import { join } from 'node:path';
import { app, BrowserWindow, ipcMain, utilityProcess, type UtilityProcess, type WebContents } from 'electron';
import { readFileSync } from 'node:fs';
import type { HostResult, MapFiles } from '../preload/api';
import { DISCOVERY_INTERVAL_MS } from '../shared/constants';
import { readMapFiles, readMapImage, resolveAssetsDir } from '../server/assets';
import { DiscoveryListener } from './discovery';

const assetsDir = app.isPackaged ? join(process.resourcesPath, 'assets') : join(app.getAppPath(), 'assets');
process.env.GOUTER_ASSETS = assetsDir;

let server: UtilityProcess | null = null;
let serverReady: Promise<HostResult> | null = null;

/** Forks the authoritative server in a utilityProcess (once) and waits for it to listen. */
function hostServer(name: string): Promise<HostResult> {
  if (serverReady) return serverReady;
  serverReady = new Promise<HostResult>((resolveReady, reject) => {
    const proc = utilityProcess.fork(join(__dirname, 'server.js'), [`--name=${String(name).slice(0, 40)}`], {
      serviceName: 'goutermageddon-server',
      env: { ...process.env, GOUTER_ASSETS: assetsDir },
      stdio: 'inherit',
    });
    server = proc;
    proc.on('message', (msg: { type: string; port?: number; message?: string }) => {
      if (msg.type === 'ready') resolveReady({ port: msg.port! });
      else if (msg.type === 'error') reject(new Error(msg.message));
    });
    proc.on('exit', (code) => {
      server = null;
      serverReady = null;
      reject(new Error(`server exited with code ${code}`));
    });
  });
  return serverReady;
}

function createWindow(): void {
  const win = new BrowserWindow({
    width: 1280,
    height: 720,
    title: 'Goûtermageddon',
    backgroundColor: '#fff1d6',
    autoHideMenuBar: true,
    webPreferences: {
      preload: join(__dirname, '../preload/index.js'),
      contextIsolation: true,
      nodeIntegration: false,
      sandbox: true,
    },
  });
  if (process.env.ELECTRON_RENDERER_URL) void win.loadURL(process.env.ELECTRON_RENDERER_URL);
  else void win.loadFile(join(__dirname, '../renderer/index.html'));
}

// LAN discovery: one listener for the app, pushed to the renderer that asked for it.
const discovery = new DiscoveryListener();
let discoveryTimer: NodeJS.Timeout | null = null;
function startDiscovery(target: WebContents): void {
  stopDiscovery();
  discovery.start((err) => console.error('[discovery] cannot listen:', err.message));
  const push = (): void => {
    if (target.isDestroyed()) return stopDiscovery();
    target.send('lan:games', discovery.list());
  };
  push();
  discoveryTimer = setInterval(push, DISCOVERY_INTERVAL_MS);
}
function stopDiscovery(): void {
  if (discoveryTimer) clearInterval(discoveryTimer);
  discoveryTimer = null;
  discovery.stop();
}

ipcMain.handle('lan:host', (_event, name: string) => hostServer(name));
ipcMain.handle('lan:discover-start', (event) => startDiscovery(event.sender));
ipcMain.handle('lan:discover-stop', () => stopDiscovery());
ipcMain.handle('assets:materials', () => JSON.parse(readFileSync(join(resolveAssetsDir(), 'materials', 'materials.json'), 'utf8')));
ipcMain.handle('assets:map', (_event, mapId: string): MapFiles => {
  const dir = resolveAssetsDir();
  const { definition, terrain } = readMapFiles(dir, mapId);
  return { definition, terrain, background: readMapImage(dir, mapId, 'background.png') };
});

void app.whenReady().then(() => {
  createWindow();
  app.on('activate', () => {
    if (BrowserWindow.getAllWindows().length === 0) createWindow();
  });
});

app.on('window-all-closed', () => {
  stopDiscovery();
  server?.kill();
  app.quit();
});