

	}

	if ( supportedBrowser ) {

		getSecret();

		document.documentElement.className = document.documentElement.className.replace( /\bno-js\b/, '' ) + ' js';

		document.addEventListener( 'DOMContentLoaded', onLoad, false );

		window.addEventListener( 'load', onLoad, false );

		window.addEventListener( 'resize', onResize, false );

	}

})( window, document );