const http = require("http");
const crypto = require("crypto");
const { URLSearchParams } = require("url");

const PORT = 3000;

const env = {
  APP_URL: process.env.APP_URL || "http://localhost:3000",
  SESSION_SECRET: process.env.SESSION_SECRET || "change-me-session-secret",
  AUTHENTIK_PUBLIC_URL: process.env.AUTHENTIK_PUBLIC_URL || "http://localhost:9000",
  AUTHENTIK_INTERNAL_URL: process.env.AUTHENTIK_INTERNAL_URL || "http://host.docker.internal:9000",
  AUTHENTIK_API_TOKEN: process.env.AUTHENTIK_API_TOKEN || "change-me-api-token",
  AUTHENTIK_LOGIN_FLOW: process.env.AUTHENTIK_LOGIN_FLOW || "mm-custom-authentication-flow",
  OIDC_CLIENT_ID: process.env.OIDC_CLIENT_ID || "mm-custom-frontend",
  OIDC_CLIENT_SECRET: process.env.OIDC_CLIENT_SECRET || "change-me-oidc-client-secret",
  OIDC_ISSUER: process.env.OIDC_ISSUER || "http://localhost:9000/application/o/mm-custom-frontend/",
  OIDC_REDIRECT_URI: process.env.OIDC_REDIRECT_URI || "http://localhost:3000/auth/callback",
  AUTH_DEBUG: process.env.AUTH_DEBUG === "true"
};

function debug(...args) {
  if (env.AUTH_DEBUG) console.log("[auth-debug]", ...args);
}

function escapeHtml(value) {
  return String(value ?? "").replace(/[&<>"']/g, (s) => ({
    "&": "&amp;", "<": "&lt;", ">": "&gt;", '"': "&quot;", "'": "&#39;"
  }[s]));
}

function b64url(input) {
  return Buffer.from(input).toString("base64url");
}

function randomString(bytes = 32) {
  return crypto.randomBytes(bytes).toString("base64url");
}

function sha256base64url(value) {
  return crypto.createHash("sha256").update(value).digest("base64url");
}

function sign(value) {
  return crypto.createHmac("sha256", env.SESSION_SECRET).update(value).digest("base64url");
}

function makeSigned(value) {
  const payload = b64url(JSON.stringify(value));
  return `${payload}.${sign(payload)}`;
}

function readSigned(value) {
  if (!value || !value.includes(".")) return null;
  const [payload, mac] = value.split(".");
  if (sign(payload) !== mac) return null;
  try {
    return JSON.parse(Buffer.from(payload, "base64url").toString("utf8"));
  } catch {
    return null;
  }
}

function makeCookie(name, value, maxAge = 3600) {
  return `${name}=${value}; Path=/; HttpOnly; SameSite=Lax; Max-Age=${maxAge}`;
}

function clearCookie(name) {
  return `${name}=; Path=/; HttpOnly; SameSite=Lax; Max-Age=0`;
}

function parseCookies(req) {
  const header = req.headers.cookie || "";
  return Object.fromEntries(
    header
      .split(";")
      .map(v => v.trim())
      .filter(Boolean)
      .map(v => {
        const i = v.indexOf("=");
        return [v.slice(0, i), v.slice(i + 1)];
      })
  );
}

function collectSetCookies(headers) {
  if (typeof headers.getSetCookie === "function") return headers.getSetCookie();
  const value = headers.get("set-cookie");
  return value ? [value] : [];
}

function mergeCookies(jar, setCookies) {
  for (const raw of setCookies) {
    const pair = String(raw).split(";")[0];
    const idx = pair.indexOf("=");
    if (idx > 0) jar[pair.slice(0, idx)] = pair.slice(idx + 1);
  }
}

function cookieHeader(jar) {
  return Object.entries(jar).map(([k, v]) => `${k}=${v}`).join("; ");
}

async function fetchWithJar(url, options = {}, jar = {}) {
  const headers = { ...(options.headers || {}) };
  const cookie = cookieHeader(jar);
  if (cookie) headers.Cookie = cookie;

