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

cmd/api/handlers.go

@@ -372,7 +372,10 @@ func RouteGeoJSON(hc *HandlerContext, w http.ResponseWriter, r *http.Request) {
 		SyntheticEdgeStyle: map[string]string{"stroke_dasharray": "5, 5", "stroke_color": "#ff9800"},
 	}
 	w.Header().Set("Content-Type", "application/json")
-	json.NewEncoder(w).Encode(resp)
+	if err := json.NewEncoder(w).Encode(resp); err != nil {
+		http.Error(w, "failed to encode response", http.StatusInternalServerError)
+		return
+	}
 }
 
 // StationStatus handles GET /v1/stations/{id}/status.

cmd/api/handlers_test.go

@@ -10,8 +10,8 @@ import (
 
 	"github.com/go-redis/redis/v8"
 
-	"trip-planner/internal/metrics"
 	"trip-planner/internal/airports"
+	"trip-planner/internal/metrics"
 	"trip-planner/internal/routing"
 	"trip-planner/internal/storage"
 	"trip-planner/internal/yandex"

cmd/api/main.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"log"
 	"net/http"
+	"os"
 
 	"github.com/go-redis/redis/v8"
 
@@ -17,7 +18,12 @@ func main() {
 	redisClient := initRedis()
 	router := routing.NewGraph()
 	m := metrics.New()
-	yandexClient := yandex.NewClient("default-key", yandex.WithMetrics(m))
+
+	apiKey := os.Getenv("YANDEX_API_KEY")
+	if apiKey == "" {
+		apiKey = "default-key" // fallback for development
+	}
+	yandexClient := yandex.NewClient(apiKey, yandex.WithMetrics(m))
 
 	handlerCtx := NewHandlerContext(redisClient, router, yandexClient, m)
 

cmd/cron/station_status.go

@@ -175,22 +175,22 @@ func (sm *StationMonitor) updateStationStatus(ctx context.Context, tripCount int
 
 	// Write updated status to cache with 24h TTL
 	if err := sm.Cache.Set(ctx, cacheKey, []byte(newStatus), 24*time.Hour); err != nil {
-		return "", fmt.Errorf("cache set status: %w", err)
+		return newStatus, fmt.Errorf("cache set status: %w", err)
 	}
 
 	// Write updated zero days count to cache with 24h TTL
 	if err := sm.Cache.Set(ctx, zeroDaysKey, []byte(fmt.Sprintf("%d", zeroDays)), 24*time.Hour); err != nil {
-		return "", fmt.Errorf("cache set zero days: %w", err)
+		return newStatus, fmt.Errorf("cache set zero days: %w", err)
 	}
 
 	// Write updated zero-since timestamp to cache with 24h TTL
 	if err := sm.Cache.Set(ctx, zeroSinceKey, []byte(fmt.Sprintf("%d", zeroSince.Unix())), 24*time.Hour); err != nil {
-		return "", fmt.Errorf("cache set zero since: %w", err)
+		return newStatus, fmt.Errorf("cache set zero since: %w", err)
 	}
 
 	// Write updated last-seen-flight timestamp to cache with 24h TTL
 	if err := sm.Cache.Set(ctx, lastSeenFlightKey, []byte(fmt.Sprintf("%d", lastSeenFlight.Unix())), 24*time.Hour); err != nil {
-		return "", fmt.Errorf("cache set last seen flight: %w", err)
+		return newStatus, fmt.Errorf("cache set last seen flight: %w", err)
 	}
 
 	return newStatus, nil

cmd/cron/station_status_test.go

@@ -235,7 +235,6 @@ func TestProcessStation_Reactivation_AfterClosure(t *testing.T) {
 	}
 }
 
-
 // TestAutoClosureChronology verifies the chronology of auto-closure detection.
 // It tests that a station closes after exactly N=3 consecutive zero-trip days,
 // and that it reactivates when trips resume.
@@ -337,4 +336,3 @@ func TestAutoClosureChronology(t *testing.T) {
 		t.Errorf("expected zero days 0 after reactivation, got %d", zeroDays4)
 	}
 }
-

internal/cache/store.go

@@ -288,14 +288,11 @@ func (c *CacheAside) Set(ctx context.Context, key *CacheKey, value []byte, ttl t
 
