/**
 * @file Initialize module works with the JSON config, and sets up various
 * settings, parameters, variables. After all setup actions are performed, it
 * invokes the video player to play the specified video. This module must be
 * invoked first. It provides several functions which do not fit in with other
 * modules.
 *
 * @external VideoPlayer
 *
 * @module Initialize
 */

(function (requirejs, require, define) {

define(
'video/01_initialize.js',
['video/03_video_player.js', 'video/00_i18n.js', 'moment'],
function (VideoPlayer, i18n, moment) {
    var moment = moment || window.moment;
    /**
     * @function
     *
     * Initialize module exports this function.
     *
     * @param {object} state The object containg the state of the video player.
     *     All other modules, their parameters, public variables, etc. are
     *     available via this object.
     * @param {DOM element} element Container of the entire Video DOM element.
     */
    var Initialize = function (state, element) {
        _makeFunctionsPublic(state);

        state.initialize(element)
            .done(function () {
                if (state.isYoutubeType()) {
                    state.parseSpeed();
                }
                // On iPhones and iPods native controls are used.
                if (/iP(hone|od)/i.test(state.isTouch[0])) {
                    _hideWaitPlaceholder(state);
                    state.el.trigger('initialize', arguments);

                    return false;
                }

                _initializeModules(state, i18n)
                    .done(function () {
                        // On iPad ready state occurs just after start playing.
                        // We hide controls before video starts playing.
                        if (/iPad|Android/i.test(state.isTouch[0])) {
                            state.el.on('play', _.once(function() {
                                state.trigger('videoControl.show', null);
                            }));
                        } else {
                        // On PC show controls immediately.
                            state.trigger('videoControl.show', null);
                        }

                        _hideWaitPlaceholder(state);
                        state.el.trigger('initialize', arguments);
                    });
            });
    },

    methodsDict = {
        bindTo: bindTo,
        fetchMetadata: fetchMetadata,
        getCurrentLanguage: getCurrentLanguage,
        getDuration: getDuration,
        getPlayerMode: getPlayerMode,
        getVideoMetadata: getVideoMetadata,
        initialize: initialize,
        isHtml5Mode: isHtml5Mode,
        isFlashMode: isFlashMode,
        isYoutubeType: isYoutubeType,
        parseSpeed: parseSpeed,
        parseYoutubeStreams: parseYoutubeStreams,
        setPlayerMode: setPlayerMode,
        setSpeed: setSpeed,
        speedToString: speedToString,
        trigger: trigger,
        youtubeId: youtubeId,
        loadHtmlPlayer: loadHtmlPlayer,
        loadYoutubePlayer: loadYoutubePlayer,
        loadYouTubeIFrameAPI: loadYouTubeIFrameAPI
    },

        _youtubeApiDeferred = null,
        _oldOnYouTubeIframeAPIReady;

    Initialize.prototype = methodsDict;

    return Initialize;

    // ***************************************************************
    // Private functions start here. Private functions start with underscore.
    // ***************************************************************

    /**
     * @function _makeFunctionsPublic
     *
     * Functions which will be accessible via 'state' object. When called,
     * these functions will get the 'state'
     * object as a context.
     *
     * @param {object} state The object containg the state (properties,
     *     methods, modules) of the Video player.
     */
    function _makeFunctionsPublic(state) {
        bindTo(methodsDict, state, state);
    }

    // function _renderElements(state)
    //
    //     Create any necessary DOM elements, attach them, and set their
    //     initial configuration. Also make the created DOM elements available
    //     via the 'state' object. Much easier to work this way - you don't
    //     have to do repeated jQuery element selects.
    function _renderElements(state) {
        // Launch embedding of actual video content, or set it up so that it
        // will be done as soon as the appropriate video player (YouTube or
        // stand-alone HTML5) is loaded, and can handle embedding.
        //
        // Note that the loading of stand alone HTML5 player API is handled by
        // Require JS. At the time when we reach this code, the stand alone
        // HTML5 player is already loaded, so no further testing in that case
        // is required.
        var video, onYTApiReady, setupOnYouTubeIframeAPIReady;

        if (state.videoType === 'youtube') {
            state.youtubeApiAvailable = false;

