/**
 * Entry point: theme init, auth gate, loadMonth, nav and swipe handlers.
 */

import { initTheme, applyTheme } from "./theme.js";
import { getLang, t, weekdayLabels } from "./i18n.js";
import { getInitData, isLocalhost } from "./auth.js";
import { RETRY_DELAY_MS, RETRY_AFTER_ACCESS_DENIED_MS } from "./constants.js";
import {
  state,
  getAccessDeniedEl,
  getPrevBtn,
  getNextBtn,
  getLoadingEl,
  getErrorEl,
  getWeekdaysEl
} from "./dom.js";
import { showAccessDenied, hideAccessDenied, showError, setNavEnabled } from "./ui.js";
import { fetchDuties, fetchCalendarEvents } from "./api.js";
import { logger } from "./logger.js";
import {
  dutiesByDate,
  calendarEventsByDate,
  renderCalendar
} from "./calendar.js";
import { initDayDetail } from "./dayDetail.js";
import { initHints } from "./hints.js";
import { renderDutyList } from "./dutyList.js";
import { showCurrentDutyView, hideCurrentDutyView } from "./currentDuty.js";
import {
  firstDayOfMonth,
  lastDayOfMonth,
  getMonday,
  localDateString,
  dutyOverlapsLocalRange
} from "./dateUtils.js";

initTheme();

state.lang = getLang();

/**
 * Apply current state.lang to document and locale-dependent UI elements (title, loading, weekdays, nav).
 * Call at startup and after re-evaluating lang when initData becomes available.
 * Exported for tests.
 */
export function applyLangToUi() {
  document.documentElement.lang = state.lang;
  document.title = t(state.lang, "app.title");
  const loadingEl = getLoadingEl();
  const loadingTextEl = loadingEl ? loadingEl.querySelector(".loading__text") : null;
  if (loadingTextEl) loadingTextEl.textContent = t(state.lang, "loading");
  const dayLabels = weekdayLabels(state.lang);
  const weekdaysEl = getWeekdaysEl();
  if (weekdaysEl) {
    const spans = weekdaysEl.querySelectorAll("span");
    spans.forEach((span, i) => {
      if (dayLabels[i]) span.textContent = dayLabels[i];
    });
  }
  const prevBtn = getPrevBtn();
  const nextBtn = getNextBtn();
  if (prevBtn) prevBtn.setAttribute("aria-label", t(state.lang, "nav.prev_month"));
  if (nextBtn) nextBtn.setAttribute("aria-label", t(state.lang, "nav.next_month"));
}

applyLangToUi();

logger.info("App init", "lang=" + state.lang);

window.__dtReady = true;

/**
 * Run callback when Telegram WebApp is ready (or immediately outside Telegram).
 * Expands and applies theme when in TWA.
 * @param {() => void} cb
 */
function runWhenReady(cb) {
  if (window.Telegram && window.Telegram.WebApp) {
    if (window.Telegram.WebApp.expand) {
      window.Telegram.WebApp.expand();
    }
    applyTheme();
    if (window.Telegram.WebApp.onEvent) {
      window.Telegram.WebApp.onEvent("theme_changed", applyTheme);
    }
    requestAnimationFrame(() => applyTheme());
    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.
 * @param {() => void} onAllowed
 */
function requireTelegramOrLocalhost(onAllowed) {
  let initData = getInitData();
  const isLocal = isLocalhost();
  if (initData) {
    onAllowed();
    return;
  }
  if (isLocal) {
    onAllowed();
    return;
  }
  if (window.Telegram && window.Telegram.WebApp) {
    setTimeout(() => {
      initData = getInitData();
      if (initData) {
        onAllowed();
        return;
      }
      showAccessDenied(undefined);
      const loading = getLoadingEl();
      if (loading) loading.classList.add("hidden");
    }, RETRY_DELAY_MS);
    return;
  }
  showAccessDenied(undefined);
  const loading = getLoadingEl();
  if (loading) loading.classList.add("hidden");
}

/** AbortController for the in-flight loadMonth request; aborted when a new load starts. */
let loadMonthAbortController = null;

/**
 * Load current month: fetch duties and events, render calendar and duty list.
 * Stale requests are cancelled when the user navigates to another month before they complete.
 */
async function loadMonth() {
  if (loadMonthAbortController) loadMonthAbortController.abort();
  loadMonthAbortController = new AbortController();
  const signal = loadMonthAbortController.signal;