 // Exists checks if a key exists in cache.
 func (c *CacheAside) Exists(ctx context.Context, key *CacheKey) (bool, error) {
-	_, err := c.store.Exists(ctx, key)
-	if errors.Is(err, redis.Nil) {
-		return false, nil
-	}
+	exists, err := c.store.Exists(ctx, key)
 	if err != nil {
 		return false, fmt.Errorf("cache exists: %w", err)
 	}
-	return true, nil
+	return exists, nil
 }
 
 // Increment increments a counter key.

internal/routing/graph.go

@@ -284,7 +284,6 @@ func (g *Graph) FindRoute(originID, destID string, opts SearchOptions, closedSta
 	// Use dynamic MCT from transfer rules if available, otherwise fall back to opts.MCT
 	mct := getMCTForTransfer(opts.MCT, g)
 
-
 	// If origin or destination station is closed, add synthetic neighbor edges as fallback
 	if closedStations[originID] || closedStations[destID] {
 		// Get list of closed station IDs
@@ -344,7 +343,7 @@ func (g *Graph) FindRoute(originID, destID string, opts SearchOptions, closedSta
 				}
 			}
 		}
-	}// Build adjacency list from edges
+	} // Build adjacency list from edges
 	adj := g.buildAdjacencyList()
 
 	// BFS with transfer tracking
@@ -1018,6 +1017,7 @@ func SelectHubStations(stations []StationInfo, minOutgoingFlights int) []*Node {
 
 	return hubs
 }
+
 // getStationNeighbors returns neighboring stations for a given station ID in the same city.
 
 // RouteStatus represents the current status of a route leg.

internal/routing/graph_test.go

@@ -336,6 +336,7 @@ func TestLazyExpansionDepthLimit(t *testing.T) {
 		t.Log("MaxTransfers=0: no direct route s1->s7 found (only chain edges exist)")
 	}
 }
+
 // TestRouteReSearchOnChange tests that the route change detection logic correctly
 // identifies when a route leg has undergone significant changes (cancellation or major delay)
 // and triggers a re-search to find an updated route.

internal/routing/search_cache.go

@@ -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 {

internal/routing/search_cache_test.go

@@ -69,21 +69,6 @@ func TestNewSearchCacheService(t *testing.T) {
 	}
 }
 
-func TestParseItineraryFromBytes(t *testing.T) {
-	// Test with empty data
-	result := Itinerary{}
-	err := parseItineraryFromBytes([]byte{}, &result)
-	if err == nil {
-		t.Error("expected error for empty data")
-	}
-
-	// Test with invalid JSON data
-	err = parseItineraryFromBytes([]byte("invalid json data"), &result)
-	if err == nil {
-		t.Error("expected error for invalid JSON data")
-	}
-}
-
 func TestConvertResponseToBytes(t *testing.T) {
 	// Test with nil response
 	_, err := convertResponseToBytes(nil)

internal/yandex/client.go

@@ -325,11 +325,15 @@ func (tb *tokenBucket) acquire() error {
 func (tb *tokenBucket) refill(now time.Time) {
 	elapsed := now.Sub(tb.lastRefill)
 	if elapsed >= time.Second {
-		// Refill tokens based on elapsed time and rate
+		tokensToAdd := int(elapsed.Seconds()) * tb.refillPerSec
+		if tb.tokens+tokensToAdd > tb.capacity {
 			tb.tokens = tb.capacity
+		} else {
+			tb.tokens += tokensToAdd
+		}
 		tb.lastRefill = now
 	}
-	// else: keep current tokens, will fully refill on next second boundary
+	// else: keep current tokens, will add on next refill
 }
 
 // --- Circuit Breaker ---
@@ -342,7 +346,6 @@ func newCircuitBreaker() *circuitBreaker {
 	}
 }
 
-
 func (cb *circuitBreaker) ResetCircuitBreaker() {
 	cb.mu.Lock()
 	defer cb.mu.Unlock()