            onYTApiReady = function () {
                console.log('[Video info]: YouTube API is available and is loaded.');

                if (state.htmlPlayerLoaded) { return; }

                console.log('[Video info]: Starting YouTube player.');
                video = VideoPlayer(state);

                state.modules.push(video);
                state.__dfd__.resolve();

                state.youtubeApiAvailable = true;
            };

            if (window.YT) {
                // If we have a Deferred object responsible for calling OnYouTubeIframeAPIReady
                // callbacks, make sure that they have all been called by trying to resolve the
                // Deferred object. Upon resolving, all the OnYouTubeIframeAPIReady will be
                // called. If the object has been already resolved, the callbacks will not
                // be called a second time.
                if (_youtubeApiDeferred) {
                    _youtubeApiDeferred.resolve();
                }

                window.YT.ready(onYTApiReady);
            } else {
                // There is only one global variable window.onYouTubeIframeAPIReady which
                // is supposed to be a function that will be called by the YouTube API
                // when it finished initializing. This function will update this global function
                // so that it resolves our Deferred object, which will call all of the
                // OnYouTubeIframeAPIReady callbacks.
                //
                // If this global function is already defined, we store it first, and make
                // sure that it gets executed when our Deferred object is resolved.
                setupOnYouTubeIframeAPIReady = function () {
                    _oldOnYouTubeIframeAPIReady = window.onYouTubeIframeAPIReady || undefined;

                    window.onYouTubeIframeAPIReady = function () {
                        window.onYouTubeIframeAPIReady.resolve();
                    };

                    window.onYouTubeIframeAPIReady.resolve = _youtubeApiDeferred.resolve;
                    window.onYouTubeIframeAPIReady.done = _youtubeApiDeferred.done;

                    if (_oldOnYouTubeIframeAPIReady) {
                        window.onYouTubeIframeAPIReady.done(_oldOnYouTubeIframeAPIReady);
                    }
                };

                // If a Deferred object hasn't been created yet, create one now. It will
                // be responsible for calling OnYouTubeIframeAPIReady callbacks once the
                // YouTube API loads. After creating the Deferred object, load the YouTube
                // API.
                if (!_youtubeApiDeferred) {
                    _youtubeApiDeferred = $.Deferred();
                    setupOnYouTubeIframeAPIReady();
                } else if (!window.onYouTubeIframeAPIReady || !window.onYouTubeIframeAPIReady.done) {
                    // The Deferred object could have been already defined in a previous
                    // initialization of the video module. However, since then the global variable
                    // window.onYouTubeIframeAPIReady could have been overwritten. If so,
                    // we should set it up again.
                    setupOnYouTubeIframeAPIReady();
                }

                // Attach a callback to our Deferred object to be called once the
                // YouTube API loads.
                window.onYouTubeIframeAPIReady.done(function () {
                    window.YT.ready(onYTApiReady);
                });
            }
        } else {
            video = VideoPlayer(state);

            state.modules.push(video);
            state.__dfd__.resolve();
            state.htmlPlayerLoaded = true;
        }
    }

    function _waitForYoutubeApi(state) {
        console.log('[Video info]: Starting to wait for YouTube API to load.');

        window.setTimeout(function () {
            // If YouTube API will load OK, it will run `onYouTubeIframeAPIReady`
            // callback, which will set `state.youtubeApiAvailable` to `true`.
            // If something goes wrong at this stage, `state.youtubeApiAvailable` is
            // `false`.
            if (!state.youtubeApiAvailable) {
                console.log('[Video info]: YouTube API is not available.');
                if (!state.htmlPlayerLoaded) {
                    state.loadHtmlPlayer();
                }
            }
            state.el.trigger('youtube_availability', [state.youtubeApiAvailable]);
        }, state.config.ytTestTimeout);

    }

    function loadYouTubeIFrameAPI(scriptTag) {
        var firstScriptTag = document.getElementsByTagName('script')[0];
        firstScriptTag.parentNode.insertBefore(scriptTag, firstScriptTag);
    }

