(function () {
  const FETCH_TIMEOUT_MS = 15000;
  const RETRY_DELAY_MS = 800;
  const RETRY_AFTER_ACCESS_DENIED_MS = 1200;

  const MONTHS = [
    "Январь", "Февраль", "Март", "Апрель", "Май", "Июнь",
    "Июль", "Август", "Сентябрь", "Октябрь", "Ноябрь", "Декабрь"
  ];

  let current = new Date();
  const calendarEl = document.getElementById("calendar");
  const monthTitleEl = document.getElementById("monthTitle");
  const dutyListEl = document.getElementById("dutyList");
  const loadingEl = document.getElementById("loading");
  const errorEl = document.getElementById("error");
  const accessDeniedEl = document.getElementById("accessDenied");
  const headerEl = document.querySelector(".header");
  const weekdaysEl = document.querySelector(".weekdays");
  const prevBtn = document.getElementById("prevMonth");
  const nextBtn = document.getElementById("nextMonth");

  function isoDate(d) {
    return d.toISOString().slice(0, 10);
  }

  function firstDayOfMonth(d) {
    return new Date(d.getFullYear(), d.getMonth(), 1);
  }

  function lastDayOfMonth(d) {
    return new Date(d.getFullYear(), d.getMonth() + 1, 0);
  }

  function getMonday(d) {
    const day = d.getDay();
    const diff = d.getDate() - day + (day === 0 ? -6 : 1);
    return new Date(d.getFullYear(), d.getMonth(), diff);
  }

  /** Get tgWebAppData value from hash when it contains unencoded & and = (URLSearchParams would split it). Value runs from tgWebAppData= until next &tgWebApp or end. */
  function getTgWebAppDataFromHash(hash) {
    var idx = hash.indexOf("tgWebAppData=");
    if (idx === -1) return "";
    var start = idx + "tgWebAppData=".length;
    var end = hash.indexOf("&tgWebApp", start);
    if (end === -1) end = hash.length;
    var raw = hash.substring(start, end);
    try {
      return decodeURIComponent(raw);
    } catch (e) {
      return raw;
    }
  }

  function getInitData() {
    var fromSdk = (window.Telegram && window.Telegram.WebApp && window.Telegram.WebApp.initData) || "";
    if (fromSdk) return fromSdk;
    var hash = window.location.hash ? window.location.hash.slice(1) : "";
    if (hash) {
      var fromHash = getTgWebAppDataFromHash(hash);
      if (fromHash) return fromHash;
      try {
        var hashParams = new URLSearchParams(hash);
        var tgFromHash = hashParams.get("tgWebAppData");
        if (tgFromHash) return decodeURIComponent(tgFromHash);
      } catch (e) { /* ignore */ }
    }
    var q = window.location.search ? new URLSearchParams(window.location.search).get("tgWebAppData") : null;
    if (q) {
      try {
        return decodeURIComponent(q);
      } catch (e) {
        return q;
      }
    }
    return "";
  }

  function isLocalhost() {
    var h = window.location.hostname;
    return h === "localhost" || h === "127.0.0.1" || h === "";
  }

  function hasTelegramHashButNoInitData() {
    var hash = window.location.hash ? window.location.hash.slice(1) : "";
    if (!hash) return false;
    try {
      var keys = Array.from(new URLSearchParams(hash).keys());
      var hasVersion = keys.indexOf("tgWebAppVersion") !== -1;
      var hasData = keys.indexOf("tgWebAppData") !== -1 || getTgWebAppDataFromHash(hash);
      return hasVersion && !hasData;
    } catch (e) { return false; }
  }

  /** @param {string} [serverDetail] - message from API 403 detail (unused; kept for callers) */
  function showAccessDenied(serverDetail) {
    if (headerEl) headerEl.hidden = true;
    if (weekdaysEl) weekdaysEl.hidden = true;
    calendarEl.hidden = true;
    dutyListEl.hidden = true;
    loadingEl.classList.add("hidden");
    errorEl.hidden = true;
    accessDeniedEl.hidden = false;
  }

  function hideAccessDenied() {
    accessDeniedEl.hidden = true;
    if (headerEl) headerEl.hidden = false;
    if (weekdaysEl) weekdaysEl.hidden = false;
    calendarEl.hidden = false;
    dutyListEl.hidden = false;
  }

  async function fetchDuties(from, to) {
    const base = window.location.origin;
    const url = base + "/api/duties?from=" + encodeURIComponent(from) + "&to=" + encodeURIComponent(to);
    const initData = getInitData();
    const headers = {};
    if (initData) headers["X-Telegram-Init-Data"] = initData;
    var controller = new AbortController();
    var timeoutId = setTimeout(function () { controller.abort(); }, FETCH_TIMEOUT_MS);
    try {
      var res = await fetch(url, { headers: headers, signal: controller.signal });
      if (res.status === 403) {
        var detail = "Доступ запрещён";
        try {
          var body = await res.json();
          if (body && body.detail !== undefined) {
            detail = typeof body.detail === "string" ? body.detail : (body.detail.msg || JSON.stringify(body.detail));
          }
        } catch (parseErr) { /* ignore */ }
        var err = new Error("ACCESS_DENIED");
        err.serverDetail = detail;
        throw err;
      }
      if (!res.ok) throw new Error("Ошибка загрузки");
      return res.json();
    } catch (e) {
      if (e.name === "AbortError") {
        throw new Error("Не удалось загрузить данные. Проверьте интернет.");
      }
      throw e;
    } finally {
      clearTimeout(timeoutId);
    }
  }

