// Accounts: the header "Sign in / account" entry, the auth modal, and the shared
// helpers other modules (subscriptions.js) use to talk to authed endpoints.
//
// Auth is a same-origin HttpOnly cookie, so the frontend stores no token — it just
// sends `credentials: same-origin` and asks `GET users/me` who it is. Loaded on
// every page the way units.js is (imported by each page's entry module).

let currentUser = null;          // {id, email, display_name} or null
const authCbs = [];              // notified on login/logout so pages can re-gate

// --- shared fetch helper -----------------------------------------------------
// Base-relative URL (resolves under /thermograph automatically), cookie sent,
// and a constant X-TG-Auth header the server can require as cheap CSRF defense
// (trivial same-origin, impossible cross-site without a preflight we never grant).
export async function apiFetch(path, { method = "GET", json, form } = {}) {
  const opts = { method, credentials: "same-origin", headers: { "X-TG-Auth": "1" } };
  if (json !== undefined) {
    opts.headers["Content-Type"] = "application/json";
    opts.body = JSON.stringify(json);
  } else if (form !== undefined) {
    opts.headers["Content-Type"] = "application/x-www-form-urlencoded";
    opts.body = new URLSearchParams(form).toString();
  }
  return fetch(path, opts);
}

// Parse a JSON response, throwing a friendly Error on failure. fastapi-users
// returns machine codes ("LOGIN_BAD_CREDENTIALS") or {detail:{reason}} for
// password rejects; map the common ones to human text.
async function readJson(res) {
  let data = null;
  try { data = await res.json(); } catch (e) { /* empty body (e.g. 204) */ }
  if (!res.ok) {
    const detail = data && data.detail;
    let msg;
    if (detail && typeof detail === "object" && detail.reason) msg = detail.reason;
    else if (detail === "LOGIN_BAD_CREDENTIALS") msg = "Wrong email or password.";
    else if (detail === "REGISTER_USER_ALREADY_EXISTS") msg = "That email is already registered.";
    else if (typeof detail === "string") msg = detail.replace(/_/g, " ").toLowerCase();
    else msg = `Request failed (${res.status}).`;
    throw new Error(msg);
  }
  return data;
}

export function getUser() { return currentUser; }
export function onAuthChange(cb) { authCbs.push(cb); }
function emitAuth() { authCbs.forEach((cb) => { try { cb(currentUser); } catch (e) {} }); }

async function refreshUser() {
  try {
    const res = await apiFetch("api/v2/users/me");
    currentUser = res.ok ? await res.json() : null;
  } catch (e) { currentUser = null; }
  return currentUser;
}

// --- auth calls --------------------------------------------------------------
async function login(email, password) {
  // fastapi-users login is an OAuth2 form: username=email, password.
  const res = await apiFetch("api/v2/auth/login", { method: "POST", form: { username: email, password } });
  await readJson(res);           // throws on bad creds; 204 body is empty
}
async function register(email, password) {
  const res = await apiFetch("api/v2/auth/register", { method: "POST", json: { email, password } });
  await readJson(res);
}
export async function logout() {
  try { await apiFetch("api/v2/auth/logout", { method: "POST" }); } catch (e) {}
  currentUser = null;
  renderHeader();
  emitAuth();
}

// --- auth modal --------------------------------------------------------------
let modal = null, mode = "login";

function buildModal() {
  modal = document.createElement("div");
  modal.className = "mp-overlay acct-overlay";
  modal.hidden = true;
  modal.innerHTML = `
    <div class="mp-modal acct-modal" role="dialog" aria-modal="true" aria-label="Account">
      <div class="mp-head">
        <h2 class="acct-title">Sign in</h2>
        <button type="button" class="mp-close" aria-label="Close">&times;</button>
      </div>
      <form class="acct-form" autocomplete="on">
        <label>Email
          <input type="email" name="email" required autocomplete="email" placeholder="you@example.com" />
        </label>
        <label>Password
          <input type="password" name="password" required minlength="8" autocomplete="current-password" placeholder="At least 8 characters" />
        </label>
        <p class="acct-error" role="alert" hidden></p>
        <button type="submit" class="acct-submit">Sign in</button>
        <p class="acct-switch"></p>
      </form>
    </div>`;
  document.body.appendChild(modal);

  modal.querySelector(".mp-close").onclick = closeAuth;
  modal.addEventListener("pointerdown", (e) => { if (e.target === modal) closeAuth(); });
  document.addEventListener("keydown", (e) => { if (!modal.hidden && e.key === "Escape") closeAuth(); });

