window.API = (function() {
  'use strict';

  const BASE = '/api/v1';
  let _agentKey = '';

  async function request(method, path, body) {
    const headers = { 'Content-Type': 'application/json' };
    const token = Auth.getToken();
    if (token) headers['Authorization'] = 'Bearer ' + token;
    if (_agentKey) headers['X-Agent-Key'] = _agentKey;

    const opts = { method, headers };
    if (body && method !== 'GET') opts.body = JSON.stringify(body);

    Logger.debug(`API ${method} ${path}`);
    let res;
    try {
      res = await fetch(BASE + path, opts);
    } catch (e) {
      Logger.error(`API fetch error: ${path} - ${e.message}`);
      throw new Error('网络请求失败，请检查网络连接');
    }

    let data;
    try { data = await res.json(); } catch (e) { data = null; }

    if (!res.ok) {
      const msg = (data && data.detail) || `请求失败 (${res.status})`;
      Logger.error(`API error: ${path} - ${msg}`);
      const err = new Error(msg);
      err.status = res.status;
      err.data = data;
      throw err;
    }
    return data;
  }

  return {
    setAgentKey(k) { _agentKey = k; },
    get:    (path)             => request('GET', path),
    post:   (path, body)       => request('POST', path, body),
    put:    (path, body)       => request('PUT', path, body),
    delete: (path)             => request('DELETE', path),
  };
})();