// Row 74 (#1568, lead decision 93): the preview mode. A request for the public name needs the
// proxy's header equal to the one user id, else 401 with nothing read; in preview mode nothing
// but GET and HEAD gets through, whatever the Host; loopback requests work as they did. Round 2:
// a repeated Host is 400, and HEADER with any Host but NAME is 403, so a proxy that rewrites Host
// fails closed instead of reaching the loopback path.
import { test } from 'node:test';
import assert from 'node:assert/strict';
import { createServer, request } from 'node:http';
import { connect } from 'node:net';
import { spawn, spawnSync } from 'node:child_process';
import { fileURLToPath } from 'node:url';
import { startServer, previewOptions } from '../src/serve.mjs';
import { close } from './fixture.mjs';

const NAME = 'mosaic-preview.example.com', HEADER = 'remote-user', ID = 'jason';
const preview = { host: NAME, header: HEADER, user: ID };
const CLI = fileURLToPath(new URL('../src/cli.mjs', import.meta.url));

// node:http, not fetch: fetch can't set Host. The length is explicit because node sends a
// DELETE or OPTIONS body without one, which breaks the next request on a kept-alive socket.
function send(port, { method = 'GET', path = '/api/bus/inbox', headers = {}, body } = {}) {
  return new Promise((resolve, reject) => {
    const length = body === undefined ? {} : { 'content-length': Buffer.byteLength(body) };
    const req = request({ host: '127.0.0.1', port, method, path, headers: { host: NAME, ...length, ...headers } }, res => {
      let text = '';
      res.on('data', c => (text += c));
      res.on('end', () => resolve({ status: res.statusCode, body: text && (res.headers['content-type'] ?? '').startsWith('application/json') ? JSON.parse(text) : text }));
    });
    req.on('error', reject);
    req.end(body);
  });
}
// A raw request, for what node:http won't send: two Host lines.
function raw(port, lines) {
  return new Promise((resolve, reject) => {
    const socket = connect(port, '127.0.0.1', () => socket.end([...lines, 'connection: close', '', ''].join('\r\n')));
    let text = '';
    socket.on('data', c => (text += c));
    // json() answers chunked: one chunk, then the zero chunk.
    socket.on('end', () => resolve({ status: Number(text.split(' ')[1]), body: JSON.parse(text.split('\r\n\r\n')[1].split('\r\n')[1]) }));
    socket.on('error', reject);
  });
}
const signedIn = { [HEADER]: ID };
const json = { 'content-type': 'application/json' };

// A board that counts what reaches it, and a bus that counts its reads.
async function setup(t, options = {}) {
  const boardHits = [];
  const upstream = createServer((req, res) => {
    boardHits.push(`${req.method} ${req.url}`);
    res.writeHead(200, json);
    res.end(req.url === '/api/board' ? '{"sessions":[]}' : '{"ok":true}');
  });
  await new Promise(r => upstream.listen(0, '127.0.0.1', r));
  // Closed first and on its own, so a refused startServer doesn't leave it holding the process open.
  t.after(() => close(upstream));
  const busCalls = [];
  const bus = Object.fromEntries(['inbox', 'tasks', 'agents', 'trail', 'decisions'].map(v => [v, async arg => { busCalls.push([v, arg]); return [{ verb: v }]; }]));
  const web = await startServer({ port: 0, board: `http://127.0.0.1:${upstream.address().port}`, bus, preview, ...options });
  t.after(() => close(web));
  return { port: web.address().port, boardHits, busCalls };
}

// startServer must refuse; a server it starts anyway is closed so the failure can't hang the run.
async function refused(options) {
  const result = await startServer({ port: 0, preview: options }).catch(err => err);
  if (!(result instanceof Error)) { await close(result); assert.fail(`served with ${JSON.stringify(options)}`); }
  assert.match(result.message, /together/);
}

