import { NextResponse } from 'next/server';
import { getRedisClient } from '@/lib/redis';
import { prisma } from '@/lib/prisma';
import { logger } from '@/lib/logger';

/**
 * Health check endpoint
 * 
 * Vérifie la santé de l'application et de ses dépendances:
 * - Base de données PostgreSQL
 * - Redis (si configuré)
 * 
 * Usage:
 *   GET /api/health
 * 
 * Réponses:
 *   200: Tous les services sont opérationnels
 *   503: Un ou plusieurs services sont indisponibles
 */
export async function GET() {
  const startTime = Date.now();
  const checks: Record<string, { status: string; message?: string; latency?: number }> = {};
  let overallStatus: 'ok' | 'degraded' | 'down' = 'ok';

  // Vérifier PostgreSQL
  try {
    const dbStart = Date.now();
    await prisma.$queryRaw`SELECT 1`;
    const dbLatency = Date.now() - dbStart;
    checks.database = {
      status: 'ok',
      latency: dbLatency,
    };
  } catch (error) {
    logger.error('[HEALTH] Database check failed', {
      error: error instanceof Error ? error.message : String(error),
    });
    checks.database = {
      status: 'error',
      message: error instanceof Error ? error.message : 'Unknown error',
    };
    overallStatus = 'degraded';
  }

  // Vérifier Redis (optionnel)
  try {
    const redis = getRedisClient();
    const redisStart = Date.now();
    await redis.ping();
    const redisLatency = Date.now() - redisStart;
    checks.redis = {
      status: 'ok',
      latency: redisLatency,
    };
  } catch (error) {
    logger.warn('[HEALTH] Redis check failed', {
      error: error instanceof Error ? error.message : String(error),
    });
    // Redis n'est pas critique, donc on ne change pas le statut global
    checks.redis = {
      status: 'error',
      message: error instanceof Error ? error.message : 'Unknown error',
    };
  }

  const totalLatency = Date.now() - startTime;

  const response = {
    status: overallStatus,
    timestamp: new Date().toISOString(),
    uptime: process.uptime(),
    checks,
    latency: totalLatency,
  };

  const statusCode = overallStatus === 'ok' ? 200 : 503;
  return NextResponse.json(response, { status: statusCode });
}