db: Add a GenreMap

For mapping tracks into a list of genres, or a genre into a list of
tracks.

Signed-off-by: Anna Schumaker <Anna@NoWheyCreamery.com>

db/__init__.py

@@ -36,3 +36,5 @@ def reset():
 
     for mod in mods: mod.Table.drop()
     for mod in mods: mod.Table.do_create()
+
+    genre.Map.reset()

db/genre.py

@@ -9,8 +9,14 @@
 # +-----------------+
 # | name -> genreid |
 # +-----------------+
+#
+# Map: genre_map
+# +---------+---------+
+# | genreid | trackid |
+# +---------+---------+
 from . import execute
 from . import objects
+from . import track
 
 class Genre(objects.Tag):
     def do_get_column(self, column):
@@ -46,4 +52,40 @@ class GenreTable(objects.Table):
                        "WHERE name=?", [ name ])
 
 
+class GenreMap(objects.Map):
+    def __init__(self):
+        objects.Map.__init__(self, "genre_map", Genre, track.Track)
+        self.lookup_tracks = self.lookup_rhs
+        self.lookup_genres = self.lookup_lhs
+
+    def do_create(self):
+        execute("CREATE TABLE IF NOT EXISTS genre_map "
+                    "(genreid INTEGER, "
+                    " trackid INTEGER, "
+                    " FOREIGN KEY(genreid) REFERENCES genres(genreid), "
+                    " FOREIGN KEY(trackid) REFERENCES tracks(trackid), "
+                    " UNIQUE(genreid, trackid))")
+
+    def do_insert(self, genre, track):
+        execute("INSERT INTO genre_map (genreid, trackid) "
+                "VALUES (?, ?)", [ int(genre), int(track) ])
+
+    def do_delete(self, genre, track):
+        return execute("DELETE FROM genre_map WHERE genreid=? AND trackid=?",
+                       [ int(genre), int(track) ])
+
+    def do_lookup_rhs(self, genre):
+        return execute("SELECT trackid FROM genre_map "
+                       "WHERE genreid=?", [ int(genre) ])
+
+    def do_lookup_lhs(self, track):
+        return execute("SELECT genreid FROM genre_map "
+                       "WHERE trackid=?", [ int(track) ])
+
+    def delete_track(self, track):
+        for genre in self.lookup_genres(track):
+            self.delete(genre, track)
+
+
 Table = GenreTable()
+Map   = GenreMap()

db/test_genre.py

@@ -44,3 +44,63 @@ class TestGenreTable(unittest.TestCase):
         genre = db.genre.Table.insert("Test Genre")
         self.assertEqual(db.genre.Table.lookup("Test Genre"), genre)
         self.assertIsNone(db.genre.Table.lookup("none"))
+
+
+class TestGenreMap(unittest.TestCase):
+    def setUp(self):
+        db.reset()
+
+    def test_genre_map_init(self):
+        self.assertIsInstance(db.genre.Map, db.genre.GenreMap)
+        self.assertEqual(db.genre.Map.map_lhs, db.genre.Genre)
+        self.assertEqual(db.genre.Map.map_rhs, db.track.Track)
+        db.execute("SELECT genreid,trackid FROM genre_map")
+
+    def test_genre_map_insert(self):
+        track = db.make_fake_track(1, 1.234, "Test Title", "/a/b.cde")
+        genre = db.genre.Table.find("Test Genre")
+
+        db.genre.Map.insert(genre, track)
+        with self.assertRaises(sqlite3.IntegrityError):
+            db.genre.Map.insert(genre, track)
+
+    def test_genre_map_delete(self):
+        track = db.make_fake_track(1, 1.234, "Test Title", "/a/b.cde")
+        genre = db.genre.Table.find("Test Genre")
+
+        db.genre.Map.insert(genre, track)
+        db.genre.Map.delete(genre, track)
+        self.assertEqual(db.genre.Map.lookup_tracks(genre), [ ])
+
+    def test_genre_map_lookup_tracks(self):
+        track1 = db.make_fake_track(1, 1.234, "Test Title", "/a/b.cde")
+        track2 = db.make_fake_track(2, 2.345, "Test Title 2", "/a/c.def")
+        genre  = db.genre.Table.find("Test Genre")
+
+        db.genre.Map.insert(genre, track1)
+        db.genre.Map.insert(genre, track2)
+
+        lookup_res = db.genre.Map.lookup_tracks(genre)
+        self.assertEqual(lookup_res, [ track1, track2 ])
+
+    def test_genre_map_lookup_genres(self):
+        track  = db.make_fake_track(1, 1.234, "Test Title", "/a/b.cde")
+        genre1 = db.genre.Table.find("Test Genre 1")
+        genre2 = db.genre.Table.find("Test Genre 2")
+
+        db.genre.Map.insert(genre1, track)
+        db.genre.Map.insert(genre2, track)
+
+        lookup_res = db.genre.Map.lookup_genres(track)
+        self.assertEqual(lookup_res, [ genre1, genre2 ])
+
+    def test_genre_map_delete_track(self):
+        track  = db.make_fake_track(1, 1.234, "Test Title", "/a/b.cde")
+        genre1 = db.genre.Table.find("Test Genre 1")
+        genre2 = db.genre.Table.find("Test Genre 2")
+
+        db.genre.Map.insert(genre1, track)
+        db.genre.Map.insert(genre2, track)
+
+        db.genre.Map.delete_track(track)
+        self.assertEqual(db.genre.Map.lookup_genres(track), [ ])