Merge branch 'feat/genres' of git://github.com/arkon/Phonograph into arkon-feat/genres

app/src/main/java/com/kabouzeid/gramophone/loader/GenreLoader.java

@@ -0,0 +1,110 @@
+package com.kabouzeid.gramophone.loader;
+
+import android.content.Context;
+import android.database.Cursor;
+import android.net.Uri;
+import android.provider.BaseColumns;
+import android.provider.MediaStore.Audio.Genres;
+import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
+
+import com.kabouzeid.gramophone.R;
+import com.kabouzeid.gramophone.model.Genre;
+import com.kabouzeid.gramophone.model.Song;
+import com.kabouzeid.gramophone.util.PreferenceUtil;
+
+import java.util.ArrayList;
+
+public class GenreLoader {
+
+    @NonNull
+    public static ArrayList<Genre> getAllGenres(@NonNull final Context context) {
+        final String[] projection = new String[]{
+                Genres._ID,
+                Genres.NAME
+        };
+        // Genres that actually have songs
+        final String selection = Genres._ID + " IN" +
+                " (SELECT " + Genres.Members.GENRE_ID + " FROM audio_genres_map WHERE " + Genres.Members.AUDIO_ID + " IN" +
+                " (SELECT " + Genres._ID + " FROM audio_meta WHERE " + SongLoader.BASE_SELECTION + "))";
+
+        final Cursor cursor = context.getContentResolver().query(
+                Genres.EXTERNAL_CONTENT_URI,
+                projection, selection, null, PreferenceUtil.getInstance(context).getGenreSortOrder());
+
+        return getGenresFromCursor(context, cursor);
+    }
+
+    @NonNull
+    public static ArrayList<Song> getSongs(@NonNull final Context context, final int genreId) {
+        // The genres table only stores songs that have a genre specified,
+        // so we need to get songs without a genre a different way.
+        if (genreId == -1) {
+            return getSongsWithNoGenre(context);
+        }
+
+        final Cursor cursor = context.getContentResolver().query(
+                Genres.Members.getContentUri("external", genreId),
+                SongLoader.BASE_PROJECTION, SongLoader.BASE_SELECTION, null, null);
+
+        return SongLoader.getSongs(cursor);
+    }
+
+    @NonNull
+    private static ArrayList<Genre> getGenresFromCursor(@NonNull final Context context, @Nullable final Cursor cursor) {
+        final ArrayList<Genre> genres = new ArrayList<>();
+
+        if (hasSongsWithNoGenre(context)) {
+            genres.add(new Genre(context.getResources().getString(R.string.unknown_genre)));
+        }
+
+        if (cursor != null) {
+            if (cursor.moveToFirst()) {
+                do {
+                    genres.add(getGenreFromCursor(cursor));
+                } while (cursor.moveToNext());
+            }
+            cursor.close();
+        }
+        return genres;
+    }
+
+    @NonNull
+    private static Genre getGenreFromCursor(@NonNull final Cursor cursor) {
+        final int id = cursor.getInt(0);
+        final String name = cursor.getString(1);
+        return new Genre(id, name);
+    }
+
+    @NonNull
+    private static ArrayList<Song> getSongsWithNoGenre(@NonNull final Context context) {
+        String selection = BaseColumns._ID + " NOT IN " +
+                "(SELECT " + Genres.Members.AUDIO_ID + " FROM audio_genres_map)";
+        return SongLoader.getSongs(SongLoader.makeSongCursor(context, selection, null));
+    }
+
+    private static boolean hasSongsWithNoGenre(@NonNull final Context context) {
+        final Cursor allSongsCursor = SongLoader.makeSongCursor(context, null, null);
+        final Cursor allSongsWithGenreCursor = makeAllSongsWithGenreCursor(context);
+
+        if (allSongsCursor == null || allSongsWithGenreCursor == null) {
+            return false;
+        }
+
+        final boolean hasSongsWithNoGenre = allSongsCursor.getCount() > allSongsWithGenreCursor.getCount();
+        allSongsCursor.close();
+        allSongsWithGenreCursor.close();
+        return hasSongsWithNoGenre;
+    }
+
+    @Nullable
+    private static Cursor makeAllSongsWithGenreCursor(@NonNull final Context context) {
+        try {
+            return context.getContentResolver().query(
+                    Uri.parse("content://media/external/audio/genres/all/members"),
+                    new String[]{Genres.Members.AUDIO_ID}, null, null, null);
+        } catch (SecurityException e) {
+            return null;
+        }
+    }
+}