  const res = await fetch(url, {
    ...options,
    headers,
    redirect: "manual"
  });

  mergeCookies(jar, collectSetCookies(res.headers));
  return res;
}

async function followRedirectsWithJar(res, jar, limit = 8) {
  let current = res;

  for (let i = 0; i < limit; i++) {
    const location = current.headers.get("location");
    if (!location || current.status < 300 || current.status >= 400) return current;

    current = await fetchWithJar(new URL(location, env.AUTHENTIK_INTERNAL_URL).toString(), {
      method: "GET",
      headers: { Accept: "text/html,application/xhtml+xml,application/json" }
    }, jar);
  }

  return current;
}

async function safeJson(res) {
  const text = await res.text();
  if (!text) return {};
  try {
    return JSON.parse(text);
  } catch {
    return { raw: text };
  }
}

function decodeJwt(token) {
  try {
    const [, payload] = token.split(".");
    return JSON.parse(Buffer.from(payload, "base64url").toString("utf8"));
  } catch {
    return {};
  }
}

function getSession(req) {
  return readSigned(parseCookies(req).mm_session);
}

async function parseBody(req) {
  let data = "";
  for await (const chunk of req) data += chunk;
  return Object.fromEntries(new URLSearchParams(data));
}

async function authentikReady() {
  try {
    const res = await fetch(`${env.AUTHENTIK_INTERNAL_URL}/api/v3/root/config/`, {
      headers: { Authorization: `Bearer ${env.AUTHENTIK_API_TOKEN}` }
    });
    return res.status < 500;
  } catch {
    return false;
  }
}

async function apiGet(path) {
  const res = await fetch(`${env.AUTHENTIK_INTERNAL_URL}${path}`, {
    headers: { Authorization: `Bearer ${env.AUTHENTIK_API_TOKEN}` }
  });
  if (!res.ok) throw new Error(`API GET ${path} failed: ${res.status}`);
  return await res.json();
}

async function apiPost(path, body) {
  const res = await fetch(`${env.AUTHENTIK_INTERNAL_URL}${path}`, {
    method: "POST",
    headers: {
      Authorization: `Bearer ${env.AUTHENTIK_API_TOKEN}`,
      "Content-Type": "application/json"
    },
    body: JSON.stringify(body)
  });
  const text = await res.text();
  if (!res.ok) {
    debug("apiPost failed", path, res.status, text);
    throw new Error(`API POST ${path} failed: ${res.status}`);
  }
  return text ? JSON.parse(text) : {};
}

async function findAuthentikUser(email) {
  const res = await fetch(`${env.AUTHENTIK_INTERNAL_URL}/api/v3/core/users/?search=${encodeURIComponent(email)}`, {
    headers: { Authorization: `Bearer ${env.AUTHENTIK_API_TOKEN}` }
  });

  if (!res.ok) return null;

  const data = await res.json();
  const users = data.results || data;

  return Array.isArray(users)
    ? users.find(u =>
        String(u.email || "").toLowerCase() === String(email).toLowerCase() ||
        String(u.username || "").toLowerCase() === String(email).toLowerCase()
      )
    : null;
}

async function createAuthentikUser({ fullName, email, password }) {
  const existing = await findAuthentikUser(email);
  if (existing) throw new Error("Пользователь с таким email уже существует.");

  const createRes = await fetch(`${env.AUTHENTIK_INTERNAL_URL}/api/v3/core/users/`, {
    method: "POST",
    headers: {
      Authorization: `Bearer ${env.AUTHENTIK_API_TOKEN}`,
      "Content-Type": "application/json"
    },
    body: JSON.stringify({
      username: String(email).toLowerCase(),
      name: fullName,
      email,
      is_active: true,
      type: "internal"
    })
  });

  const createText = await createRes.text();
  if (!createRes.ok) {
    debug("create user failed", createRes.status, createText);
    throw new Error("Не удалось создать аккаунт. Попробуйте позже.");
  }