test('preview options are all three or none, and each is checked', async () => {
  assert.equal(previewOptions({}), null);
  assert.deepEqual(previewOptions({ publicHost: 'Mosaic-Preview.Example.com', authHeader: 'Remote-User', allowUser: ID }), preview);
  for (const partial of [{ publicHost: NAME }, { authHeader: HEADER }, { allowUser: ID }, { publicHost: NAME, authHeader: HEADER }, { publicHost: NAME, allowUser: ID }, { authHeader: HEADER, allowUser: ID }]) {
    assert.throws(() => previewOptions(partial), /all|together/, JSON.stringify(partial));
    await refused({ host: partial.publicHost, header: partial.authHeader, user: partial.allowUser });
  }
  await refused({});
  for (const host of ['https://' + NAME, NAME + ':443', NAME + '/', 'localhost', '127.0.0.1', '::1', 'preview', '', 'a..b.com', '-a.example.com'])
    assert.throws(() => previewOptions({ publicHost: host, authHeader: HEADER, allowUser: ID }), /public host/, host);
  for (const header of ['host', 'Origin', 'remote user', 'x:y', '', 'a'.repeat(65), 'remote_user', '_', '-remote-user'])
    assert.throws(() => previewOptions({ publicHost: NAME, authHeader: header, allowUser: ID }), /auth header/, header);
  for (const user of ['', 'jason woltje', 'a,b', 'é', 'a'.repeat(257)])
    assert.throws(() => previewOptions({ publicHost: NAME, authHeader: HEADER, allowUser: user }), /allowed user/, user);
});

test('the CLI refuses a partial or invalid preview flag set at start', () => {
  const sets = [
    ['--public-host', NAME], ['--auth-header', HEADER], ['--allow-user', ID],
    ['--public-host', NAME, '--auth-header', HEADER], ['--public-host', NAME, '--allow-user', ID], ['--auth-header', HEADER, '--allow-user', ID],
    ['--public-host', NAME + ':443', '--auth-header', HEADER, '--allow-user', ID],
  ];
  for (const flags of sets) {
    const result = spawnSync(process.execPath, [CLI, 'serve', '--port', '0', ...flags], { encoding: 'utf8', timeout: 10000 });
    assert.equal(result.status, 2, flags.join(' '));
    assert.match(result.stderr, /^refused: (preview mode needs|public host)/, flags.join(' '));
    assert.equal(result.stdout, '');
  }
});

test('the CLI with all three flags serves the preview mode', async t => {
  // No system config, so the bus routes answer not-configured; the gate runs before them.
  const env = { ...process.env, MOSAIC_CONFIG: fileURLToPath(new URL('./no-such-config.json', import.meta.url)) };
  const child = spawn(process.execPath, [CLI, 'serve', '--port', '0', '--board', 'http://127.0.0.1:9', '--public-host', NAME, '--auth-header', 'Remote-User', '--allow-user', ID], { env, stdio: ['ignore', 'pipe', 'pipe'] });
  t.after(() => child.kill());
  let out = '';
  const port = await new Promise((resolve, reject) => {
    child.stdout.on('data', c => { out += c; const m = out.match(/^Mosaic Console: http:\/\/127\.0\.0\.1:(\d+)\/$/m); if (m && out.includes('Ctrl-C')) resolve(Number(m[1])); });
    child.on('exit', code => reject(new Error(`exited ${code}: ${out}`)));
  });
  assert.match(out, new RegExp(`^Preview: https://${NAME}/ through the proxy, signed-in user from remote-user, read-only$`, 'm'));
  assert.deepEqual((await send(port, {})).body, { error: 'sign-in required' });
  assert.equal((await send(port, { path: '/healthz', headers: signedIn })).status, 200);
  assert.equal((await send(port, { method: 'POST', path: '/api/seen', headers: { host: `127.0.0.1:${port}`, ...json }, body: '{}' })).status, 403);
});

test('a request for the public name needs the header equal to the user id, else 401 and nothing read', async t => {
  const { port, boardHits, busCalls } = await setup(t);
  for (const [why, headers] of [
    ['no header', {}],
    ['another user', { [HEADER]: 'mallory' }],
    ['the id with a suffix', { [HEADER]: ID + 'x' }],
    ['a different header', { 'x-remote-user': ID }],
    ['two values', { [HEADER]: [ID, ID] }],
  ]) {
    for (const path of ['/api/bus/inbox', '/api/bus/trail?subject=row-1', '/api/board', '/']) {
      const r = await send(port, { path, headers });
      assert.equal(r.status, 401, `${why} ${path}`);
      assert.deepEqual(r.body, { error: 'sign-in required' });
    }
    // HEAD is held to the same check; its answer has no body.
    assert.equal((await send(port, { method: 'HEAD', path: '/', headers })).status, 401, `${why} HEAD`);
  }
  assert.deepEqual(busCalls, []);
  assert.deepEqual(boardHits, []);
});

