/**
 * API 封装：baseURL、Token、POST JSON、统一错误与 401 处理
 * 依据：backend/API.md，全部 POST，JSON，Bearer Token
 */
(function (global) {
  'use strict';

  var BASE_URL = 'http://127.0.0.1:8000';
  var TOKEN_KEY = 'pm_token';
  var USER_KEY = 'pm_user';

  function getToken() {
    try {
      return localStorage.getItem(TOKEN_KEY) || '';
    } catch (e) {
      return '';
    }
  }

  function setToken(token) {
    try {
      if (token) localStorage.setItem(TOKEN_KEY, token);
      else localStorage.removeItem(TOKEN_KEY);
    } catch (e) {}
  }

  function getUser() {
    try {
      var raw = localStorage.getItem(USER_KEY);
      return raw ? JSON.parse(raw) : null;
    } catch (e) {
      return null;
    }
  }

  function setUser(user) {
    try {
      if (user) localStorage.setItem(USER_KEY, JSON.stringify(user));
      else localStorage.removeItem(USER_KEY);
    } catch (e) {}
  }

  function clearAuth() {
    setToken('');
    setUser(null);
  }

  /**
   * POST /api/xxx 请求
   * @param {string} path - 如 '/api/auth/login'
   * @param {object} body - 请求体
   * @param {boolean} [requireAuth=true] - 是否携带 Token
   * @returns {Promise<{ ok: boolean, data?: object, status?: number, message?: string }>}
   */
  function post(path, body, requireAuth) {
    if (requireAuth === undefined) requireAuth = true;
    var url = BASE_URL + path;
    var headers = {
      'Content-Type': 'application/json',
    };
    var token = getToken();
    if (requireAuth && token) {
      headers['Authorization'] = 'Bearer ' + token;
    }
    return fetch(url, {
      method: 'POST',
      headers: headers,
      body: JSON.stringify(body || {}),
    })
      .then(function (res) {
        return res.text().then(function (text) {
          var data = null;
          try {
            data = text ? JSON.parse(text) : null;
          } catch (e) {
            data = null;
          }
          if (res.status === 401) {
            clearAuth();
            if (typeof global.onAuthRequired === 'function') {
              global.onAuthRequired();
            }
            return { ok: false, status: 401, message: data && data.message ? data.message : '未登录' };
          }
          if (!res.ok) {
            var msg = (data && data.message) || res.statusText || '请求失败';
            return { ok: false, status: res.status, data: data, message: msg };
          }
          return { ok: true, data: data };
        });
      })
      .catch(function (err) {
        return { ok: false, message: err && err.message ? err.message : '网络错误' };
      });
  }

  global.API = {
    BASE_URL: BASE_URL,
    getToken: getToken,
    setToken: setToken,
    getUser: getUser,
    setUser: setUser,
    clearAuth: clearAuth,
    post: post,
  };
})(typeof window !== 'undefined' ? window : this);