  const user = JSON.parse(createText);
  const userId = user.pk || user.id;

  const passRes = await fetch(`${env.AUTHENTIK_INTERNAL_URL}/api/v3/core/users/${userId}/set_password/`, {
    method: "POST",
    headers: {
      Authorization: `Bearer ${env.AUTHENTIK_API_TOKEN}`,
      "Content-Type": "application/json"
    },
    body: JSON.stringify({ password })
  });

  const passText = await passRes.text();
  if (!passRes.ok) {
    debug("set password failed", passRes.status, passText);
    throw new Error("Аккаунт создан, но пароль не был сохранён.");
  }

  return user;
}

async function discoverOidc() {
  const publicDiscovery = `${env.OIDC_ISSUER.replace(/\/$/, "")}/.well-known/openid-configuration`;
  const internalDiscovery = publicDiscovery.replace(env.AUTHENTIK_PUBLIC_URL, env.AUTHENTIK_INTERNAL_URL);
  const res = await fetch(internalDiscovery);
  if (!res.ok) throw new Error("OIDC provider ещё не применился. Подождите 1-2 минуты или запустите docker compose down -v && docker compose up --build.");
  const config = await res.json();

  return {
    authorization_endpoint: config.authorization_endpoint.replace(env.AUTHENTIK_PUBLIC_URL, env.AUTHENTIK_INTERNAL_URL),
    public_authorization_endpoint: config.authorization_endpoint,
    token_endpoint: config.token_endpoint.replace(env.AUTHENTIK_PUBLIC_URL, env.AUTHENTIK_INTERNAL_URL)
  };
}

// Best-effort OIDC setup. Authentik APIs can differ by version, so README has manual fallback.


async function ensureOidcProvider() {
  if (ensureOidcProvider.done) return;
  try {
    await discoverOidc();
    ensureOidcProvider.done = true;
  } catch (e) {
    debug("OIDC provider not ready yet", e.message);
  }
}
ensureOidcProvider.done = false;

function isSuccessChallenge(res, challenge) {
  const component = challenge.component || "";
  return (
    res.status === 302 ||
    component === "xak-flow-redirect" ||
    component === "ak-flow-redirect" ||
    component === "ak-stage-redirect" ||
    challenge.type === "redirect" ||
    Boolean(challenge.redirect)
  );
}

async function authentikPasswordLogin(email, password) {
  const jar = {};
  const flow = env.AUTHENTIK_LOGIN_FLOW;
  const instanceUrl = `${env.AUTHENTIK_INTERNAL_URL}/api/v3/flows/instances/${flow}/execute/?next=/`;
  const executorUrl = `${env.AUTHENTIK_INTERNAL_URL}/api/v3/flows/executor/${flow}/?query=${encodeURIComponent("next=/")}`;

  await fetchWithJar(instanceUrl, {
    method: "GET",
    headers: { Accept: "application/json" }
  }, jar);

  async function getChallenge() {
    const res = await fetchWithJar(executorUrl, {
      method: "GET",
      headers: { Accept: "application/json" }
    }, jar);
    return { res, challenge: await safeJson(res) };
  }

  async function postChallenge(component, payload = {}) {
    const res = await fetchWithJar(executorUrl, {
      method: "POST",
      headers: { "Content-Type": "application/json", Accept: "application/json" },
      body: JSON.stringify({ component, ...payload })
    }, jar);
    return { res, challenge: await safeJson(res) };
  }

  let { res, challenge } = await getChallenge();
  if (!res.ok) throw new Error("Сервис авторизации запускается. Попробуйте позже.");

  let passwordChecked = false;

  for (let step = 0; step < 12; step++) {
    const component = challenge.component || "";
    debug("auth step", step, component, res.status, challenge);

    if (component === "ak-stage-access-denied") {
      throw new Error("Неверный email или пароль.");
    }

