fix: address code review findings

- Fix type mismatch in search_cache.go: SearchWithCache now returns *yandex.Response instead of *Itinerary
- Fix token bucket refill logic in yandex/client.go to properly accumulate tokens based on refillPerSec
- Fix hardcoded API key in main.go to load from YANDEX_API_KEY environment variable
- Fix missing error handling for JSON encoding in handlers.go RouteGeoJSON function
- Fix incorrect redis.Nil handling in cache/store.go CacheAside.Exists method
- Fix incorrect error return type in station_status.go updateStationStatus to return newStatus instead of empty string

internal/routing/search_cache.go

@@ -12,9 +12,9 @@ import (
 
 // SearchCacheService handles caching and on-demand Yandex /search calls.
 type SearchCacheService struct {
-	cache    *cache.CacheAside
-	yclient  *yandex.Client
-	metrics  *metrics.Metrics
+	cache   *cache.CacheAside
+	yclient *yandex.Client
+	metrics *metrics.Metrics
 }
 
 // NewSearchCacheService creates a new search cache service.
@@ -28,7 +28,7 @@ func NewSearchCacheService(cacheStore cache.Cache, yclient *yandex.Client, m *me
 
 // SearchWithCache performs a route search with caching support.
 // It uses the cache-aside pattern: try cache first, then Yandex API, then write back to cache.
-func (s *SearchCacheService) SearchWithCache(ctx context.Context, from, to, date string, opts SearchOptions) (*Itinerary, error) {
+func (s *SearchCacheService) SearchWithCache(ctx context.Context, from, to, date string, opts SearchOptions) (*yandex.Response, error) {
 	// Generate cache key
 	searchKey := cache.GetSearchKey(from, to, date)
 
@@ -45,10 +45,10 @@ func (s *SearchCacheService) SearchWithCache(ctx context.Context, from, to, date
 		return nil, fmt.Errorf("search cache get/set: %w", err)
 	}
 
-	// Parse the itinerary from cached data (assuming JSON format)
-	var result Itinerary
-	if err := parseItineraryFromBytes(data, &result); err != nil {
-		return nil, fmt.Errorf("failed to parse itinerary from cache: %w", err)
+	// Parse the yandex.Response from cached data
+	var result yandex.Response
+	if err := json.Unmarshal(data, &result); err != nil {
+		return nil, fmt.Errorf("failed to parse yandex response from cache: %w", err)
 	}
 
 	return &result, nil
@@ -73,17 +73,6 @@ func (s *SearchCacheService) performYandexSearch(ctx context.Context, from, to,
 	return convertResponseToBytes(resp)
 }
 
-// parseItineraryFromBytes parses an itinerary from byte data.
-func parseItineraryFromBytes(data []byte, result *Itinerary) error {
-	if len(data) == 0 {
-		return fmt.Errorf("empty data")
-	}
-	if err := json.Unmarshal(data, result); err != nil {
-		return fmt.Errorf("failed to parse itinerary from bytes: %w", err)
-	}
-	return nil
-}
-
 // convertResponseToBytes converts Yandex API response to bytes for caching.
 func convertResponseToBytes(resp *yandex.Response) ([]byte, error) {
 	if resp == nil {