/**
 * Current duty view: full-screen card when opened via Mini App deep link (startapp=duty).
 * Fetches today's duties, finds the active one (start <= now < end), shows name, shift, contacts.
 */

import { getCurrentDutyViewEl, state, getLoadingEl } from "./dom.js";
import { t } from "./i18n.js";
import { escapeHtml } from "./utils.js";
import { buildContactLinksHtml } from "./contactHtml.js";
import { fetchDuties } from "./api.js";
import {
  localDateString,
  dateKeyToDDMM,
  formatHHMM
} from "./dateUtils.js";

/** Empty calendar icon for "no duty" state (outline, stroke). */
const ICON_NO_DUTY =
  '<svg xmlns="http://www.w3.org/2000/svg" width="48" height="48" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.5" stroke-linecap="round" stroke-linejoin="round" aria-hidden="true"><rect x="3" y="4" width="18" height="18" rx="2" ry="2"/><line x1="16" y1="2" x2="16" y2="6"/><line x1="8" y1="2" x2="8" y2="6"/><line x1="3" y1="10" x2="21" y2="10"/></svg>';

/** @type {(() => void)|null} Callback when user taps "Back to calendar". */
let onBackCallback = null;
/** @type {(() => void)|null} Handler registered with Telegram BackButton.onClick. */
let backButtonHandler = null;

/**
 * Compute remaining time until end of shift. Call only when now < end (active duty).
 * @param {string|Date} endAt - ISO end time of the shift
 * @returns {{ hours: number, minutes: number }}
 */
export function getRemainingTime(endAt) {
  const end = new Date(endAt).getTime();
  const now = Date.now();
  const ms = Math.max(0, end - now);
  const hours = Math.floor(ms / (1000 * 60 * 60));
  const minutes = Math.floor((ms % (1000 * 60 * 60)) / (1000 * 60));
  return { hours, minutes };
}

/**
 * Find the duty that is currently active (start <= now < end). Prefer event_type === "duty".
 * @param {object[]} duties - List of duties with start_at, end_at, event_type
 * @returns {object|null}
 */
export function findCurrentDuty(duties) {
  const now = Date.now();
  const dutyType = (duties || []).filter((d) => d.event_type === "duty");
  const candidates = dutyType.length ? dutyType : duties || [];
  for (const d of candidates) {
    const start = new Date(d.start_at).getTime();
    const end = new Date(d.end_at).getTime();
    if (start <= now && now < end) return d;
  }
  return null;
}

/**
 * Render the current duty view content (card with duty or no-duty message).
 * @param {object|null} duty - Active duty or null
 * @param {string} lang
 * @returns {string}
 */
export function renderCurrentDutyContent(duty, lang) {
  const backLabel = t(lang, "current_duty.back");
  const title = t(lang, "current_duty.title");

  if (!duty) {
    const noDuty = t(lang, "current_duty.no_duty");
    return (
      '<div class="current-duty-card current-duty-card--no-duty">' +
      '<h2 class="current-duty-title">' +
      escapeHtml(title) +
      "</h2>" +
      '<div class="current-duty-no-duty-wrap">' +
      '<span class="current-duty-no-duty-icon">' +
      ICON_NO_DUTY +
      "</span>" +
      '<p class="current-duty-no-duty">' +
      escapeHtml(noDuty) +
      "</p>" +
      "</div>" +
      '<button type="button" class="current-duty-back-btn" data-action="back">' +
      escapeHtml(backLabel) +
      "</button>" +
      "</div>"
    );
  }

  const startLocal = localDateString(new Date(duty.start_at));
  const endLocal = localDateString(new Date(duty.end_at));
  const startDDMM = dateKeyToDDMM(startLocal);
  const endDDMM = dateKeyToDDMM(endLocal);
  const startTime = formatHHMM(duty.start_at);
  const endTime = formatHHMM(duty.end_at);
  const shiftStr =
    startDDMM +
    " " +
    startTime +
    " — " +
    endDDMM +
    " " +
    endTime;
  const shiftLabel = t(lang, "current_duty.shift");
  const { hours: remHours, minutes: remMinutes } = getRemainingTime(duty.end_at);
  const remainingStr = t(lang, "current_duty.remaining", {
    hours: String(remHours),
    minutes: String(remMinutes)
  });
  const contactHtml = buildContactLinksHtml(lang, duty.phone, duty.username, {
    classPrefix: "current-duty-contact",
    showLabels: true,
    separator: " ",
    layout: "block"
  });

