server/services/music_brainz.js

var request = require("request");
var notifier = require("./notifier");

var album_cover_queue = [];
var album_cover_requst_is_running = false;

var artist_cover_queue = [];
var artist_cover_queue_is_running = false;

let options = {
  headers: {
    "User-Agent":
      "WebPlay/0.1.0 (https://gitea.com/WebPlay)"
  }
};

exports.find_album_cover = function(album) {
  album_cover_queue.push(album);
  console.log("MB Album: " + album.title + " by " + album.artist_name);
  run_album_cover_request();
};

exports.find_artist_cover = function(artist) {
  artist_cover_queue.push(artist);
  console.log("MB Artist: " + artist.name);
  run_artist_cover_request();
};

// ARTIST COVER
async function run_artist_cover_request() {
  console.log("started request for artist covers");
  if (artist_cover_queue_is_running) {
    return;
  }
  artist_cover_queue_is_running = true;
  while (artist_cover_queue && artist_cover_queue.length > 0) {
    await sleep(1500);
    let artist = artist_cover_queue.shift();
    console.log("SHIFT Artist: " + artist.name);
    for (let i = 0; i < artist.albums.length; i++) {
      await sleep(1500);
      if (artist.image_downloaded) {
        break;
      }
      let album = artist.albums[i];
      let album_title = album.title.replace("&", "%26").replace("/", "_");
      let artist_name = artist.name.replace("&", "%26").replace("/", "_");
      let url = `https://musicbrainz.org/ws/2/release/?query=release:${album_title} AND artist:${artist_name}&fmt=json`;

      options.url = url;
      request(options, (err, res, body) => {
        if (err) {
          console.log(err);
          return;
        }
        let json = json_parser(body, url);
        if (!json) {
          return;
        }
        if (json.releases && json.releases.length > 0) {
          let release = json.releases[0];
          if (release["artist-credit"] && release["artist-credit"].length > 0) {
            let artist_id = release["artist-credit"][0].artist.id;
            console.log(artist_id);
            get_image_by_artist_id(artist, artist_id);
          }
        }
      });
    }
  }
  artist_cover_queue_is_running = false;
}

async function get_image_by_artist_id(artist, artist_id) {
  let url = `https://musicbrainz.org/ws/2/artist/${artist_id}?inc=url-rels&fmt=json`;
  console.log(url);
  options.url = url;
  request(options, (err, res, body) => {
    let json = json_parser(body, url);
    if (!json) {
      return;
    }
    if (!json.relations) {
      return;
    }

    json.relations.forEach(relation => {
      if (relation.type == "image" && relation.url && relation.url.resource) {
        let resource = relation.url.resource;
        if (resource.includes("commons.wikimedia.org")) {
          get_image_by_wikimedia(artist, resource);
        } else {
          artist.image_downloaded = true;
          notifier.emit("found_music_brainz_artist_cover", {
            artist: artist,
            mb: resource
          });
        }
      }
    });
  });
}

function get_image_by_wikimedia(artist, url) {
  let regex = RegExp("(?<=File:)[^<]*", "g");
  let result = regex.exec(url);
  if (result) {
    console.log(result[0]);
    let file = result[0];
    let url = `https://en.wikipedia.org/w/api.php?action=query&titles=File:${file}&prop=imageinfo&iiprop=url&iiurlwidth=600&iiurlheight=600&format=json`;
    console.log(url);
    options.url = url;
    request(options, (err, res, body) => {
      let json = json_parser(body, url);
      if (!json) {
        return;
      }

      if (json.query.pages["-1"].imageinfo[0].thumburl) {
        console.log(json.query.pages["-1"].imageinfo[0].thumburl);
        artist.image_downloaded = true;
        notifier.emit("found_music_brainz_artist_cover", {
          artist: artist,
          mb: json.query.pages["-1"].imageinfo[0].thumburl
        });
      }
    });
  }
}

// ALBUM COVER
async function run_album_cover_request() {
  console.log("started request for album covers");
  if (album_cover_requst_is_running) {
    return;
  }
  album_cover_requst_is_running = true;
  while (album_cover_queue && album_cover_queue.length > 0) {
    await sleep(1500);
    let album = album_cover_queue.shift();
    console.log("SHIFT Album: " + album.title);
    let album_title = album.title.replace("&", "%26").replace("/", "_");
    let artist_name = album.artist_name.replace("&", "%26").replace("/", "_");

    let url = `https://musicbrainz.org/ws/2/release/?query=release:${album_title} AND artist:${artist_name}&fmt=json`;
    console.log(url);

    options.url = url;
    request(options, (err, res, body) => {
      let json;
      try {
        json = JSON.parse(body);
      } catch (err) {
        console.log(err);
        return;
      }
      if (json.releases && json.releases.length > 0) {
        let release_id = json.releases[0].id;
        let title = json.releases[0].title;
        console.log(release_id + ": " + title);
        get_album_cover_url(album, release_id);
      }
    });
  }

  album_cover_requst_is_running = false;
}

function get_album_cover_url(album, id) {
  let url = "https://coverartarchive.org/release/" + id;
  options.url = url;
  request(options, (err, res, body) => {
    if (err) {
      console.log(err);
      return;
    }

    if (res.statusCode != 200) {
      return;
    }

    let json = JSON.parse(body);
    if (json.images && json.images.length > 0) {
      if (json.images[0].thumbnails.large) {
        notifier.emit("found_music_brainz_album_cover", {
          album: album,
          mb: json.images[0].thumbnails.large
        });
      } else if (json.images[0].image) {
        notifier.emit("found_music_brainz_album_cover", {
          album: album,
          mb: json.images[0].image
        });
      }
    }
  });
}

function sleep(milliseconds) {
  return new Promise(resolve => setTimeout(resolve, milliseconds));
}

function json_parser(body, url) {
  let json;
  try {
    json = JSON.parse(body);
  } catch (err) {
    console.log(err);
    console.log(url);
    console.log("BODY============BEGIN");
    console.log(body);
    console.log("BODY============END");
  }
  return json;
}