    if (isSuccessChallenge(res, challenge)) {
      if (passwordChecked) {
        await followRedirectsWithJar(res, jar);
        return jar;
      }
      throw new Error("OIDC provider ещё не применился. Подождите 1-2 минуты или запустите docker compose down -v && docker compose up --build.");
    }

    if (component === "ak-stage-identification") {
      const payload = { uid_field: email };
      const hasPasswordOnIdentification =
        challenge.password_fields === true ||
        (Array.isArray(challenge.password_fields) && challenge.password_fields.length > 0);

      if (hasPasswordOnIdentification) {
        payload.password = password;
        passwordChecked = true;
      }

      ({ res, challenge } = await postChallenge("ak-stage-identification", payload));
      continue;
    }

    if (component === "ak-stage-password") {
      passwordChecked = true;
      ({ res, challenge } = await postChallenge("ak-stage-password", { password }));
      continue;
    }

    if (component === "ak-stage-user-login") {
      if (!passwordChecked) throw new Error("Authentik flow не запросил пароль.");
      ({ res, challenge } = await postChallenge("ak-stage-user-login"));
      continue;
    }

    if (component === "ak-stage-consent") {
      if (!passwordChecked) throw new Error("Authentik flow не запросил пароль.");
      ({ res, challenge } = await postChallenge("ak-stage-consent", { consent: true }));
      continue;
    }

    if (component === "ak-stage-authenticator-validate") {
      throw new Error("Для пользователя требуется дополнительная проверка.");
    }

    if (passwordChecked && res.ok && !component) {
      await followRedirectsWithJar(res, jar);
      return jar;
    }

    throw new Error("Не удалось завершить вход. Проверь custom flow Authentik.");
  }

  throw new Error("Неверный email или пароль.");
}

async function getAuthentikIdTokenWithSession(jar) {
  const config = await discoverOidc();

  const state = randomString(24);
  const verifier = randomString(48);
  const challenge = sha256base64url(verifier);

  const authorizeUrl = `${config.authorization_endpoint}?${new URLSearchParams({
    response_type: "code",
    client_id: env.OIDC_CLIENT_ID,
    redirect_uri: env.OIDC_REDIRECT_URI,
    scope: "openid profile email",
    state,
    code_challenge: challenge,
    code_challenge_method: "S256",
    prompt: "none"
  }).toString()}`;

  const authRes = await fetchWithJar(authorizeUrl, {
    method: "GET",
    headers: { Accept: "text/html,application/xhtml+xml,application/json" }
  }, jar);

  const location = authRes.headers.get("location");
  debug("authorize status", authRes.status, "location", location);

  if (!location) {
    throw new Error("Authentik не вернул authorization code. Проверь OIDC Provider.");
  }

  const redirectUrl = new URL(location, env.APP_URL);
  const code = redirectUrl.searchParams.get("code");
  const returnedState = redirectUrl.searchParams.get("state");

  if (!code || returnedState !== state) {
    throw new Error("Не удалось получить authorization code от Authentik.");
  }

  const tokenRes = await fetch(config.token_endpoint, {
    method: "POST",
    headers: { "Content-Type": "application/x-www-form-urlencoded" },
    body: new URLSearchParams({
      grant_type: "authorization_code",
      code,
      redirect_uri: env.OIDC_REDIRECT_URI,
      client_id: env.OIDC_CLIENT_ID,
      client_secret: env.OIDC_CLIENT_SECRET,
      code_verifier: verifier
    })
  });

  const tokens = await tokenRes.json();
  debug("token response", tokenRes.status, tokens);

  if (!tokenRes.ok || !tokens.id_token) {
    throw new Error("Не удалось получить JWT от Authentik.");
  }

