'use strict';

exports.main = async (event, context) => {
  // uniCloud HTTP 触发器：event 本身就是请求信息
  // event.httpMethod = 'GET'/'POST'/'OPTIONS'
  // event.body = 请求体
  // event.headers = 请求头
  // context.callbackWaitsForEmptyEventLoop = true 保持连接

  const corsHeaders = {
    'Access-Control-Allow-Origin': '*',
    'Access-Control-Allow-Methods': 'GET, POST, OPTIONS',
    'Access-Control-Allow-Headers': 'Content-Type, Authorization',
    'Access-Control-Max-Age': '86400'
  };

  // 处理 CORS 预检
  if (event.httpMethod === 'OPTIONS') {
    return {
      statusCode: 204,
      headers: corsHeaders,
      body: ''
    };
  }

  // 设置等待空事件循环（保持 SSE 连接）
  context.callbackWaitsForEmptyEventLoop = false;

  // 解析请求体
  let body = {};
  try {
    const raw = event.body || '';
    if (event.isBase64Encoded) {
      body = JSON.parse(Buffer.from(raw, 'base64').toString());
    } else {
      try { body = JSON.parse(raw); } catch (e) {
        const params = new URLSearchParams(raw);
        for (const [k, v] of params) body[k] = v;
      }
    }
  } catch (e) {}

  const { file_id, user_id, file_name, file_size, record_id } = body;

  if (!file_id) {
    return {
      statusCode: 400,
      headers: { ...corsHeaders, 'Content-Type': 'application/json' },
      body: JSON.stringify({ error: '缺少 file_id' })
    };
  }

  const COZE_TOKEN = 'sat_OiXlI4Da5Q99fxmul6pNfExmA6hR898UbxBDwrvjZ638APxRSlFnXbz6zyFedKNG';
  const BOT_ID = '7689821072762011698';

  const objectString = JSON.stringify([
    { type: 'file', file_id: file_id },
    { type: 'text', text: '请审查这份合同' }
  ]);

  // 调用扣子（流式）
  try {
    const chatRes = await uniCloud.httpclient.request('https://api.coze.cn/v3/chat', {
      method: 'POST',
      dataType: 'text',
      contentType: 'json',
      timeout: 300000,
      headers: { 'Authorization': 'Bearer ' + COZE_TOKEN },
      data: {
        bot_id: BOT_ID,
        user_id: user_id || 'anonymous',
        stream: true,
        auto_save_history: true,
        additional_messages: [{
          role: 'user',
          content: objectString,
          content_type: 'object_string'
        }]
      }
    });

    // 返回 SSE 格式
    const text = chatRes.data || '';
    const sseBody = text.split('\n').map(line => {
      if (line.startsWith('data:')) return line + '\n\n';
      return '';
    }).join('') + 'data: [DONE]\n\n';

    return {
      statusCode: 200,
      headers: {
        ...corsHeaders,
        'Content-Type': 'text/event-stream',
        'Cache-Control': 'no-cache',
        'Connection': 'keep-alive'
      },
      body: sseBody
    };
  } catch (e) {
    return {
      statusCode: 500,
      headers: { ...corsHeaders, 'Content-Type': 'application/json' },
      body: JSON.stringify({ error: e.message })
    };
  }
};