const WEEKDAY_BREAKS = [
  { start: "10:15", end: "10:30" },
  { start: "12:00", end: "12:30" },
  { start: "14:00", end: "14:15" },
  { start: "16:30", end: "17:00" },
  { start: "19:45", end: "20:00" },
  { start: "21:00", end: "21:15" },
];

const WEEKEND_BREAKS = [
  { start: "11:00", end: "11:15" },
  { start: "14:30", end: "15:00" },
  { start: "17:30", end: "17:45" },
  { start: "20:00", end: "20:15" },
];

let clockEl, dateEl, nextBreakEl;
let breakNodes = [];
let lastDayKey = "";

function pad2(n) {
  return n < 10 ? "0" + n : "" + n;
}

function formatClock(d) {
  return pad2(d.getHours()) + ":" + pad2(d.getMinutes()) + ":" + pad2(d.getSeconds());
}

function formatDate(d) {
  return pad2(d.getDate()) + "." + pad2(d.getMonth() + 1) + "." + d.getFullYear();
}

function breakTimeToMinutes(t) {
  const parts = t.split(":");
  return parseInt(parts[0], 10) * 60 + parseInt(parts[1], 10);
}

function breakMsForToday(t, now) {
  const d = new Date(now);
  const parts = t.split(":");
  d.setHours(parseInt(parts[0], 10), parseInt(parts[1], 10), 0, 0);
  return d.getTime();
}

function getBreaksForToday(now) {
  const day = now.getDay();
  return day === 0 || day === 6 ? WEEKEND_BREAKS : WEEKDAY_BREAKS;
}

function formatDuration(ms) {
  const totalSeconds = Math.floor(ms / 1000);
  const h = Math.floor(totalSeconds / 3600);
  const m = Math.floor((totalSeconds % 3600) / 60);
  const s = totalSeconds % 60;
  return pad2(h) + ":" + pad2(m) + ":" + pad2(s);
}

function buildCalendar() {
  const calendar = document.getElementById("calendar");
  calendar.innerHTML = "";

  const now = new Date();
  const daysOfWeek = ["Mo", "Tu", "We", "Th", "Fr", "Sa", "Su"];

  const thead = document.createElement("thead");
  const headerRow = document.createElement("tr");
  daysOfWeek.forEach(function (day, index) {
    const th = document.createElement("th");
    th.textContent = day;
    if (index === 5 || index === 6) {
      th.classList.add("weekend-text");
    }
    headerRow.appendChild(th);
  });
  thead.appendChild(headerRow);
  calendar.appendChild(thead);

  const tbody = document.createElement("tbody");
  const year = now.getFullYear();
  const month = now.getMonth();
  const firstDayOfMonth = new Date(year, month, 1);
  let firstDayWeek = firstDayOfMonth.getDay();
  firstDayWeek = firstDayWeek === 0 ? 7 : firstDayWeek;

  const daysInMonth = new Date(year, month + 1, 0).getDate();
  const daysInPrevMonth = new Date(year, month, 0).getDate();

  let dayCounter = 1;
  let nextMonthDayCounter = 1;
  let startDay = daysInPrevMonth - firstDayWeek + 2;

  const totalRows = Math.ceil((firstDayWeek - 1 + daysInMonth) / 7);
  for (let row = 0; row < totalRows; row++) {
    const tr = document.createElement("tr");
    for (let col = 0; col < 7; col++) {
      const td = document.createElement("td");

      let cellDay;
      let isCurrentMonth = true;

      if (row === 0 && col < firstDayWeek - 1) {
        cellDay = startDay + col;
        isCurrentMonth = false;
      } else if (dayCounter <= daysInMonth) {
        cellDay = dayCounter;
        dayCounter++;
      } else {
        cellDay = nextMonthDayCounter;
        nextMonthDayCounter++;
        isCurrentMonth = false;
      }

      td.textContent = cellDay;

      if (isCurrentMonth && cellDay === now.getDate()) {
        td.classList.add("today-text");
      }
      if (col === 5 || col === 6) {
        td.classList.add("weekend-text");
      }
      if (!isCurrentMonth) {
        td.classList.add("other-month");
      }
      tr.appendChild(td);
    }
    tbody.appendChild(tr);
  }
  calendar.appendChild(tbody);
}

function updateClock() {
  const now = new Date();
  clockEl.textContent = formatClock(now);
  scheduleNextClockTick();
}