  hideAccessDenied();
  setNavEnabled(false);
  const loadingEl = getLoadingEl();
  if (loadingEl) loadingEl.classList.remove("hidden");
  const errorEl = getErrorEl();
  if (errorEl) errorEl.hidden = true;
  const current = state.current;
  const first = firstDayOfMonth(current);
  const start = getMonday(first);
  const gridEnd = new Date(start);
  gridEnd.setDate(gridEnd.getDate() + 41);
  const from = localDateString(start);
  const to = localDateString(gridEnd);
  try {
    logger.debug("Loading month", from, to);
    const dutiesPromise = fetchDuties(from, to, signal);
    const eventsPromise = fetchCalendarEvents(from, to, signal);
    const duties = await dutiesPromise;
    const events = await eventsPromise;
    const byDate = dutiesByDate(duties);
    const calendarByDate = calendarEventsByDate(events);
    renderCalendar(current.getFullYear(), current.getMonth(), byDate, calendarByDate);
    const last = lastDayOfMonth(current);
    const firstKey = localDateString(first);
    const lastKey = localDateString(last);
    const dutiesInMonth = duties.filter((d) =>
      dutyOverlapsLocalRange(d, firstKey, lastKey)
    );
    state.lastDutiesForList = dutiesInMonth;
    renderDutyList(dutiesInMonth);
    if (state.todayRefreshInterval) {
      clearInterval(state.todayRefreshInterval);
    }
    state.todayRefreshInterval = null;
    const viewedMonth = current.getFullYear() * 12 + current.getMonth();
    const thisMonth =
      new Date().getFullYear() * 12 + new Date().getMonth();
    if (viewedMonth === thisMonth) {
      state.todayRefreshInterval = setInterval(() => {
        if (
          current.getFullYear() * 12 + current.getMonth() !==
          new Date().getFullYear() * 12 + new Date().getMonth()
        ) {
          return;
        }
        renderDutyList(state.lastDutiesForList);
      }, 60000);
    }
  } catch (e) {
    if (e.name === "AbortError") {
      return;
    }
    if (e.message === "ACCESS_DENIED") {
      logger.warn("Access denied in loadMonth", e.serverDetail);
      showAccessDenied(e.serverDetail);
      setNavEnabled(true);
      if (
        window.Telegram &&
        window.Telegram.WebApp &&
        !state.initDataRetried
      ) {
        state.initDataRetried = true;
        setTimeout(loadMonth, RETRY_AFTER_ACCESS_DENIED_MS);
      }
      return;
    }
    logger.error("Load month failed", e);
    showError(e.message || t(state.lang, "error_generic"), loadMonth);
    setNavEnabled(true);
    return;
  }
  const errorEl2 = getErrorEl();
  if (errorEl2) errorEl2.hidden = true;
  const loading = getLoadingEl();
  if (loading) loading.classList.add("hidden");
  setNavEnabled(true);
}

const prevBtnEl = getPrevBtn();
if (prevBtnEl) {
  prevBtnEl.addEventListener("click", () => {
    if (document.body.classList.contains("day-detail-sheet-open")) return;
    const accessDeniedEl = getAccessDeniedEl();
    if (accessDeniedEl && !accessDeniedEl.hidden) return;
    state.current.setMonth(state.current.getMonth() - 1);
    loadMonth();
  });
}
const nextBtnEl = getNextBtn();
if (nextBtnEl) {
  nextBtnEl.addEventListener("click", () => {
    if (document.body.classList.contains("day-detail-sheet-open")) return;
    const accessDeniedEl = getAccessDeniedEl();
    if (accessDeniedEl && !accessDeniedEl.hidden) return;
    state.current.setMonth(state.current.getMonth() + 1);
    loadMonth();
  });
}

(function bindSwipeMonth() {
  const swipeEl = document.getElementById("calendarSticky");
  if (!swipeEl) return;
  let startX = 0;
  let startY = 0;
  const SWIPE_THRESHOLD = 50;
  swipeEl.addEventListener(
    "touchstart",
    (e) => {
      if (e.changedTouches.length === 0) return;
      const touch = e.changedTouches[0];
      startX = touch.clientX;
      startY = touch.clientY;
    },
    { passive: true }
  );
  swipeEl.addEventListener(
    "touchend",
    (e) => {
      if (e.changedTouches.length === 0) return;
      if (document.body.classList.contains("day-detail-sheet-open")) return;
      const accessDeniedEl = getAccessDeniedEl();
      if (accessDeniedEl && !accessDeniedEl.hidden) return;
      const touch = e.changedTouches[0];
      const deltaX = touch.clientX - startX;
      const deltaY = touch.clientY - startY;
      if (Math.abs(deltaX) <= SWIPE_THRESHOLD) return;
      if (Math.abs(deltaY) > Math.abs(deltaX)) return;
      const prevBtn = getPrevBtn();
      const nextBtn = getNextBtn();
      if (deltaX > SWIPE_THRESHOLD) {
        if (prevBtn && prevBtn.disabled) return;
        state.current.setMonth(state.current.getMonth() - 1);
        loadMonth();
      } else if (deltaX < -SWIPE_THRESHOLD) {
        if (nextBtn && nextBtn.disabled) return;
        state.current.setMonth(state.current.getMonth() + 1);
        loadMonth();
      }
    },
    { passive: true }
  );
})();

function bindStickyScrollShadow() {
  const stickyEl = document.getElementById("calendarSticky");
  if (!stickyEl || state.stickyScrollBound) return;
  state.stickyScrollBound = true;
  function updateScrolled() {
    stickyEl.classList.toggle("is-scrolled", window.scrollY > 0);
  }
  window.addEventListener("scroll", updateScrolled, { passive: true });
  updateScrolled();
}

runWhenReady(() => {
  requireTelegramOrLocalhost(() => {
    const newLang = getLang();
    if (newLang !== state.lang) {
      state.lang = newLang;
      applyLangToUi();
    }
    bindStickyScrollShadow();
    initDayDetail();
    initHints();
    const startParam =
      (window.Telegram && window.Telegram.WebApp && window.Telegram.WebApp.initDataUnsafe &&
        window.Telegram.WebApp.initDataUnsafe.start_param) ||
      "";
    if (startParam === "duty") {
      showCurrentDutyView(() => {
        hideCurrentDutyView();
        loadMonth();
      });
    } else {
      loadMonth();
    }
  });
});