  return tokens.id_token;
}

function page(title, body) {
  return `<!doctype html>
<html lang="ru">
<head>
<meta charset="utf-8"/>
<meta name="viewport" content="width=device-width, initial-scale=1"/>
<title>${escapeHtml(title)}</title>
<style>
:root{--gold:#D4AF37;--gold-light:#F0D77D;--bg:#050505;--line:rgba(255,255,255,.11);--muted:rgba(255,255,255,.62);--muted2:rgba(255,255,255,.42)}
*{box-sizing:border-box}
body{margin:0;min-height:100vh;background:#050505;color:#fff;font-family:Inter,Manrope,ui-sans-serif,system-ui,-apple-system,BlinkMacSystemFont,"Segoe UI",Arial,sans-serif}
a{color:inherit;text-decoration:none}button,input{font:inherit}
.screen{min-height:100vh;display:grid;place-items:center;padding:28px;background:radial-gradient(circle at 78% 12%,rgba(212,175,55,.16),transparent 27%),radial-gradient(circle at 8% 86%,rgba(18,44,90,.38),transparent 34%),linear-gradient(180deg,#111,#060606 58%,#030303)}
.shell{width:min(1080px,100%);min-height:700px;display:grid;grid-template-columns:1fr 455px;overflow:hidden;border:1px solid var(--line);border-radius:38px;background:rgba(255,255,255,.025);box-shadow:0 38px 120px rgba(0,0,0,.58)}
.brand-side{position:relative;padding:44px;display:flex;flex-direction:column;justify-content:space-between;background:radial-gradient(circle at 70% 24%,rgba(212,175,55,.18),transparent 34%),linear-gradient(145deg,rgba(255,255,255,.06),rgba(255,255,255,.015))}
.logo{display:flex;align-items:center;gap:14px}
.logo-mark{width:46px;height:46px;border-radius:50%;display:grid;place-items:center;border:1px solid rgba(212,175,55,.38);background:linear-gradient(145deg,rgba(212,175,55,.28),rgba(255,255,255,.045));color:var(--gold);font-weight:800;box-shadow:0 0 40px rgba(212,175,55,.12)}
.logo-title{display:block;font-size:15px;font-weight:800;letter-spacing:.22em;text-transform:uppercase}
.logo-sub{display:block;margin-top:3px;font-size:12px;color:var(--muted2);letter-spacing:.12em}
.brand-copy h1{margin:0;max-width:560px;font-size:clamp(50px,6vw,80px);line-height:.9;letter-spacing:-.075em}
.gold{color:var(--gold)}
.brand-copy p{max-width:520px;margin:28px 0 0;color:var(--muted);font-size:18px;line-height:1.75}
.decor-car{position:absolute;left:44px;right:44px;bottom:132px;height:150px;opacity:.55;pointer-events:none}
.decor-car:before{content:"";position:absolute;left:0;right:0;bottom:28px;height:96px;border-bottom:2px solid rgba(212,175,55,.55);border-radius:50% 50% 18% 18% / 70% 70% 20% 20%;filter:drop-shadow(0 0 18px rgba(212,175,55,.24))}
.decor-car:after{content:"";position:absolute;left:18%;right:24%;bottom:82px;height:52px;border-top:2px solid rgba(255,255,255,.23);border-radius:70% 60% 0 0}
.brand-footer{display:flex;gap:12px;flex-wrap:wrap;color:var(--muted2);font-size:13px}
.brand-footer span{min-width:118px;padding-top:12px;border-top:1px solid var(--line)}
.form-side{padding:42px;display:grid;align-items:center;background:rgba(8,8,8,.78);backdrop-filter:blur(28px);border-left:1px solid var(--line)}
