feat(api): GET /api/albums/{id} with nested tracks

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

internal/api/library.go

@@ -45,9 +45,50 @@ func (h *handlers) handleGetTrack(w http.ResponseWriter, r *http.Request) {
 	writeJSON(w, http.StatusOK, trackRefFrom(track, album.Title, artist.Name))
 }
 
-// handleGetAlbum is implemented in Task 7.
+// handleGetAlbum implements GET /api/albums/{id}. Returns the album plus its
+// tracks (ordered by disc/track number via the underlying query) with
+// duration summed from the track list — keeps one source of truth.
 func (h *handlers) handleGetAlbum(w http.ResponseWriter, r *http.Request) {
-	writeErr(w, http.StatusNotImplemented, "not_implemented", "stub")
+	id, ok := parseUUID(chi.URLParam(r, "id"))
+	if !ok {
+		writeErr(w, http.StatusBadRequest, "bad_request", "invalid album id")
+		return
+	}
+	q := dbq.New(h.pool)
+	album, err := q.GetAlbumByID(r.Context(), id)
+	if err != nil {
+		if errors.Is(err, pgx.ErrNoRows) {
+			writeErr(w, http.StatusNotFound, "not_found", "album not found")
+			return
+		}
+		h.logger.Error("api: get album failed", "err", err)
+		writeErr(w, http.StatusInternalServerError, "server_error", "lookup failed")
+		return
+	}
+	artist, err := q.GetArtistByID(r.Context(), album.ArtistID)
+	if err != nil {
+		h.logger.Error("api: get album artist failed", "err", err)
+		writeErr(w, http.StatusInternalServerError, "server_error", "lookup failed")
+		return
+	}
+	tracks, err := q.ListTracksByAlbum(r.Context(), id)
+	if err != nil {
+		h.logger.Error("api: list tracks failed", "err", err)
+		writeErr(w, http.StatusInternalServerError, "server_error", "lookup failed")
+		return
+	}
+	refs := make([]TrackRef, 0, len(tracks))
+	durSec := 0
+	for _, t := range tracks {
+		ref := trackRefFrom(t, album.Title, artist.Name)
+		refs = append(refs, ref)
+		durSec += ref.DurationSec
+	}
+	detail := AlbumDetail{
+		AlbumRef: albumRefFrom(album, artist.Name, len(tracks), durSec),
+		Tracks:   refs,
+	}
+	writeJSON(w, http.StatusOK, detail)
 }
 
 // handleGetArtist is implemented in Task 8.

internal/api/library_test.go

@@ -74,3 +74,93 @@ func TestHandleGetTrack_NotFound(t *testing.T) {
 		t.Errorf("status = %d, want 404", w.Code)
 	}
 }
+
+func TestHandleGetAlbum_HappyPath(t *testing.T) {
+	h, pool := testHandlers(t)
+	truncateLibrary(t, pool)
+	artist := seedArtist(t, pool, "Beatles")
+	album := seedAlbum(t, pool, artist.ID, "Abbey Road", 1969)
+	seedTrack(t, pool, album.ID, artist.ID, "Come Together", 1, 259_000)
+	seedTrack(t, pool, album.ID, artist.ID, "Something", 2, 183_000)
+
+	req := httptest.NewRequest(http.MethodGet, "/api/albums/"+uuidToString(album.ID), nil)
+	w := httptest.NewRecorder()
+	newLibraryRouter(h).ServeHTTP(w, req)
+
+	if w.Code != http.StatusOK {
+		t.Fatalf("status = %d body = %s", w.Code, w.Body.String())
+	}
+	var got AlbumDetail
+	if err := json.Unmarshal(w.Body.Bytes(), &got); err != nil {
+		t.Fatalf("decode: %v body=%s", err, w.Body.String())
+	}
+	if got.Title != "Abbey Road" || got.ArtistName != "Beatles" || got.Year != 1969 {
+		t.Errorf("album = %+v", got)
+	}
+	if len(got.Tracks) != 2 {
+		t.Fatalf("tracks len = %d, want 2", len(got.Tracks))
+	}
+	if got.Tracks[0].Title != "Come Together" || got.Tracks[1].Title != "Something" {
+		t.Errorf("tracks = %+v", got.Tracks)
+	}
+	if got.TrackCount != 2 || got.DurationSec != 442 { // 259 + 183
+		t.Errorf("counts = track=%d duration=%d", got.TrackCount, got.DurationSec)
+	}
+	want := "/api/albums/" + uuidToString(album.ID) + "/cover"
+	if got.CoverURL != want {
+		t.Errorf("cover_url = %q", got.CoverURL)
+	}
+	// StreamURL on nested tracks must be set
+	if got.Tracks[0].StreamURL == "" {
+		t.Error("nested track missing stream_url")
+	}
+}
+
+func TestHandleGetAlbum_NoTracks(t *testing.T) {
+	h, pool := testHandlers(t)
+	truncateLibrary(t, pool)
+	artist := seedArtist(t, pool, "Beatles")
+	album := seedAlbum(t, pool, artist.ID, "Empty", 0)
+
+	req := httptest.NewRequest(http.MethodGet, "/api/albums/"+uuidToString(album.ID), nil)
+	w := httptest.NewRecorder()
+	newLibraryRouter(h).ServeHTTP(w, req)
+
+	if w.Code != http.StatusOK {
+		t.Fatalf("status = %d body = %s", w.Code, w.Body.String())
+	}
+	var got AlbumDetail
+	_ = json.Unmarshal(w.Body.Bytes(), &got)
+	if got.Tracks == nil {
+		t.Error("tracks = nil, want [] for JSON encoding")
+	}
+	if len(got.Tracks) != 0 {
+		t.Errorf("tracks len = %d, want 0", len(got.Tracks))
+	}
+	// Year omitempty: releaseYear=0 => Year=0 => field should be absent from JSON
+	if got.Year != 0 {
+		t.Errorf("year = %d, want 0", got.Year)
+	}
+}
+
+func TestHandleGetAlbum_BadUUID(t *testing.T) {
+	h, _ := testHandlers(t)
+	req := httptest.NewRequest(http.MethodGet, "/api/albums/not-a-uuid", nil)
+	w := httptest.NewRecorder()
+	newLibraryRouter(h).ServeHTTP(w, req)
+	if w.Code != http.StatusBadRequest {
+		t.Errorf("status = %d, want 400", w.Code)
+	}
+}
+
+func TestHandleGetAlbum_NotFound(t *testing.T) {
+	h, pool := testHandlers(t)
+	truncateLibrary(t, pool)
+	req := httptest.NewRequest(http.MethodGet,
+		"/api/albums/00000000-0000-0000-0000-000000000001", nil)
+	w := httptest.NewRecorder()
+	newLibraryRouter(h).ServeHTTP(w, req)
+	if w.Code != http.StatusNotFound {
+		t.Errorf("status = %d, want 404", w.Code)
+	}
+}