import { when } from 'jest-when';
import { NetworkResponse } from '../src/types';

interface XhrMock {
  readyState: number
  status: number
  responseText: string
  open: jest.Mock
  onreadystatechange: jest.Mock
  send: jest.Mock
  setRequestHeader: jest.Mock
}

interface ProcessRequestResponse {
  result: NetworkResponse
  mock: XhrMock
}

export default class MockBuilder {
  mock: XhrMock

  constructor() {
    this.mock = {
      readyState: 4,
      responseText: '',
      status: 0,
      open: jest.fn(),
      onreadystatechange: jest.fn(),
      send: jest.fn(),
      setRequestHeader: jest.fn(),
    };
  }

  getXMLHttpRequest(): jest.Mock {
    const constructr = jest.fn();
    when(constructr).calledWith().mockReturnValue(this.mock);
    return constructr;
  }

  status(s: number): MockBuilder {
    this.mock.status = s;
    return this;
  }

  response(r: unknown): MockBuilder {
    this.mock.responseText = JSON.stringify(r);
    return this;
  }

  readyStateChange(state = 4): MockBuilder {
    this.mock.readyState = state;
    this.mock.onreadystatechange();
    return this;
  }

  async processRequest(promise: Promise<unknown>): Promise<ProcessRequestResponse> {
    this.readyStateChange();
    const result = await promise as NetworkResponse;
    const { mock } = this;
    return { result, mock };
  }
}