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

export interface MockRequestOptions {
  url: string
  method?: string
  headers?: Record<string, string>
  credentials?: string
  body?: Serializable
}

export interface MockResponseOptions {
  status?: number
  body?: Serializable
}

export default class FetchMockBuilder {
  req: MockRequestOptions

  res: MockResponseOptions

  constructor(req: MockRequestOptions, res: MockResponseOptions) {
    this.req = {
      method: 'GET',
      credentials: 'same-origin',
      headers: {},
      ...req,
    };

    this.res = {
      status: 200,
      body: '',
      ...res,
    };
  }

  buildInit(): Partial<MockRequestOptions> {
    const init: Partial<MockRequestOptions> = {};

    init.method = this.req.method;

    if (this.req.method) {
      init.method = this.req.method;
    }

    if (this.req.headers) {
      init.headers = this.req.headers;
    }

    if (this.req.credentials) {
      init.credentials = this.req.credentials;
    }

    if (this.req.body) {
      init.body = JSON.stringify(this.req.body);
    }

    return init;
  }

  build(): jest.Mock {
    const text = jest.fn();
    when(text).calledWith().mockResolvedValue(JSON.stringify(this.res.body));
    const mockResponse = {
      status: this.res.status,
      text,
    };
    const mockFetch = jest.fn();
    when(mockFetch)
      .expectCalledWith(this.req.url, this.buildInit())
      .mockResolvedValue(mockResponse);

    return mockFetch;
  }
}