  const form = modal.querySelector(".acct-form");
  form.addEventListener("submit", onSubmit);
  modal.querySelector(".acct-switch").addEventListener("click", (e) => {
    const b = e.target.closest("button");
    if (b) setMode(mode === "login" ? "register" : "login");
  });
  setMode("login");
}

function setMode(m) {
  mode = m;
  const isLogin = m === "login";
  modal.querySelector(".acct-title").textContent = isLogin ? "Sign in" : "Create account";
  modal.querySelector(".acct-submit").textContent = isLogin ? "Sign in" : "Create account";
  modal.querySelector('input[name="password"]').setAttribute(
    "autocomplete", isLogin ? "current-password" : "new-password");
  modal.querySelector(".acct-switch").innerHTML = isLogin
    ? 'Need an account? <button type="button">Create one</button>'
    : 'Already have an account? <button type="button">Sign in</button>';
  showError("");
}

function showError(msg) {
  const el = modal.querySelector(".acct-error");
  el.textContent = msg || "";
  el.hidden = !msg;
}

async function onSubmit(e) {
  e.preventDefault();
  const email = modal.querySelector('input[name="email"]').value.trim();
  const password = modal.querySelector('input[name="password"]').value;
  const btn = modal.querySelector(".acct-submit");
  btn.disabled = true;
  showError("");
  try {
    if (mode === "register") { await register(email, password); }
    await login(email, password);      // register flow signs in right after
    await refreshUser();
    closeAuth();
    renderHeader();
    emitAuth();
  } catch (err) {
    showError(err.message || "Something went wrong.");
  } finally {
    btn.disabled = false;
  }
}

export function openAuth(startMode = "login") {
  if (!modal) buildModal();
  setMode(startMode);
  modal.querySelector('input[name="email"]').value = "";
  modal.querySelector('input[name="password"]').value = "";
  modal.hidden = false;
  modal.querySelector('input[name="email"]').focus();
}
function closeAuth() { if (modal) modal.hidden = true; }

// --- notifications (header bell) ---------------------------------------------
const BELL_IC = `<svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" aria-hidden="true"><path d="M18 8a6 6 0 0 0-12 0c0 7-3 9-3 9h18s-3-2-3-9"/><path d="M13.73 21a2 2 0 0 1-3.46 0"/></svg>`;

let notifications = [];
let unreadCount = 0;
let notifTimer = null;

function timeAgo(sec) {
  const d = Date.now() / 1000 - sec;
  if (d < 60) return "just now";
  if (d < 3600) return `${Math.floor(d / 60)}m ago`;
  if (d < 86400) return `${Math.floor(d / 3600)}h ago`;
  return `${Math.floor(d / 86400)}d ago`;
}

async function loadNotifications() {
  try {
    const res = await apiFetch("api/v2/notifications?limit=50");
    if (!res.ok) return;
    const data = await res.json();
    notifications = data.notifications || [];
    unreadCount = data.unread_count || 0;
    paintBadge();
    paintNotifList();
  } catch (e) { /* offline — leave prior state */ }
}

function paintBadge() {
  if (!acctEl) return;
  const badge = acctEl.querySelector(".notif-badge");
  if (!badge) return;
  badge.textContent = unreadCount > 99 ? "99+" : String(unreadCount);
  badge.hidden = unreadCount === 0;
}

function paintNotifList() {
  if (!acctEl) return;
  const list = acctEl.querySelector(".notif-list");
  if (!list) return;
  if (!notifications.length) {
    list.innerHTML = `<li class="notif-empty muted">No alerts yet. Weather notifications will show up here.</li>`;
    return;
  }
  list.innerHTML = notifications.map((n) => `
    <li class="notif-item ${n.read_at ? "" : "is-unread"}" data-id="${n.id}">
      <div class="notif-item-title">${escapeHtml(n.title)}</div>
      <div class="notif-item-body">${escapeHtml(n.body || "")}</div>
      <div class="notif-item-time muted">${timeAgo(n.created_at)}</div>
    </li>`).join("");
  list.querySelectorAll(".notif-item.is-unread").forEach((li) => {
    li.addEventListener("click", () => markRead(Number(li.dataset.id), li));
  });
}

async function markRead(id, li) {
  try {
    const res = await apiFetch(`api/v2/notifications/${id}/read`, { method: "POST" });
    if (!res.ok) return;
    const n = notifications.find((x) => x.id === id);
    if (n && !n.read_at) { n.read_at = Date.now() / 1000; unreadCount = Math.max(0, unreadCount - 1); }
    li.classList.remove("is-unread");
    paintBadge();
  } catch (e) {}
}

