piano-midi-monitor/src/main/index.ts

import { app, BrowserWindow, ipcMain } from 'electron'
import { join } from 'path'
import { readFile, stat, writeFile } from 'fs/promises'
import { electronApp, optimizer, is } from '@electron-toolkit/utils'
import icon from '../../resources/icon.png?asset'
import { Config, defaultConfig } from '../common/config'
import { getNaturalKeys } from './utils/display'
import { Stats } from 'fs'

const configPath = './config.json'
const height = 160

const ALLOWED_PERMISSIONS = ['midi']

const defineWindowCommonSecurity = (browserWindow: BrowserWindow): void => {
  browserWindow.webContents.setWindowOpenHandler(() => {
    return { action: 'deny' }
  })
}

const addWindowEvents = (browserWindow: BrowserWindow): void => {
  browserWindow.on('ready-to-show', () => {
    browserWindow.show()
  })
}

const addMidiPermissions = (browserWindow: BrowserWindow): void => {
  browserWindow.webContents.session.setPermissionRequestHandler(
    (_webContents, permission, callback) => {
      callback(ALLOWED_PERMISSIONS.includes(permission))
    }
  )

  browserWindow.webContents.session.setPermissionCheckHandler((_webContents, permission) => {
    return ALLOWED_PERMISSIONS.includes(permission)
  })
}

const assignWindowView = async (
  browserWindow: BrowserWindow,
  routeName: string,
  config: Config
): Promise<BrowserWindow> => {
  let search = new URLSearchParams()
  let url: URL | undefined
  if (is.dev && process.env['ELECTRON_RENDERER_URL']) {
    url = new URL(process.env['ELECTRON_RENDERER_URL'])
    search = new URLSearchParams(url.searchParams)
  }

  Object.entries(config).forEach(([key, value]) => {
    search.set(key, value)
  })
  search.set('window', routeName)

  if (typeof url !== 'undefined') {
    url.search = search.toString()
    await browserWindow.loadURL(url.toString())
    return browserWindow
  }

  await browserWindow.loadFile(join(__dirname, '../renderer/index.html'), {
    search: search.toString()
  })
  return browserWindow
}

const createMainWindow = async (config: Config): Promise<BrowserWindow> => {
  const naturalKeys = getNaturalKeys(config.range)
  const width = naturalKeys * Number(config.naturalKeyWidth || 20) + Number(config.scaleFactor)
  const mainWindow = new BrowserWindow({
    width,
    height,
    show: false,
    autoHideMenuBar: true,
    ...(process.platform === 'linux' ? { icon } : {}),
    webPreferences: {
      preload: join(__dirname, '../preload/index.js'),
      sandbox: false,
      devTools: is.dev
    },
    title: 'Piano MIDI Monitor',
    maximizable: is.dev,
    minimizable: false,
    maxHeight: is.dev ? undefined : height,
    minHeight: is.dev ? undefined : height,
    minWidth: is.dev ? undefined : width,
    maxWidth: is.dev ? undefined : width,
    fullscreenable: false,
    resizable: is.dev,
    useContentSize: true
  })
  defineWindowCommonSecurity(mainWindow)
  addMidiPermissions(mainWindow)
  addWindowEvents(mainWindow)
  return assignWindowView(mainWindow, 'main', config)
}

const createSettingsWindow = async (
  parent: BrowserWindow,
  config: Config
): Promise<BrowserWindow> => {
  const settingsWindow = new BrowserWindow({
    width: 360,
    height: 640,
    show: false,
    autoHideMenuBar: true,
    modal: true,
    ...(process.platform === 'linux' ? { icon } : {}),
    webPreferences: {
      preload: join(__dirname, '../preload/index.js'),
      sandbox: false,
      devTools: is.dev
    },
    title: 'Settings',
    maximizable: false,
    minimizable: false,
    fullscreenable: false,
    resizable: false,
    useContentSize: true,
    parent
  })
  defineWindowCommonSecurity(settingsWindow)
  addMidiPermissions(settingsWindow)
  addWindowEvents(settingsWindow)
  return assignWindowView(settingsWindow, 'settings', config)
}

const ensureConfig = async (defaultConfig: Config): Promise<Config> => {
  const effectiveConfig = { ...defaultConfig }
  let theStat: Stats
  try {
    theStat = await stat(configPath)
  } catch {
    await writeFile(configPath, JSON.stringify(defaultConfig))
    return effectiveConfig
  }

  if (theStat.isDirectory()) {
    throw new Error('Config path is a directory.')
  }

  try {
    const jsonRaw = await readFile(configPath, 'utf-8')
    const json = JSON.parse(jsonRaw)
    Object.entries(json).forEach(([key, value]) => {
      effectiveConfig[key] = value
    })
  } catch {
    await writeFile(configPath, JSON.stringify(defaultConfig))
  }

  return effectiveConfig
}

const main = async (): Promise<void> => {
  const effectiveConfig = await ensureConfig(defaultConfig)

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

  await app.whenReady()
  electronApp.setAppUserModelId('sh.modal.pianomidimonitor')

  app.on('browser-window-created', (_, window) => {
    optimizer.watchWindowShortcuts(window)
  })

  ipcMain.on('action', async (event, value, formData) => {
    const webContents = event.sender
    const win = BrowserWindow.fromWebContents(webContents)
    if (!win) {
      return
    }
    switch (value) {
      case 'showSettings': {
        await createSettingsWindow(win, effectiveConfig)
        return
      }
      case 'cancelSaveConfig': {
        win.close()
        return
      }
      case 'resetConfig': {
        Object.entries(defaultConfig).forEach(([key, value]) => {
          effectiveConfig[key] = value
        })
        await writeFile(configPath, JSON.stringify(effectiveConfig))
        win.close()
        win.getParentWindow()?.close()
        await createMainWindow(effectiveConfig)
        return
      }
      case 'saveConfig': {
        Object.entries(formData).forEach(([key, value]) => {
          effectiveConfig[key] = value
        })
        await writeFile(configPath, JSON.stringify(effectiveConfig))
        win.close()
        win.getParentWindow()?.close()
        await createMainWindow(effectiveConfig)
        return
      }
    }
  })

  await createMainWindow(effectiveConfig)

  app.on('activate', async () => {
    if (BrowserWindow.getAllWindows().length === 0) {
      await createMainWindow(effectiveConfig)
    }
  })
}

void main()