// app/api/live/telemetry/route.ts
// Server-Sent Events endpoint streaming from C++ Unix socket

import { getTelemetryBridge } from '@/lib/telemetryBridge';

export const dynamic = 'force-dynamic';
export const runtime = 'nodejs';

export async function GET(request: Request) {
  const { searchParams } = new URL(request.url);
  const serverId = searchParams.get('serverId');
  const filterServerId = serverId ? parseInt(serverId) : null;

  const encoder = new TextEncoder();
  const bridge = getTelemetryBridge();
  
  const stream = new ReadableStream({
    start(controller) {
      console.log('[SSE] Client connected', filterServerId ? `(server ${filterServerId})` : '(all servers)');
      
      // Send initial connection message
      controller.enqueue(encoder.encode(`data: ${JSON.stringify({ 
        type: 'connected',
        bridge_status: bridge.isConnected() ? 'connected' : 'connecting'
      })}\n\n`));

      // Subscribe to telemetry updates
      const unsubscribe = bridge.subscribe((packet) => {
        // Filter by server if specified
        if (filterServerId && packet.server_id !== filterServerId) {
          return;
        }

        // Transform to client format
        const telemetry = {
          type: 'update',
          timestamp: Date.now(),
          server_id: packet.server_id,
          cars: packet.cars.map((car, index) => ({
            carID: car.carID,
            driver_guid: car.driver_guid,
            driver_name: car.driver_name,
            car_model: car.car_model,
            position: car.position || index + 1,
            current_lap: car.current_lap,
            normalizedSplinePos: car.normalizedSplinePos,
            speed: Math.round(car.speed_kmh),
            gear: car.gear,
            rpm: car.rpm,
            last_lap_time: car.last_lap_time || null,
            best_lap_time: car.best_lap_time || null,
          })),
        };

        try {
          controller.enqueue(encoder.encode(`data: ${JSON.stringify(telemetry)}\n\n`));
        } catch (error) {
          console.error('[SSE] Error sending data:', error);
        }
      });

      // Heartbeat every 30 seconds
      const heartbeat = setInterval(() => {
        try {
          controller.enqueue(encoder.encode(`: heartbeat\n\n`));
        } catch (error) {
          clearInterval(heartbeat);
        }
      }, 30000);

      // Cleanup on connection close
      request.signal.addEventListener('abort', () => {
        console.log('[SSE] Client disconnected');
        unsubscribe();
        clearInterval(heartbeat);
        controller.close();
      });
    },
  });

  return new Response(stream, {
    headers: {
      'Content-Type': 'text/event-stream',
      'Cache-Control': 'no-cache',
      'Connection': 'keep-alive',
      'X-Accel-Buffering': 'no', // Disable nginx buffering
    },
  });
}