refactor: split modules and harden scraping workflows

internal/service/scraper_artwork.go

@@ -0,0 +1,67 @@
+package service
+
+import (
+	"context"
+	"strings"
+	"time"
+
+	"go.uber.org/zap"
+)
+
+func (s *ScraperService) prepareScrapedArtworkURL(ctx context.Context, mediaID, field, current, candidate string) (string, string) {
+	current = strings.TrimSpace(current)
+	candidate = strings.TrimSpace(candidate)
+	if candidate == "" {
+		return current, ""
+	}
+	if candidate == current {
+		return candidate, ""
+	}
+	if s == nil || s.images == nil || !isHTTPish(candidate) {
+		return candidate, ""
+	}
+	fetchCtx, cancel := context.WithTimeout(context.WithoutCancel(ctx), 15*time.Second)
+	err := s.images.PrefetchRemote(fetchCtx, candidate)
+	cancel()
+	if err != nil {
+		if current != "" {
+			s.log.Warn("scrape artwork prefetch failed; keeping existing artwork",
+				zap.String("media_id", mediaID),
+				zap.String("field", field),
+				zap.String("candidate", candidate),
+				zap.String("existing", current),
+				zap.Error(err))
+			return current, ""
+		}
+		s.log.Warn("scrape artwork prefetch failed; keeping new artwork URL for retry",
+			zap.String("media_id", mediaID),
+			zap.String("field", field),
+			zap.String("candidate", candidate),
+			zap.Error(err))
+		return candidate, ""
+	}
+	if current != "" && isHTTPish(current) {
+		return candidate, current
+	}
+	return candidate, ""
+}
+
+func (s *ScraperService) removeCachedScrapedArtwork(urls ...string) {
+	if s == nil || s.images == nil {
+		return
+	}
+	seen := map[string]struct{}{}
+	for _, raw := range urls {
+		raw = strings.TrimSpace(raw)
+		if raw == "" {
+			continue
+		}
+		if _, ok := seen[raw]; ok {
+			continue
+		}
+		seen[raw] = struct{}{}
+		if err := s.images.RemoveCached(raw); err != nil {
+			s.log.Debug("remove old scraped artwork cache failed", zap.String("url", raw), zap.Error(err))
+		}
+	}
+}