.form-card h2{margin:0;font-size:36px;letter-spacing:-.045em}
.form-card p{margin:12px 0 28px;color:var(--muted);line-height:1.65}
.label{display:block;margin:18px 0 8px;color:rgba(255,255,255,.66);font-size:14px}
.input{width:100%;border:1px solid var(--line);background:rgba(255,255,255,.045);border-radius:18px;padding:16px;color:#fff;outline:none;transition:.2s}
.input::placeholder{color:rgba(255,255,255,.28)}
.input:focus{border-color:rgba(212,175,55,.75);background:rgba(255,255,255,.065);box-shadow:0 0 0 4px rgba(212,175,55,.06)}
.btn{width:100%;min-height:52px;margin-top:24px;border:0;border-radius:999px;background:linear-gradient(135deg,var(--gold),var(--gold-light));color:#050505;font-weight:750;cursor:pointer;transition:.2s}
.btn:hover{transform:translateY(-1px);box-shadow:0 20px 48px rgba(212,175,55,.22)}
.link-row{margin-top:24px;text-align:center;color:var(--muted2);font-size:14px}
.link-row a{color:var(--gold)}
.alert{margin:0 0 18px;padding:14px 16px;border:1px solid;border-radius:18px;font-size:14px;line-height:1.5}
.alert.error{color:#fecaca;background:rgba(248,113,113,.09);border-color:rgba(248,113,113,.25)}
.alert.ok{color:#bbf7d0;background:rgba(52,211,153,.08);border-color:rgba(52,211,153,.25)}
.dashboard-card{width:min(980px,100%);padding:34px;border:1px solid var(--line);border-radius:36px;background:rgba(255,255,255,.04);box-shadow:0 38px 120px rgba(0,0,0,.58)}
.dashboard-top{display:flex;align-items:center;justify-content:space-between;gap:20px}
.logout{width:auto;min-height:46px;margin:0;padding:0 20px}
.profile{margin-top:34px;display:flex;align-items:center;gap:22px}
.avatar{width:82px;height:82px;border-radius:26px;display:grid;place-items:center;background:linear-gradient(145deg,var(--gold),var(--gold-light));color:#050505;font-size:30px;font-weight:800}
.profile h1{margin:0;font-size:42px;letter-spacing:-.05em}
.profile p{margin:8px 0 0;color:var(--muted)}
.jwt-info{margin-top:24px;border:1px solid rgba(212,175,55,.22);border-radius:24px;background:rgba(212,175,55,.055);padding:20px}
.jwt-info h2{margin:0 0 16px;font-size:22px;letter-spacing:-.035em}
.jwt-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:12px}
.jwt-item{border:1px solid rgba(255,255,255,.09);background:rgba(0,0,0,.22);border-radius:18px;padding:14px}
.jwt-item b{display:block;margin-bottom:8px;color:var(--muted2);font-size:11px;text-transform:uppercase;letter-spacing:.12em}
.jwt-item span{color:rgba(255,255,255,.88);word-break:break-word;font-size:14px}
@media(max-width:900px){.shell{grid-template-columns:1fr}.brand-side{min-height:390px}.form-side{border-left:0;border-top:1px solid var(--line)}.jwt-grid{grid-template-columns:1fr}}
@media(max-width:620px){.screen{padding:14px}.brand-side,.form-side,.dashboard-card{padding:24px}.dashboard-top,.profile{align-items:flex-start;flex-direction:column}}
</style>
</head>
<body>${body}</body>
</html>`;
}

