audio: Implement the previous() function

To iterate backwards through the list of recently played songs.

Signed-off-by: Anna Schumaker <schumaker.anna@gmail.com>

include/audio.h

@@ -18,6 +18,7 @@ namespace audio
 	void pause();
 	void stop();
 	void next();
+	void previous();
 	unsigned int current_trackid();
 
 	void seek_to(long);

lib/audio.cpp

@@ -16,6 +16,8 @@ static bool o_pause_enabled = false;
 static unsigned int o_pause_count = 0;
 static bool o_should_pause = false;
 
+static Playqueue o_recently_played(PQ_ENABLED);
+
 static void parse_error(GstMessage *error)
 {
 	GError *err;
@@ -94,6 +96,7 @@ void audio :: init(int *argc, char ***argv)
 {
 	GstBus *bus;
 
+	o_recently_played.set_flag(PQ_REPEAT);
 	gst_init(argc, argv);
 
 	ocarina_player = gst_element_factory_make("playbin", "ocarina_player");
@@ -149,8 +152,25 @@ void audio :: next()
 	id = deck :: next();
 	library :: lookup(id, &song);
 	load_song(song);
-	cur_trackid = id;
 	track_loaded = true;
+
+	cur_trackid = id;
+	o_recently_played.add_front(id);
+	o_recently_played.reset_cur();
+}
+
+void audio :: previous()
+{
+	library :: Song song;
+	unsigned int id;
+
+	id = o_recently_played.next();
+	if (id == cur_trackid)
+		return;
+
+	library :: lookup(id, &song);
+	load_song(song);
+	cur_trackid = id;
 }
 
 unsigned int audio :: current_trackid()

lib/playqueue.cpp

@@ -116,5 +116,5 @@ unsigned int Playqueue :: next()
 
 void Playqueue :: reset_cur()
 {
-	cur = -1;
+	cur = 0;
 }

tests/audio/audio.cpp

@@ -45,7 +45,7 @@ void check_error(int error, int expected)
 			print("Failed with error: %d\n", error);
 	} else {
 		if (error == 0)
-			print("Failed (expected error: %d)\n", error);
+			print("Failed (expected error: %d)\n", expected);
 		else
 			print("Success!\n");
 	}
@@ -90,6 +90,7 @@ void test_0()
 	} catch (int error) {
 		check_error(error, -E_EXIST);
 	}
+	call_func("0i", audio :: previous, -E_EXIST);
 	print("\n");
 }
 
@@ -105,6 +106,14 @@ void test_1()
 	call_func("1e", audio :: stop, 0);
 	check_ret("1f", audio :: current_trackid() == 0, true);
 	check_ret("1g", audio :: position(), 0);
+	call_func("1h", audio :: previous, 0);
+	check_ret("1i", audio :: current_trackid() == 0, true);
+	audio :: next();
+	audio :: next();
+	call_func("1j", audio :: previous, 0);
+	check_ret("1k", audio :: current_trackid() == 1, true);
+	call_func("1l", audio :: previous, 0);
+	check_ret("1m", audio :: current_trackid() == 0, true);
 	print("\n");
 }
 

tests/playqueue/playqueue.good

@@ -20,7 +20,6 @@ Selecting id: 1
 Selecting id: 2
 Selecting id: 3
 Selecting id: 4
-Selecting id: 0
 Selecting id: 1
 Selecting id: 2
 Selecting id: 3
@@ -40,6 +39,7 @@ Selecting id: 0
 Selecting id: 1
 Selecting id: 2
 Selecting id: 3
+Selecting id: 4
 Test 3b: size: 16, length: 2153
 
 Test 4a: SUCCESS