    // function _configureCaptions(state)
    //     Configure displaying of captions.
    //
    //     Option
    //         this.config.showCaptions = true | false
    //
    //     Defines whether or not captions are shown on first viewing.
    //
    //     Option
    //          this.hide_captions = true | false
    //
    //     represents the user's choice of having the subtitles shown or
    //     hidden. This choice is stored in cookies.
    function _configureCaptions(state) {
        if (state.config.showCaptions) {
            state.hide_captions = ($.cookie('hide_captions') === 'true');
        } else {
            state.hide_captions = true;

            $.cookie('hide_captions', state.hide_captions, {
                expires: 3650,
                path: '/'
            });

            state.el.addClass('closed');
        }
    }

    // function _parseYouTubeIDs(state)
    //     The function parse YouTube stream ID's.
    //     @return
    //         false: We don't have YouTube video IDs to work with; most likely
    //             we have HTML5 video sources.
    //         true: Parsing of YouTube video IDs went OK, and we can proceed
    //             onwards to play YouTube videos.
    function _parseYouTubeIDs(state) {
        if (state.parseYoutubeStreams(state.config.streams)) {
            state.videoType = 'youtube';

            return true;
        }

        console.log(
            '[Video info]: Youtube Video IDs are incorrect or absent.'
        );

        return false;
    }

    // function _prepareHTML5Video(state)
    // The function prepare HTML5 video, parse HTML5
    // video sources etc.
    function _prepareHTML5Video(state) {
        state.speeds = ['0.75', '1.0', '1.25', '1.50'];
        // If none of the supported video formats can be played and there is no
        // short-hand video links, than hide the spinner and show error message.
        if (!state.config.sources.length) {
            _hideWaitPlaceholder(state);
            state.el
                .find('.video-player div')
                    .addClass('hidden');
            state.el
                .find('.video-player .video-error')
                    .removeClass('hidden');

            return false;
        }

        state.videoType = 'html5';

        if (!_.keys(state.config.transcriptLanguages).length) {
            state.config.showCaptions = false;
        }
        state.setSpeed(state.speed);

        return true;
    }

    function _hideWaitPlaceholder(state) {
        state.el
            .addClass('is-initialized')
            .find('.spinner')
            .attr({
                'aria-hidden': 'true',
                'tabindex': -1
            });
    }

    function _setConfigurations(state) {
        _configureCaptions(state);
        state.setPlayerMode(state.config.mode);
        // Possible value are: 'visible', 'hiding', and 'invisible'.
        state.controlState = 'visible';
        state.controlHideTimeout = null;
        state.captionState = 'invisible';
        state.captionHideTimeout = null;
    }

    function _initializeModules(state, i18n) {
        var dfd = $.Deferred(),
            modulesList = $.map(state.modules, function(module) {
                var options = state.options[module.moduleName] || {};
                if (_.isFunction(module)) {
                    return module(state, i18n, options);
                } else if ($.isPlainObject(module)) {
                    return module;
                }
        });

        $.when.apply(null, modulesList)
            .done(dfd.resolve);

        return dfd.promise();
    }

    function _getConfiguration(data, storage) {
            var isBoolean = function (value) {
                    var regExp = /^true$/i;
                    return regExp.test(value.toString());
                },
                // List of keys that will be extracted form the configuration.
                extractKeys = [],
                // Compatibility keys used to change names of some parameters in
                // the final configuration.
                compatKeys = {
                    'start': 'startTime',
                    'end': 'endTime'
                },
                // Conversions used to pre-process some configuration data.
                conversions = {
                    'showCaptions': isBoolean,
                    'autoplay': isBoolean,
                    'autohideHtml5': isBoolean,
                    'savedVideoPosition': function (value) {
                        return storage.getItem('savedVideoPosition', true) ||
                            Number(value) ||
                            0;
                    },
                    'speed': function (value) {
                        return storage.getItem('speed', true) || value;
                     },
                    'generalSpeed': function (value) {
                        return storage.getItem('general_speed') ||
                            value ||
                            '1.0';
                     },
                    'transcriptLanguage': function (value) {
                        return storage.getItem('language') ||
                            value ||
                            'en';
                     },
                    'ytTestTimeout': function (value) {
                        value = parseInt(value, 10);

                        if (!isFinite(value)) {
                            value = 1500;
                        }

