/* RustBox UI module: 71-calendar.js */
function startOfCalendarDay(date) {
  return new Date(date.getFullYear(), date.getMonth(), date.getDate());
}

function addCalendarDays(date, count) {
  const next = new Date(date);
  next.setDate(next.getDate() + count);
  return next;
}

function startOfCalendarWeek(date) {
  const start = startOfCalendarDay(date);
  const day = start.getDay();
  const mondayOffset = day === 0 ? -6 : 1 - day;
  return addCalendarDays(start, mondayOffset);
}

function calendarRange(date, view = state.calendarView) {
  if (view === "week") {
    const start = startOfCalendarWeek(date);
    return { start, end: addCalendarDays(start, 7) };
  }
  if (view === "day") {
    const start = startOfCalendarDay(date);
    return { start, end: addCalendarDays(start, 1) };
  }
  if (view === "agenda") {
    const start = startOfCalendarDay(date);
    return { start, end: addCalendarDays(start, 30) };
  }
  const first = new Date(date.getFullYear(), date.getMonth(), 1);
  const start = startOfCalendarWeek(first);
  return { start, end: addCalendarDays(start, 42) };
}

function calendarDayKey(value) {
  const date = value instanceof Date ? value : new Date(value);
  if (Number.isNaN(date.getTime())) return "";
  return `${date.getFullYear()}-${String(date.getMonth() + 1).padStart(2, "0")}-${String(date.getDate()).padStart(2, "0")}`;
}

function calendarRangeLabel() {
  const cursor = state.calendarCursor;
  if (state.calendarView === "month") return cursor.toLocaleDateString([], { month: "long", year: "numeric" });
  if (state.calendarView === "day") return cursor.toLocaleDateString([], { weekday: "long", year: "numeric", month: "long", day: "numeric" });
  const { start, end } = calendarRange(cursor);
  const last = addCalendarDays(end, -1);
  if (state.calendarView === "agenda") return `${start.toLocaleDateString()} – ${last.toLocaleDateString()}`;
  return `${start.toLocaleDateString([], { month: "short", day: "numeric" })} – ${last.toLocaleDateString([], { month: "short", day: "numeric", year: "numeric" })}`;
}

function shiftCalendarCursor(direction) {
  const cursor = new Date(state.calendarCursor);
  if (state.calendarView === "month") cursor.setMonth(cursor.getMonth() + direction);
  else if (state.calendarView === "week") cursor.setDate(cursor.getDate() + (7 * direction));
  else if (state.calendarView === "agenda") cursor.setDate(cursor.getDate() + (30 * direction));
  else cursor.setDate(cursor.getDate() + direction);
  state.calendarCursor = cursor;
}

function toLocalInput(value) {
  const date = new Date(value);
  if (Number.isNaN(date.getTime())) return "";
  const local = new Date(date.getTime() - date.getTimezoneOffset() * 60000);
  return local.toISOString().slice(0, 16);
}

async function importCalendarIcs(files) {
  const file = files?.[0];
  if (!file) return;
  if (file.size > 10 * 1024 * 1024) return toast("ICS file is too large", "error");
  try {
    const text = await file.text();
    const headers = new Headers({ "Content-Type": "text/calendar; charset=utf-8", "X-Requested-With": "XMLHttpRequest" });
    if (state.accountId) headers.set("X-Active-Account", state.accountId);
    const response = await fetch(apiPath("/calendar/events/import-ics"), { method: "POST", credentials: "include", headers, body: text });
    const data = await response.json().catch(() => ({}));
    if (!response.ok) throw new Error(data?.error?.message || `ICS import failed (${response.status})`);
    toast(`ICS import: ${data.created || 0} created, ${data.skipped || 0} skipped`);
    await loadCalendar();
  } catch (error) { toast(error.message, "error"); }
  finally { $("#calendar-import-file").value = ""; }
}

async function exportCalendarIcs() {
  try {
    const headers = new Headers();
    if (state.accountId) headers.set("X-Active-Account", state.accountId);
    const response = await fetch(apiPath("/calendar/events/export-ics"), { credentials: "include", headers });
    if (!response.ok) throw new Error(`Calendar export failed (${response.status})`);
    const blob = await response.blob();
    const url = URL.createObjectURL(blob);
    const link = document.createElement("a");
    link.href = url;
    link.download = "rustbox-calendar.ics";
    document.body.append(link);
    link.click();
    link.remove();
    setTimeout(() => URL.revokeObjectURL(url), 1000);
  } catch (error) { toast(error.message, "error"); }
}

