feat: Implement user preferences (saved cities, search history) with Redis storage and API handlers

cmd/cron/station_status.go

@@ -19,6 +19,13 @@ type StationMonitor struct {
 	// ScheduleFunc is the function used to check a station's schedule.
 	// Defaults to checkStationSchedule if not set.
 	ScheduleFunc func(context.Context, string) (int, error)
+
+	// ZeroSince is the timestamp when the current zero-trip streak began.
+	// Zero if the station is not in a zero-trip streak.
+	ZeroSince time.Time
+
+	// LastSeenFlight is the timestamp of the last successful schedule check.
+	LastSeenFlight time.Time
 }
 
 // Status represents the current status of a station.
@@ -47,6 +54,22 @@ func zeroDaysKey(id string) *cache.CacheKey {
 	}
 }
 
+// zeroSinceKey returns the Redis key for tracking the zero-trip streak start timestamp.
+func zeroSinceKey(id string) *cache.CacheKey {
+	return &cache.CacheKey{
+		Kind: "station_zero_since",
+		Code: id,
+	}
+}
+
+// lastSeenFlightKey returns the Redis key for tracking the last seen flight timestamp.
+func lastSeenFlightKey(id string) *cache.CacheKey {
+	return &cache.CacheKey{
+		Kind: "station_last_seen_flight",
+		Code: id,
+	}
+}
+
 // checkStationSchedule queries the Yandex /schedule endpoint for a station
 // and returns the number of trips found.
 func checkStationSchedule(ctx context.Context, yc *yandex.Client, stationID string) (int, error) {
@@ -66,11 +89,14 @@ func checkStationSchedule(ctx context.Context, yc *yandex.Client, stationID stri
 }
 
 // updateStationStatus updates the station's status in cache based on trip count.
-// It returns the new status. Writes status and zero-days count separately;
-// partial failures may leave cache inconsistent but do not lose the core state.
+// It returns the new status. Writes status, zero-days count, zero-since timestamp,
+// and last-seen-flight timestamp separately; partial failures may leave cache
+// inconsistent but do not lose the core state.
 func (sm *StationMonitor) updateStationStatus(ctx context.Context, tripCount int) (Status, error) {
 	cacheKey := stationStatusKey(sm.ID)
 	zeroDaysKey := zeroDaysKey(sm.ID)
+	zeroSinceKey := zeroSinceKey(sm.ID)
+	lastSeenFlightKey := lastSeenFlightKey(sm.ID)
 
 	// Get current status from cache
 	data, err := sm.Cache.Get(ctx, cacheKey)
@@ -101,14 +127,39 @@ func (sm *StationMonitor) updateStationStatus(ctx context.Context, tripCount int
 		}
 	}
 
+	// Get current zero-since timestamp
+	zeroSinceData, err := sm.Cache.Get(ctx, zeroSinceKey)
+	var zeroSince time.Time
+	if err == nil && zeroSinceData != nil {
+		_, err := fmt.Sscanf(string(zeroSinceData), "%d", (&zeroSince).Unix())
+		if err != nil {
+			zeroSince = time.Time{}
+		}
+	}
+
+	// Get current last-seen-flight timestamp
+	lastSeenFlightData, err := sm.Cache.Get(ctx, lastSeenFlightKey)
+	var lastSeenFlight time.Time
+	if err == nil && lastSeenFlightData != nil {
+		_, err := fmt.Sscanf(string(lastSeenFlightData), "%d", (&lastSeenFlight).Unix())
+		if err != nil {
+			lastSeenFlight = time.Time{}
+		}
+	}
+
 	// Update status based on trip count
 	var newStatus Status
 
 	if tripCount > 0 {
 		newStatus = StatusActive
 		zeroDays = 0
+		zeroSince = time.Time{}
+		lastSeenFlight = time.Now()
 	} else {
 		zeroDays++
+		if zeroSince.IsZero() {
+			zeroSince = time.Now()
+		}
 		if zeroDays >= 3 {
 			newStatus = StatusClosed
 		} else {
@@ -126,6 +177,16 @@ func (sm *StationMonitor) updateStationStatus(ctx context.Context, tripCount int
 		return "", 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)
+	}
+
+	// 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, nil
 }