const requestManager = new RequestManager();
const instance = axios.create();
requestManager.patchAxiosInstance(instance);

const search = q =>
  instance.get('/search', {
    cancelable: true, // this is no longer possible in 0.19.0
    params: { q },
  });

class RequestManager {
  constructor() {
    this.pendingRequests = new Map();
  }

  patchAxiosInstance(instance) {
    instance.interceptors.request.use(config => {
      if (!config.cancelable) return config; // this is no longer possible in 0.19.0

      const source = axios.CancelToken.source();
      const requestId = `${config.method}_${config.url}`;
      const cancelToken = source.token;
      this.addRequest(requestId, source.cancel);
      return { ...config, cancelToken, requestId };
    });

    instance.interceptors.response.use(response => {
      const { requestId } = response.config; // this is no longer possible in 0.19.0
      if (requestId) {
        this.removeRequest(requestId);
      }
      return response;
    });
  }

  addRequest(requestId, cancelFn) {
    this.cancelRequest(requestId);
    this.pendingRequests.set(requestId, cancelFn);
  }

  removeRequest(requestId) {
    this.pendingRequests.delete(requestId);
  }

  cancelRequest(requestId) {
    if (this.pendingRequests.has(requestId)) {
      const cancelFn = this.pendingRequests.get(requestId);
      cancelFn();
      this.removeRequest(requestId);
    }
  }
}