sync/playlist.js

var ULList = require("./ullist").ULList;
var Media = require("./media").Media;
var InfoGetter = require("./get-info");

function PlaylistItem(media, uid) {
    this.media = media;
    this.uid = uid;
    this.temp = false;
    this.queueby = "";
    this.prev = null;
    this.next = null;
}

PlaylistItem.prototype.pack = function() {
    return {
        media: this.media.pack(),
        uid: this.uid,
        temp: this.temp,
        queueby: this.queueby
    };
}

function Playlist(chan) {
    this.items = new ULList();
    this.next_uid = 0;
    this._leadInterval = false;
    this._lastUpdate = 0;
    this._counter = 0;
    this.leading = true;
    this.callbacks = {
        "changeMedia": [],
        "mediaUpdate": [],
        "remove": [],
    };
    this.lock = false;
    this.alter_queue = [];
    this._qaInterval = false;

    if(chan) {
        var pl = this;
        this.on("mediaUpdate", function(m) {
            chan.sendAll("mediaUpdate", m.timeupdate());
        });
        this.on("changeMedia", function(m) {
            chan.sendAll("setCurrent", pl.current.uid);
            chan.sendAll("changeMedia", m.fullupdate());
        });
        this.on("remove", function(item) {
            chan.sendAll("delete", {
                uid: item.uid
            });
        });
    }
}

Playlist.prototype.queueAction = function(data) {
    this.alter_queue.push(data);
    if(this._qaInterval)
        return;
    var pl = this;
    this._qaInterval = setInterval(function() {
        if(!pl.lock) {
            var data = pl.alter_queue.shift();
            pl[data.fn].apply(pl, data.args);
            if(pl.alter_queue.length == 0) {
                clearInterval(pl._qaInterval);
            }
        }
    }, 100);
}

Playlist.prototype.dump = function() {
    var arr = this.items.toArray();
    var pos = 0;
    for(var i in arr) {
        if(arr[i].uid == this.current.uid) {
            pos = i;
            break;
        }
    }

    var time = 0;
    if(this.current)
        time = this.current.media.currentTime;

    return {
        pl: arr,
        pos: pos,
        time: time
    };
}

Playlist.prototype.load = function(data, callback) {
    this.clear();
    for(var i in data.pl) {
        var e = data.pl[i].media;
        var m = new Media(e.id, e.title, e.seconds, e.type);
        var it = this.makeItem(m);
        it.temp = data.pl[i].temp;
        it.queueby = data.pl[i].queueby;
        this.items.append(it);
        if(i == parseInt(data.pos)) {
            this.current = it;
            this.startPlayback(data.time);
        }
    }

    if(callback)
        callback();
}

Playlist.prototype.on = function(ev, fn) {
    if(typeof fn === "undefined") {
        var pl = this;
        return function() {
            for(var i = 0; i < pl.callbacks[ev].length; i++) {
                pl.callbacks[ev][i].apply(this, arguments);
            }
        }
    }
    else if(typeof fn === "function") {
        this.callbacks[ev].push(fn);
    }
}

Playlist.prototype.makeItem = function(media) {
    return new PlaylistItem(media, this.next_uid++);
}

Playlist.prototype.add = function(item, pos) {
    if(pos == "append")
        return this.items.append(item);
    else if(pos == "prepend")
        return this.items.prepend(item);
    else
        return this.items.insertAfter(item, pos);
}

Playlist.prototype.addMedia = function(data, callback) {
    if(this.lock) {
        this.queueAction({
            fn: "addMedia",
            args: arguments
        });
        return;
    }
    this.lock = true;
    var pos = "append";
    if(data.pos == "next") {
        if(!this.current)
            pos = "prepend";
        else
            pos = this.current.uid;
    }

    var pl = this;
    InfoGetter.getMedia(data.id, data.type, function(err, media) {
        if(err) {
            callback(err, null);
            pl.lock = false;
            return;
        }

        var it = pl.makeItem(media);
        it.temp = data.temp;
        it.queueby = data.queueby;
        if(!pl.add(it, pos))
            callback(true, null);
        else
            callback(false, it);
        pl.lock = false;
    });
}

