import Axios, { AxiosInstance, AxiosResponse, AxiosRequestConfig, Canceler } from 'axios';
import { RequestType } from './index.type';

class Request implements RequestType {
  public instance: AxiosInstance;
  private theQueue: {
    info: string;
    c: Canceler;
  }[] = [];

  constructor(config: AxiosRequestConfig) {
    this.instance = this.genInstance(config);
    this.interceptorsRequest();
    this.interceptorsResponse();
  }

  async request(config: AxiosRequestConfig) {
    return await this.instance.request(config);
  }

  private genInstance(config: AxiosRequestConfig) {
    return Axios.create({
      timeout: 1000 * 10,
      ...config,
    });
  }

  // 添加请求拦截器
  private interceptorsRequest() {
    this.instance.interceptors.request.use(
      (config: any) => {
        config.cancelToken = new Axios.CancelToken((c) => {
          this.findInQueue({
            info: `${config.url}_${config.method}`,
            c,
          });
          // 类似这种取消请求
          // 其实服务端是有收到的
          // 只是浏览器层面做了一层处理
        });
        return config;
      },
      function (error) {
        // 对请求错误做些什么
        return Promise.reject(error);
      },
    );
  }

  // 添加响应拦截器
  private interceptorsResponse() {
    this.instance.interceptors.response.use(
      (response: AxiosResponse<any>) => {
        const config = response.config;
        this.removeQueue({
          info: `${config.url}_${config.method}`,
        });

        // 格式化响应数据
        return Promise.resolve({
          ...response,
          code: 0,
          message: 'success',
        });
      },
      (error) => {
        // 遗留问题: 超时时拿不到响应对象，就无法删除 theQueue 队列
        const config = (error.response && error.response.config) || {};
        this.removeQueue({
          info: `${config.url}_${config.method}`,
        });
        const { data } = error.response || {};

        return Promise.reject({
          ...error.response,
          code: -1,
          message: data?.error_description || error.message,
        });
      },
    );
  }

  private findInQueue(requestInfo: any) {
    const index = this.theQueue.findIndex((request) => request.info === requestInfo.info);

    if (index >= 0) {
      this.theQueue[index].c('取消请求');
      this.theQueue.splice(index, 1);
    }
    this.theQueue.push(requestInfo);
  }

  private removeQueue(requestInfo: any) {
    const index = this.theQueue.findIndex((request) => request.info === requestInfo.info);
    if (index < 0) return;
    this.theQueue.splice(index, 1);
  }
}

export default Request;