/** Copyright (c) 2018 Uber Technologies, Inc.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
 */

/* eslint-env node */

import {parse} from 'url';
import type {Context} from 'fusion-core';

declare var __BROWSER__: boolean;

type ContextOptions = {
  headers?: {
    [key: string]: string;
  };
  body?: unknown;
  method?: string;
  ctxCallback?: (ctx: Context) => any;
};

const defaultContextOptions: ContextOptions = {
  headers: {},
};

export function createRequestContext(
  url: string,
  options: ContextOptions = defaultContextOptions
): Context {
  if (__BROWSER__) {
    const parsedUrl = {...parse(url)};
    const {path} = parsedUrl;
    parsedUrl.path = parsedUrl.pathname;
    //@ts-expect-error
    parsedUrl.url = path;
    //@ts-expect-error
    return {parsedUrl};
  }
  const httpMocks = require('node-mocks-http');
  const Stream = require('stream');
  const Koa = require('koa');
  let req = httpMocks.createRequest({url, ...options});
  let res = httpMocks.createResponse({
    /* Import the event emitter as described here:
    /* https://github.com/howardabrams/node-mocks-http/tree/a88c9e31e08a95976973ea7d79e46496dbfefb9d#createresponse
    */
    eventEmitter: require('events').EventEmitter,
  });

  const outHeadersKey = Object.getOwnPropertySymbols(
    // $FlowFixMe
    new (require('http').OutgoingMessage)()
  ).filter(
    (sym) =>
      // Node 10
      /outHeadersKey/.test(sym.toString()) ||
      // Node 12
      /kOutHeaders/.test(sym.toString())
  )[0];
  res[outHeadersKey] = null; // required for headers to work correctly in Node >10

  /**
   * Copied from https://github.com/koajs/koa/blob/master/test/helpers/context.js
   * Copyright (c) 2016 Koa contributors
   * MIT License
   * https://github.com/koajs/koa/blob/master/LICENSE
   */
  const socket = new Stream.Duplex();
  //$FlowFixMe
  req = Object.assign({headers: {}, socket}, Stream.Readable.prototype, req);
  if (!req.connection) {
    req.connection = {
      encrypted: false,
    };
  }
  const onEmitter = res.on;
  //$FlowFixMe
  res = Object.assign({_headers: {}, socket}, Stream.Writable.prototype, res, {
    statusCode: 404,
  });
  res.on = onEmitter;
  req.socket.remoteAddress = req.socket.remoteAddress || '127.0.0.1';
  res.getHeader = (k) => res._headers[k.toLowerCase()];
  res.setHeader = (k, v) => (res._headers[k.toLowerCase()] = v);
  res.removeHeader = (k) => delete res._headers[k.toLowerCase()];
  res.removeListener = () => {};

  // createContext is missing in Koa typings
  const ctx = (new Koa() as any).createContext(req, res);

  ctx.memoized = new Map();
  ctx.template = {
    htmlAttrs: {},
    bodyAttrs: {},
    title: '',
    head: [],
    body: [],
  };

  if (options.body) {
    ctx.request.body = options.body;
  }

  if (typeof options.ctxCallback === 'function') {
    // This will allow full control of context for tests
    options.ctxCallback(ctx);
  }

  return ctx;
}

export function createRenderContext(
  url: string,
  options: ContextOptions = defaultContextOptions
): Context {
  return createRequestContext(url, {
    ...options,
    // $FlowFixMe
    headers: {
      accept: 'text/html',
      ...(options.headers || {}),
    },
  });
}