import { createRequire } from 'node:module';
import { randomUUID } from 'node:crypto';
import { spawn } from 'node:child_process';
import dns from 'node:dns/promises';
import fs from 'node:fs';
import net from 'node:net';

import { appConfigDb } from '@/modules/database/repositories/app-config.js';

const require = createRequire(import.meta.url);
const IS_PLATFORM = process.env.VITE_IS_PLATFORM === 'true';
const MAX_SESSIONS_PER_OWNER = Number.parseInt(process.env.CLOUDCLI_BROWSER_USE_MAX_SESSIONS_PER_OWNER || '3', 10);
const SESSION_TTL_MS = Number.parseInt(process.env.CLOUDCLI_BROWSER_USE_SESSION_TTL_MS || String(30 * 60 * 1000), 10);
const ALLOW_PRIVATE_NETWORKS = process.env.CLOUDCLI_BROWSER_USE_ALLOW_PRIVATE_NETWORKS === '1';
const BROWSER_USE_SETTINGS_KEY = 'browser_use_settings';

type BrowserUseRuntime = 'cloud' | 'local';
type BrowserUseSessionStatus = 'ready' | 'stopped' | 'unavailable';

type BrowserUseSession = {
  id: string;
  ownerId: string;
  runtime: BrowserUseRuntime;
  status: BrowserUseSessionStatus;
  url: string | null;
  title: string | null;
  screenshotDataUrl: string | null;
  createdAt: string;
  updatedAt: string;
  lastAction: string | null;
  message: string | null;
};

type PublicBrowserUseSession = Omit<BrowserUseSession, 'ownerId'>;

type RuntimeHandle = {
  browser?: any;
  page?: any;
};

type BrowserUseOwner = {
  id: string | number;
};

type BrowserUseSettings = {
  enabled: boolean;
};

type RuntimeReadiness = {
  playwright: any | null;
  playwrightInstalled: boolean;
  chromiumInstalled: boolean;
  chromiumExecutablePath: string | null;
  installInProgress: boolean;
  installMessage: string | null;
};

const sessions = new Map<string, BrowserUseSession>();
const handles = new Map<string, RuntimeHandle>();
let installPromise: Promise<{ success: boolean; message: string }> | null = null;
let lastInstallMessage: string | null = null;

const DEFAULT_SETTINGS: BrowserUseSettings = {
  enabled: true,
};

function getRuntime(): BrowserUseRuntime {
  return IS_PLATFORM ? 'cloud' : 'local';
}

function readSettings(): BrowserUseSettings {
  try {
    const raw = appConfigDb.get(BROWSER_USE_SETTINGS_KEY);
    if (!raw) {
      return DEFAULT_SETTINGS;
    }

    const parsed = JSON.parse(raw) as Partial<BrowserUseSettings>;
    return {
      enabled: parsed.enabled !== false,
    };
  } catch (error: any) {
    console.warn('[Browser Use] Failed to read settings:', error?.message || error);
    return DEFAULT_SETTINGS;
  }
}

function writeSettings(settings: BrowserUseSettings): BrowserUseSettings {
  const normalized = {
    enabled: settings.enabled !== false,
  };

  appConfigDb.set(BROWSER_USE_SETTINGS_KEY, JSON.stringify(normalized));
  return normalized;
}

function getSetupMessage(settings: BrowserUseSettings, readiness: RuntimeReadiness): string {
  if (!settings.enabled) {
    return 'Browser Use is disabled in settings.';
  }

  if (!readiness.playwrightInstalled) {
    return 'Install Playwright and Chromium to use browser sessions.';
  }

  if (!readiness.chromiumInstalled) {
    return 'Playwright is installed, but Chromium is missing. Install the Chromium runtime to continue.';
  }

  return readiness.installMessage || 'Browser Use runtime is not ready.';
}

function getPlaywright(): any | null {
  try {
    return require('playwright');
  } catch {
    return null;
  }
}