  return (
    '<div class="current-duty-card">' +
    '<h2 class="current-duty-title">' +
    '<span class="current-duty-live-dot"></span> ' +
    escapeHtml(title) +
    "</h2>" +
    '<p class="current-duty-name">' +
    escapeHtml(duty.full_name) +
    "</p>" +
    '<div class="current-duty-shift">' +
    escapeHtml(shiftLabel) +
    ": " +
    escapeHtml(shiftStr) +
    "</div>" +
    '<div class="current-duty-remaining">' +
    escapeHtml(remainingStr) +
    "</div>" +
    contactHtml +
    '<button type="button" class="current-duty-back-btn" data-action="back">' +
    escapeHtml(backLabel) +
    "</button>" +
    "</div>"
  );
}

/**
 * Show the current duty view: fetch today's duties, render card or no-duty, show back button.
 * Hides calendar/duty list and shows #currentDutyView. Optionally shows Telegram BackButton.
 * @param {() => void} onBack - Callback when user taps "Back to calendar"
 */
export async function showCurrentDutyView(onBack) {
  const currentDutyViewEl = getCurrentDutyViewEl();
  const container = currentDutyViewEl && currentDutyViewEl.closest(".container");
  const calendarSticky = document.getElementById("calendarSticky");
  const dutyList = document.getElementById("dutyList");
  if (!currentDutyViewEl) return;

  onBackCallback = onBack;
  currentDutyViewEl.classList.remove("hidden");
  if (container) container.setAttribute("data-view", "currentDuty");
  if (calendarSticky) calendarSticky.hidden = true;
  if (dutyList) dutyList.hidden = true;
  const loadingEl = getLoadingEl();
  if (loadingEl) loadingEl.classList.add("hidden");

  const lang = state.lang;
  currentDutyViewEl.innerHTML =
    '<div class="current-duty-loading">' +
    escapeHtml(t(lang, "loading")) +
    "</div>";

  if (window.Telegram && window.Telegram.WebApp && window.Telegram.WebApp.BackButton) {
    window.Telegram.WebApp.BackButton.show();
    const handler = () => {
      if (onBackCallback) onBackCallback();
    };
    backButtonHandler = handler;
    window.Telegram.WebApp.BackButton.onClick(handler);
  }

  const today = new Date();
  const from = localDateString(today);
  const to = from;
  try {
    const duties = await fetchDuties(from, to);
    const duty = findCurrentDuty(duties);
    currentDutyViewEl.innerHTML = renderCurrentDutyContent(duty, lang);
  } catch (e) {
    currentDutyViewEl.innerHTML =
      '<div class="current-duty-card">' +
      '<p class="current-duty-error">' +
      escapeHtml(e.message || t(lang, "error_generic")) +
      "</p>" +
      '<button type="button" class="current-duty-back-btn" data-action="back">' +
      escapeHtml(t(lang, "current_duty.back")) +
      "</button>" +
      "</div>";
  }

  currentDutyViewEl.addEventListener("click", handleCurrentDutyClick);
}

/**
 * Delegate click for back button.
 * @param {MouseEvent} e
 */
function handleCurrentDutyClick(e) {
  const btn = e.target && e.target.closest("[data-action='back']");
  if (!btn) return;
  if (onBackCallback) onBackCallback();
}

/**
 * Hide the current duty view and show calendar/duty list again.
 * Hides Telegram BackButton and calls loadMonth so calendar is populated.
 */
export function hideCurrentDutyView() {
  const currentDutyViewEl = getCurrentDutyViewEl();
  const container = currentDutyViewEl && currentDutyViewEl.closest(".container");
  const calendarSticky = document.getElementById("calendarSticky");
  const dutyList = document.getElementById("dutyList");

  if (window.Telegram && window.Telegram.WebApp && window.Telegram.WebApp.BackButton) {
    if (backButtonHandler) {
      window.Telegram.WebApp.BackButton.offClick(backButtonHandler);
    }
    window.Telegram.WebApp.BackButton.hide();
  }
  if (currentDutyViewEl) {
    currentDutyViewEl.removeEventListener("click", handleCurrentDutyClick);
    currentDutyViewEl.classList.add("hidden");
    currentDutyViewEl.innerHTML = "";
  }
  onBackCallback = null;
  backButtonHandler = null;
  if (container) container.removeAttribute("data-view");
  if (calendarSticky) calendarSticky.hidden = false;
  if (dutyList) dutyList.hidden = false;
}