Playlist.prototype.remove = function(uid, callback) {
    if(this.lock) {
        this.queueAction({
            fn: "remove",
            args: arguments
        });
        return;
    }
    this.lock = true;
    var item = this.items.find(uid);
    if(this.items.remove(uid)) {
        if(item == this.current)
            this._next();
        if(callback)
            callback();
    }
    this.lock = false;
}

Playlist.prototype.move = function(from, after, callback) {
    if(this.lock) {
        this.queueAction({
            fn: "move",
            args: arguments
        });
        return;
    }
    this.lock = true;
    this._move(from, after, callback);
    this.lock = false;
}

Playlist.prototype._move = function(from, after, callback) {
    var it = this.items.find(from);
    if(!this.items.remove(from))
        return;

    if(after === "prepend") {
        if(!this.items.prepend(it))
            return;
    }

    else if(after === "append") {
        if(!this.items.append(it))
            return;
    }

    else if(!this.items.insertAfter(it, after))
        return;

    callback();
}

Playlist.prototype.next = function() {
    if(!this.current)
        return;

    var it = this.current;
    this._next();

    if(it.temp) {
        var pl = this;
        this.remove(it.uid, function() {
            pl.on("remove")(it);
        });
    }

    return this.current;
}

Playlist.prototype._next = function() {
    if(!this.current)
        return;
    this.current = this.current.next;
    if(this.current === null && this.items.first !== null)
        this.current = this.items.first;

    if(this.current) {
        this.startPlayback();
    }
}

Playlist.prototype.jump = function(uid) {
    if(!this.current)
        return false;

    var jmp = this.items.find(uid);
    if(!jmp)
        return false;

    var it = this.current;

    this.current = jmp;

    if(this.current) {
        this.startPlayback();
    }

    if(it.temp) {
        this.remove(it.uid);
    }

    return this.current;
}

Playlist.prototype.clear = function() {
    this.items.clear();
    this.next_uid = 0;
    clearInterval(this._leadInterval);
}

Playlist.prototype.lead = function(lead) {
    this.leading = lead;
    var pl = this;
    if(!this.leading && this._leadInterval) {
        clearInterval(this._leadInterval);
        this._leadInterval = false;
    }
    else if(this.leading && !this._leadInterval) {
        this._leadInterval = setInterval(function() {
            pl._leadLoop();
        }, 1000);
    }
}

Playlist.prototype.startPlayback = function(time) {
    if(this.current.media === "loading") {
        setTimeout(function() {
            this.startPlayback(time);
        }.bind(this), 100);
        return;
    }
    this.current.media.paused = false;
    this.current.media.currentTime = time || -1;
    var pl = this;
    if(this.leading && !this._leadInterval && !isLive(this.current.media.type)) {
        this._lastUpdate = Date.now();
        this._leadInterval = setInterval(function() {
            pl._leadLoop();
        }, 1000);
    }
    else if(!this.leading && this._leadInterval) {
        clearInterval(this._leadInterval);
        this._leadInterval = false;
    }
    this.on("changeMedia")(this.current.media);
}

function isLive(type) {
    return type == "li" // Livestream.com
        || type == "tw" // Twitch.tv
        || type == "jt" // Justin.tv
        || type == "rt" // RTMP
        || type == "jw" // JWPlayer
        || type == "us" // Ustream.tv
        || type == "im";// Imgur album
}

const UPDATE_INTERVAL = 5;

Playlist.prototype._leadLoop = function() {
    if(this.current == null)
        return;

    this.current.media.currentTime += (Date.now() - this._lastUpdate) / 1000.0;
    this._lastUpdate = Date.now();
    this._counter++;

    if(this.current.media.currentTime >= this.current.media.seconds + 2) {
        this.next();
    }
    else if(this._counter % UPDATE_INTERVAL == 0) {
        this.on("mediaUpdate")(this.current.media);
    }
}

module.exports = Playlist;