function getRuntimeReadiness(): RuntimeReadiness {
  const playwright = getPlaywright();
  const readiness: RuntimeReadiness = {
    playwright,
    playwrightInstalled: Boolean(playwright),
    chromiumInstalled: false,
    chromiumExecutablePath: null,
    installInProgress: Boolean(installPromise),
    installMessage: lastInstallMessage,
  };

  if (!playwright) {
    return readiness;
  }

  try {
    const executablePath = playwright.chromium.executablePath();
    readiness.chromiumExecutablePath = executablePath;
    readiness.chromiumInstalled = Boolean(executablePath && fs.existsSync(executablePath));
  } catch {
    readiness.chromiumInstalled = false;
  }

  return readiness;
}

function runCommand(command: string, args: string[]): Promise<void> {
  return new Promise((resolve, reject) => {
    const child = spawn(command, args, {
      cwd: process.cwd(),
      env: process.env,
      shell: false,
      stdio: ['ignore', 'pipe', 'pipe'],
    });
    const output: string[] = [];

    child.stdout.on('data', (chunk) => output.push(String(chunk)));
    child.stderr.on('data', (chunk) => output.push(String(chunk)));
    child.on('error', reject);
    child.on('close', (code) => {
      if (code === 0) {
        resolve();
        return;
      }

      reject(new Error(output.join('').trim() || `${command} ${args.join(' ')} exited with code ${code}`));
    });
  });
}

async function installRuntime(): Promise<{ success: boolean; message: string }> {
  if (installPromise) {
    return installPromise;
  }

  const npmCommand = process.platform === 'win32' ? 'npm.cmd' : 'npm';
  installPromise = (async () => {
    try {
      lastInstallMessage = 'Installing Playwright package...';
      await runCommand(npmCommand, ['install', '--no-save', '--no-package-lock', 'playwright']);

      lastInstallMessage = 'Installing Chromium runtime...';
      await runCommand(npmCommand, ['exec', '--', 'playwright', 'install', 'chromium']);

      lastInstallMessage = 'Browser Use runtime installed.';
      return { success: true, message: lastInstallMessage };
    } catch (error) {
      lastInstallMessage = error instanceof Error ? error.message : 'Failed to install Browser Use runtime.';
      return { success: false, message: lastInstallMessage };
    }
  })();

  try {
    return await installPromise;
  } finally {
    installPromise = null;
  }
}

function getOwnerId(owner: BrowserUseOwner): string {
  if (owner.id === undefined || owner.id === null || String(owner.id).trim() === '') {
    throw new Error('Authenticated user is required.');
  }

  return String(owner.id);
}

function isPrivateIpv4(address: string): boolean {
  const parts = address.split('.').map((part) => Number.parseInt(part, 10));
  if (parts.length !== 4 || parts.some((part) => Number.isNaN(part) || part < 0 || part > 255)) {
    return true;
  }

  const [first, second] = parts;
  return first === 0
    || first === 10
    || first === 127
    || (first === 169 && second === 254)
    || (first === 172 && second >= 16 && second <= 31)
    || (first === 192 && second === 168)
    || first >= 224;
}

function isPrivateIpv6(address: string): boolean {
  const normalized = address.toLowerCase();
  return normalized === '::1'
    || normalized === '::'
    || normalized.startsWith('fc')
    || normalized.startsWith('fd')
    || normalized.startsWith('fe80:')
    || normalized.startsWith('::ffff:127.')
    || normalized.startsWith('::ffff:10.')
    || normalized.startsWith('::ffff:192.168.')
    || /^::ffff:172\.(1[6-9]|2\d|3[0-1])\./.test(normalized)
    || /^::ffff:169\.254\./.test(normalized);
}

export function isBlockedBrowserUseAddress(address: string): boolean {
  const version = net.isIP(address);
  if (version === 4) {
    return isPrivateIpv4(address);
  }
  if (version === 6) {
    return isPrivateIpv6(address);
  }
  return true;
}

