DevtoolBackend.js

const WebSocket = require('ws')



class DevtoolBackend {
  constructor(options) {
    this.options = options
    this.onError = this.onError.bind(this)

    this.onClientConnection = this.onClientConnection.bind(this)
    this.onDevtoolConnection = this.onDevtoolConnection.bind(this)
    this.onConnection = this.onConnection.bind(this)
    this.onClientMessage = this.onClientMessage.bind(this)
    this.onDevtoolMessage = this.onDevtoolMessage.bind(this)
    
    this.devtoolServer = new WebSocket.Server(
      {
        port: options.port,
      },
      () => {}
    )

    this.devtoolServer.on('connection', this.onConnection)
    this.devtoolServer.on('error', this.onError)
  }

  onConnection(ws, req) {
    // devtools connects with ?devtools=1 in url
    if (req.url.indexOf("devtools") !== -1) {
      this.onDevtoolConnection(ws, req)
    } else {
      this.onClientConnection(ws, req)
    }
  }

  onDevtoolConnection(ws) {
    this.devtoolSocket = ws
    this.devtoolSocket.on('message', this.onDevtoolMessage)
  }
  async onDevtoolMessage(message) {
    const parsedMessage = JSON.parse(message)

    switch (parsedMessage.type) {
      case 'storage:get':
        this.evaluateDevtoolMessage(parsedMessage, () =>
          this.options.storage.get(parsedMessage.data.key)
        )
        break
      case 'storage:set':
        this.evaluateDevtoolMessage(parsedMessage, () =>
          this.options.storage.set(parsedMessage.data.key, parsedMessage.data.data)
        )
        break
      case 'storage:clear':
        this.evaluateDevtoolMessage(parsedMessage, () =>
          this.options.storage.clear()
        )
        break
      case 'relaunch':
        this.options.onRelaunch()
        break
      case 'connect':
          console.log('TODO: connect'); // TODO: Let devtools know that they are connected to server?
        // this.createClientServer(parsedMessage.data)
        break
      default:
        this.clientSocket.send(JSON.stringify(parsedMessage.data))
    }
  }
  onError(e) {
    console.log('TODO: onError',e);
    // this.devtoolServer.emit('port:exists')
  }
  onClientConnection(ws) {
    this.clientSocket = ws
    this.clientSocket.on('message', this.onClientMessage)
  }
  onClientMessage(message) {
    this.devtoolSocket.send(`
    {
      "type": "message",
      "data": ${message}
    }
    `)
  }
  async evaluateDevtoolMessage(message, cb) {
    const result = await cb()

    if ('evaluate' in message) {
      this.devtoolSocket.send(
        JSON.stringify({
          type: 'evaluated',
          data: {
            id: message.evaluate,
            data: result,
          },
        })
      )
    }
  }
}

DevtoolBackend.create = (options) => new DevtoolBackend(options)

module.exports = DevtoolBackend