/**
 * @file This script is for watching the whole IDE and spawning the electron process.
 *
 * It sets up watchers for the client and content, and spawns the electron process with the IDE.
 * The spawned electron process can then use its refresh capability to pull the latest changes
 * from the watchers.
 *
 * If the electron app is closed, the script will restart it, allowing to test the IDE setup.
 * To stop, use Ctrl+C.
 */
import * as childProcess from 'node:child_process'
import * as fs from 'node:fs/promises'
import * as path from 'node:path'
import process from 'node:process'

import * as esbuild from 'esbuild'

import * as clientBundler from './esbuildConfig'
import * as paths from './paths'

// =============
// === Types ===
// =============

/** Set of esbuild watches for the client and content. */
interface Watches {
  readonly client: esbuild.BuildResult
}

// =================
// === Constants ===
// =================

const IDE_DIR_PATH = paths.getIdeDirectory()
const PROJECT_MANAGER_BUNDLE_PATH = paths.getProjectManagerBundlePath()

// =============
// === Watch ===
// =============

// @ts-expect-error This is the only place where an environment variable should be written to.
process.env.ELECTRON_DEV_MODE = 'true'
console.log('Cleaning IDE dist directory.')
await fs.rm(IDE_DIR_PATH, { recursive: true, force: true })
await fs.mkdir(IDE_DIR_PATH, { recursive: true })
const NODE_MODULES_PATH = path.resolve('./node_modules')

const ALL_BUNDLES_READY = new Promise<Watches>((resolve, reject) => {
  void (async () => {
    console.log('Bundling client.')
    const devMode = true
    const clientBundlerOpts = clientBundler.bundlerOptionsFromEnv(devMode)
    clientBundlerOpts.outdir = path.resolve(IDE_DIR_PATH)
    ;(clientBundlerOpts.plugins ??= []).push({
      name: 'enso-on-rebuild',
      setup: build => {
        build.onEnd(result => {
          if (result.errors.length) {
            // We cannot carry on if the client failed to build, because electron
            // would immediately exit with an error.
            console.error('Client watch bundle failed:', result.errors[0])
            reject(result.errors[0])
          } else {
            console.log('Client bundle updated.')
          }
        })
      },
    })
    const clientBuilder = await esbuild.context(clientBundlerOpts)
    const client = await clientBuilder.rebuild()
    console.log('Result of client bundling: ', client)
    void clientBuilder.watch()

    resolve({ client })
  })()
})

await ALL_BUNDLES_READY
console.log('Exposing Project Manager bundle.')
console.log(
  `Linking '${PROJECT_MANAGER_BUNDLE_PATH}' to '${path.join(
    IDE_DIR_PATH,
    paths.PROJECT_MANAGER_BUNDLE,
  )}'.`,
)
await fs.symlink(
  PROJECT_MANAGER_BUNDLE_PATH,
  path.join(IDE_DIR_PATH, paths.PROJECT_MANAGER_BUNDLE),
  'dir',
)

const ELECTRON_FLAGS =
  process.env.ELECTRON_FLAGS == null ? [] : String(process.env.ELECTRON_FLAGS).split(' ')
const ELECTRON_ARGS = [
  path.join(IDE_DIR_PATH, 'index.mjs'),
  ...ELECTRON_FLAGS,
  '--',
  ...process.argv.slice(2).map(arg => `'${arg}'`),
]

process.on('SIGINT', () => {
  console.log('SIGINT received. Exiting.')
  void fs.rm(IDE_DIR_PATH, { recursive: true, force: true }).then(() => {
    // The `esbuild` process seems to remain alive at this point and will keep our process
    // from ending. Thus, we exit manually. It seems to terminate the child `esbuild` process
    // as well.
    process.exit(0)
  })
})

/** Starts the electron process with the IDE. */
function startElectronProcess() {
  console.log('Spawning Electron process.')

  const electronProcess = childProcess.spawn('electron', ELECTRON_ARGS, {
    stdio: 'inherit',
    shell: true,
    env: Object.assign({ NODE_MODULES_PATH }, process.env),
  })

  electronProcess.on('close', code => {
    if (code === 0) {
      electronProcess.removeAllListeners()
      process.exit(0)
    }
  })
  electronProcess.on('error', error => {
    console.error('Electron process failed:', error)
    console.error('Killing electron process.')
    electronProcess.removeAllListeners()
    electronProcess.kill()
    process.exit(1)
  })
}

startElectronProcess()