feat(playlist): add methods for RWD access checking

Author: nadiamoe

playlist/playlist.go

@@ -36,6 +36,17 @@ type Playlist struct {
 	IsPublic   bool
 	SharedWith []int
 }
+
+func (p Playlist) CanRead(uid int) bool {
+	return p.IsPublic || p.CanWrite(uid)
+}
+
+func (p Playlist) CanWrite(uid int) bool {
+	return p.UserID == uid || slices.Contains(p.SharedWith, uid)
+}
+
+func (p Playlist) CanDelete(uid int) bool {
+	return p.UserID == uid
 }
 
 type Store struct {

playlist/playlist_test.go

@@ -57,3 +57,70 @@ It has multiple lines 👍
 	require.NoError(t, err)
 	require.True(t, len(playlistIDs) == 1)
 }
+
+func TestAccess(t *testing.T) {
+	t.Parallel()
+
+	for _, tc := range []struct {
+		name         string
+		playlist     playlist.Playlist
+		userID       int
+		expectRead   bool
+		expectWrite  bool
+		expectDelete bool
+	}{
+		{
+			name: "owner can do anything",
+			playlist: playlist.Playlist{
+				UserID: 7,
+			},
+			userID:       7,
+			expectRead:   true,
+			expectWrite:  true,
+			expectDelete: true,
+		},
+		{
+			name: "third party cannot do anything",
+			playlist: playlist.Playlist{
+				UserID: 7,
+			},
+			userID:       99,
+			expectRead:   false,
+			expectWrite:  false,
+			expectDelete: false,
+		},
+		{
+			name: "third party can read if public",
+			playlist: playlist.Playlist{
+				IsPublic: true,
+				UserID:   7,
+			},
+			userID:       99,
+			expectRead:   true,
+			expectWrite:  false,
+			expectDelete: false,
+		},
+		{
+			name: "shared user can read and write",
+			playlist: playlist.Playlist{
+				IsPublic:   true,
+				UserID:     7,
+				SharedWith: []int{99},
+			},
+			userID:       99,
+			expectRead:   true,
+			expectWrite:  true,
+			expectDelete: false,
+		},
+	} {
+		tc := tc
+
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			require.Equal(t, tc.expectRead, tc.playlist.CanRead(tc.userID))
+			require.Equal(t, tc.expectWrite, tc.playlist.CanWrite(tc.userID))
+			require.Equal(t, tc.expectDelete, tc.playlist.CanDelete(tc.userID))
+		})
+	}
+}