(function () {
	'use strict';

	var document = typeof window !== 'undefined' && typeof window.document !== 'undefined' ? window.document : {};
	var isCommonjs = typeof module !== 'undefined' && module.exports;
	var keyboardAllowed = typeof Element !== 'undefined' && 'ALLOW_KEYBOARD_INPUT' in Element;

	var fn = (function () {
		var val;

		var fnMap = [
			[
				'requestFullscreen',
				'exitFullscreen',
				'fullscreenElement',
				'fullscreenEnabled',
				'fullscreenchange',
				'fullscreenerror'
			],
			// New WebKit
			[
				'webkitRequestFullscreen',
				'webkitExitFullscreen',
				'webkitFullscreenElement',
				'webkitFullscreenEnabled',
				'webkitfullscreenchange',
				'webkitfullscreenerror'

			],
			// Old WebKit (Safari 5.1)
			[
				'webkitRequestFullScreen',
				'webkitCancelFullScreen',
				'webkitCurrentFullScreenElement',
				'webkitCancelFullScreen',
				'webkitfullscreenchange',
				'webkitfullscreenerror'

			],
			[
				'mozRequestFullScreen',
				'mozCancelFullScreen',
				'mozFullScreenElement',
				'mozFullScreenEnabled',
				'mozfullscreenchange',
				'mozfullscreenerror'
			],
			[
				'msRequestFullscreen',
				'msExitFullscreen',
				'msFullscreenElement',
				'msFullscreenEnabled',
				'MSFullscreenChange',
				'MSFullscreenError'
			]
		];

		var i = 0;
		var l = fnMap.length;
		var ret = {};

		for (; i < l; i++) {
			val = fnMap[i];
			if (val && val[1] in document) {
				for (i = 0; i < val.length; i++) {
					ret[fnMap[0][i]] = val[i];
				}
				return ret;
			}
		}

		return false;
	})();

	var eventNameMap = {
		change: fn.fullscreenchange,
		error: fn.fullscreenerror
	};

	var screenfull = {
		request: function (elem) {
			var request = fn.requestFullscreen;

			elem = elem || document.documentElement;

			// Work around Safari 5.1 bug: reports support for
			// keyboard in fullscreen even though it doesn't.
			// Browser sniffing, since the alternative with
			// setTimeout is even worse.
			if (/ Version\/5\.1(?:\.\d+)? Safari\//.test(navigator.userAgent)) {
				elem[request]();
			} else {
				elem[request](keyboardAllowed && Element.ALLOW_KEYBOARD_INPUT);
			}
		},
		exit: function () {
			document[fn.exitFullscreen]();
		},
		toggle: function (elem) {
			if (this.isFullscreen) {
				this.exit();
			} else {
				this.request(elem);
			}
		},
		onchange: function (callback) {
			this.on('change', callback);
		},
		onerror: function (callback) {
			this.on('error', callback);
		},
		on: function (event, callback) {
			var eventName = eventNameMap[event];
			if (eventName) {
				document.addEventListener(eventName, callback, false);
			}
		},
		off: function (event, callback) {
			var eventName = eventNameMap[event];
			if (eventName) {
				document.removeEventListener(eventName, callback, false);
			}
		},
		raw: fn
	};

	if (!fn) {
		if (isCommonjs) {
			module.exports = false;
		} else {
			window.screenfull = false;
		}

		return;
	}

	Object.defineProperties(screenfull, {
		isFullscreen: {
			get: function () {
				return Boolean(document[fn.fullscreenElement]);
			}
		},
		element: {
			enumerable: true,
			get: function () {
				return document[fn.fullscreenElement];
			}
		},
		enabled: {
			enumerable: true,
			get: function () {
				// Coerce to boolean in case of old WebKit
				return Boolean(document[fn.fullscreenEnabled]);
			}
		}
	});

	if (isCommonjs) {
		module.exports = screenfull;
	} else {
		window.screenfull = screenfull;
	}
})();