Add demo Node application

Author: jodal

README.md

@@ -73,7 +73,7 @@ To build updated JavaScript files for browser use in `dist/`, run:
 yarn build
 ```
 
-## Demo application
+## Demo web application
 
 ![Web demo](examples/web.png)
 
@@ -103,6 +103,29 @@ application files, `examples/web.{html,js}`, will instantly be visible in
 your browser. Thus, this can serve as a nice playing ground to get to know
 the capabilities of Mopidy and Mopidy.js.
 
+## Demo console application
+
+In the `examples/` directory of the Gir repo, you can find `mpc.js`, a partial
+clone of the `mpc` utility built using Mopidy.js on Node.
+
+Output from the original command:
+
+```
+$ mpc
+Jon Hopkins - C O S M
+[playing] #6/12   2:33/7:08 (35%)
+volume:100%   repeat: off   random: on    single: off   consume: off
+```
+
+Output from the `mpc.js` example:
+
+```
+$ ./examples/mpc.js
+Jon Hopkins - C O S M
+[playing] #6/-   2:33/7:08 (36%)
+volume:100%   repeat: off   random: on    single: off   consume: off
+```
+
 ## Changelog
 
 See [CHANGELOG.md](CHANGELOG.md).

examples/mpc.js

@@ -0,0 +1,102 @@
+#!/usr/bin/env node
+
+/* eslint-env node */
+/* eslint-disable no-console */
+
+/*
+Output when offline:
+
+  WebSocket error: ...
+
+Output when not playing:
+
+  volume:100%   repeat: off   random: on    single: off   consume: off
+
+Output when playing:
+
+  Kiasmos - Shed
+  [playing] #9/14   0:26/5:35 (7%)
+  volume:100%   repeat: off   random: on    single: off   consume: off
+*/
+
+const Mopidy = require("../mopidy");
+
+const mopidy = new Mopidy({
+  autoConnect: false,
+  webSocketUrl: "ws://localhost:6680/mopidy/ws",
+});
+
+function renderTrackNumber(track) {
+  return `#${track.track_no}/${track.album.num_tracks || "-"}`;
+}
+
+function renderTime(timeInSeconds) {
+  const minutes = Math.floor(timeInSeconds / 1000 / 60);
+  const seconds = Math.floor((timeInSeconds / 1000) % 60)
+    .toString()
+    .padStart(2, "0");
+  return `${minutes}:${seconds}`;
+}
+
+function renderPosition(track, timePosition) {
+  const pos = renderTime(timePosition);
+  const length = renderTime(track.length);
+  const percentage = Math.floor((timePosition * 100) / track.length);
+  return `${pos}/${length} (${percentage}%)`;
+}
+
+async function showPlaybackInfo() {
+  const trackPromise = mopidy.playback.getCurrentTrack();
+  const statePromise = mopidy.playback.getState();
+  const timePositionPromise = mopidy.playback.getTimePosition();
+
+  const track = await trackPromise;
+  const state = await statePromise;
+  const timePosition = await timePositionPromise;
+
+  if (state === "stopped") {
+    return;
+  }
+
+  const artists = track.artists.map(a => a.name).join(", ");
+  console.log(`${artists} - ${track.name}`);
+  console.log(
+    `[${state}] ${renderTrackNumber(track)}   ` +
+      `${renderPosition(track, timePosition)}`
+  );
+}
+
+async function showTracklistInfo() {
+  const volumePromise = mopidy.mixer.getVolume();
+  const repeatPromise = mopidy.tracklist.getRepeat();
+  const randomPromise = mopidy.tracklist.getRandom();
+  const singlePromise = mopidy.tracklist.getSingle();
+  const consumePromise = mopidy.tracklist.getConsume();
+
+  const volume = (await volumePromise).toString().padStart(3, " ");
+  const repeat = ((await repeatPromise) && "on ") || "off";
+  const random = ((await randomPromise) && "on ") || "off";
+  const single = ((await singlePromise) && "on ") || "off";
+  const consume = ((await consumePromise) && "on ") || "off";
+
+  console.log(
+    `volume:${volume}%   ` +
+      `repeat: ${repeat}   ` +
+      `random: ${random}   ` +
+      `single: ${single}   ` +
+      `consume: ${consume}`
+  );
+}
+
+mopidy.on("state:online", async () => {
+  await showPlaybackInfo();
+  await showTracklistInfo();
+  process.exit();
+});
+
+mopidy.on("websocket:error", error => {
+  console.log(`WebSocket error: ${error.message}`);
+  process.exit(1);
+});
+
+mopidy.connect();