function scheduleNextClockTick() {
  const delay = 1000 - new Date().getMilliseconds();
  setTimeout(updateClock, delay);
}

function buildBreakBlocks() {
  const breakTimesElement = document.getElementById("breakTimes");
  breakTimesElement.innerHTML = "";
  breakTimesElement.appendChild(buildLabel("BK"));

  const blocks = [];
  getBreaksForToday(new Date()).forEach(function (b) {
    blocks.push(buildTimeBlock(b.start + "-" + b.end));
  });

  breakNodes = blocks;
  distributeBlocks(breakTimesElement, blocks);
}

function buildLabel(text) {
  const span = document.createElement("span");
  span.className = "time-block label-block";
  span.textContent = text;
  return span;
}

function buildTimeBlock(text) {
  const span = document.createElement("span");
  span.className = "time-block";
  span.textContent = text;
  return span;
}

function distributeBlocks(container, blocks) {
  const screenWidth = window.innerWidth;
  const blockWidth = 120;
  const labelWidth = 40;

  const availableWidth = screenWidth - labelWidth;
  const blocksPerRow = Math.floor(availableWidth / blockWidth);

  while (container.childNodes.length > 1) {
    container.removeChild(container.lastChild);
  }

  if (blocksPerRow > blocks.length) {
    blocks.forEach(function (b) { container.appendChild(b); });
    return;
  }

  const totalBlocks = blocks.length;
  const halfBlocks = Math.ceil(totalBlocks / 2);

  const rowsContainer = document.createElement("div");
  rowsContainer.className = "multi-rows-container";

  const topRow = document.createElement("div");
  topRow.className = "time-row";
  for (let i = 0; i < halfBlocks; i++) {
    topRow.appendChild(blocks[i]);
  }
  rowsContainer.appendChild(topRow);

  const bottomRow = document.createElement("div");
  bottomRow.className = "time-row";
  for (let i = halfBlocks; i < totalBlocks; i++) {
    bottomRow.appendChild(blocks[i]);
  }
  rowsContainer.appendChild(bottomRow);

  container.appendChild(rowsContainer);
}

function updateNextBreak() {
  const now = new Date();
  const nowMinutes = now.getHours() * 60 + now.getMinutes() + now.getSeconds() / 60;
  const breaks = getBreaksForToday(now);

  let current = null;
  let next = null;

  breaks.forEach(function (b, index) {
    const startM = breakTimeToMinutes(b.start);
    const endM = breakTimeToMinutes(b.end);
    if (nowMinutes >= startM && nowMinutes < endM) {
      current = index;
    } else if (endM > nowMinutes && next === null) {
      next = index;
    }
  });

  breakNodes.forEach(function (node, index) {
    node.classList.remove("break-current", "break-next");
    if (index === current) {
      node.classList.add("break-current");
    } else if (index === next) {
      node.classList.add("break-next");
    }
  });

  if (current !== null) {
    const b = breaks[current];
    const endMs = breakMsForToday(b.end, now);
    nextBreakEl.textContent =
      "Перерыв " + b.start + "-" + b.end +
      " · до конца " + formatDuration(endMs - now.getTime());
  } else if (next !== null) {
    const b = breaks[next];
    const startMs = breakMsForToday(b.start, now);
    nextBreakEl.textContent =
      "До перерыва " + b.start + "-" + b.end +
      " · " + formatDuration(startMs - now.getTime());
  } else {
    nextBreakEl.textContent = "Перерывов больше нет";
  }

  scheduleNextBreakTick();
}

function scheduleNextBreakTick() {
  const delay = 1000 - new Date().getMilliseconds();
  setTimeout(updateNextBreak, delay);
}

function checkDayChange() {
  const now = new Date();
  const key =
    now.getFullYear() + "-" + (now.getMonth() + 1) + "-" + now.getDate();
  if (key !== lastDayKey) {
    lastDayKey = key;
    dateEl.textContent = formatDate(now);
    buildCalendar();
    buildBreakBlocks();
  }
}

function init() {
  clockEl = document.getElementById("currentTime");
  dateEl = document.getElementById("currentDate");
  nextBreakEl = document.getElementById("nextBreak");

  buildBreakBlocks();
  buildCalendar();

  const now = new Date();
  lastDayKey = now.getFullYear() + "-" + (now.getMonth() + 1) + "-" + now.getDate();
  dateEl.textContent = formatDate(now);

  updateClock();
  updateNextBreak();

  setInterval(checkDayChange, 60000);
}

init();