async function openCalendar() {
  $("#calendar-dialog").showModal();
  await loadCalendar();
}

async function loadCalendar() {
  const { start, end } = calendarRange(state.calendarCursor);
  $("#calendar-view").value = state.calendarView;
  $("#calendar-range").textContent = calendarRangeLabel();
  try {
    const data = await request(`/calendar/events?start=${encodeURIComponent(start.toISOString())}&end=${encodeURIComponent(end.toISOString())}`, { method: "GET" });
    state.calendarEvents = data.events || [];
    renderCalendarEvents();
  } catch (error) { toast(error.message, "error"); }
}

function createCalendarEventButton(event, compact = false) {
  const button = el("button", compact ? "calendar-event-chip" : "calendar-event");
  button.type = "button";
  const color = /^#[0-9a-f]{6}$/i.test(String(event.color || "")) ? event.color : "var(--accent)";
  button.style.setProperty("--event-color", color);
  if (compact) {
    const time = event.all_day ? "All day" : new Date(event.start_time).toLocaleTimeString([], { hour: "2-digit", minute: "2-digit" });
    button.innerHTML = `<span>${escapeHtml(time)}</span><strong>${escapeHtml(event.title)}</strong>`;
  } else {
    button.innerHTML = `<time>${escapeHtml(formatDate(event.start_time, true))}</time><div><strong>${escapeHtml(event.title)}</strong><small>${escapeHtml(event.location || "")}</small></div><span>${escapeHtml(event.status || "")}</span>`;
  }
  button.addEventListener("click", () => editCalendarEvent(event));
  return button;
}

function renderCalendarMonthOrWeek(view) {
  const host = $("#calendar-events");
  const { start, end } = calendarRange(state.calendarCursor, view);
  const days = view === "week" ? 7 : 42;
  const grid = el("div", `calendar-grid calendar-${view}-grid`);
  for (const label of ["Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun"]) grid.append(el("div", "calendar-weekday", label));
  const byDay = new Map();
  for (const event of state.calendarEvents) {
    const key = calendarDayKey(event.start_time);
    if (!byDay.has(key)) byDay.set(key, []);
    byDay.get(key).push(event);
  }
  for (let i = 0; i < days; i++) {
    const date = addCalendarDays(start, i);
    const cell = el("section", "calendar-day-cell");
    if (view === "month" && date.getMonth() !== state.calendarCursor.getMonth()) cell.classList.add("outside-month");
    if (calendarDayKey(date) === calendarDayKey(new Date())) cell.classList.add("today");
    const heading = el("button", "calendar-day-number", String(date.getDate()));
    heading.type = "button";
    heading.title = "Create event on this day";
    heading.addEventListener("click", () => {
      const startDate = new Date(date); startDate.setHours(9, 0, 0, 0);
      const endDate = new Date(startDate.getTime() + 3600000);
      editCalendarEvent(null);
      $("#calendar-start").value = toLocalInput(startDate);
      $("#calendar-end").value = toLocalInput(endDate);
    });
    cell.append(heading);
    const dayEvents = (byDay.get(calendarDayKey(date)) || []).sort((a, b) => new Date(a.start_time) - new Date(b.start_time));
    for (const event of dayEvents.slice(0, view === "month" ? 4 : 12)) cell.append(createCalendarEventButton(event, true));
    if (view === "month" && dayEvents.length > 4) cell.append(el("span", "calendar-more", `+${dayEvents.length - 4} more`));
    grid.append(cell);
  }
  host.append(grid);
}

function renderCalendarAgenda() {
  const host = $("#calendar-events");
  const groups = new Map();
  for (const event of state.calendarEvents) {
    const key = calendarDayKey(event.start_time);
    if (!groups.has(key)) groups.set(key, []);
    groups.get(key).push(event);
  }
  if (!groups.size) { host.append(el("div", "empty-list", "No events in this range")); return; }
  for (const [key, events] of [...groups.entries()].sort(([a], [b]) => a.localeCompare(b))) {
    const date = new Date(`${key}T12:00:00`);
    const section = el("section", "calendar-agenda-day");
    section.append(el("h4", "", date.toLocaleDateString([], { weekday: "long", month: "long", day: "numeric", year: "numeric" })));
    for (const event of events.sort((a, b) => new Date(a.start_time) - new Date(b.start_time))) section.append(createCalendarEventButton(event));
    host.append(section);
  }
}