async function assertPublicHttpTarget(parsedUrl: URL): Promise<void> {
  if (ALLOW_PRIVATE_NETWORKS) {
    return;
  }

  const hostname = parsedUrl.hostname;
  if (!hostname) {
    throw new Error('URL hostname is required.');
  }

  if (net.isIP(hostname)) {
    if (isBlockedBrowserUseAddress(hostname)) {
      throw new Error('Browser Use cannot navigate to private or local network addresses.');
    }
    return;
  }

  const addresses = await dns.lookup(hostname, { all: true, verbatim: true });
  if (addresses.length === 0 || addresses.some((entry) => isBlockedBrowserUseAddress(entry.address))) {
    throw new Error('Browser Use cannot navigate to private or local network addresses.');
  }
}

async function normalizeUrl(rawUrl: string): Promise<string> {
  const trimmed = rawUrl.trim();
  if (!trimmed) {
    throw new Error('URL is required.');
  }

  const withProtocol = /^[a-zA-Z][a-zA-Z\d+\-.]*:/.test(trimmed)
    ? trimmed
    : `https://${trimmed}`;
  const parsed = new URL(withProtocol);
  if (!['http:', 'https:'].includes(parsed.protocol)) {
    throw new Error('Only http and https URLs are supported.');
  }

  await assertPublicHttpTarget(parsed);

  return parsed.toString();
}

async function assertAllowedBrowserRequest(rawUrl: string): Promise<void> {
  const parsed = new URL(rawUrl);
  if (!['http:', 'https:'].includes(parsed.protocol)) {
    return;
  }

  await assertPublicHttpTarget(parsed);
}

async function attachRequestGuard(page: any): Promise<void> {
  await page.route('**/*', async (route: any) => {
    try {
      await assertAllowedBrowserRequest(route.request().url());
      await route.continue();
    } catch {
      await route.abort('blockedbyclient');
    }
  });
}

function publicSession(session: BrowserUseSession): PublicBrowserUseSession {
  const { ownerId: _ownerId, ...publicFields } = session;
  return publicFields;
}

function ownerSessions(ownerId: string): BrowserUseSession[] {
  return [...sessions.values()].filter((session) => session.ownerId === ownerId);
}

async function closeHandle(sessionId: string): Promise<void> {
  const handle = handles.get(sessionId);
  handles.delete(sessionId);
  await handle?.browser?.close().catch(() => undefined);
}

async function expireStaleSessions(now = Date.now()): Promise<void> {
  await Promise.all([...sessions.values()].map(async (session) => {
    if (session.status !== 'ready') {
      return;
    }

    const updatedAt = Date.parse(session.updatedAt);
    if (!Number.isFinite(updatedAt) || now - updatedAt <= SESSION_TTL_MS) {
      return;
    }

    await closeHandle(session.id);
    session.status = 'stopped';
    session.updatedAt = new Date(now).toISOString();
    session.lastAction = 'expire';
    session.message = 'Browser session expired after inactivity.';
  }));
}

async function captureSession(session: BrowserUseSession, page: any): Promise<void> {
  const screenshot = await page.screenshot({ type: 'jpeg', quality: 72, fullPage: false });
  session.screenshotDataUrl = `data:image/jpeg;base64,${Buffer.from(screenshot).toString('base64')}`;
  session.title = await page.title().catch(() => null);
  session.url = page.url() || session.url;
  session.updatedAt = new Date().toISOString();
}

export const browserUseService = {
  async getSettings() {
    return readSettings();
  },

  async updateSettings(settings: Partial<BrowserUseSettings>) {
    const current = readSettings();
    return writeSettings({
      ...current,
      enabled: settings.enabled ?? current.enabled,
    });
  },

  async getStatus() {
    const settings = readSettings();
    const readiness = getRuntimeReadiness();
    const available = settings.enabled && readiness.playwrightInstalled && readiness.chromiumInstalled;

