Expand backend debug logging

backend/services/gemini.go

@@ -22,6 +22,7 @@ type GeminiService struct {
 	Client            *http.Client
 	GenerateEndpoint  string
 	TranslateEndpoint string
+	Debug             func(message string, data any)
 }
 
 type AIRecommendation struct {
@@ -50,7 +51,13 @@ func NewGeminiService(apiKey string) *GeminiService {
 
 func (g *GeminiService) ExpandQuery(query string) ([]string, error) {
 	englishBase := g.TranslateQuery(query)
-	return buildSearchQueries(query, englishBase), nil
+	expanded := buildSearchQueries(query, englishBase)
+	g.debug("gemini:expand_query", map[string]any{
+		"original": query,
+		"english":  englishBase,
+		"expanded": expanded,
+	})
+	return expanded, nil
 }
 
 func (g *GeminiService) TranslateQuery(query string) string {
@@ -67,6 +74,7 @@ func (g *GeminiService) TranslateQuery(query string) string {
 	}
 
 	if g.APIKey != "" {
+		g.debug("gemini:translate_attempt", map[string]any{"mode": "gemini", "query": trimmed})
 		body := map[string]any{
 			"systemInstruction": map[string]any{
 				"parts": []map[string]string{
@@ -95,17 +103,25 @@ func (g *GeminiService) TranslateQuery(query string) string {
 		if err == nil {
 			translated := sanitizePlainEnglishLine(rawText)
 			if translated != "" && !strings.EqualFold(translated, trimmed) && !isOvercompressedTranslation(trimmed, translated) {
+				g.debug("gemini:translate_success", map[string]any{"mode": "gemini", "query": trimmed, "translated": translated})
 				return translated
 			}
 		}
+		if err != nil {
+			g.debug("gemini:translate_error", map[string]any{"mode": "gemini", "query": trimmed, "error": err.Error()})
+		}
 	}
 
+	g.debug("gemini:translate_attempt", map[string]any{"mode": "google", "query": trimmed})
 	if translated, err := g.translateViaGoogle(trimmed); err == nil && translated != "" && isLikelyEnglishQuery(translated) && !isOvercompressedTranslation(trimmed, translated) {
+		g.debug("gemini:translate_success", map[string]any{"mode": "google", "query": trimmed, "translated": translated})
 		return translated
 	}
 	if translated := translateKoreanMediaTerms(normalizedIntent); translated != "" && !strings.EqualFold(translated, trimmed) {
+		g.debug("gemini:translate_success", map[string]any{"mode": "dictionary", "query": trimmed, "translated": translated})
 		return translated
 	}
+	g.debug("gemini:translate_fallback_original", map[string]any{"query": trimmed, "normalized": normalizedIntent})
 	return strings.TrimSpace(normalizedIntent)
 }
 
@@ -148,6 +164,10 @@ func (g *GeminiService) Recommend(query string, candidates []SearchResult) ([]AI
 	if len(candidates) == 0 {
 		return []AIRecommendation{}, nil
 	}
+	g.debug("gemini:vision_start", map[string]any{
+		"query":          query,
+		"candidateCount": len(candidates),
+	})
 
 	type geminiPart map[string]any
 	parts := []geminiPart{
@@ -169,6 +189,12 @@ User query: ` + query,
 	for idx := 0; idx < maxImages; idx++ {
 		img, mimeType, err := fetchCandidateVisualInlineData(g.Client, candidates[idx])
 		if err != nil {
+			g.debug("gemini:vision_candidate_visual_error", map[string]any{
+				"index":  idx,
+				"link":   candidates[idx].Link,
+				"source": candidates[idx].Source,
+				"error":  err.Error(),
+			})
 			continue
 		}
 		visualCount++
@@ -180,6 +206,11 @@ User query: ` + query,
 	if visualCount == 0 {
 		return nil, fmt.Errorf("no candidate thumbnails or preview frames could be fetched for gemini vision")
 	}
+	g.debug("gemini:vision_visuals_prepared", map[string]any{
+		"query":       query,
+		"visualCount": visualCount,
+		"maxImages":   maxImages,
+	})
 
 	body := map[string]any{
 		"contents": []map[string]any{
@@ -254,10 +285,20 @@ User query: ` + query,
 			Recommended:     recommended,
 		})
 	}
+	g.debug("gemini:vision_complete", map[string]any{
+		"query":               query,
+		"recommendationCount": len(recommendations),
+	})
 
 	return recommendations, nil
 }
 
+func (g *GeminiService) debug(message string, data any) {
+	if g != nil && g.Debug != nil {
+		g.Debug(message, data)
+	}
+}
+
 func fetchImageAsInlineData(client *http.Client, imageURL, referer string) (string, string, error) {
 	if strings.TrimSpace(imageURL) == "" {
 		return "", "", fmt.Errorf("image url is empty")