// Jeremie Miserez <jeremie@miserez.org>, 2015
//
// A little bit of Javascript to let you export your Google Music library, playlists, and album track lists :)
//
// I posted this as an answer here: 
//
// 1. Go to: https://play.google.com/music/listen#/all (or your playlist)
//
// 2. Open a developer console (F12 for Chrome). Paste 
//    code below into the console.
//
// 3. All scraped songs are stored in the `allsongs` object
//    and a text version of the list is copied to the clipboard. I recommend running
//    `songsToText("all",true)` afterwards to get the full CSV information.
//
// 4. If you would like the output in a text format, can call
//    the songsToText() function. You can select a style, choose 
//    the format, and if only liked/thumbed up songs should be exported. 
//    The resulting list will then be pasted into the clipboard. 
//    Styles are ` all`, `artist`, `artistalbum`, `artistsong`, 
//    `artistalbumsong`. 
//    CSV will result in a CSV file and can be left out (defaults to false).
//    Likedonly can be left out (defaults to 
//    false) or set to true, and will filter all songs with 
//    ratings greater or equal to 5. 
//    E.g: 
//    - `songsToText("all",true,false)` will export all songs in csv format.
//    - `songsToText("all",true,true)` will export only liked songs in csv format.
//    - `songsToText("artistsong",false,false)` will export all songs as text.
//
// 5. You can then paste the data anywhere you like, for 
//    example http://www.ivyishere.org/ if you want to add the
//    songs or albums to your Spotify account. To make Ivy 
//    recognize full albums, use the "artistalbum" style. For 
//    songs, use the "artistsong" style.

// see my answer here for questions: http://webapps.stackexchange.com/a/73791/77056

var allsongs = []
var songsToText = function(style, csv, likedonly){
  if (style === undefined){
    console.log("style is undefined.");
    return;
  }
  var csv = csv || false; // defaults to false
  var likedonly = likedonly || false; // defaults to false
  if (likedonly) {
    console.log("Only selecting liked songs");
  }
  if (style == "all" && !csv){
    console.log("Duration, ratings, and playcount will only be exported with the CSV flag");
  }
  var outText = "";
  if (csv) {
    if (style == "all") {
      //extra line
      outText = "index,artist,album,title,duration,playcount,rating" + "\n";
    } else if (style == "artist") {
    } else if (style == "artistsong") {
    } else if (style == "artistalbum") {
    } else if (style == "artistalbumsong") {
    } else {
      console.log("style not defined");
    }
  }
  var numEntries = 0;
  var seen = {};
  for (var i = 0; i < allsongs.length; i++) {
    var curr = "";
    if (!likedonly || (likedonly && allsongs[i].rating >= 5)){
      if (csv) {
        if (style == "all") {
          //extra line
          curr = allsongs[i].artist + ",";
          curr += allsongs[i].album + ",";
          curr += allsongs[i].title + ",";
          curr += allsongs[i].duration + ",";
          curr += allsongs[i].index + ",";
          curr += allsongs[i].playcount + ",";
          curr += allsongs[i].rating;
        } else if (style == "artist") {
          curr = allsongs[i].artist;
        } else if (style == "artistsong") {
          curr = allsongs[i].artist + ",";
          curr += allsongs[i].title;
        } else if (style == "artistalbum") {
          curr = allsongs[i].artist + ",";
          curr += allsongs[i].album;
        } else if (style == "artistalbumsong") {
          curr = allsongs[i].artist + ",";
          curr += allsongs[i].album + ",";
          curr += allsongs[i].title;
        } else {
          console.log("style not defined");
        }
      } else {
        if (style == "all"){
          curr = "";
          curr += (allsongs[i].index.length > 0 ? allsongs[i].index + ". " : "");
          curr += allsongs[i].artist + " - ";
          curr += allsongs[i].album + " - ";
          curr += allsongs[i].title;
        } else if (style == "artist"){
          curr = allsongs[i].artist;
        } else if (style == "artistalbum"){