  function renderCalendar(year, month, dutiesByDate) {
    const first = firstDayOfMonth(new Date(year, month, 1));
    const last = lastDayOfMonth(new Date(year, month, 1));
    const start = getMonday(first);
    const today = isoDate(new Date());

    calendarEl.innerHTML = "";
    let d = new Date(start);
    const cells = 42;
    for (let i = 0; i < cells; i++) {
      const key = isoDate(d);
      const isOther = d.getMonth() !== month;
      const dayDuties = dutiesByDate[key] || [];
      const isToday = key === today;

      const cell = document.createElement("div");
      cell.className = "day" + (isOther ? " other-month" : "") + (isToday ? " today" : "") + (dayDuties.length ? " has-duty" : "");
      cell.innerHTML =
        "<span class=\"num\">" + d.getDate() + "</span>" +
        (dayDuties.length ? "<span class=\"day-duties\">" + dayDuties.map(function (x) { return escapeHtml(x.full_name); }).join(", ") + "</span>" : "");
      calendarEl.appendChild(cell);
      d.setDate(d.getDate() + 1);
    }

    monthTitleEl.textContent = MONTHS[month] + " " + year;
  }

  function renderDutyList(duties) {
    if (duties.length === 0) {
      dutyListEl.innerHTML = "<p class=\"muted\">В этом месяце дежурств нет.</p>";
      return;
    }
    const grouped = {};
    duties.forEach(function (d) {
      const date = d.start_at.slice(0, 10);
      if (!grouped[date]) grouped[date] = [];
      grouped[date].push(d);
    });
    const dates = Object.keys(grouped).sort();
    let html = "";
    dates.forEach(function (date) {
      const list = grouped[date];
      html += "<h2>" + date + "</h2>";
      list.forEach(function (d) {
        const start = d.start_at.slice(11, 16);
        const end = d.end_at.slice(11, 16);
        html += "<div class=\"duty-item\"><span class=\"name\">" + escapeHtml(d.full_name) + "</span><div class=\"time\">" + start + " – " + end + "</div></div>";
      });
    });
    dutyListEl.innerHTML = html;
  }

  function escapeHtml(s) {
    const div = document.createElement("div");
    div.textContent = s;
    return div.innerHTML;
  }

  function dutiesByDate(duties) {
    const byDate = {};
    duties.forEach(function (d) {
      const start = new Date(d.start_at);
      const end = new Date(d.end_at);
      for (let t = new Date(start); t <= end; t.setDate(t.getDate() + 1)) {
        const key = isoDate(t);
        if (!byDate[key]) byDate[key] = [];
        byDate[key].push(d);
      }
    });
    return byDate;
  }

  function showError(msg) {
    errorEl.textContent = msg;
    errorEl.hidden = false;
    loadingEl.classList.add("hidden");
  }

  function runWhenReady(cb) {
    if (window.Telegram && window.Telegram.WebApp) {
      if (window.Telegram.WebApp.ready) {
        window.Telegram.WebApp.ready();
      }
      if (window.Telegram.WebApp.expand) {
        window.Telegram.WebApp.expand();
      }
      setTimeout(cb, 0);
    } else {
      cb();
    }
  }

  /** If allowed (initData or localhost), call onAllowed(); otherwise show access denied. When inside Telegram WebApp but initData is empty, retry once after a short delay (initData may be set asynchronously). */
  function requireTelegramOrLocalhost(onAllowed) {
    var initData = getInitData();
    var isLocal = isLocalhost();
    if (initData) { onAllowed(); return; }
    if (isLocal) { onAllowed(); return; }
    if (window.Telegram && window.Telegram.WebApp) {
      setTimeout(function () {
        initData = getInitData();
        if (initData) { onAllowed(); return; }
        showAccessDenied();
        loadingEl.classList.add("hidden");
      }, RETRY_DELAY_MS);
      return;
    }
    showAccessDenied();
    loadingEl.classList.add("hidden");
  }

  function setNavEnabled(enabled) {
    if (prevBtn) prevBtn.disabled = !enabled;
    if (nextBtn) nextBtn.disabled = !enabled;
  }

  async function loadMonth() {
    hideAccessDenied();
    setNavEnabled(false);
    loadingEl.classList.remove("hidden");
    errorEl.hidden = true;
    const from = isoDate(firstDayOfMonth(current));
    const to = isoDate(lastDayOfMonth(current));
    try {
      const duties = await fetchDuties(from, to);
      const byDate = dutiesByDate(duties);
      renderCalendar(current.getFullYear(), current.getMonth(), byDate);
      renderDutyList(duties);
    } catch (e) {
      if (e.message === "ACCESS_DENIED") {
        showAccessDenied(e.serverDetail);
        setNavEnabled(true);
        if (window.Telegram && window.Telegram.WebApp && !window._initDataRetried) {
          window._initDataRetried = true;
          setTimeout(loadMonth, RETRY_AFTER_ACCESS_DENIED_MS);
        }
        return;
      }
      showError(e.message || "Не удалось загрузить данные.");
      setNavEnabled(true);
      return;
    }
    loadingEl.classList.add("hidden");
    setNavEnabled(true);
  }

  document.getElementById("prevMonth").addEventListener("click", function () {
    if (!accessDeniedEl.hidden) return;
    current.setMonth(current.getMonth() - 1);
    loadMonth();
  });
  document.getElementById("nextMonth").addEventListener("click", function () {
    if (!accessDeniedEl.hidden) return;
    current.setMonth(current.getMonth() + 1);
    loadMonth();
  });

  runWhenReady(function () {
    requireTelegramOrLocalhost(function () {
      loadMonth();
    });
  });
})();