/** @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 './esbuild-config'
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)
        // Eslint is wrong here; `clientBundlerOpts.plugins` is actually `undefined`.
        // eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
        ;(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 =
    // eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
    process.env.ELECTRON_FLAGS == null ? [] : String(process.env.ELECTRON_FLAGS).split(' ')
const ELECTRON_ARGS = [
    path.join(IDE_DIR_PATH, 'index.cjs'),
    ...ELECTRON_FLAGS,
    '--',
    ...process.argv.slice(2),
]

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,
        // eslint-disable-next-line @typescript-eslint/naming-convention
        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()