db: Give playlists a next_track() function

For picking the next track (with or without random enabled)

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

db/playlist.py

@@ -1,4 +1,5 @@
 # Copyright 2021 (c) Anna Schumaker.
+import random
 from gi.repository import GObject
 from . import sql
 from . import state
@@ -65,6 +66,14 @@ class Playlist(GObject.GObject):
     def remove_track(self, track):
         self.emit("track-removed", track)
 
+    def next_track(self):
+        n = self.get_n_tracks()
+        if self.random  and n > 0:
+            self.current += random.randint(1, int((3*n)/4))
+        else:
+            self.current += 1
+        return self.get_current_track()
+
     def refresh(self):
         self.emit("refreshed")
 
@@ -82,11 +91,12 @@ class Playlist(GObject.GObject):
 
     @current.setter
     def current(self, newval):
-        if newval >= self.get_n_tracks():
-            if self.get_n_tracks() == 0: newval = -1
-            elif self.random: newval = newval % self.get_n_tracks()
+        n_tracks = self.get_n_tracks()
+        if newval >= n_tracks:
+            if n_tracks == 0: newval = -1
+            elif self.random: newval = newval % n_tracks
             elif self.loop: newval = 0
-            else: newval = -1
+            else: newval = n_tracks
         self._plstate.set_property("current", newval)
 
     @GObject.Property(type=bool,default=False)

db/test_playlist.py

@@ -1,5 +1,6 @@
 # Copyright 2021 (c) Anna Schumaker.
 import db
+import random
 import unittest
 from gi.repository import GObject
 from . import playlist
@@ -58,7 +59,11 @@ class TestPlaylist(unittest.TestCase):
         self.assertEqual(plist.get_current_track(), plist.get_track(1))
 
         plist.set_property("current", 2)
-        self.assertEqual(plist.get_property("current"), -1)
+        self.assertEqual(plist.get_property("current"), 2)
+        self.assertIsNone(plist.get_current_track())
+
+        plist.set_property("current", 3)
+        self.assertEqual(plist.get_property("current"), 2)
         self.assertIsNone(plist.get_current_track())
 
     def test_loop(self):
@@ -127,6 +132,34 @@ class TestPlaylist(unittest.TestCase):
         plist.set_property("sort", [ "tracks.number ASC" ])
         self.assertEqual(plist.get_property("current"), 1)
 
+    def test_next_track(self):
+        plist = db.user.Table.find("Test Playlist")
+        self.assertIsNone(plist.next_track())
+        self.assertEqual(plist.get_property("current"), -1)
+
+        plist.add_track(db.make_fake_track(1, 1, "Track 1", "/a/b/c/1.ogg"))
+        plist.add_track(db.make_fake_track(2, 2, "Track 2", "/a/b/c/2.ogg"))
+        self.assertEqual(plist.next_track(), plist.get_track(0))
+        self.assertEqual(plist.next_track(), plist.get_track(1))
+        self.assertIsNone(plist.next_track())
+        self.assertIsNone(plist.next_track())
+
+    def test_random_next_track(self):
+        plist = db.user.Table.find("Test Playlist")
+        plist.random = True
+        self.assertIsNone(plist.next_track())
+        self.assertEqual(plist.get_property("current"), -1)
+
+        plist.add_track(db.make_fake_track(1, 1, "Track 1", "/a/b/c/1.ogg"))
+        plist.add_track(db.make_fake_track(2, 2, "Track 2", "/a/b/c/2.ogg"))
+        plist.add_track(db.make_fake_track(3, 3, "Track 3", "/a/b/c/3.ogg"))
+
+        random.seed(20210318)
+        self.assertEqual(plist.next_track(), plist.get_track(1))
+        self.assertEqual(plist.next_track(), plist.get_track(2))
+        self.assertEqual(plist.next_track(), plist.get_track(0))
+        self.assertEqual(plist.next_track(), plist.get_track(2))
+
 
 class TestMappedPlaylist(unittest.TestCase):
     def test_init(self):