script.js

const FALL_ASLEEP_MINS = 14;
const CYCLE_MINS = 90;
const CYCLES = [1, 2, 3, 4, 5, 6, 7];

function pad(n) { return String(n).padStart(2, '0'); }

function formatTime(date) {
  const h = date.getHours();
  const m = date.getMinutes();
  return {
    display: `${pad(h)}:${pad(m)}`,
  };
}

function cycleLabel(n) {
  const totalMins = n * CYCLE_MINS;
  const h = Math.floor(totalMins / 60);
  const m = totalMins % 60;
  const parts = [`${n} cycle${n !== 1 ? 's' : ''}`];
  if (h > 0) parts.push(`${h} hour${h !== 1 ? 's' : ''}`);
  if (m > 0) parts.push(`${m} minutes`);
  return parts.join(' · ');
}

function icsDateTime(date) {
  const Y = date.getFullYear();
  const M = pad(date.getMonth() + 1);
  const D = pad(date.getDate());
  const h = pad(date.getHours());
  const m = pad(date.getMinutes());
  const s = pad(date.getSeconds());
  return `${Y}${M}${D}T${h}${m}${s}`;
}

function downloadICS(wakeDate, cycles) {
  const uid = `slumber-${Date.now()}@sleepcalc`;
  const dtStart = icsDateTime(wakeDate);
  const dtEnd = icsDateTime(new Date(wakeDate.getTime() + 15 * 60 * 1000));
  const now = icsDateTime(new Date());
  const { display } = formatTime(wakeDate);
  const label = cycleLabel(cycles);

  const ics = [
    'BEGIN:VCALENDAR',
    'VERSION:2.0',
    'PRODID:-//SleepCalc//Wake Up Alarm//EN',
    'CALSCALE:GREGORIAN',
    'METHOD:PUBLISH',
    'BEGIN:VEVENT',
    `UID:${uid}`,
    `DTSTAMP:${now}`,
    `DTSTART:${dtStart}`,
    `DTEND:${dtEnd}`,
    `SUMMARY:Wake up \u2014 ${display}`,
    `DESCRIPTION:${label}`,
    'BEGIN:VALARM',
    'ACTION:DISPLAY',
    'DESCRIPTION:Time to wake up!',
    'TRIGGER:PT0S',
    'END:VALARM',
    'END:VEVENT',
    'END:VCALENDAR',
  ].join('\r\n');

  const blob = new Blob([ics], { type: 'text/calendar;charset=utf-8' });
  const url = URL.createObjectURL(blob);
  const a = Object.assign(document.createElement('a'), {
    href: url,
    download: `wake-${display.replace(':', '')}.ics`,
  });
  document.body.appendChild(a);
  a.click();
  a.remove();
  URL.revokeObjectURL(url);
}

function buildWakeList(now) {
  const list = document.getElementById('wake-list');
  list.innerHTML = '';

  CYCLES.forEach((cycles, idx) => {
    const totalMins = FALL_ASLEEP_MINS + cycles * CYCLE_MINS;
    const wakeDate = new Date(now.getTime() + totalMins * 60 * 1000);
    const { display } = formatTime(wakeDate);

    const li = document.createElement('li');
    li.className = 'wake-item';
    li.style.setProperty('--item-delay', `${idx * 0.08}s`);
    li.setAttribute('role', 'listitem');
    li.setAttribute('aria-label', `${display} — ${cycleLabel(cycles)}`);

    li.innerHTML = `
      <div class="card-left">
        <span class="wake-time">${display}</span>
        <span class="wake-meta">${cycleLabel(cycles)}</span>
      </div>
      <button class="alarm-icon" aria-label="Add to calendar" title="Download .ics alarm" data-wake="${wakeDate.getTime()}" data-cycles="${cycles}">
        <svg viewBox="0 0 24 24" fill="none" stroke="white" stroke-width="1.8" stroke-linecap="round" stroke-linejoin="round">
          <circle cx="12" cy="13" r="7"/>
          <path d="M12 10v3l2 2"/>
          <path d="M5 3L2 6"/>
          <path d="M19 3l3 3"/>
        </svg>
      </button>
    `;

    li.querySelector('.alarm-icon').addEventListener('click', (e) => {
      e.stopPropagation();
      const ts = parseInt(e.currentTarget.dataset.wake, 10);
      const c = parseInt(e.currentTarget.dataset.cycles, 10);
      downloadICS(new Date(ts), c);
    });

    list.appendChild(li);
  });
}

let lastMinute = -1;

function tick() {
  const now = new Date();
  const m = now.getMinutes();

  const { display } = formatTime(now);
  const label = document.getElementById('sleep-at-time');
  if (label) label.textContent = display;

  if (m !== lastMinute) {
    lastMinute = m;
    buildWakeList(now);
  }
}

tick();
setInterval(tick, 1000);