import { tap, expect } from '@git.zone/tstest/tapbundle';
import * as net from 'net';
import * as dgram from 'dgram';
import { VpnClient, VpnServer } from '../ts/index.js';
import type { IVpnClientOptions, IVpnServerOptions, IVpnKeypair, IVpnServerConfig } from '../ts/index.js';

// ---------------------------------------------------------------------------
// Helpers
// ---------------------------------------------------------------------------

async function findFreePort(): Promise<number> {
  const server = net.createServer();
  await new Promise<void>((resolve) => server.listen(0, '127.0.0.1', resolve));
  const port = (server.address() as net.AddressInfo).port;
  await new Promise<void>((resolve) => server.close(() => resolve()));
  return port;
}

async function findFreeUdpPort(): Promise<number> {
  const sock = dgram.createSocket('udp4');
  await new Promise<void>((resolve) => sock.bind(0, '127.0.0.1', resolve));
  const port = (sock.address() as net.AddressInfo).port;
  await new Promise<void>((resolve) => sock.close(resolve));
  return port;
}

function delay(ms: number): Promise<void> {
  return new Promise((resolve) => setTimeout(resolve, ms));
}

async function waitFor(
  fn: () => Promise<boolean>,
  timeoutMs: number = 10000,
  pollMs: number = 500,
): Promise<void> {
  const deadline = Date.now() + timeoutMs;
  while (Date.now() < deadline) {
    if (await fn()) return;
    await delay(pollMs);
  }
  throw new Error(`waitFor timed out after ${timeoutMs}ms`);
}

// ---------------------------------------------------------------------------
// Test state
// ---------------------------------------------------------------------------

let server: VpnServer;
let wsPort: number;
let quicPort: number;
let keypair: IVpnKeypair;

// ---------------------------------------------------------------------------
// Tests: QUIC-only server + QUIC client
// ---------------------------------------------------------------------------

tap.test('setup: start VPN server in QUIC mode', async () => {
  quicPort = await findFreeUdpPort();

  const options: IVpnServerOptions = {
    transport: { transport: 'stdio' },
  };
  server = new VpnServer(options);

  const started = await server['bridge'].start();
  expect(started).toBeTrue();

  keypair = await server.generateKeypair();

  const serverConfig: IVpnServerConfig = {
    listenAddr: `127.0.0.1:${quicPort}`,
    privateKey: keypair.privateKey,
    publicKey: keypair.publicKey,
    subnet: '10.9.0.0/24',
    transportMode: 'quic',
    keepaliveIntervalSecs: 3,
  };
  await server['bridge'].sendCommand('start', { config: serverConfig });

  const status = await server.getStatus();
  expect(status.state).toEqual('connected');
});

tap.test('QUIC client connects and gets IP', async () => {
  const options: IVpnClientOptions = {
    transport: { transport: 'stdio' },
  };
  const client = new VpnClient(options);
  const started = await client.start();
  expect(started).toBeTrue();

  const result = await client.connect({
    serverUrl: `127.0.0.1:${quicPort}`,
    serverPublicKey: keypair.publicKey,
    transport: 'quic',
    keepaliveIntervalSecs: 3,
  });

  expect(result.assignedIp).toBeTypeofString();
  expect(result.assignedIp).toStartWith('10.9.0.');

  const clientStatus = await client.getStatus();
  expect(clientStatus.state).toEqual('connected');

  // Verify server sees the client
  await waitFor(async () => {
    const clients = await server.listClients();
    return clients.length >= 1;
  });

  await client.stop();
});

tap.test('teardown: stop QUIC server', async () => {
  await server.stop();
  await delay(500);
});

// ---------------------------------------------------------------------------
// Tests: dual-mode server (both) + auto client
// ---------------------------------------------------------------------------

let dualServer: VpnServer;
let dualWsPort: number;
let dualQuicPort: number;
let dualKeypair: IVpnKeypair;

tap.test('setup: start VPN server in both mode', async () => {
  dualWsPort = await findFreePort();
  dualQuicPort = await findFreeUdpPort();

  const options: IVpnServerOptions = {
    transport: { transport: 'stdio' },
  };
  dualServer = new VpnServer(options);

  const started = await dualServer['bridge'].start();
  expect(started).toBeTrue();

  dualKeypair = await dualServer.generateKeypair();

  const serverConfig: IVpnServerConfig = {
    listenAddr: `127.0.0.1:${dualWsPort}`,
    privateKey: dualKeypair.privateKey,
    publicKey: dualKeypair.publicKey,
    subnet: '10.10.0.0/24',
    transportMode: 'both',
    quicListenAddr: `127.0.0.1:${dualQuicPort}`,
    keepaliveIntervalSecs: 3,
  };
  await dualServer['bridge'].sendCommand('start', { config: serverConfig });

  const status = await dualServer.getStatus();
  expect(status.state).toEqual('connected');
});

tap.test('auto client connects to dual-mode server (QUIC preferred)', async () => {
  const options: IVpnClientOptions = {
    transport: { transport: 'stdio' },
  };
  const client = new VpnClient(options);
  const started = await client.start();
  expect(started).toBeTrue();

  // "auto" mode (default): tries QUIC first at same host:port, falls back to WS
  // Since the WS port and QUIC port differ, auto will try QUIC on WS port (fail),
  // then fall back to WebSocket
  const result = await client.connect({
    serverUrl: `ws://127.0.0.1:${dualWsPort}`,
    serverPublicKey: dualKeypair.publicKey,
    // transport defaults to 'auto'
    keepaliveIntervalSecs: 3,
  });

  expect(result.assignedIp).toBeTypeofString();
  expect(result.assignedIp).toStartWith('10.10.0.');

  const clientStatus = await client.getStatus();
  expect(clientStatus.state).toEqual('connected');

  await waitFor(async () => {
    const clients = await dualServer.listClients();
    return clients.length >= 1;
  });

  await client.stop();
});

tap.test('explicit QUIC client connects to dual-mode server', async () => {
  const options: IVpnClientOptions = {
    transport: { transport: 'stdio' },
  };
  const client = new VpnClient(options);
  const started = await client.start();
  expect(started).toBeTrue();

  const result = await client.connect({
    serverUrl: `127.0.0.1:${dualQuicPort}`,
    serverPublicKey: dualKeypair.publicKey,
    transport: 'quic',
    keepaliveIntervalSecs: 3,
  });

  expect(result.assignedIp).toBeTypeofString();
  expect(result.assignedIp).toStartWith('10.10.0.');

  const clientStatus = await client.getStatus();
  expect(clientStatus.state).toEqual('connected');

  await client.stop();
});

tap.test('keepalive exchange over QUIC', async () => {
  const options: IVpnClientOptions = {
    transport: { transport: 'stdio' },
  };
  const client = new VpnClient(options);
  await client.start();

  await client.connect({
    serverUrl: `127.0.0.1:${dualQuicPort}`,
    serverPublicKey: dualKeypair.publicKey,
    transport: 'quic',
    keepaliveIntervalSecs: 3,
  });

  // Wait for keepalive exchange
  await delay(8000);

  const clientStats = await client.getStatistics();
  expect(clientStats.keepalivesSent).toBeGreaterThanOrEqual(1);
  expect(clientStats.keepalivesReceived).toBeGreaterThanOrEqual(1);

  await client.stop();
});

tap.test('teardown: stop dual-mode server', async () => {
  await dualServer.stop();
  await delay(500);
});

export default tap.start();