main.js

const electron = require( "electron" );
const path = require( "path" );
const reload = require( "electron-reload" );
const isDev = require( "electron-is-dev" );
const { app, BrowserWindow, ipcMain, dialog } = electron;


/*************************************************************
 * py process
 *************************************************************/

const PY_DIST_FOLDER = 'pyDLdist'
const PY_FOLDER = 'pyDL'
const PY_MODULE = 'api' // without .py suffix

let pyProc = null
let pyPort = null

const guessPackaged = () => {
  const fullPath = path.join(__dirname, PY_DIST_FOLDER)
  return require('fs').existsSync(fullPath)
}

const getScriptPath = () => {
  if (!guessPackaged()) {
    return path.join(__dirname, PY_FOLDER, PY_MODULE + '.py')
  }
  if (process.platform === 'win32') {
    return path.join(__dirname, PY_DIST_FOLDER, PY_MODULE, PY_MODULE + '.exe')
  }
  return path.join(__dirname, PY_DIST_FOLDER, PY_MODULE, PY_MODULE)
}

const selectPort = () => {
  pyPort = 4242
  return pyPort
}

const createPyProc = () => {
  let script = getScriptPath()
  let port = '' + selectPort()

  if (guessPackaged()) {
    pyProc = require('child_process').execFile(script, [port])
  } else {
    pyProc = require('child_process').spawn('python', [script, port])
  }
 
  if (pyProc != null) {
    //console.log(pyProc)
    console.log('child process success on port ' + port)
  }
}

const exitPyProc = () => {
  pyProc.kill()
  pyProc = null
  pyPort = null
}

app.on('ready', createPyProc)
app.on('will-quit', exitPyProc)

/*************************************************************
 * window management
 *************************************************************/


let mainWindow = null;

if ( isDev ) {
    const electronPath = path.join( __dirname, "node_modules", ".bin", "electron" );
    reload( __dirname, { electron: electronPath } );
}

app.on( "window-all-closed", () => {
    if ( process.platform !== "darwin" ) {
        app.quit();
    }
} );

//app.on( "ready", function() {
//    mainWindow = new BrowserWindow( { width: 800, height: 600 } );
//    mainWindow.loadURL( `file://${ __dirname }/index.html` );

//    mainWindow.on( "closed", function() {
//        mainWindow = null;
//    } );
//} );

app.on( "ready", () => {
    mainWindow = new BrowserWindow( { width: 800, height: 600, show: false } );
    mainWindow.loadURL( `file://${ __dirname }/index.html` );
    if ( isDev ) {
        mainWindow.webContents.openDevTools();
    }
    mainWindow.once( "ready-to-show", () => {
        mainWindow.show();
    } );
    mainWindow.on( "closed", () => {
        mainWindow = null;
    } );
} );

ipcMain.on( "show-dialog", ( e, arg ) => {
    const msgInfo = {
        title: "My App Alert",
        message: arg.message,
        buttons: [ "OK" ]
    };
    dialog.showMessageBox( msgInfo );
} );