import express, { Request, Response } from 'express';
import GtfsRealtimeBindings from 'gtfs-realtime-bindings';
import { loadGtfsStops, loadGtfsRoutes } from './lib/gtfs';
import { config, StopConfig, RouteConfig } from './config';

const app = express();

// Load GTFS data
const stops = loadGtfsStops();
const routes = loadGtfsRoutes();

// Serve static files
import * as path from 'path';
app.use(express.static(path.join(__dirname, 'public')));

// API Endpoints
app.get('/api/config', (req: Request, res: Response) => {
  const stopId = (req.query.stopId as string) || config.defaultStop.stopId;
  const routeId = (req.query.routeId as string) || config.defaultRoute.routeId;
  
  const stop = stops.get(stopId);
  const route = routes.get(routeId);
  
  res.json({
    stop: {
      id: stopId,
      code: stop?.stop_code,
      name: stop?.stop_name,
      lat: stop?.stop_lat,
      lon: stop?.stop_lon,
    },
    route: {
      id: routeId,
      shortName: route?.route_short_name,
      longName: route?.route_long_name,
    },
    defaults: {
      stopId: config.defaultStop.stopId,
      routeId: config.defaultRoute.routeId,
    }
  });
});

app.get('/api/stops', (req: Request, res: Response) => {
  const stopsList = Array.from(stops.values()).map(stop => ({
    id: stop.stop_id,
    code: stop.stop_code,
    name: stop.stop_name,
    lat: stop.stop_lat,
    lon: stop.stop_lon,
  }));
  res.json(stopsList);
});

app.get('/api/routes', (req: Request, res: Response) => {
  const routesList = Array.from(routes.values()).map(route => ({
    id: route.route_id,
    shortName: route.route_short_name,
    longName: route.route_long_name,
  }));
  res.json(routesList);
});

app.get('/api/arrivals', async (req: Request, res: Response) => {
  try {
    const stopId = (req.query.stopId as string) || config.defaultStop.stopId;
    const routeId = (req.query.routeId as string) || config.defaultRoute.routeId;
    
    const stop = stops.get(stopId);
    if (!stop) {
      return res.status(404).json({ error: `Stop ${stopId} not found` });
    }
    
    const radius = 50;
    const nearbyUrl = `${config.baseUrl}/transport/planner/stops/nearbyTimes?latitude=${stop.stop_lat}&longitude=${stop.stop_lon}&radius=${radius}`;
    
    const response = await fetch(nearbyUrl);
    const nearbyData = await response.json() as any[];
    
    const now = new Date();
    const arrivals: any[] = [];
    
    for (const stopData of nearbyData) {
      if (stopData.id.toString() !== stopId) continue;
      
      for (const pattern of stopData.patterns) {
        if (pattern.routeId.toString() !== routeId) continue;
        
        const routeInfo = routes.get(pattern.routeId.toString());
        
        for (const stopTime of pattern.stopTimes) {
          const serviceDay = new Date(stopTime.serviceDay * 1000);
          const arrivalTime = new Date(serviceDay.getTime() + stopTime.realtimeArrival * 1000);
          const scheduledTime = new Date(serviceDay.getTime() + stopTime.scheduledArrival * 1000);
          
          const minutesUntil = Math.floor((arrivalTime.getTime() - now.getTime()) / 60000);
          
          if (minutesUntil >= -2 && minutesUntil <= config.tracking.minutesAhead) {
            arrivals.push({
              arrivalTime: arrivalTime.toISOString(),
              scheduledTime: scheduledTime.toISOString(),
              minutesUntil: minutesUntil,
              delaySeconds: stopTime.arrivalDelay,
              headsign: stopTime.headsign,
              isRealtime: stopTime.realtime,
              realtimeState: stopTime.realtimeState,
            });
          }
        }
      }
    }
    
    arrivals.sort((a, b) => new Date(a.arrivalTime).getTime() - new Date(b.arrivalTime).getTime());
    
    res.json(arrivals);
  } catch (error) {
    res.status(500).json({ error: 'Failed to fetch arrivals' });
  }
});

app.get('/api/vehicles', async (req: Request, res: Response) => {
  try {
    const routeId = (req.query.routeId as string) || config.defaultRoute.routeId;
    
    // Fetch all vehicles from JSON API
    const vehiclesResponse = await fetch(config.apiEndpoints.vehiclesJson);
    
    if (!vehiclesResponse.ok) {
      throw new Error(`HTTP error! status: ${vehiclesResponse.status}`);
    }
    
    const allVehicles = await vehiclesResponse.json() as any[];
    
