// import ExpressRequestObj from 'express/lib/request'
// import express from 'express'
// const req = new ExpressRequestObj()
// const app = express()
// const req = Object.create(ExpressRequestObj, {
//   app: {
//     configurable: true,
//     enumerable: true,
//     writable: true,
//     value: app,
//   },
// })
import { Socket } from 'net'
import { Transform } from 'stream'
import { IncomingMessage, IncomingHttpHeaders } from 'http'

/**
 * @see https://github.com/apollographql/apollo-server/blob/master/packages/apollo-server-core/src/__tests__/runQuery.test.ts
 * @see https://github.com/diachedelic/mock-req/blob/master/index.js
 *
 * @see https://github.com/howardabrams/node-mocks-http
 * @see https://github.com/expressjs/express/blob/master/lib/express.js#L46
 *
 * @see https://github.com/diachedelic/mock-req
 */

export interface MockRequestOptions {
  url: string
  method: 'PUT' | 'PATCH' | 'POST' | 'GET' | 'OPTIONS'
  headers: {
    [key: string]: string
  }
  [key: string]: any
}
export class MockIncomingMessage extends Transform implements IncomingMessage {
  _writableState: any
  _readableState: any
  _failError: any

  method: string
  url: string
  headers: IncomingHttpHeaders | { [key: string]: any } | any
  rawHeaders: any

  // from IncomingMessage
  socket: Socket
  connection: Socket
  destroy: any
  httpVersion: string
  httpVersionMajor: number
  httpVersionMinor: number
  trailers: { [key: string]: string | undefined }
  rawTrailers: any
  setTimeout: (msecs: number, callback: () => void) => this

  constructor(options: MockRequestOptions = {} as MockRequestOptions) {
    super()

    this._writableState.objectMode = true
    this._readableState.objectMode = false

    // Copy unreserved options
    const reservedOptions = ['method', 'url', 'headers', 'rawHeaders']

    Object.keys(options).forEach(key => {
      if (reservedOptions.includes(key) === false) {
        this[key] = options[key]
      }
    })

    this.method = options.method || 'GET'
    this.url = options.url || ''

    // Set header names
    this.headers = {}
    this.rawHeaders = []
    if (options.headers) {
      Object.keys(options.headers).forEach(key => {
        let val = options.headers[key]

        if (val !== undefined) {
          if (typeof val !== 'string') {
            // I think this is trying to convert it to a string? @@fork
            val += ''
          }

          this.headers[key.toLowerCase()] = val
          this.rawHeaders.push(key)
          this.rawHeaders.push(val)
        }
      })
    }

    // Auto-end when no body
    if (
      this.method === 'GET' ||
      this.method === 'HEAD' ||
      this.method === 'DELETE'
    ) {
      this.end()
    }
  }

  _transform(chunk: string | Buffer, encoding, next) {
    if (this._failError) {
      return this.emit('error', this._failError)
    }

    if (typeof chunk !== 'string' && !Buffer.isBuffer(chunk)) {
      chunk = JSON.stringify(chunk)
    }

    this.push(chunk)

    next()
  }

  // Causes the request to emit an error when the body is read.
  _fail(error: Error | string) {
    this._failError = error
  }
}