Linked names stage 1: artist and album names link everywhere (MAD-837, MAD-838)

api/openapi.yaml

@@ -1491,6 +1491,65 @@ paths:
         default:
           $ref: "#/components/responses/Error"
 
+  /resolve/artist:
+    get:
+      operationId: resolveArtist
+      summary: Find an artist on a service you can use
+      description: |
+        For a name that came from somewhere you can't browse (a song queued
+        from someone else's service, or one without an artist ID). Looks
+        for the artist by name on your links, then on shared ones, and
+        returns the first exact match. 404 when none has it.
+      tags: [browse]
+      parameters:
+        - name: name
+          in: query
+          required: true
+          schema:
+            type: string
+            minLength: 1
+            maxLength: 200
+      responses:
+        "200":
+          description: Where to open the artist
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/ResolvedRef"
+        default:
+          $ref: "#/components/responses/Error"
+
+  /resolve/album:
+    get:
+      operationId: resolveAlbum
+      summary: Find an album on a service you can use
+      description: |
+        Like `resolveArtist`, for an album by its title and, when known, its
+        artist.
+      tags: [browse]
+      parameters:
+        - name: title
+          in: query
+          required: true
+          schema:
+            type: string
+            minLength: 1
+            maxLength: 200
+        - name: artist
+          in: query
+          schema:
+            type: string
+            maxLength: 200
+      responses:
+        "200":
+          description: Where to open the album
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/ResolvedRef"
+        default:
+          $ref: "#/components/responses/Error"
+
   /links/{id}/artists/{artistId}/shuffle:
     parameters:
       - name: id
@@ -7115,6 +7174,16 @@ components:
         artist:
           $ref: "#/components/schemas/ArtistResult"
 
+    ResolvedRef:
+      type: object
+      description: An artist or album to open with `linkId` and `id`.
+      required: [linkId, id]
+      properties:
+        linkId:
+          type: string
+        id:
+          type: string
+
     AlbumAbout:
       type: object
       required: [labels, genres]

server/internal/artistpage/artistpage.go

@@ -433,6 +433,29 @@ func Elsewhere(ctx context.Context, sess provider.Session, caps provider.Capabil
 	return nil
 }
 
+// AlbumElsewhere finds an album by title on another link, by the same
+// artist when artist isn't empty, or nil.
+func AlbumElsewhere(ctx context.Context, sess provider.Session, caps provider.Capabilities, title, artist string) *provider.Album {
+	if !caps.CanSearch(provider.KindAlbum) {
+		return nil
+	}
+	page, err := sess.Search(ctx, provider.SearchQuery{Text: title, Kinds: []provider.EntityKind{provider.KindAlbum}, Limit: 10})
+	if err != nil {
+		slog.Debug("artistpage: looking for an album elsewhere", "album", title, "err", err)
+		return nil
+	}
+	want, by := match.Simplify(title), match.Simplify(artist)
+	for _, a := range page.Albums {
+		if match.Simplify(a.Title) != want {
+			continue
+		}
+		if by == "" || slices.ContainsFunc(a.Artists, func(c provider.ArtistCredit) bool { return match.Simplify(c.Name) == by }) {
+			return &a
+		}
+	}
+	return nil
+}
+
 // each runs f for 0..n-1, a few at a time.
 func each(n int, f func(i int)) {
 	sem := make(chan struct{}, parallel)

server/internal/artistpage/artistpage_test.go

@@ -214,5 +214,18 @@ func TestElsewhere(t *testing.T) {
 	}
 }
 
+func TestAlbumElsewhere(t *testing.T) {
+	sess, caps := open(t, fake.Options{})
+	if a := artistpage.AlbumElsewhere(t.Context(), sess, caps, "zero zero", "Null Island"); a == nil || a.Title != "Zero Zero" {
+		t.Errorf("AlbumElsewhere = %+v", a)
+	}
+	if a := artistpage.AlbumElsewhere(t.Context(), sess, caps, "A440", ""); a == nil || a.Title != "A440" {
+		t.Errorf("without an artist = %+v", a)
+	}
+	if a := artistpage.AlbumElsewhere(t.Context(), sess, caps, "Zero Zero", "Sine Language"); a != nil {
+		t.Errorf("another artist's album found %+v", a)
+	}
+}
+
 // seeded is the same "random" order every run.
 func seeded() *rand.Rand { return rand.New(rand.NewPCG(1, 2)) } //nolint:gosec // a test's fixed order