/**
 * Readiness Probe Endpoint
 * Agent 4: Production Deployment
 *
 * GET /api/health/ready
 * Returns readiness status for Kubernetes/container orchestration.
 * Used to determine if the application is ready to receive traffic.
 */

import type { NextApiRequest, NextApiResponse } from 'next';
import { healthChecks } from '../../../lib/monitoring';

interface ReadyResponse {
  ready: boolean;
  checks: Array<{
    name: string;
    status: string;
  }>;
  timestamp: string;
}

interface ErrorResponse {
  ready: boolean;
  error: string;
  timestamp: string;
}

export default async function handler(
  req: NextApiRequest,
  res: NextApiResponse<ReadyResponse | ErrorResponse>
) {
  if (req.method !== 'GET') {
    res.setHeader('Allow', ['GET']);
    return res.status(405).json({
      ready: false,
      error: `Method ${req.method} is not allowed`,
      timestamp: new Date().toISOString(),
    });
  }

  try {
    const health = await healthChecks.checkReadiness();
    const isReady = health.status === 'healthy' || health.status === 'degraded';

    // Add cache headers - don't cache readiness checks
    res.setHeader('Cache-Control', 'no-cache, no-store, must-revalidate');
    res.setHeader('Pragma', 'no-cache');
    res.setHeader('Expires', '0');

    return res.status(isReady ? 200 : 503).json({
      ready: isReady,
      checks: health.checks.map((c) => ({
        name: c.name,
        status: c.status,
      })),
      timestamp: health.timestamp,
    });
  } catch (error) {
    return res.status(503).json({
      ready: false,
      error: error instanceof Error ? error.message : 'Unknown error',
      timestamp: new Date().toISOString(),
    });
  }
}