Research for Launching Neuron from DApp

[IronLu233]

TL;DR

Deep can launch user local Neuron wallet without it already started. If Neuron not run on the user's PC, it will launch it first and receive the wallet connect URL.

The implement of deep link

There are two necessary steps, register and listen.

Register deep link

On the Neuron, we should invoke these code when its main process start.

      if (process.argv.length >= 2) {
        app.setAsDefaultProtocolClient('neuron', process.execPath, [path.resolve(process.argv[1])])
      } else {
        app.setAsDefaultProtocolClient('neuron')
      }

The method setAsDefaultProtocolClient sets the current executable as the default handler for a protocol (aka URI scheme).

Extra works on MacOS and Linux

On MacOS, all registered URL scheme should be declared beforehand in MacOS Info.plist.
Meanwhile, on Linux, the linux desktop file for the app should include new protocol handler.

By using electron-builder, These build config options should be added.

protocols:
  name: 'Neuron'
  # Don't forget to set `MimeType: "x-scheme-handler/deeplink"` for `linux.desktop` entry!
  schemes: ['neuron']
# other config
linux:
  desktop:
    MimeType: "x-scheme-handler/deeplink"

response deep link

Previous step allows DApp to wake neuron and send the Wallet Connect URL, this step is for handling it.

function responseDeepLink(event: Electron.Event, url: string) {
    console.log(url)

}

app.on('open-url', responseDeepLink)

if (process.os === 'win32') {
  const gotTheLock = app.requestSingleInstanceLock()
  if (!gotTheLock) {
    app.quit()
  } else {
    app.on('second-instance', (event, commandLine, workingDirectory) => {
      // Someone tried to run a second instance, we should focus our window.
      if (mainWindow) {
        if (mainWindow.isMinimized()) mainWindow.restore()
        mainWindow.focus()
      }
      // the commandLine is array of strings in which last element is deep link url
      // the url str ends with /
       responseDeeplink(event, commandLine.pop().slice(0, -1)!)
    })
  }
}

On DApp

On the Dapp, just use a html <a> label, or use window.open can pass the wallet connect url to Neuron.

<a href={`neuron://connect?url=${url}`}>Connect</a>
window.open(`neuron://connect?url=${url}`)

Known bug

On Windows platfrom, process.defaultApp will return undefined when application is packed. In electron official document, it has a if clause before call app.setDefaultProtocolClient.

if (process.defaultApp) {
  if (process.argv.length >= 2) {
    app.setAsDefaultProtocolClient('electron-fiddle', process.execPath, [path.resolve(process.argv[1])])
  }
} else {
  app.setAsDefaultProtocolClient('electron-fiddle')
}