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queue.js
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queue.js
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const EventEmitter = require("events");
const log = require("./log.js").log;
class Response extends EventEmitter {
constructor(mpd) {
super();
this._mpd = mpd;
this._buffer = Buffer.alloc(0);
this._dataListener = data => this._onData(data);
mpd.on("data", this._dataListener);
}
_onData(data) {
log("<-- mpd", data);
this._buffer = Buffer.concat([this._buffer, data]);
this._processBuffer();
}
_processBuffer() {} // abstract
_done(data) {
this._mpd.off("data", this._dataListener);
this._buffer = null;
this.emit("done", data);
}
_getLine() {
let index = this._buffer.indexOf(0x0a);
if (index == -1) { return null; }
let str = this._buffer.slice(0, index).toString("utf8");
this._buffer = this._buffer.slice(index+1);
return str;
}
}
class Normal extends Response {
constructor(mpd) {
super(mpd);
this._lines = [];
}
_processBuffer() {
while (1) {
let line = this._getLine();
if (!line) { break; }
this._lines.push(line);
if (line.startsWith("OK") || line.startsWith("ACK")) { return this._done(this._lines); }
}
}
}
class Password extends Normal {}
class Idle extends Normal {}
class Welcome extends Response {
_processBuffer() {
let line = this._getLine();
if (line) { this._done([line]); }
}
}
class Binary extends Response {
constructor(mpd) {
super(mpd);
this._size = 0;
this._binary = 0;
this._data = null;
this._lines = [];
}
_processBuffer() {
if (!this._size) {
let line = this._getLine();
if (!line) { return; }
this._lines.push(line);
if (line.startsWith("ACK")) { // no art!
this._done(this._lines);
return;
}
this._size = Number(line.split(": ").pop());
log("size", this._size);
}
if (!this._binary) {
let line = this._getLine();
if (!line) { return; }
this._lines.push(line);
this._binary = Number(line.split(": ").pop());
log("binary", this._binary);
}
if (!this._data) {
// binary data has this._binary bytes + 1 newline
if (this._buffer.length >= this._binary+1) {
this._data = this._buffer.slice(0, this._binary);
this._buffer = this._buffer.slice(this._binary+1);
this._lines.push([...this._data]);
log("data", this._data.length);
} else { return; }
}
let line = this._getLine();
if (!line) { return; }
this._lines.push(line);
this._done(this._lines);
}
}
exports.Queue = class extends EventEmitter {
constructor(mpd) {
super();
this._mpd = mpd;
this._waiting = [];
this._current = null;
this._create(Welcome);
}
add(str) {
if (str == "noidle") {
if (this._current instanceof Idle) {
this._mpd.write(str + "\n");
} else {
log("throwing away rogue noidle");
}
return;
}
this._waiting.push(str);
this._process();
}
_process() {
if (this._current || !this._waiting.length) { return; }
let str = this._waiting.shift();
this._create(getCtor(str));
log("--> mpd", str);
this._mpd.write(str + "\n");
}
_create(ctor) {
let cmd = new ctor(this._mpd);
this._current = cmd;
cmd.on("done", data => {
if (ctor != Password) { this.emit("response", data); } // do not pass password check result back
this._current = null;
this._process();
});
}
}
function getCtor(command) {
switch (true) {
case command.startsWith("password"): return Password;
case command.startsWith("idle"): return Idle;
case command.startsWith("albumart") || command.startsWith("readpicture"): return Binary;
default: return Normal;
}
}