/**
 * server.js - API 代理服务主入口
 *
 * 对外暴露 OpenAI / Anthropic 兼容的 API 端点
 * 对内通过账号池轮换使用 chataibot.pro 试用额度
 *
 * 启动: node server.js
 * 端口: config.server.port (默认 9090)
 */

import http from 'http';
import config from './config.js';
import { AccountPool } from './pool.js';
import { handleChatCompletions } from './openai-adapter.js';
import { handleMessages } from './anthropic-adapter.js';
import { getModelList } from './message-convert.js';
import { getDashboardHTML } from './ui.js';

// ==================== 初始化 ====================

const pool = new AccountPool();
await pool.init();

// ==================== HTTP 服务器 ====================

function parseBody(req, maxSize = 2 * 1024 * 1024) {  // 默认 2MB
  return new Promise((resolve, reject) => {
    let data = '';
    let size = 0;
    req.on('data', chunk => {
      size += chunk.length;
      if (size > maxSize) {
        req.destroy();
        reject(new Error('Request body too large'));
        return;
      }
      data += chunk;
    });
    req.on('end', () => {
      try { resolve(JSON.parse(data)); }
      catch { reject(new Error('Invalid JSON body')); }
    });
    req.on('error', reject);
  });
}

function sendJson(res, status, data) {
  res.writeHead(status, {
    'Content-Type': 'application/json',
    'Access-Control-Allow-Origin': '*',
  });
  res.end(JSON.stringify(data));
}

function sendError(res, status, message) {
  sendJson(res, status, {
    error: { message, type: 'invalid_request_error', code: status },
  });
}

function sendHtml(res, html) {
  res.writeHead(200, { 'Content-Type': 'text/html; charset=utf-8', 'Cache-Control': 'no-cache' });
  res.end(html);
}

function checkAuth(req) {
  if (!config.server.apiKey) return true;
  // Bearer token
  const auth = req.headers['authorization'] || '';
  if (auth.startsWith('Bearer ') && auth.slice(7) === config.server.apiKey) return true;
  // x-api-key header (Anthropic 风格)
  if (req.headers['x-api-key'] === config.server.apiKey) return true;
  return false;
}

const server = http.createServer(async (req, res) => {
  const url = new URL(req.url, `http://${req.headers.host}`);
  const pathname = url.pathname;
  const method = req.method;

  // CORS 预检
  if (method === 'OPTIONS') {
    res.writeHead(204, {
      'Access-Control-Allow-Origin': '*',
      'Access-Control-Allow-Methods': 'GET, POST, OPTIONS',
      'Access-Control-Allow-Headers': 'Content-Type, Authorization, x-api-key, anthropic-version',
      'Access-Control-Max-Age': '86400',
    });
    res.end();
    return;
  }

  // 健康检查 (不需要认证)
  if (method === 'GET' && pathname === '/health') {
    sendJson(res, 200, { status: 'ok', uptime: process.uptime() });
    return;
  }

  // Dashboard 控制台
  if (method === 'GET' && (pathname === '/' || pathname === '/ui')) {
    sendHtml(res, getDashboardHTML());
    return;
  }

  // 模型列表 (Dashboard 需要免认证访问)
  if (method === 'GET' && pathname === '/v1/models') {
    sendJson(res, 200, { object: 'list', data: getModelList() });
    return;
  }

  // 账号池状态 (Dashboard 需要免认证访问)
  if (method === 'GET' && pathname === '/pool/status') {
    sendJson(res, 200, pool.getStatus());
    return;
  }

  // 注册日志 (Dashboard 需要免认证访问)
  if (method === 'GET' && pathname === '/pool/logs') {
    const since = parseInt(url.searchParams.get('since')) || 0;
    sendJson(res, 200, { logs: pool.getLogs(since) });
    return;
  }

  // 手动注册账号 (Dashboard 调用)
  if (method === 'POST' && pathname === '/pool/register') {
    try {
      const body = await parseBody(req);
      const count = Math.min(Math.max(1, body.count || 5), 50);
      const provider = body.provider || undefined;
      const concurrency = body.concurrency ? Math.min(Math.max(1, body.concurrency), 20) : undefined;
      const result = pool.manualRegister(count, provider, concurrency);
      sendJson(res, 200, { ok: true, message: `已提交 ${result.queued} 个注册任务`, ...result });
    } catch (e) {
      sendJson(res, 200, { ok: false, message: e.message });
    }
    return;
  }

  // 认证校验
  if (!checkAuth(req)) {
    sendError(res, 401, 'Invalid API key');
    return;
  }

  try {
    // ==================== 路由 ====================

    // OpenAI: POST /v1/chat/completions
    if (method === 'POST' && pathname === '/v1/chat/completions') {
      const body = await parseBody(req);
      await handleChatCompletions(body, res, pool);
      return;
    }

    // Anthropic: POST /v1/messages
    if (method === 'POST' && pathname === '/v1/messages') {
      const body = await parseBody(req);
      await handleMessages(body, res, pool);
      return;
    }

    // 404
    sendError(res, 404, `Not found: ${method} ${pathname}`);
  } catch (e) {
    console.error(`[Server] 请求错误: ${e.message}`);
    if (!res.headersSent) {
      sendError(res, 500, 'Internal server error');
    }
  }
});

// ==================== 启动 ====================

const { port, host } = config.server;
server.listen(port, host, () => {
  console.log(`\n  ┌──────────────────────────────────────────┐`);
  console.log(`  │  ChatAIBot API Proxy                     │`);
  console.log(`  │  http://${host}:${port}                    │`);
  console.log(`  ├──────────────────────────────────────────┤`);
  console.log(`  │  Dashboard: http://${host}:${port}/          │`);
  console.log(`  │  OpenAI:    POST /v1/chat/completions    │`);
  console.log(`  │  Anthropic: POST /v1/messages            │`);
  console.log(`  │  Models:    GET  /v1/models              │`);
  console.log(`  │  Pool:      GET  /pool/status            │`);
  console.log(`  │  Health:    GET  /health                 │`);
  console.log(`  ├──────────────────────────────────────────┤`);
  console.log(`  │  Auth: ${config.server.apiKey ? 'Bearer ' + config.server.apiKey.substring(0, 8) + '...' : '无 (开放访问)'}${' '.repeat(Math.max(0, 24 - (config.server.apiKey ? 16 : 13)))}│`);
  console.log(`  │  Pool: ${pool.getStatus().active} active / ${pool.getStatus().total} total${' '.repeat(Math.max(0, 22 - String(pool.getStatus().active).length - String(pool.getStatus().total).length))}│`);
  console.log(`  └──────────────────────────────────────────┘\n`);
});

// 优雅退出
process.on('SIGINT', () => {
  console.log('\n[Server] 正在关闭...');
  pool.destroy();
  server.close(() => process.exit(0));
});

process.on('SIGTERM', () => {
  pool.destroy();
  server.close(() => process.exit(0));
});