const jsmediatags = require('jsmediatags');
const fs = require('fs');

const INPUT = './public/audio/';
const OUTPUT = 'src/data.json';


const data = {"albums" : []};
const promises = [];

try {
  if (fs.existsSync(INPUT)) {
    //file exists
  }
  else {
    console.log("\n============== Weband Error ====================\n\n");
    console.log("Audio files are missing. Please run first : \n\n$ ./scripts/weband-init.sh <input_directory> \n");
    console.log("\n================================================\n\n");
    process.exit(1);
  }
} catch(err) {
  console.log(err);
  process.exit(1);
}


function is_dir(path) {
    try {
        var stat = fs.lstatSync(path);
        return stat.isDirectory();
    } catch (e) {
        // lstatSync throws an error if path doesn't exist
        return false;
    }
}




function id3ToJSON(path){
  fs.readdirSync(path).forEach(file => {
    let isDir = is_dir(path + file);
    if(isDir)
      id3ToJSON(path +  file + '/');
    else {
      let filePath = path + file;
      if(!filePath.endsWith(".mp3") && !filePath.endsWith(".wav"))
        return;
      promises.push(new Promise((resolve, reject) => {
        new jsmediatags.Reader(filePath)
          .read({
            onSuccess: (tag) => {
              var tags = tag.tags;
              if(!data.artist)
                data.artist = tags.artist;
              let album = getAlbum(tags.album);
              if(!album){
                album = {"title": tags.album, "tracks": [], "year": tags.year}
                if (fs.existsSync(path + 'cover.png'))
                  album.cover = (path + 'cover.png').replace(INPUT,'audio/');
                data.albums.push(album);
              }
              let track = {"title": tags.title, "file" : filePath.replace(INPUT,'audio/')};
              album.tracks.push(track);
              resolve(tag);
            },
            onError: (error) => {
              console.log('Error');
              console.log(error);
              reject(error);
            }
        });
      }));
    }
  });
}


function getAlbum(albumTitle){
  for(let i = 0 ; i < data.albums.length; i++){
    if(data.albums[i].title === albumTitle)
      return data.albums[i];
  }
  return null;
}

id3ToJSON(INPUT);


Promise.all(promises).then((values) => {
  var jsonContent = JSON.stringify(data, null, 2);
  console.log(jsonContent);
  fs.writeFile(OUTPUT, jsonContent, 'utf8', function (err) {
      if (err) {
          console.log("An error occured while writing JSON Object to File.");
          return console.log(err);
      }

      console.log("JSON file has been saved : " + OUTPUT);
  });

});