/**
 * Calendar grid and events-by-date mapping.
 */

import { calendarEl, monthTitleEl } from "./dom.js";
import { MONTHS } from "./constants.js";
import { escapeHtml } from "./utils.js";
import {
  localDateString,
  firstDayOfMonth,
  lastDayOfMonth,
  getMonday
} from "./dateUtils.js";
import { bindInfoButtonTooltips } from "./hints.js";
import { bindDutyMarkerTooltips } from "./hints.js";

/**
 * Build { localDateKey -> array of summary strings }. API date is UTC YYYY-MM-DD; map to local.
 * @param {object[]} events - Calendar events with date, summary
 * @returns {Record<string, string[]>}
 */
export function calendarEventsByDate(events) {
  const byDate = {};
  (events || []).forEach((e) => {
    const utcMidnight = new Date(e.date + "T00:00:00Z");
    const key = localDateString(utcMidnight);
    if (!byDate[key]) byDate[key] = [];
    if (e.summary) byDate[key].push(e.summary);
  });
  return byDate;
}

/**
 * Group duties by local date (start_at/end_at are UTC).
 * @param {object[]} duties - Duties with start_at, end_at
 * @returns {Record<string, object[]>}
 */
export function dutiesByDate(duties) {
  const byDate = {};
  duties.forEach((d) => {
    const start = new Date(d.start_at);
    const end = new Date(d.end_at);
    const endLocal = localDateString(end);
    let t = new Date(start);
    while (true) {
      const key = localDateString(t);
      if (!byDate[key]) byDate[key] = [];
      byDate[key].push(d);
      if (key === endLocal) break;
      t.setDate(t.getDate() + 1);
    }
  });
  return byDate;
}

/**
 * Render calendar grid for given month with duties and calendar events.
 * @param {number} year
 * @param {number} month - 0-based
 * @param {Record<string, object[]>} dutiesByDateMap
 * @param {Record<string, string[]>} calendarEventsByDateMap
 */
export function renderCalendar(
  year,
  month,
  dutiesByDateMap,
  calendarEventsByDateMap
) {
  if (!calendarEl || !monthTitleEl) return;
  const first = firstDayOfMonth(new Date(year, month, 1));
  const last = lastDayOfMonth(new Date(year, month, 1));
  const start = getMonday(first);
  const today = localDateString(new Date());
  const calendarEventsByDate = calendarEventsByDateMap || {};

  calendarEl.innerHTML = "";
  let d = new Date(start);
  const cells = 42;
  for (let i = 0; i < cells; i++) {
    const key = localDateString(d);
    const isOther = d.getMonth() !== month;
    const dayDuties = dutiesByDateMap[key] || [];
    const dutyList = dayDuties.filter((x) => x.event_type === "duty");
    const unavailableList = dayDuties.filter((x) => x.event_type === "unavailable");
    const vacationList = dayDuties.filter((x) => x.event_type === "vacation");
    const hasAny = dayDuties.length > 0;
    const isToday = key === today;
    const eventSummaries = calendarEventsByDate[key] || [];
    const hasEvent = eventSummaries.length > 0;

    const showMarkers = !isOther;
    const cell = document.createElement("div");
    cell.className =
      "day" +
      (isOther ? " other-month" : "") +
      (isToday ? " today" : "") +
      (showMarkers && hasAny ? " has-duty" : "") +
      (showMarkers && hasEvent ? " holiday" : "");

    const namesAttr = (list) =>
      list.length
        ? escapeHtml(list.map((x) => x.full_name).join("\n"))
        : "";
    const dutyItemsJson = dutyList.length
      ? JSON.stringify(
          dutyList.map((x) => ({
            full_name: x.full_name,
            start_at: x.start_at,
            end_at: x.end_at
          }))
        ).replace(/'/g, "&#39;")
      : "";

    let html =
      '<span class="num">' +
      d.getDate() +
      '</span><div class="day-markers">';
    if (showMarkers) {
      if (dutyList.length) {
        html +=
          '<button type="button" class="duty-marker" data-event-type="duty" data-date="' +
          escapeHtml(key) +
          '" data-names="' +
          namesAttr(dutyList) +
          '" data-duty-items=\'' +
          dutyItemsJson +
          "' aria-label=\"Дежурные\">Д</button>";
      }
      if (unavailableList.length) {
        html +=
          '<button type="button" class="unavailable-marker" data-event-type="unavailable" data-names="' +
          namesAttr(unavailableList) +
          '" aria-label="Недоступен">Н</button>';
      }
      if (vacationList.length) {
        html +=
          '<button type="button" class="vacation-marker" data-event-type="vacation" data-names="' +
          namesAttr(vacationList) +
          '" aria-label="Отпуск">О</button>';
      }
      if (hasEvent) {
        html +=
          '<button type="button" class="info-btn" aria-label="Информация о дне" data-summary="' +
          escapeHtml(eventSummaries.join("\n")) +
          '">i</button>';
      }
    }
    html += "</div>";
    cell.innerHTML = html;
    calendarEl.appendChild(cell);
    d.setDate(d.getDate() + 1);
  }

  monthTitleEl.textContent = MONTHS[month] + " " + year;
  bindInfoButtonTooltips();
  bindDutyMarkerTooltips();
}