test('the header name matches without regard to case, and the value compare is exact', async t => {
  // The shape of the first deployment: a mixed-case header flag and a 64-hex user id.
  const uid = 'a3f1'.repeat(16);
  const { port, busCalls } = await setup(t, { preview: { host: NAME, header: 'X-authentik-uid', user: uid } });
  for (const name of ['x-authentik-uid', 'X-authentik-uid', 'X-AUTHENTIK-UID'])
    assert.equal((await send(port, { headers: { [name]: uid } })).status, 200, name);
  for (const value of [uid.toUpperCase(), uid.slice(1), ` ${uid}x`, uid + ',' + uid])
    assert.equal((await send(port, { headers: { 'x-authentik-uid': value } })).status, 401, value);
  assert.equal(busCalls.length, 3);
});

test('the public name with the header reads the bus views, and the Host and Origin are checked first', async t => {
  const { port, boardHits, busCalls } = await setup(t);
  for (const verb of ['inbox', 'tasks', 'agents']) {
    const r = await send(port, { path: `/api/bus/${verb}`, headers: signedIn });
    assert.equal(r.status, 200, verb); assert.deepEqual(r.body.rows, [{ verb }]);
  }
  const trail = await send(port, { path: '/api/bus/trail?subject=row-1', headers: { ...signedIn, origin: `https://${NAME}` } });
  assert.equal(trail.status, 200);
  assert.equal((await send(port, { path: '/api/board', headers: signedIn })).status, 200);
  // A hostname compares without regard to case.
  assert.equal((await send(port, { path: '/healthz', headers: { ...signedIn, host: 'Mosaic-Preview.Example.COM' } })).status, 200);
  assert.equal((await send(port, { path: '/', headers: { 'Remote-User': ID } })).status, 200);
  assert.equal((await send(port, { method: 'HEAD', path: '/', headers: signedIn })).status, 200);
  assert.deepEqual(busCalls, [['inbox', undefined], ['tasks', undefined], ['agents', undefined], ['trail', 'row-1']]);
  assert.deepEqual(boardHits, ['GET /api/board']);
  // Any Host but NAME exactly is refused: without the header as non-local, with it as a proxy
  // that didn't forward Host unchanged. GET and HEAD alike.
  for (const host of ['evil.example', NAME + ':443', `${NAME}.evil.example`, `x.${NAME}`, `x${NAME}`]) {
    for (const method of ['GET', 'HEAD']) {
      const path = method === 'GET' ? '/api/bus/inbox' : '/';
      const bare = await send(port, { method, path, headers: { host } });
      assert.equal(bare.status, 403, `${method} ${host}`);
      const signed = await send(port, { method, path, headers: { ...signedIn, host } });
      assert.equal(signed.status, 403, `${method} ${host} signed`);
      if (method === 'GET') {
        assert.deepEqual(bare.body, { error: 'non-local Host refused' });
        assert.deepEqual(signed.body, { error: 'proxy Host refused', message: 'the proxy must forward Host unchanged' });
      }
    }
  }
  for (const origin of [`http://${NAME}`, 'https://evil.example', `https://${NAME}:443`, `http://127.0.0.1:${port}`]) {
    const r = await send(port, { headers: { ...signedIn, origin } });
    assert.equal(r.status, 403, origin); assert.deepEqual(r.body, { error: 'cross-origin request refused' });
    assert.equal((await send(port, { method: 'HEAD', path: '/', headers: { ...signedIn, origin } })).status, 403, `HEAD ${origin}`);
  }
  assert.equal(busCalls.length, 4);
});

test('in preview mode every write answers 403 read-only, from the public name and loopback, and reaches nothing', async t => {
  const { port, boardHits, busCalls } = await setup(t);
  const loopback = { host: `127.0.0.1:${port}` };
  const seen = JSON.stringify({ project: 'p', agent: 'a', lastActivity: 'x', seen: true }), reply = JSON.stringify({ agent: 'p/a', text: 'hi' });
  for (const headers of [signedIn, loopback, { ...loopback, origin: `http://127.0.0.1:${port}` }]) {
    for (const [path, body] of [['/api/seen', seen], ['/api/reply', reply], ['/api/bus/inbox', '{}'], ['/', '{}']]) {
      const r = await send(port, { method: 'POST', path, headers: { ...headers, ...json }, body });
      assert.equal(r.status, 403, `${headers.host ?? NAME} POST ${path}`);
      assert.deepEqual(r.body, { error: 'read-only', message: 'the Console preview is read-only' });
    }
    for (const method of ['PUT', 'DELETE', 'PATCH', 'OPTIONS'])
      assert.equal((await send(port, { method, path: '/api/seen', headers: { ...headers, ...json }, body: seen })).status, 403, method);
  }
  // A write without the header is still a sign-in refusal first.
  assert.equal((await send(port, { method: 'POST', path: '/api/reply', headers: json, body: reply })).status, 401);
  assert.deepEqual(boardHits, []);
  assert.deepEqual(busCalls, []);
});