async function markAllRead() {
  try {
    const res = await apiFetch("api/v2/notifications/read-all", { method: "POST" });
    if (!res.ok) return;
    notifications.forEach((n) => { n.read_at = n.read_at || Date.now() / 1000; });
    unreadCount = 0;
    paintBadge();
    paintNotifList();
  } catch (e) {}
}

function startNotifPolling() {
  loadNotifications();
  if (notifTimer) return;
  notifTimer = setInterval(loadNotifications, 120000);   // refresh unread every 2 min
}
function stopNotifPolling() {
  if (notifTimer) { clearInterval(notifTimer); notifTimer = null; }
  notifications = []; unreadCount = 0;
}

// --- header entry ------------------------------------------------------------
const USER_IC = `<svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" aria-hidden="true"><path d="M20 21v-2a4 4 0 0 0-4-4H8a4 4 0 0 0-4 4v2"/><circle cx="12" cy="7" r="4"/></svg>`;

let acctEl = null;

function ensureAcctEl() {
  const brand = document.querySelector(".brand");
  if (!brand) return null;
  if (!acctEl) {
    acctEl = document.createElement("div");
    acctEl.className = "acct";
    // The account/bell live inside the nav menu panel: on desktop the panel is
    // display:contents so they render inline top-right; on phones they stack
    // inside the hamburger dropdown. Fall back to a brand sibling if unwrapped.
    const panel = brand.querySelector(".nav-panel");
    if (panel) panel.appendChild(acctEl);
    else brand.insertBefore(acctEl, brand.querySelector(".view-nav"));
  }
  return acctEl;
}

function renderHeader() {
  const el = ensureAcctEl();
  if (!el) return;
  if (currentUser) {
    const name = currentUser.display_name || currentUser.email;
    el.innerHTML = `
      <div class="notif">
        <button type="button" class="acct-btn notif-btn" aria-haspopup="true" aria-expanded="false" aria-label="Notifications">
          ${BELL_IC}<span class="notif-badge" hidden>0</span>
        </button>
        <div class="notif-pop" hidden>
          <div class="notif-head">
            <span>Notifications</span>
            <button type="button" class="notif-readall">Mark all read</button>
          </div>
          <ul class="notif-list"></ul>
          <a href="alerts" class="notif-manage">Manage alerts →</a>
        </div>
      </div>
      <div class="acct-menu">
        <button type="button" class="acct-btn" aria-haspopup="true" aria-expanded="false" aria-label="Account: ${escapeHtml(name)}">
          ${USER_IC}<span class="acct-name">${escapeHtml(name)}</span>
        </button>
        <div class="acct-pop" hidden>
          <a href="alerts" class="acct-pop-link">My alerts</a>
          <button type="button" class="acct-pop-link acct-signout">Sign out</button>
        </div>
      </div>`;
    const btn = el.querySelector(".acct-btn:not(.notif-btn)");
    const pop = el.querySelector(".acct-pop");
    btn.addEventListener("click", () => {
      const open = pop.hidden;
      pop.hidden = !open;
      btn.setAttribute("aria-expanded", open ? "true" : "false");
    });
    // Notification bell dropdown.
    const nBtn = el.querySelector(".notif-btn");
    const nPop = el.querySelector(".notif-pop");
    nBtn.addEventListener("click", () => {
      const open = nPop.hidden;
      nPop.hidden = !open;
      nBtn.setAttribute("aria-expanded", open ? "true" : "false");
      if (open) loadNotifications();     // refresh on open
    });
    el.querySelector(".notif-readall").addEventListener("click", markAllRead);
    document.addEventListener("click", (e) => {
      if (!el.contains(e.target)) {
        pop.hidden = true; btn.setAttribute("aria-expanded", "false");
        nPop.hidden = true; nBtn.setAttribute("aria-expanded", "false");
      }
    });
    el.querySelector(".acct-signout").addEventListener("click", logout);
    paintBadge();
    paintNotifList();
    startNotifPolling();
  } else {
    stopNotifPolling();
    el.innerHTML = `<button type="button" class="acct-btn acct-signin" aria-label="Sign in">${USER_IC}<span>Sign in</span></button>`;
    el.querySelector(".acct-signin").addEventListener("click", () => openAuth("login"));
  }
}

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

// --- boot --------------------------------------------------------------------
(async function initAccount() {
  ensureAcctEl();
  renderHeader();               // paint the signed-out state immediately
  await refreshUser();          // then confirm session from the cookie
  renderHeader();
  emitAuth();
})();