PlayerAndroid/app/src/main/java/code/name/monkey/retromusic/loaders/TopAndRecentlyPlayedTracksLoader.java

package code.name.monkey.retromusic.loaders;

import android.content.Context;
import android.database.Cursor;
import android.provider.BaseColumns;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import code.name.monkey.retromusic.model.Album;
import code.name.monkey.retromusic.model.Artist;
import code.name.monkey.retromusic.model.Song;
import code.name.monkey.retromusic.providers.HistoryStore;
import code.name.monkey.retromusic.providers.SongPlayCountStore;
import io.reactivex.Observable;
import java.util.ArrayList;

/**
 * Created by hemanths on 16/08/17.
 */

public class TopAndRecentlyPlayedTracksLoader {

  private static final int NUMBER_OF_TOP_TRACKS = 99;

  @NonNull
  public static Observable<ArrayList<Song>> getRecentlyPlayedTracks(@NonNull Context context) {
    return SongLoader.getSongs(makeRecentTracksCursorAndClearUpDatabase(context));
  }

  @NonNull
  public static Observable<ArrayList<Song>> getTopTracks(@NonNull Context context) {
    return SongLoader.getSongs(makeTopTracksCursorAndClearUpDatabase(context));
  }

  @Nullable
  private static Cursor makeRecentTracksCursorAndClearUpDatabase(@NonNull final Context context) {
    SortedLongCursor retCursor = makeRecentTracksCursorImpl(context);

    // clean up the databases with any ids not found
    if (retCursor != null) {
      ArrayList<Long> missingIds = retCursor.getMissingIds();
      if (missingIds != null && missingIds.size() > 0) {
        for (long id : missingIds) {
          HistoryStore.getInstance(context).removeSongId(id);
        }
      }
    }
    return retCursor;
  }

  @Nullable
  private static Cursor makeTopTracksCursorAndClearUpDatabase(@NonNull final Context context) {
    SortedLongCursor retCursor = makeTopTracksCursorImpl(context);

    // clean up the databases with any ids not found
    if (retCursor != null) {
      ArrayList<Long> missingIds = retCursor.getMissingIds();
      if (missingIds != null && missingIds.size() > 0) {
        for (long id : missingIds) {
          SongPlayCountStore.getInstance(context).removeItem(id);
        }
      }
    }
    return retCursor;
  }

  @Nullable
  private static SortedLongCursor makeRecentTracksCursorImpl(@NonNull final Context context) {
    // first get the top results ids from the internal database
    Cursor songs = HistoryStore.getInstance(context).queryRecentIds();

    try {
      return makeSortedCursor(context, songs,
          songs.getColumnIndex(HistoryStore.RecentStoreColumns.ID));
    } finally {
      if (songs != null) {
        songs.close();
      }
    }
  }

  @Nullable
  private static SortedLongCursor makeTopTracksCursorImpl(@NonNull final Context context) {
    // first get the top results ids from the internal database
    Cursor songs = SongPlayCountStore.getInstance(context)
        .getTopPlayedResults(NUMBER_OF_TOP_TRACKS);

    try {
      return makeSortedCursor(context, songs,
          songs.getColumnIndex(SongPlayCountStore.SongPlayCountColumns.ID));
    } finally {
      if (songs != null) {
        songs.close();
      }
    }
  }

  @Nullable
  private static SortedLongCursor makeSortedCursor(@NonNull final Context context,
      @Nullable final Cursor cursor, final int idColumn) {

    if (cursor != null && cursor.moveToFirst()) {
      // create the list of ids to select against
      StringBuilder selection = new StringBuilder();
      selection.append(BaseColumns._ID);
      selection.append(" IN (");

      // this tracks the order of the ids
      long[] order = new long[cursor.getCount()];

      long id = cursor.getLong(idColumn);
      selection.append(id);
      order[cursor.getPosition()] = id;

      while (cursor.moveToNext()) {
        selection.append(",");

        id = cursor.getLong(idColumn);
        order[cursor.getPosition()] = id;
        selection.append(String.valueOf(id));
      }

      selection.append(")");

      // get a list of songs with the data given the selection statement
      Cursor songCursor = SongLoader.makeSongCursor(context, selection.toString(), null);
      if (songCursor != null) {
        // now return the wrapped TopTracksCursor to handle sorting given order
        return new SortedLongCursor(songCursor, order, BaseColumns._ID);
      }
    }

    return null;
  }

  @NonNull
  public static Observable<ArrayList<Album>> getTopAlbums(@NonNull Context context) {
    return Observable.create(e -> {
      getTopTracks(context).subscribe(songs -> {
        if (songs.size() > 0) {
          e.onNext(AlbumLoader.splitIntoAlbums(songs));
        }
        e.onComplete();
      });
    });
  }

  @NonNull
  public static Observable<ArrayList<Artist>> getTopArtists(@NonNull Context context) {
    return Observable.create(e -> {
      getTopAlbums(context).subscribe(albums -> {
        if (albums.size() > 0) {
          e.onNext(ArtistLoader.splitIntoArtists(albums));
        }
        e.onComplete();
      });
    });
  }
}