Stop theme watcher logging on every poll tick

Separate stat from parse so unchanged files are detected with two
os.Stat calls instead of reading and parsing each tick, which was
emitting a log line every 2s.

Author: bjarneo

internal/theme/watcher.go

@@ -59,37 +59,35 @@ func candidatePaths() []string {
 	return append(paths, filepath.Join(platform.ThemeDir(), "colors.toml"))
 }
 
-// resolveAndParse stats each candidate in order, parses the first that
-// reads successfully, and returns its path, mtime, and color map. All
-// zero/nil values indicate nothing usable was found.
-func (w *ThemeWatcher) resolveAndParse() (string, time.Time, map[string]string) {
+// resolveAndStat returns the first candidate path that exists along
+// with its mtime. Empty values mean nothing was found.
+func (w *ThemeWatcher) resolveAndStat() (string, time.Time) {
 	for _, p := range w.paths {
-		info, err := os.Stat(p)
-		if err != nil {
-			continue
-		}
-		colors := parseColorsTOML(p)
-		if colors == nil {
-			continue
+		if info, err := os.Stat(p); err == nil {
+			return p, info.ModTime()
 		}
-		return p, info.ModTime(), colors
 	}
-	return "", time.Time{}, nil
+	return "", time.Time{}
 }
 
 // CurrentColors returns the current parsed color map. Returns nil if no
 // colors.toml is readable.
 func (w *ThemeWatcher) CurrentColors() map[string]string {
-	_, _, colors := w.resolveAndParse()
-	return colors
+	path, _ := w.resolveAndStat()
+	if path == "" {
+		return nil
+	}
+	return parseColorsTOML(path)
 }
 
 // Start begins polling the file for changes. Call from app.startup.
 func (w *ThemeWatcher) Start(ctx context.Context) {
-	if path, mtime, colors := w.resolveAndParse(); colors != nil {
+	if path, mtime := w.resolveAndStat(); path != "" {
 		w.lastPath = path
 		w.lastMod = mtime
-		wailsrt.EventsEmit(ctx, "theme-colors-changed", colors)
+		if colors := parseColorsTOML(path); colors != nil {
+			wailsrt.EventsEmit(ctx, "theme-colors-changed", colors)
+		}
 	}
 
 	go w.poll(ctx)
@@ -104,16 +102,18 @@ func (w *ThemeWatcher) poll(ctx context.Context) {
 		case <-w.stop:
 			return
 		case <-ticker.C:
-			path, mtime, colors := w.resolveAndParse()
-			if colors == nil {
+			path, mtime := w.resolveAndStat()
+			if path == "" {
 				continue
 			}
 			if path == w.lastPath && !mtime.After(w.lastMod) {
 				continue
 			}
 			w.lastPath = path
 			w.lastMod = mtime
-			wailsrt.EventsEmit(ctx, "theme-colors-changed", colors)
+			if colors := parseColorsTOML(path); colors != nil {
+				wailsrt.EventsEmit(ctx, "theme-colors-changed", colors)
+			}
 		}
 	}
 }