Moves drag & drop support from main-controller.js to queue.js

Adds a indexOfSong method to player-service. It is used in play, nextTrack and previousTrack so the player can adapt to changes to the queue order. Previously it wasn't taken into account and when we changed the order of the queue (through drag & drop or shuffle), the next song wasn't what we expected it to be.

app/queue/queue_test.js

@@ -18,6 +18,7 @@ describe("Queue controller", function() {
             });
         });
         song = { id: 7310 };
+        player.queue = [];
     });
 
     it("When I play a song, it calls play in the player service", function() {
@@ -77,4 +78,57 @@ describe("Queue controller", function() {
 
         expect($.fn.scrollTo).toHaveBeenCalled();
     });
+
+    describe("reorders the queue by drag and drop - ", function() {
+        var mockUI;
+        beforeEach(function() {
+            player.queue = [
+                {id: 2246},
+                {id: 8869},
+                {id: 285}
+            ];
+            mockUI = {
+                item: {}
+            };
+        });
+
+        it("given a song in the queue, when I start dragging it, it records what its starting position in the queue was", function() {
+            mockUI.item.index = jasmine.createSpy("index").and.returnValue('1');
+            mockUI.item.data = jasmine.createSpy("data");
+
+            scope.dragStart({}, mockUI);
+
+            expect(mockUI.item.index).toHaveBeenCalled();
+            expect(mockUI.item.data).toHaveBeenCalledWith('start', '1');
+        });
+
+        it("given a song in the queue that I started dragging, when I drop it, its position in the queue has changed", function() {
+            mockUI.item.index = jasmine.createSpy("index").and.returnValue('0');
+            mockUI.item.data = jasmine.createSpy("data").and.returnValue('1');
+
+            scope.dragEnd({}, mockUI);
+
+            expect(mockUI.item.index).toHaveBeenCalled();
+            expect(mockUI.item.data).toHaveBeenCalledWith('start');
+            // The second song should now be first
+            expect(player.queue).toEqual([
+                {id: 8869},
+                {id: 2246},
+                {id: 285}
+            ]);
+        });
+
+        // TODO: Hyz: Maybe it should be an end-to-end test
+        it("given that the player is playing the second song (B), when I swap the first (A) and the second song (B), the player's next song should be A", function() {
+            player.play({id: 8869});
+            mockUI.item.index = jasmine.createSpy("index").and.returnValue('0');
+            mockUI.item.data = jasmine.createSpy("data").and.returnValue('1');
+
+            scope.dragEnd({}, mockUI);
+
+            player.nextTrack();
+            expect(player._playingIndex).toBe(1);
+            expect(player._playingSong).toEqual({id: 2246});
+        });
+    });
 });