function authLayout({ title, subtitle, heading, text, form }) {
  return `<main class="screen">
    <section class="shell">
      <div class="brand-side">
        <a class="logo" href="/login">
          <span class="logo-mark">MM</span>
          <span><span class="logo-title">Million Miles</span><span class="logo-sub">Private Client Access</span></span>
        </a>
        <div class="brand-copy"><h1>${heading}</h1><p>${text}</p></div>
        <div class="decor-car"></div>
        <div class="brand-footer"><span>Secure access</span><span>Private area</span><span>Premium service</span></div>
      </div>
      <div class="form-side"><div class="form-card"><h2>${title}</h2><p>${subtitle}</p>${form}</div></div>
    </section>
  </main>`;
}

function loginPage(req, res, msg = "", headers = {}) {
  const form = `<form method="post" action="/login">
    ${msg}
    <label class="label">Email</label>
    <input class="input" name="email" type="email" autocomplete="email" placeholder="you@example.com" required />
    <label class="label">Пароль</label>
    <input class="input" name="password" type="password" autocomplete="current-password" placeholder="Ваш пароль" required />
    <button class="btn" type="submit">Войти</button>
    <div class="link-row">Нет аккаунта? <a href="/register">Зарегистрироваться</a></div>
  </form>`;

  send(res, 200, page("Вход | Million Miles", authLayout({
    title: "Вход",
    subtitle: "Войдите в личный кабинет Million Miles.",
    heading: `Добро пожаловать`,
    text: "Закрытый доступ для клиентов премиального сервиса.",
    form
  })), headers);
}

function registerPage(req, res, msg = "") {
  const form = `<form method="post" action="/register">
    ${msg}
    <label class="label">Полное имя</label>
    <input class="input" name="fullName" autocomplete="name" placeholder="Ваше имя" required minlength="2" />
    <label class="label">Email</label>
    <input class="input" name="email" type="email" autocomplete="email" placeholder="you@example.com" required />
    <label class="label">Пароль</label>
    <input class="input" name="password" type="password" autocomplete="new-password" placeholder="Минимум 8 символов" minlength="8" required />
    <button class="btn" type="submit">Зарегистрироваться</button>
    <div class="link-row">Уже есть аккаунт? <a href="/login">Войти</a></div>
  </form>`;

  send(res, 200, page("Регистрация | Million Miles", authLayout({
    title: "Регистрация",
    subtitle: "Создайте личный кабинет Million Miles.",
    heading: `Персональный доступ <span class="gold">Million Miles</span>`,
    text: "Создайте профиль для доступа в личный кабинет Million Miles.",
    form
  })));
}

async function registerPost(req, res) {
  const data = await parseBody(req);
  const email = String(data.email || "").trim().toLowerCase();
  const fullName = String(data.fullName || "").trim();
  const password = String(data.password || "");

  try {
    if (!fullName || !email || password.length < 8) throw new Error("Проверьте заполненные данные.");
    if (!(await authentikReady())) throw new Error("Сервис авторизации запускается. Попробуйте позже.");

    await createAuthentikUser({ fullName, email, password });

    return redirect(res, "/login", {
      "Set-Cookie": makeCookie("mm_flash", "registered", 120)
    });
  } catch (e) {
    return registerPage(req, res, `<div class="alert error">${escapeHtml(e.message || "Не удалось создать аккаунт.")}</div>`);
  }
}

async function loginPost(req, res) {
  const data = await parseBody(req);
  const email = String(data.email || "").trim().toLowerCase();
  const password = String(data.password || "");

  try {
    if (!email || !password) throw new Error("Введите email и пароль.");
    if (!(await authentikReady())) throw new Error("Сервис авторизации запускается. Попробуйте позже.");

    await ensureOidcProvider();

    const jar = await authentikPasswordLogin(email, password);
    const idToken = await getAuthentikIdTokenWithSession(jar);
    const claims = decodeJwt(idToken);

    const session = makeSigned({
      id_token: idToken,
      claims,
      sub: claims.sub,
      name: claims.name || claims.preferred_username || claims.email || email,
      email: claims.email || email,
      username: claims.preferred_username || claims.email || email,
      iss: claims.iss,
      aud: claims.aud,
      iat: claims.iat,
      exp: claims.exp
    });

    return redirect(res, "/dashboard", {
      "Set-Cookie": makeCookie("mm_session", session, 3600 * 8)
    });
  } catch (e) {
    debug("login failed", e);
    return loginPage(req, res, `<div class="alert error">${escapeHtml(e.message || "Неверный email или пароль.")}</div>`);
  }
}

function initials(name, email) {
  const source = name || email || "MM";
  return source.split(/[ ._-]+/).filter(Boolean).slice(0, 2).map(x => x[0]).join("").toUpperCase();
}

function dashboard(req, res) {
  const session = getSession(req);
  if (!session) return redirect(res, "/login");