test('loopback requests are unchanged in preview mode, and the bus views work with the board down', async t => {
  const probe = createServer(); await new Promise(r => probe.listen(0, '127.0.0.1', r));
  const dead = `http://127.0.0.1:${probe.address().port}`; await close(probe);
  const { port, busCalls } = await setup(t, { board: dead, timeout: 200 });
  const loopback = { host: `127.0.0.1:${port}` };
  const inbox = await send(port, { headers: loopback });
  assert.equal(inbox.status, 200); assert.deepEqual(inbox.body.rows, [{ verb: 'inbox' }]);
  assert.equal((await send(port, { path: '/healthz', headers: { host: `localhost:${port}` } })).status, 200);
  assert.equal((await send(port, { headers: { ...loopback, origin: `https://${NAME}` } })).status, 403);
  assert.equal((await send(port, { headers: { host: `127.0.0.1:${port + 1}` } })).status, 403);
  // The board panel's existing error; the bus views still answer.
  const board = await send(port, { path: '/api/board', headers: signedIn });
  assert.equal(board.status, 502); assert.equal(board.body.board, dead);
  assert.equal((await send(port, { path: '/api/bus/agents', headers: signedIn })).status, 200);
  assert.deepEqual(busCalls.map(c => c[0]), ['inbox', 'agents']);
});

test('a proxy that rewrites Host to the loopback port gets 403 on its first request, whatever the user', async t => {
  // nginx's default proxy_set_header Host $proxy_host sends the upstream's Host, the operator's path.
  const { port, boardHits, busCalls } = await setup(t);
  for (const host of [`127.0.0.1:${port}`, `localhost:${port}`, `[::1]:${port}`]) {
    for (const [name, value] of [[HEADER, 'mallory'], [HEADER, ID], ['Remote-User', ID], [HEADER, '']]) {
      for (const [method, path] of [['GET', '/api/bus/inbox'], ['GET', '/api/config'], ['HEAD', '/'], ['POST', '/api/seen']]) {
        const r = await send(port, { method, path, headers: { host, [name]: value, ...(method === 'POST' ? json : {}) }, body: method === 'POST' ? '{}' : undefined });
        assert.equal(r.status, 403, `${host} ${name}=${value} ${method} ${path}`);
        if (method !== 'HEAD') assert.deepEqual(r.body, { error: 'proxy Host refused', message: 'the proxy must forward Host unchanged' });
      }
    }
    // The operator's browser sends no HEADER and still gets through.
    assert.equal((await send(port, { headers: { host } })).status, 200, host);
  }
  assert.deepEqual(busCalls.map(c => c[0]), ['inbox', 'inbox', 'inbox']);
  assert.deepEqual(boardHits, []);
});

test('a repeated Host is 400 before any other check, in preview mode and without it', async t => {
  for (const options of [{}, { preview: null }]) {
    const { port, boardHits, busCalls } = await setup(t, options);
    const loopback = `host: 127.0.0.1:${port}`, named = `host: ${NAME}`;
    // Filbert's case: a loopback Host, then NAME, with no header; before round 2 this was 200.
    for (const hosts of [[loopback, named], [named, loopback], [named, named], [loopback, loopback]]) {
      for (const extra of [[], [`${HEADER}: ${ID}`]]) {
        const r = await raw(port, ['GET /api/bus/inbox HTTP/1.1', ...hosts, ...extra]);
        assert.equal(r.status, 400, hosts.concat(extra).join(' | '));
        assert.deepEqual(r.body, { error: 'repeated Host refused' });
      }
    }
    // One Host still works.
    assert.equal((await raw(port, ['GET /api/bus/inbox HTTP/1.1', loopback])).status, 200);
    assert.deepEqual(busCalls.map(c => c[0]), ['inbox']);
    assert.deepEqual(boardHits, []);
  }
});

test('without the preview flags the public name is refused and writes still reach the board', async t => {
  const { port, boardHits } = await setup(t, { preview: null });
  const r = await send(port, { headers: signedIn });
  assert.equal(r.status, 403); assert.deepEqual(r.body, { error: 'non-local Host refused' });
  const seen = await send(port, { method: 'POST', path: '/api/seen', headers: { host: `127.0.0.1:${port}`, ...json }, body: '{"seen":true}' });
  assert.equal(seen.status, 200);
  assert.deepEqual(boardHits, ['POST /api/seen']);
});