'use strict';

const { app, BrowserWindow, clipboard, dialog, ipcMain, net, protocol, shell } = require('electron');
const fs = require('node:fs/promises');
const path = require('node:path');
const { pathToFileURL } = require('node:url');
const { buildCsv } = require('./static/export-utils');
const { APP_RENDERER_URL, resolveAppAssetPath } = require('./src/app-protocol');
const { KEY_PATTERN } = require('./src/discovery');
const { createScanSession } = require('./src/scan-session');

protocol.registerSchemesAsPrivileged([{
  scheme: 'app',
  privileges: { standard: true, secure: true, supportFetchAPI: true },
}]);

let mainWindow = null;
const scanSession = createScanSession();

function isTrustedSender(event) {
  if (!mainWindow || mainWindow.isDestroyed() || !event || !event.senderFrame) return false;
  return event.sender === mainWindow.webContents &&
    event.senderFrame === mainWindow.webContents.mainFrame &&
    event.senderFrame.url === APP_RENDERER_URL;
}

function registerIpc(channel, handler) {
  ipcMain.handle(channel, async (event, ...args) => {
    if (!isTrustedSender(event)) throw new Error('Forbidden IPC sender');
    return handler(...args);
  });
}

async function openCameraUrl(value) {
  const url = scanSession.allowedCameraUrl(value);
  if (!url) return;
  await shell.openExternal(url);
}

function registerIpcHandlers() {
  registerIpc('scan-cameras', scanSession.scanOnce);
  registerIpc('copy-text', (value) => {
    const text = String(value || '');
    if (!KEY_PATTERN.test(text)) throw new Error('Invalid Alta Key.');
    clipboard.writeText(text);
    return { ok: true };
  });
  registerIpc('export-csv', async () => {
    const csv = buildCsv(scanSession.getLatestCameras());
    if (Buffer.byteLength(csv, 'utf8') > 1024 * 1024) throw new Error('CSV export is too large.');
    const result = await dialog.showSaveDialog(mainWindow, {
      title: 'Export discovered Alta cameras',
      defaultPath: 'alta-camera-keys.csv',
      filters: [{ name: 'CSV file', extensions: ['csv'] }],
    });
    if (result.canceled || !result.filePath) return { ok: false, canceled: true };
    await fs.writeFile(result.filePath, csv, 'utf8');
    return { ok: true, canceled: false };
  });
}

function registerAppProtocol() {
  const staticDir = path.join(__dirname, 'static');
  protocol.handle('app', (request) => {
    const assetPath = resolveAppAssetPath(request.url, staticDir);
    if (!assetPath) return new Response('Not found', { status: 404 });
    return net.fetch(pathToFileURL(assetPath).href);
  });
}

function denyRendererPermissions(targetSession) {
  targetSession.setPermissionCheckHandler(() => false);
  targetSession.setPermissionRequestHandler((_webContents, _permission, callback) => callback(false));
}

function createWindow() {
  mainWindow = new BrowserWindow({
    width: 1180,
    height: 760,
    minWidth: 820,
    minHeight: 620,
    backgroundColor: '#f5f6f8',
    icon: path.join(__dirname, 'assets', 'icon.png'),
    title: 'Alta Local Camera Discovery',
    autoHideMenuBar: true,
    webPreferences: {
      nodeIntegration: false,
      contextIsolation: true,
      sandbox: true,
      preload: path.join(__dirname, 'preload.js'),
    },
  });
  denyRendererPermissions(mainWindow.webContents.session);
  mainWindow.webContents.setWindowOpenHandler(({ url }) => {
    openCameraUrl(url).catch(() => {});
    return { action: 'deny' };
  });
  mainWindow.webContents.on('will-navigate', (event) => event.preventDefault());
  mainWindow.loadURL(APP_RENDERER_URL);
  if (!app.isPackaged && process.argv.includes('--dev')) mainWindow.webContents.openDevTools();
}

app.whenReady().then(() => {
  registerAppProtocol();
  registerIpcHandlers();
  createWindow();
});

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

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