                        return value;
                    },
                    'startTime': function (value) {
                        value = parseInt(value, 10);
                        if (!isFinite(value) || value < 0) {
                            return 0;
                        }

                        return value;
                    },
                    'endTime': function (value) {
                        value = parseInt(value, 10);

                        if (!isFinite(value) || value === 0) {
                            return null;
                        }

                        return value;
                     }
                },
                config = {};

            data = _.extend({
                startTime: 0,
                endTime: null,
                sub: '',
                streams: ''
            }, data);

            $.each(data, function(option, value) {
                // Extract option that is in `extractKeys`.
                if ($.inArray(option, extractKeys) !== -1) {
                    return;
                }

                // Change option name to key that is in `compatKeys`.
                if (compatKeys[option]) {
                    option = compatKeys[option];
                }

                // Pre-process data.
                if (conversions[option]) {
                    if (_.isFunction(conversions[option])) {
                        value = conversions[option].call(this, value);
                    } else {
                        throw new TypeError(option + ' is not a function.');
                    }
                }
                config[option] = value;
            });

            return config;
        }

    // ***************************************************************
    // Public functions start here.
    // These are available via the 'state' object. Their context ('this'
    // keyword) is the 'state' object. The magic private function that makes
    // them available and sets up their context is makeFunctionsPublic().
    // ***************************************************************


    // function bindTo(methodsDict, obj, context, rewrite)
    // Creates a new function with specific context and assigns it to the provided
    // object.
    function bindTo(methodsDict, obj, context, rewrite) {
        $.each(methodsDict, function(name, method) {
            if (_.isFunction(method)) {

                if (_.isUndefined(rewrite)) {
                    rewrite = true;
                }

                if (_.isUndefined(obj[name]) || rewrite) {
                    obj[name] = _.bind(method, context);
                }
            }
        });
    }

    function loadYoutubePlayer() {
        if (this.htmlPlayerLoaded) { return; }

        console.log(
            '[Video info]: Fetch metadata for YouTube video.'
        );

        this.fetchMetadata();
        this.parseSpeed();
    }

    function loadHtmlPlayer() {

        // When the youtube link doesn't work for any reason
        // (for example, firewall) any
        // alternate sources should automatically play.
        if (!_prepareHTML5Video(this)) {
            console.log(
                '[Video info]: Continue loading ' +
                'YouTube video.'
            );

            // Non-YouTube sources were not found either.

            this.el.find('.video-player div')
                .removeClass('hidden');
            this.el.find('.video-player .video-error')
                .addClass('hidden');

            // If in reality the timeout was to short, try to
            // continue loading the YouTube video anyways.
            this.loadYoutubePlayer();
        } else {
            console.log(
                '[Video info]: Start HTML5 player.'
            );

            // In-browser HTML5 player does not support quality
            // control.
            this.el.find('.quality_control').hide();
            _renderElements(this);
        }
    }

    // function initialize(element)
    // The function set initial configuration and preparation.

    function initialize(element) {
        var self = this,
            el = this.el,
            id = this.id,
            container = el.find('.video-wrapper'),
            __dfd__ = $.Deferred(),
            isTouch = onTouchBasedDevice() || '';

        if (isTouch) {
            el.addClass('is-touch');
        }

        $.extend(this, {
            __dfd__: __dfd__,
            container: container,
            isFullScreen: false,
            isTouch: isTouch
        });

        console.log('[Video info]: Initializing video with id "%s".', id);

        // We store all settings passed to us by the server in one place. These
        // are "read only", so don't modify them. All variable content lives in
        // 'state' object.
        // jQuery .data() return object with keys in lower camelCase format.
        this.config = $.extend({}, _getConfiguration(this.metadata, this.storage), {
            element: element,
            fadeOutTimeout: 1400,
            captionsFreezeTime: 10000,
            mode: $.cookie('edX_video_player_mode'),
            // Available HD qualities will only be accessible once the video has
            // been played once, via player.getAvailableQualityLevels.
            availableHDQualities: []
        });

        if (this.config.endTime < this.config.startTime) {
            this.config.endTime = null;
        }

        this.lang = this.config.transcriptLanguage;
        this.speed = this.speedToString(
            this.config.speed || this.config.generalSpeed
        );
        this.htmlPlayerLoaded = false;