          curr = allsongs[i].artist + " - " + allsongs[i].album;
        } else if (style == "artistsong"){
          curr = allsongs[i].artist + " - " + allsongs[i].title;
        } else if (style == "artistalbumsong"){
          curr = allsongs[i].artist + " - " + allsongs[i].album + " - " + allsongs[i].title;
        } else {
          console.log("style not defined");
        }
      }
      if (!seen.hasOwnProperty(curr)){ // hashset
        outText = outText + curr + "\n";
        numEntries++;
        seen[curr] = true;
      } else {
        console.log("Skipping (duplicate) " + curr);
      }
    }
  }
  copy(outText);
  console.log("Done! " + numEntries + " lines copied to clipboard. Used " + numEntries + " songs out of " + allsongs.length + ".");
};
var scrapeSongs = function(){
  var intervalms = 1; //in ms
  var timeoutms = 3000; //in ms
  var retries = timeoutms / intervalms;
  var total = [];
  var seen = {};
  var topId = "";
  var interval = setInterval(function(){
    var songs = document.querySelectorAll("table.song-table tbody tr.song-row");
    if (songs.length > 0) {
      // detect order
      var colNames = {
        index: -1,
        title: -1,
        duration: -1,
        artist: -1,
        album: -1,
        playcount: -1,
        rating: -1
        };
      for (var i = 0; i < songs[0].childNodes.length; i++) {
        colNames.index = songs[0].childNodes[i].getAttribute("data-col") == "index" ? i : colNames.index;
        colNames.title = songs[0].childNodes[i].getAttribute("data-col") == "title" ? i : colNames.title;
        colNames.duration = songs[0].childNodes[i].getAttribute("data-col") == "duration" ? i : colNames.duration;
        colNames.artist = songs[0].childNodes[i].getAttribute("data-col") == "artist" ? i : colNames.artist;
        colNames.album = songs[0].childNodes[i].getAttribute("data-col") == "album" ? i : colNames.album;
        colNames.playcount = songs[0].childNodes[i].getAttribute("data-col") == "playcount" ? i : colNames.playcount;
        colNames.rating = songs[0].childNodes[i].getAttribute("data-col") == "rating" ? i : colNames.rating;
      }
      // check if page has updated/scrolled
      var currId = songs[0].getAttribute("data-id");
      if (currId == topId){ // page has not yet changed
        retries--;
        scrollDiv = document.querySelector("div#music-content");
        isAtBottom = scrollDiv.scrollTop == (scrollDiv.scrollHeight - scrollDiv.offsetHeight)
        if (isAtBottom || retries <= 0) {
          clearInterval(interval); //done
          allsongs = total;
          console.log("Got " + total.length + " songs and stored them in the allsongs variable.");
          console.log("Calling songsToText with style all, csv flag true, likedonly false: songsToText(\"all\", false).");
          songsToText("all", false, false);
        }
      } else {
        retries = timeoutms / intervalms;
        topId = currId;
        // read page
        for (var i = 0; i < songs.length; i++) {
          var curr = {
            dataid: songs[i].getAttribute("data-id"),
            index: (colNames.index != -1 ? songs[i].childNodes[colNames.index].textContent : ""),
            title: (colNames.title != -1 ? songs[i].childNodes[colNames.title].textContent : ""),
            duration: (colNames.duration != -1 ? songs[i].childNodes[colNames.duration].textContent : ""),
            artist: (colNames.artist != -1 ? songs[i].childNodes[colNames.artist].textContent : ""),
            album: (colNames.album != -1 ? songs[i].childNodes[colNames.album].textContent : ""),
            playcount: (colNames.playcount != -1 ? songs[i].childNodes[colNames.playcount].textContent : ""),
            rating: (colNames.rating != -1 ? songs[i].childNodes[colNames.rating].textContent : ""),
            }
          if (!seen.hasOwnProperty(curr.dataid)){ // hashset
            total.push(curr);
            seen[curr.id] = true;
          }
        }
        songs[songs.length-1].scrollIntoView(true); // go to next page
      }
    }
  }, intervalms);
};
scrapeSongs();
// for the full CSV version you can now call songsToText("all", true);