googlephotos: create feature/favorites directory - Fixes #4189

Enable access “Favorite” images on Google Photos backend.

This adds a “feature/favorites” folder in the Google Photos backend
and uses the Feature Filter API:

https://developers.google.com/photos/library/reference/rest/v1/mediaItems/search#Filters

backend/googlephotos/pattern.go

@@ -53,6 +53,7 @@ var patterns = dirPatterns{
 				fs.NewDir(prefix+"album", f.dirTime()),
 				fs.NewDir(prefix+"shared-album", f.dirTime()),
 				fs.NewDir(prefix+"upload", f.dirTime()),
+				fs.NewDir(prefix+"feature", f.dirTime()),
 			}, nil
 		},
 	},
@@ -190,6 +191,28 @@ var patterns = dirPatterns{
 		re:     `^shared-album/(.+?)/([^/]+)$`,
 		isFile: true,
 	},
+	{
+		re: `^feature$`,
+		toEntries: func(ctx context.Context, f lister, prefix string, match []string) (entries fs.DirEntries, err error) {
+			return fs.DirEntries{
+				fs.NewDir(prefix+"favorites", f.dirTime()),
+			}, nil
+		},
+	},
+	{
+		re: `^feature/favorites$`,
+		toEntries: func(ctx context.Context, f lister, prefix string, match []string) (entries fs.DirEntries, err error) {
+			filter := featureFilter(ctx, f, match)
+			if err != nil {
+				return nil, err
+			}
+			return f.listDir(ctx, prefix, filter)
+		},
+	},
+	{
+		re:     `^feature/favorites/([^/]+)$`,
+		isFile: true,
+	},
 }.mustCompile()
 
 // mustCompile compiles the regexps in the dirPatterns
@@ -290,6 +313,24 @@ func yearMonthDayFilter(ctx context.Context, f lister, match []string) (sf api.S
 	return sf, nil
 }
 
+// featureFilter creates a filter for the Feature enum
+//
+// The API only supports one feature, FAVORITES, so hardcode that feature
+//
+// https://developers.google.com/photos/library/reference/rest/v1/mediaItems/search#FeatureFilter
+func featureFilter(ctx context.Context, f lister, match []string) (sf api.SearchFilter) {
+	sf = api.SearchFilter{
+		Filters: &api.Filters{
+			FeatureFilter: &api.FeatureFilter{
+				IncludedFeatures: []string{
+					"FAVORITES",
+				},
+			},
+		},
+	}
+	return sf
+}
+
 // Turns an albumPath into entries
 //
 // These can either be synthetic directory entries if the album path

backend/googlephotos/pattern_test.go

@@ -155,6 +155,38 @@ func TestPatternMatch(t *testing.T) {
 			wantPrefix:  "file.jpg/",
 			wantPattern: &patterns[5],
 		},
+		{
+			root:        "",
+			itemPath:    "feature",
+			isFile:      false,
+			wantMatch:   []string{"feature"},
+			wantPrefix:  "feature/",
+			wantPattern: &patterns[23],
+		},
+		{
+			root:        "feature/favorites",
+			itemPath:    "",
+			isFile:      false,
+			wantMatch:   []string{"feature/favorites"},
+			wantPrefix:  "",
+			wantPattern: &patterns[24],
+		},
+		{
+			root:        "feature",
+			itemPath:    "favorites",
+			isFile:      false,
+			wantMatch:   []string{"feature/favorites"},
+			wantPrefix:  "favorites/",
+			wantPattern: &patterns[24],
+		},
+		{
+			root:        "feature/favorites",
+			itemPath:    "file.jpg",
+			isFile:      true,
+			wantMatch:   []string{"feature/favorites/file.jpg", "file.jpg"},
+			wantPrefix:  "file.jpg/",
+			wantPattern: &patterns[25],
+		},
 	} {
 		t.Run(fmt.Sprintf("#%d,root=%q,itemPath=%q,isFile=%v", testNumber, test.root, test.itemPath, test.isFile), func(t *testing.T) {
 			gotMatch, gotPrefix, gotPattern := patterns.match(test.root, test.itemPath, test.isFile)

docs/content/googlephotos.md

@@ -173,6 +173,10 @@ into albums.
 - shared-album
     - album name
     - album name/sub
+- feature
+    - favorites
+        - file1.jpg
+        - file2.jpg
 ```
 
 There are two writable parts of the tree, the `upload` directory and