        _setConfigurations(this);

        if (!(_parseYouTubeIDs(this))) {

            // If we do not have YouTube ID's, try parsing HTML5 video sources.
            if (!_prepareHTML5Video(this)) {

                __dfd__.reject();
                // Non-YouTube sources were not found either.
                return __dfd__.promise();
            }

            console.log('[Video info]: Start player in HTML5 mode.');
            _renderElements(this);
        } else {
            _renderElements(this);

            _waitForYoutubeApi(this);

            var scriptTag = document.createElement('script');

            scriptTag.src = this.config.ytApiUrl;
            scriptTag.async = true;

            $(scriptTag).on('load', function() {
                self.loadYoutubePlayer();
            });
            $(scriptTag).on('error', function() {
                console.log(
                    '[Video info]: YouTube returned an error for ' +
                    'video with id "' + self.id + '".'
                );
                // If the video is already loaded in `_waitForYoutubeApi` by the
                // time we get here, then we shouldn't load it again.
                if (!self.htmlPlayerLoaded) {
                    self.loadHtmlPlayer();
                }
            });

            window.Video.loadYouTubeIFrameAPI(scriptTag);
        }
        return __dfd__.promise();
    }

    // function parseYoutubeStreams(state, youtubeStreams)
    //
    //     Take a string in the form:
    //         "iCawTYPtehk:0.75,KgpclqP-LBA:1.0,9-2670d5nvU:1.5"
    //     parse it, and make it available via the 'state' object. If we are
    //     not given a string, or it's length is zero, then we return false.
    //
    //     @return
    //         false: We don't have YouTube video IDs to work with; most likely
    //             we have HTML5 video sources.
    //         true: Parsing of YouTube video IDs went OK, and we can proceed
    //             onwards to play YouTube videos.
    function parseYoutubeStreams(youtubeStreams) {
        if (_.isUndefined(youtubeStreams) || !youtubeStreams.length) {
            return false;
        }

        this.videos = {};

        _.each(youtubeStreams.split(/,/), function (video) {
            var speed;
            video = video.split(/:/);
            speed = this.speedToString(video[0]);
            this.videos[speed] = video[1];
        }, this);

        return _.isString(this.videos['1.0']);
    }

    // function fetchMetadata()
    //
    //     When dealing with YouTube videos, we must fetch meta data that has
    //     certain key facts not available while the video is loading. For
    //     example the length of the video can be determined from the meta
    //     data.
    function fetchMetadata() {
        var self = this,
            metadataXHRs = [];

        this.metadata = {};

        metadataXHRs = _.map(this.videos, function (url, speed) {
            return self.getVideoMetadata(url, function (data) {
                if (data.items.length > 0) {
                    var metaDataItem = data.items[0];
                    self.metadata[metaDataItem.id] = metaDataItem.contentDetails;
                }
            });
        });

        $.when.apply(this, metadataXHRs).done(function () {
            self.el.trigger('metadata_received');

            // Not only do we trigger the "metadata_received" event, we also
            // set a flag to notify that metadata has been received. This
            // allows for code that will miss the "metadata_received" event
            // to know that metadata has been received. This is important in
            // cases when some code will subscribe to the "metadata_received"
            // event after it has been triggered.
            self.youtubeMetadataReceived = true;

        });
    }

    // function parseSpeed()
    //
    //     Create a separate array of available speeds.
    function parseSpeed() {
        this.speeds = _.keys(this.videos).sort();
    }

    function setSpeed(newSpeed) {
        // Possible speeds for each player type.
        // HTML5 =          [0.75, 1, 1.25, 1.5]
        // Youtube Flash =  [0.75, 1, 1.25, 1.5]
        // Youtube HTML5 =  [0.25, 0.5, 1, 1.5, 2]
        var map = {
            '0.25': '0.75', // Youtube HTML5 -> HTML5 or Youtube Flash
            '0.50': '0.75', // Youtube HTML5 -> HTML5 or Youtube Flash
            '0.75': '0.50', // HTML5 or Youtube Flash -> Youtube HTML5
            '1.25': '1.50', // HTML5 or Youtube Flash -> Youtube HTML5
            '2.0': '1.50'   // Youtube HTML5 -> HTML5 or Youtube Flash
        };