    return {
      enabled: settings.enabled,
      runtime: getRuntime(),
      available,
      playwrightInstalled: readiness.playwrightInstalled,
      chromiumInstalled: readiness.chromiumInstalled,
      installInProgress: readiness.installInProgress,
      sessionCount: sessions.size,
      mcpRecommended: true,
      message: available
        ? 'Browser Use runtime is available.'
        : getSetupMessage(settings, readiness),
    };
  },

  async installRuntime() {
    const result = await installRuntime();
    return {
      ...result,
      status: await this.getStatus(),
    };
  },

  async listSessions(owner: BrowserUseOwner) {
    const ownerId = getOwnerId(owner);
    await expireStaleSessions();
    return ownerSessions(ownerId).map(publicSession);
  },

  async createSession(owner: BrowserUseOwner) {
    const ownerId = getOwnerId(owner);
    await expireStaleSessions();

    const now = new Date().toISOString();
    const session: BrowserUseSession = {
      id: randomUUID(),
      ownerId,
      runtime: getRuntime(),
      status: 'unavailable',
      url: null,
      title: null,
      screenshotDataUrl: null,
      createdAt: now,
      updatedAt: now,
      lastAction: 'create',
      message: null,
    };

    const activeOwnerSessions = ownerSessions(ownerId).filter((item) => item.status === 'ready');
    if (activeOwnerSessions.length >= MAX_SESSIONS_PER_OWNER) {
      throw new Error(`Browser Use is limited to ${MAX_SESSIONS_PER_OWNER} active sessions per user.`);
    }

    const settings = readSettings();
    const readiness = getRuntimeReadiness();
    if (!settings.enabled || !readiness.playwrightInstalled || !readiness.chromiumInstalled || !readiness.playwright) {
      session.message = getSetupMessage(settings, readiness);
      sessions.set(session.id, session);
      return publicSession(session);
    }

    const browser = await readiness.playwright.chromium.launch({
      headless: true,
      args: ['--disable-dev-shm-usage'],
    });
    const page = await browser.newPage({ viewport: { width: 1440, height: 900 } });
    await attachRequestGuard(page);
    session.status = 'ready';
    session.message = 'Browser session is ready.';
    sessions.set(session.id, session);
    handles.set(session.id, { browser, page });
    await captureSession(session, page);
    return publicSession(session);
  },

  async navigate(owner: BrowserUseOwner, sessionId: string, rawUrl: string) {
    const ownerId = getOwnerId(owner);
    await expireStaleSessions();

    const session = sessions.get(sessionId);
    if (!session || session.ownerId !== ownerId) {
      throw new Error('Browser session not found.');
    }

    if (session.status !== 'ready') {
      throw new Error(session.message || 'Browser session is not available.');
    }

    const handle = handles.get(sessionId);
    if (!handle?.page) {
      throw new Error('Browser runtime handle is not available.');
    }

    const url = await normalizeUrl(rawUrl);
    await handle.page.goto(url, { waitUntil: 'domcontentloaded', timeout: 30_000 });
    session.lastAction = `navigate:${url}`;
    await captureSession(session, handle.page);
    return publicSession(session);
  },

  async stopSession(owner: BrowserUseOwner, sessionId: string) {
    const ownerId = getOwnerId(owner);
    const session = sessions.get(sessionId);
    if (!session || session.ownerId !== ownerId) {
      return { stopped: false };
    }

    await closeHandle(sessionId);

    session.status = 'stopped';
    session.updatedAt = new Date().toISOString();
    session.lastAction = 'stop';
    session.message = 'Browser session stopped.';
    return { stopped: true, session: publicSession(session) };
  },

  async stopAllSessions() {
    await Promise.all([...sessions.keys()].map(async (sessionId) => {
      await closeHandle(sessionId);
      const session = sessions.get(sessionId);
      if (session) {
        session.status = 'stopped';
        session.updatedAt = new Date().toISOString();
        session.lastAction = 'shutdown';
        session.message = 'Browser session stopped during server shutdown.';
      }
    }));
  },
};

process.once('beforeExit', () => {
  void browserUseService.stopAllSessions();
});