import axios from 'axios';

class RequestHttp {
  constructor(config) {
    this.instance = axios.create(config);
    this.abortControllers = new Map();
    this._setupInterceptors();
  }

  _generateRequestKey(config) {
    const { method, url, params, data } = config;
    return `${method}-${url}-${JSON.stringify(params || {})}-${JSON.stringify(data || {})}`;
  }

  _addPendingRequest(config) {
    const requestKey = this._generateRequestKey(config);
    const controller = new AbortController();
    config.signal = controller.signal;
    this.abortControllers.set(requestKey, controller);
  }

  _removePendingRequest(config, cancel = false) {
    const requestKey = this._generateRequestKey(config);
    if (this.abortControllers.has(requestKey)) {
      if (cancel) {
        this.abortControllers.get(requestKey).abort();
      }
      this.abortControllers.delete(requestKey);
    }
  }

  _setupInterceptors() {
    // 请求拦截器
    this.instance.interceptors.request.use(
      (config) => {
        // 防重复请求
        if (config.cancelDuplicate !== false) {
          this._removePendingRequest(config, true);
          this._addPendingRequest(config);
        }

        // 注入 Token
        if (config.withToken !== false) {
          const token = localStorage.getItem('token');
          if (token && config.headers) {
            config.headers.Authorization = `Bearer ${token}`;
          }
        }

        return config;
      },
      (error) => {
        return Promise.reject(error);
      }
    );

    // 响应拦截器
    this.instance.interceptors.response.use(
      (response) => {
        this._removePendingRequest(response.config);

        const { data, config } = response;

        // 业务成功：脱壳返回
        if (data.code === 200) {
          return data.data;
        }

        // 业务错误
        if (!config.skipGlobalError) {
          console.error('Business Error:', data.message);
        }

        // Token 过期：仅在非 skipGlobalError 的请求上触发整站跳登录页，
        // 否则像登录接口（凭证错也是 401）会被强制 reload，覆盖掉本地 hint。
        if (data.code === 401 && !config.skipGlobalError) {
          console.warn('Token已过期，请重新登录');
          localStorage.removeItem('token');
          window.location.href = '/login';
        }

        return Promise.reject(new Error(data.message || 'Error'));
      },
      (error) => {
        if (axios.isCancel(error)) {
          return Promise.reject('Request Canceled by Duplicate Prevention');
        }

        if (error.config) {
          this._removePendingRequest(error.config);
        }

        const status = error.response?.status;
        let errorMsg = error.message;

        switch (status) {
          case 400: errorMsg = '请求参数错误'; break;
          case 401: errorMsg = '未授权，请重新登录'; break;
          case 403: errorMsg = '拒绝访问'; break;
          case 404: errorMsg = '请求地址不存在'; break;
          case 500: errorMsg = '服务器内部错误'; break;
          case 502: errorMsg = '网关错误'; break;
          case 503: errorMsg = '服务不可用'; break;
          case 504: errorMsg = '网关超时'; break;
          default: errorMsg = '网络连接异常';
        }

        console.error('HTTP Error:', errorMsg);
        return Promise.reject(error);
      }
    );
  }

  get(url, config) {
    return this.instance.get(url, config);
  }

  post(url, data, config) {
    return this.instance.post(url, data, config);
  }

  put(url, data, config) {
    return this.instance.put(url, data, config);
  }

  delete(url, config) {
    return this.instance.delete(url, config);
  }
}

export const http = new RequestHttp({
  baseURL: process.env.VUE_APP_API_BASE || '',
  timeout: Number(process.env.VUE_APP_REQUEST_TIMEOUT) || 15000,
  cancelDuplicate: true,
});