/**
 * Cloudflare Worker - Server Recommendation System Entry Point
 *
 * AI-powered server recommendation service using Workers AI, D1, and KV.
 */

import type { Env } from './types';
import { getAllowedOrigin, checkRateLimit, jsonResponse } from './utils';
import { handleHealth } from './handlers/health';
import { handleGetServers } from './handlers/servers';
import { handleRecommend } from './handlers/recommend';

/**
 * Main request handler
 */
export default {
  async fetch(request: Request, env: Env): Promise<Response> {
    const requestId = crypto.randomUUID();

    try {
      const url = new URL(request.url);
      const path = url.pathname;

      // Rate limiting (except for health checks)
      if (path !== '/api/health') {
        const clientIP = request.headers.get('CF-Connecting-IP') || 'unknown';
        const rateCheck = await checkRateLimit(clientIP, env);

        if (!rateCheck.allowed) {
          const origin = getAllowedOrigin(request);
          return jsonResponse(
            { error: 'Too many requests', request_id: rateCheck.requestId },
            429,
            {
              'Access-Control-Allow-Origin': origin,
              'Vary': 'Origin',
            }
          );
        }
      }

      // CORS headers for all responses
      const origin = getAllowedOrigin(request);
      const corsHeaders = {
        'Access-Control-Allow-Origin': origin,
        'Access-Control-Allow-Methods': 'GET, POST, OPTIONS',
        'Access-Control-Allow-Headers': 'Content-Type',
        'Vary': 'Origin',
      };

      // Handle preflight requests
      if (request.method === 'OPTIONS') {
        return new Response(null, { headers: corsHeaders });
      }

      // Route handling
      if (path === '/api/health') {
        return handleHealth(corsHeaders);
      }

      if (path === '/api/servers' && request.method === 'GET') {
        return handleGetServers(request, env, corsHeaders);
      }

      if (path === '/api/recommend' && request.method === 'POST') {
        return handleRecommend(request, env, corsHeaders);
      }

      return jsonResponse(
        { error: 'Not found', request_id: requestId },
        404,
        corsHeaders
      );
    } catch (error) {
      console.error('[Worker] Unhandled error:', error);
      const origin = getAllowedOrigin(request);
      return jsonResponse(
        {
          error: 'Internal server error',
          request_id: requestId,
        },
        500,
        {
          'Access-Control-Allow-Origin': origin,
          'Vary': 'Origin',
        }
      );
    }
  },
};