微信公众号 API 代理配置

export default {
  async fetch(request, env) {
    const corsHeaders = {
      'Access-Control-Allow-Origin': '*',
      'Access-Control-Allow-Methods': 'POST, OPTIONS',
      'Access-Control-Allow-Headers': 'Content-Type',
    };

    // 处理 CORS 预检请求
    if (request.method === 'OPTIONS') {
      return new Response(null, { headers: corsHeaders });
    }

    if (request.method !== 'POST') {
      return new Response('Method Not Allowed', { status: 405, headers: corsHeaders });
    }

    try {
      const body = await request.json();
      const { url, method = 'GET', data, fileData, fileName, mimeType, fieldName } = body;
      
      // === Debug Logging ===
      console.log('Received URL:', url);
      
      // 安全校验：只允许访问微信 API
      if (!url || !url.startsWith('https://api.weixin.qq.com/')) {
        const errorMsg = `Invalid URL. Expected: starts with https://api.weixin.qq.com/. FLASH: Received [${typeof url}]: ${url}`;
        return new Response(JSON.stringify({ error: errorMsg, receivedBody: body }), { status: 400, headers: corsHeaders });
      }

      let response;
      if (method === 'UPLOAD' && fileData) {
        // 文件上传处理：Base64 -> Binary -> FormData
        const binary = atob(fileData);
        const bytes = new Uint8Array(binary.length);
        for (let i = 0; i < binary.length; i++) bytes[i] = binary.charCodeAt(i);
        
        const formData = new FormData();
        formData.append(fieldName || 'media', new Blob([bytes], { type: mimeType }), fileName);
        response = await fetch(url, { method: 'POST', body: formData });
      } else {
        // 普通 JSON 请求
        const opts = { method, headers: { 'Content-Type': 'application/json' } };
        if (method !== 'GET' && data) opts.body = JSON.stringify(data);
        response = await fetch(url, opts);
      }

      const result = await response.json();
      return new Response(JSON.stringify(result), {
        headers: { ...corsHeaders, 'Content-Type': 'application/json' }
      });
    } catch (error) {
      return new Response(JSON.stringify({ error: `Server Error: ${error.message}`, stack: error.stack }), { status: 500, headers: corsHeaders });
    }
  }
};