// Shared helpers used by all pages.

const el = (tag, attrs, ...children) => {
  const node = document.createElement(tag);
  if (attrs) {
    for (const k in attrs) {
      if (k === "class") node.className = attrs[k];
      else if (k === "style") Object.assign(node.style, attrs[k]);
      else if (k.startsWith("on") && typeof attrs[k] === "function") node.addEventListener(k.slice(2), attrs[k]);
      else if (k === "checked" || k === "disabled" || k === "selected") {
        if (attrs[k]) node.setAttribute(k, "");
      } else if (attrs[k] !== false && attrs[k] !== null && attrs[k] !== undefined) {
        node.setAttribute(k, attrs[k]);
      }
    }
  }
  for (const c of children.flat()) {
    if (c === null || c === undefined || c === false) continue;
    node.appendChild(typeof c === "string" || typeof c === "number" ? document.createTextNode(String(c)) : c);
  }
  return node;
};

function clearNode(node) {
  while (node.firstChild) node.removeChild(node.firstChild);
}

function naturalCompare(a, b) {
  if (a == null) a = "";
  if (b == null) b = "";
  return String(a).localeCompare(String(b), undefined, { numeric: true, sensitivity: "base" });
}

// Page navigation helpers (true multi-page navigation, not SPA routing).
const PAGES = {
  login: "login.html",
  competitions: "competitions.html",
  competition: "competition.html",
  forcePassword: "force-password.html",
};

function navigate(page, params) {
  let url = PAGES[page] || page;
  if (params) {
    const qs = new URLSearchParams(params).toString();
    if (qs) url += "?" + qs;
  }
  location.assign(url);
}

// Bootstraps a page: loads the current user, enforces auth rules.
// options:
//   requireAuth: true       — redirect to login if no session
//   forbidIfMustChange: true — redirect to force-password.html
//   onlyIfMustChange: true  — redirect AWAY if user must NOT change
async function bootstrapAuth(options) {
  options = options || {};
  // Make sure English (fallback) and the browser-detected language are loaded
  // before we attempt to render anything.
  await setLang(detectInitialLang());
  let user = null;
  try {
    user = await API.me();
  } catch (e) {
    user = null;
  }
  if (options.requireAuth && !user) {
    navigate("login");
    return null;
  }
  if (!user) return null;
  await setLang(user.language || CURRENT_LANG);
  if (user.must_change_password && options.forbidIfMustChange) {
    navigate("forcePassword");
    return null;
  }
  if (!user.must_change_password && options.onlyIfMustChange) {
    navigate("competitions");
    return null;
  }
  return user;
}

// Standard topbar shown on authenticated pages.
function renderTopbar(user, opts) {
  opts = opts || {};
  const langSelect = el("select",
    { onchange: async (e) => {
        const lang = e.target.value;
        try { await API.updateMe({ language: lang }); } catch (_) {}
        user.language = lang;
        await setLang(lang);
        location.reload();
      } },
    ...I18N_AVAILABLE.map((l) => el("option", { value: l, selected: l === user.language }, I18N_NAMES[l]))
  );

  const logoutBtn = el("button", { class: "ghost", onclick: async () => {
    try { await API.logout(); } catch (_) {}
    navigate("login");
  } }, t("logout"));

  const brand = el("a", { href: PAGES.competitions, class: "brand" }, "Penalty Tracker");

  const profileBtn = el("button", { class: "ghost", onclick: () => openProfileModal(user) },
    user.display_name || user.username);

  return el("div", { class: "topbar" },
    brand,
    el("div", { class: "nav" },
      opts.extra || null,
      profileBtn,
      langSelect,
      logoutBtn,
    )
  );
}

// Self-contained profile modal: language and password only. Username/display
// name are read-only here (only system admin can change them).
function openProfileModal(user) {
  const backdrop = el("div", { class: "modal-backdrop",
    onclick: (e) => { if (e.target === backdrop) backdrop.remove(); } });

  const password = el("input", { type: "password", placeholder: t("leave_blank_keep") });
  const lang = el("select", null,
    ...I18N_AVAILABLE.map((l) => el("option", { value: l, selected: l === user.language }, I18N_NAMES[l]))
  );
  const err = el("div", { class: "muted", style: { color: "var(--danger)", display: "none" } });
  const ok = el("div", { class: "muted", style: { color: "var(--accent)", display: "none" } });

  const usernameField = el("input", { type: "text", value: user.username, disabled: true });
  const displayField = el("input", { type: "text", value: user.display_name || "", disabled: true });

  const modal = el("div", { class: "modal" },
    el("h3", null, t("profile")),
    el("div", { class: "field" }, el("label", null, t("username")), usernameField,
      el("div", { class: "muted small" }, t("profile_username_readonly"))),
    el("div", { class: "field" }, el("label", null, t("display_name")), displayField,
      el("div", { class: "muted small" }, t("profile_displayname_readonly"))),
    el("div", { class: "field" }, el("label", null, t("language")), lang),
    el("div", { class: "field" }, el("label", null, t("new_password")), password),
    err, ok,
    el("div", { class: "row", style: { justifyContent: "flex-end", marginTop: "1rem" } },
      el("button", { onclick: () => backdrop.remove() }, t("cancel")),
      el("button", { class: "primary", onclick: async () => {
        err.style.display = "none"; ok.style.display = "none";
        const body = {};
        if (lang.value !== user.language) body.language = lang.value;
        if (password.value) body.password = password.value;
        if (Object.keys(body).length === 0) { backdrop.remove(); return; }
        try {
          const u = await API.updateMe(body);
          if (u.language !== user.language) {
            user.language = u.language;
            await setLang(u.language);
          }
          ok.textContent = t("saved");
          ok.style.display = "block";
          setTimeout(() => { backdrop.remove(); location.reload(); }, 600);
        } catch (e) {
          err.textContent = (e.data && e.data.error) || e.message || "error";
          err.style.display = "block";
        }
      } }, t("save")),
    ),
  );
  backdrop.appendChild(modal);
  document.body.appendChild(backdrop);
}

// Read URL search params as an object.
function queryParams() {
  const out = {};
  const sp = new URLSearchParams(location.search);
  for (const [k, v] of sp.entries()) out[k] = v;
  return out;
}