    // Fetch trip updates to find which vehicles are on our route
    const tripUpdatesResponse = await fetch(config.apiEndpoints.gtfsRtTripUpdates);
    
    if (!tripUpdatesResponse.ok) {
      console.warn('Could not fetch trip updates, returning all vehicles');
      // Return all vehicles with basic info
      res.json(allVehicles.slice(0, 20).map((v: any) => ({
        id: v.id,
        vehicleId: v.identificationNumber,
        label: v.inventoryNumber,
        lat: v.positionLatitude,
        lon: v.positionLongitude,
        bearing: v.positionBearing,
        speed: v.positionSpeed,
        timestamp: v.positionModifiedAt,
        tripId: '',
        currentStopSequence: 0,
        currentStatus: 'UNKNOWN',
      })));
      return;
    }
    
    const buffer = await tripUpdatesResponse.arrayBuffer();
    
    if (buffer.byteLength === 0) {
      console.warn('Empty trip updates feed');
      res.json([]);
      return;
    }
    
    let feed;
    try {
      feed = GtfsRealtimeBindings.transit_realtime.FeedMessage.decode(
        new Uint8Array(buffer)
      );
    } catch (decodeError) {
      console.error('Failed to decode GTFS-RT feed:', decodeError);
      res.json([]);
      return;
    }
    
    // Find trip IDs and vehicle IDs for our route
    const routeVehicleIds = new Set<string>();
    const vehicleTripMap = new Map<string, any>();
    
    for (const entity of feed.entity) {
      if (!entity.tripUpdate) continue;
      
      const tripUpdate = entity.tripUpdate;
      
      // Filter by target route
      if (tripUpdate.trip?.routeId !== routeId) continue;
      
      // Get vehicle ID if available
      if (tripUpdate.vehicle?.id) {
        routeVehicleIds.add(tripUpdate.vehicle.id);
        vehicleTripMap.set(tripUpdate.vehicle.id, {
          tripId: tripUpdate.trip.tripId,
          routeId: tripUpdate.trip.routeId,
        });
      }
      
      // Also try vehicle label
      if (tripUpdate.vehicle?.label) {
        routeVehicleIds.add(tripUpdate.vehicle.label);
        vehicleTripMap.set(tripUpdate.vehicle.label, {
          tripId: tripUpdate.trip.tripId,
          routeId: tripUpdate.trip.routeId,
        });
      }
    }
    
    // Filter vehicles by route
    const activeVehicles: any[] = [];
    
    for (const vehicle of allVehicles) {
      // Try to match by identification number or inventory number
      const vehicleId = vehicle.identificationNumber || vehicle.inventoryNumber?.toString();
      
      if (vehicleId && (routeVehicleIds.has(vehicleId) || routeVehicleIds.has(vehicle.inventoryNumber?.toString()))) {
        const tripInfo = vehicleTripMap.get(vehicleId) || vehicleTripMap.get(vehicle.inventoryNumber?.toString());
        
        activeVehicles.push({
          id: vehicle.id,
          vehicleId: vehicle.identificationNumber,
          label: vehicle.inventoryNumber,
          lat: vehicle.positionLatitude,
          lon: vehicle.positionLongitude,
          bearing: vehicle.positionBearing,
          speed: vehicle.positionSpeed,
          timestamp: vehicle.positionModifiedAt,
          tripId: tripInfo?.tripId || '',
          currentStopSequence: 0,
          currentStatus: vehicle.status === 2 ? 'IN_TRANSIT_TO' : 'UNKNOWN',
        });
      }
    }
    
    console.log(`Found ${routeVehicleIds.size} vehicle IDs for route ${routeId}`);
    console.log(`Matched ${activeVehicles.length} vehicles from JSON API`);
    
    res.json(activeVehicles);
  } catch (error) {
    console.error('Error fetching vehicles:', error);
    res.status(500).json({ error: 'Failed to fetch vehicles', details: String(error) });
  }
});

// Start server
app.listen(config.server.port, () => {
  console.log(`
===========================================================================
  BUS TRACKER WEB APP
===========================================================================
  Server running at: http://localhost:${config.server.port}
  
  Open your browser and navigate to the URL above to view the map.
  
  Features:
  - Real-time bus arrivals
  - Live vehicle locations on map
  - Interactive map interface
  
  Press Ctrl+C to stop the server
===========================================================================
  `);
});