function renderCalendarEvents() {
  const list = $("#calendar-events");
  list.replaceChildren();
  if (state.calendarView === "month" || state.calendarView === "week") {
    renderCalendarMonthOrWeek(state.calendarView);
    return;
  }
  if (!state.calendarEvents.length) {
    list.append(el("div", "empty-list", state.calendarView === "day" ? "No events today" : "No events in this range"));
    return;
  }
  renderCalendarAgenda();
}

function updateCalendarRecurrenceUi() {
  $("#calendar-rrule-wrap").classList.toggle("hidden", $("#calendar-recurrence").value !== "custom");
}

function editCalendarEvent(event = null) {
  $("#calendar-form").classList.remove("hidden");
  $("#calendar-event-id").value = event?.id || "";
  $("#calendar-title").value = event?.title || "";
  $("#calendar-start").value = event ? toLocalInput(event.start_time) : toLocalInput(new Date());
  $("#calendar-end").value = event ? toLocalInput(event.end_time) : toLocalInput(new Date(Date.now() + 3600000));
  $("#calendar-all-day").checked = Boolean(event?.all_day);
  const rule = event?.recurrence_rule || "";
  const commonRules = new Set(["", "FREQ=DAILY", "FREQ=WEEKLY", "FREQ=MONTHLY", "FREQ=YEARLY"]);
  $("#calendar-recurrence").value = commonRules.has(rule) ? rule : "custom";
  $("#calendar-rrule").value = commonRules.has(rule) ? "" : rule;
  updateCalendarRecurrenceUi();
  let attendees = [];
  try { attendees = JSON.parse(event?.attendees || "[]"); } catch (_) { }
  $("#calendar-attendees").value = Array.isArray(attendees) ? attendees.join(", ") : "";
  $("#calendar-organizer").value = event?.organizer || state.accounts.find((item) => item.id === state.accountId)?.email || "";
  $("#calendar-status").value = String(event?.status || "confirmed").toLowerCase();
  $("#calendar-location").value = event?.location || "";
  $("#calendar-meeting-url").value = event?.meeting_url || "";
  $("#calendar-description").value = event?.description || "";
  const color = String(event?.color || "");
  $("#calendar-color").value = /^#[0-9a-f]{6}$/i.test(color) ? color : "#6b7280";
  const reminder = event?.reminder_minutes == null ? "" : String(event.reminder_minutes);
  $("#calendar-reminder").value = Array.from($("#calendar-reminder").options).some((option) => option.value === reminder) ? reminder : "";
  $("#calendar-delete").disabled = !event;
}

async function saveCalendarEvent(event) {
  event.preventDefault();
  const id = $("#calendar-event-id").value;
  const recurrenceChoice = $("#calendar-recurrence").value;
  const recurrenceRule = recurrenceChoice === "custom" ? $("#calendar-rrule").value.trim() : recurrenceChoice;
  const attendees = $("#calendar-attendees").value.split(",").map((value) => value.trim()).filter(Boolean);
  const startValue = $("#calendar-start").value;
  const endValue = $("#calendar-end").value;
  if (!startValue || !endValue) return toast("Start and end are required", "error");
  const base = {
    title: $("#calendar-title").value.trim(),
    description: $("#calendar-description").value,
    location: $("#calendar-location").value.trim(),
    start_time: new Date(startValue).toISOString(),
    end_time: new Date(endValue).toISOString(),
    all_day: $("#calendar-all-day").checked,
    recurrence_rule: recurrenceRule || null,
    attendees: JSON.stringify(attendees),
    organizer: $("#calendar-organizer").value.trim(),
    status: $("#calendar-status").value || "confirmed",
    meeting_url: $("#calendar-meeting-url").value.trim() || null,
    color: $("#calendar-color").value || null,
    reminder_minutes: $("#calendar-reminder").value === "" ? null : Number($("#calendar-reminder").value),
  };
  const payload = id ? base : { ...base, source: "manual", source_uid: null, source_message_uid: null, source_message_folder: null };
  try { await request(id ? `/calendar/events/${encodeURIComponent(id)}` : "/calendar/events", { method: id ? "PUT" : "POST", body: JSON.stringify(payload) }); $("#calendar-form").classList.add("hidden"); await loadCalendar(); toast("Event saved"); }
  catch (error) { toast(error.message, "error"); }
}

async function deleteCalendarEvent() {
  const id = $("#calendar-event-id").value;
  if (!id || !await appConfirm("Delete this event?", { title: "Delete event", confirmLabel: "Delete", danger: true })) return;
  try { await request(`/calendar/events/${encodeURIComponent(id)}`, { method: "DELETE" }); $("#calendar-form").classList.add("hidden"); await loadCalendar(); toast("Event deleted"); }
  catch (error) { toast(error.message, "error"); }
}