  const claims = session.claims || {};
  const name = session.name || "Клиент";
  const email = session.email || "—";
  const idToken = session.id_token || "—";
  const iat = claims.iat ? new Date(claims.iat * 1000).toLocaleString("ru-RU") : "—";
  const exp = claims.exp ? new Date(claims.exp * 1000).toLocaleString("ru-RU") : "—";

  const body = `<main class="screen">
    <section class="dashboard-card">
      <div class="dashboard-top">
        <a class="logo" href="/dashboard">
          <span class="logo-mark">MM</span>
          <span><span class="logo-title">Million Miles</span><span class="logo-sub">Private Client Access</span></span>
        </a>
        <form method="post" action="/logout"><button class="btn logout" type="submit">Выйти</button></form>
      </div>

      <div class="profile">
        <div class="avatar">${escapeHtml(initials(name, email))}</div>
        <div><h1>${escapeHtml(name)}</h1><p>Данные ниже получены из JWT Authentik</p></div>
      </div>

      <div class="jwt-info">
        <h2>JWT</h2>
        <div class="jwt-grid">
          <div class="jwt-item"><b>sub</b><span>${escapeHtml(claims.sub || "—")}</span></div>
          <div class="jwt-item"><b>name</b><span>${escapeHtml(claims.name || "—")}</span></div>
          <div class="jwt-item"><b>email</b><span>${escapeHtml(claims.email || "—")}</span></div>
          <div class="jwt-item"><b>username</b><span>${escapeHtml(claims.preferred_username || claims.email || "—")}</span></div>
          <div class="jwt-item"><b>iat</b><span>${escapeHtml(iat)}</span></div>
          <div class="jwt-item"><b>exp</b><span>${escapeHtml(exp)}</span></div>
          <div class="jwt-item"><b>iss</b><span>${escapeHtml(claims.iss || "—")}</span></div>
          <div class="jwt-item"><b>aud</b><span>${escapeHtml(Array.isArray(claims.aud) ? claims.aud.join(", ") : claims.aud || "—")}</span></div>
        </div>
        <div class="jwt-item" style="margin-top:12px">
          <b>full id_token</b>
          <span>${escapeHtml(idToken)}</span>
        </div>
      </div>
    </section>
  </main>`;

  send(res, 200, page("Dashboard | Million Miles", body));
}

function redirect(res, location, headers = {}) {
  res.writeHead(302, { Location: location, ...headers });
  res.end();
}

function send(res, status, content, headers = {}) {
  res.writeHead(status, { "Content-Type": "text/html; charset=utf-8", ...headers });
  res.end(content);
}

function logout(req, res) {
  redirect(res, "/login", { "Set-Cookie": clearCookie("mm_session") });
}

http.createServer(async (req, res) => {
  const url = new URL(req.url, env.APP_URL);

  if (req.method === "GET" && url.pathname === "/") return redirect(res, "/login");

  if (req.method === "GET" && url.pathname === "/login") {
    const cookies = parseCookies(req);
    if (cookies.mm_flash === "registered") {
      return loginPage(req, res, `<div class="alert ok">Аккаунт создан. Теперь можно войти.</div>`, {
        "Set-Cookie": clearCookie("mm_flash")
      });
    }
    return loginPage(req, res);
  }

  if (req.method === "POST" && url.pathname === "/login") return loginPost(req, res);
  if (req.method === "GET" && url.pathname === "/register") return registerPage(req, res);
  if (req.method === "POST" && url.pathname === "/register") return registerPost(req, res);
  if (req.method === "GET" && url.pathname === "/dashboard") return dashboard(req, res);
  if (req.method === "POST" && url.pathname === "/logout") return logout(req, res);

  if (req.method === "GET" && url.pathname === "/health") {
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify({ ok: true }));
  }

  redirect(res, "/login");
}).listen(PORT, () => {
  ensureOidcProvider().catch(e => debug("startup oidc setup failed", e.message));
  console.log(`Million Miles Authentik 100% POC on http://localhost:${PORT}`);
});