const app = getApp();

// 客户端缓存：key → { data, expireAt }
const CACHE_PREFIX = 'api_cache_';
const DEFAULT_TTL = 30 * 60 * 1000; // 默认 30 分钟

function request(method, path, data) {
  return new Promise((resolve, reject) => {
    wx.request({
      url: app.globalData.baseUrl + path,
      method: method,
      data: data,
      header: { 'Content-Type': 'application/json' },
      success: (res) => {
        if (res.statusCode === 200 && res.data.code === 200) {
          resolve(res.data.data);
        } else {
          reject(res.data);
        }
      },
      fail: (err) => {
        reject(err);
      }
    });
  });
}

/**
 * 带客户端缓存的 GET 请求
 * @param {string} path   请求路径
 * @param {object} data   请求参数
 * @param {number} ttlMs  缓存时长(毫秒)，默认 30 分钟
 */
function getWithCache(path, data, ttlMs) {
  const cacheKey = CACHE_PREFIX + path + '_' + JSON.stringify(data || {});
  const ttl = ttlMs || DEFAULT_TTL;

  // 读缓存
  try {
    const cached = wx.getStorageSync(cacheKey);
    if (cached && cached.expireAt > Date.now()) {
      return Promise.resolve(cached.data);
    }
  } catch (e) {
    // 读取失败，忽略
  }

  return request('GET', path, data).then((result) => {
    // 写缓存
    try {
      wx.setStorageSync(cacheKey, {
        data: result,
        expireAt: Date.now() + ttl
      });
    } catch (e) {
      // 写入失败，忽略（存储满了等）
    }
    return result;
  });
}

/**
 * 清除过期缓存
 */
function clearExpiredCache() {
  try {
    const info = wx.getStorageInfoSync();
    const keys = info.keys || [];
    const now = Date.now();
    keys.forEach((key) => {
      if (key.startsWith(CACHE_PREFIX)) {
        const cached = wx.getStorageSync(key);
        if (cached && cached.expireAt < now) {
          wx.removeStorageSync(key);
        }
      }
    });
  } catch (e) {
    // 静默失败
  }
}

module.exports = {
  get: (path, data) => request('GET', path, data),
  post: (path, data) => request('POST', path, data),
  getWithCache,
  clearExpiredCache
};