        if (_.contains(this.speeds, newSpeed)) {
            this.speed = newSpeed;
        } else {
            newSpeed = map[newSpeed];
            this.speed = _.contains(this.speeds, newSpeed) ? newSpeed : '1.0';
        }
    }

    function getVideoMetadata(url, callback) {
        if (!(_.isString(url))) {
            url = this.videos['1.0'] || '';
        }
        // Will hit the API URL iF YT key is defined in settings.
        if (this.config.ytKey) {
            return $.ajax({
                url: [this.config.ytMetadataUrl, '?id=', url, '&part=contentDetails&key=', this.config.ytKey].join(''),
                timeout: this.config.ytTestTimeout,
                success: _.isFunction(callback) ? callback : null
            });
        } else {
            return $.Deferred().reject().promise();
        }
    }

    function youtubeId(speed) {
        var currentSpeed = this.isFlashMode() ? this.speed : '1.0';

        return  this.videos[speed] ||
                this.videos[currentSpeed] ||
                this.videos['1.0'];
    }

    function getDuration() {
        try {
            return moment.duration(this.metadata[this.youtubeId()].duration, moment.ISO_8601).asSeconds();
        } catch (err) {
            return _.result(this.metadata[this.youtubeId('1.0')], 'duration') || 0;
        }
    }

    /**
     * Sets player mode.
     *
     * @param {string} mode Mode to set for the video player if it is supported.
     *                      Otherwise, `html5` is used by default.
     */
    function setPlayerMode(mode) {
        var supportedModes = ['html5', 'flash'];

        mode = _.contains(supportedModes, mode) ? mode : 'html5';
        this.currentPlayerMode = mode;
    }

    /**
     * Returns current player mode.
     *
     * @return {string} Returns string that describes player mode
     */
    function getPlayerMode() {
        return this.currentPlayerMode;
    }

    /**
     * Checks if current player mode is Flash.
     *
     * @return {boolean} Returns `true` if current mode is `flash`, otherwise
     *                   it returns `false`
     */
    function isFlashMode() {
        return this.getPlayerMode() === 'flash';
    }

    /**
     * Checks if current player mode is Html5.
     *
     * @return {boolean} Returns `true` if current mode is `html5`, otherwise
     *                   it returns `false`
     */
    function isHtml5Mode() {
        return this.getPlayerMode() === 'html5';
    }

    function isYoutubeType() {
        return this.videoType === 'youtube';
    }

    function speedToString(speed) {
        return parseFloat(speed).toFixed(2).replace(/\.00$/, '.0');
    }

    function getCurrentLanguage() {
        var keys = _.keys(this.config.transcriptLanguages);

        if (keys.length) {
            if (!_.contains(keys, this.lang)) {
                if (_.contains(keys, 'en')) {
                    this.lang = 'en';
                } else {
                    this.lang = keys.pop();
                }
            }
        } else {
            return null;
        }

        return this.lang;
    }

    /*
     * The trigger() function will assume that the @objChain is a complete
     * chain with a method (function) at the end. It will call this function.
     * So for example, when trigger() is called like so:
     *
     *     state.trigger('videoPlayer.pause', {'param1': 10});
     *
     * Then trigger() will execute:
     *
     *     state.videoPlayer.pause({'param1': 10});
     */
    function trigger(objChain) {
        var extraParameters = Array.prototype.slice.call(arguments, 1),
            i, tmpObj, chain;

        // Remember that 'this' is the 'state' object.
        tmpObj = this;
        chain = objChain.split('.');

        // At the end of the loop the variable 'tmpObj' will either be the
        // correct object/function to trigger/invoke. If the 'chain' chain of
        // object is incorrect (one of the link is non-existent), then the loop
        // will immediately exit.
        while (chain.length) {
            i = chain.shift();

            if (tmpObj.hasOwnProperty(i)) {
                tmpObj = tmpObj[i];
            } else {
                // An incorrect object chain was specified.

                return false;
            }
        }

        tmpObj.apply(this, extraParameters);

        return true;
    }
});

}(RequireJS.requirejs, RequireJS.require, RequireJS.define));
