(() => {
  'use strict';

  const canvas = document.getElementById('confetti');
  const ctx = canvas.getContext('2d');
  const start = document.getElementById('startButton');
  const encore = document.getElementById('encoreButton');
  const rapButton = document.getElementById('rapButton');
  const twinButton = document.getElementById('twinButton');
  const toast = document.getElementById('toast');
  const liveText = document.getElementById('liveText');
  const reduced = matchMedia('(prefers-reduced-motion: reduce)');
  const colors = ['#f22e3a', '#f6ff00', '#ffffff', '#111018', '#72d7ff', '#ff9fcf'];

  let pieces = [];
  let frame = null;
  let toastTimer = null;
  let rapTimer = null;
  let twinTimer = null;

  function resize() {
    const density = Math.min(devicePixelRatio || 1, 2);
    canvas.width = innerWidth * density;
    canvas.height = innerHeight * density;
    canvas.style.width = `${innerWidth}px`;
    canvas.style.height = `${innerHeight}px`;
    ctx.setTransform(density, 0, 0, density, 0, 0);
  }

  function piece(x, y, index) {
    const angle = -Math.PI * 0.9 + (index % 50) / 49 * Math.PI * 0.8;
    const speed = 7 + Math.random() * 14;
    return {
      x,
      y,
      vx: Math.cos(angle) * speed + (Math.random() - 0.5) * 5,
      vy: Math.sin(angle) * speed - Math.random() * 5,
      gravity: 0.18 + Math.random() * 0.14,
      drag: 0.988,
      rotation: Math.random() * 6.28,
      spin: (Math.random() - 0.5) * 0.3,
      size: 6 + Math.random() * 12,
      color: colors[index % colors.length],
      life: 160 + Math.random() * 80,
      shape: index % 3
    };
  }

  function burst(x = innerWidth / 2, y = innerHeight * 0.7) {
    if (reduced.matches) return;
    for (let index = 0; index < 220; index += 1) pieces.push(piece(x, y, index));
    if (!frame) animate();
  }

  function animate() {
    ctx.clearRect(0, 0, innerWidth, innerHeight);
    pieces = pieces.filter(item => item.life > 0 && item.y < innerHeight + 90);
    pieces.forEach(item => {
      item.vx *= item.drag;
      item.vy = item.vy * item.drag + item.gravity;
      item.x += item.vx;
      item.y += item.vy;
      item.rotation += item.spin;
      item.life -= 1;
      ctx.save();
      ctx.translate(item.x, item.y);
      ctx.rotate(item.rotation);
      ctx.fillStyle = item.color;
      ctx.strokeStyle = '#111018';
      ctx.lineWidth = 1;
      if (item.shape === 0) {
        ctx.fillRect(-item.size / 2, -item.size / 4, item.size, item.size / 2);
        ctx.strokeRect(-item.size / 2, -item.size / 4, item.size, item.size / 2);
      } else if (item.shape === 1) {
        ctx.beginPath();
        ctx.moveTo(0, -item.size / 2);
        ctx.lineTo(item.size / 2, item.size / 2);
        ctx.lineTo(-item.size / 2, item.size / 2);
        ctx.closePath();
        ctx.fill();
        ctx.stroke();
      } else {
        ctx.fillRect(-item.size / 3, -item.size / 2, item.size * 0.66, item.size);
      }
      ctx.restore();
    });
    if (pieces.length) frame = requestAnimationFrame(animate);
    else {
      frame = null;
      ctx.clearRect(0, 0, innerWidth, innerHeight);
    }
  }

  function count() {
    document.querySelectorAll('[data-count]').forEach(element => {
      const target = Number(element.dataset.count);
      if (Number(element.textContent) === target) return;
      let value = 0;
      const step = Math.max(1, Math.ceil(target / 55));
      function tick() {
        value = Math.min(target, value + step);
        element.textContent = value;
        if (value < target) requestAnimationFrame(tick);
      }
      tick();
    });
  }

  function showToast(text = 'SVEIKINIMO BISAS PALEISTAS — PLOJIMAI DONATUI!') {
    clearTimeout(toastTimer);
    toast.textContent = text;
    toast.classList.add('visible');
    toastTimer = setTimeout(() => toast.classList.remove('visible'), 3200);
  }

  function launch(event) {
    document.body.classList.add('started');
    liveText.textContent = 'BISAS PALEISTAS';
    start.querySelector('span').textContent = 'SVEIKINIMO BISAS ATIDARYTAS!';
    const rect = event?.currentTarget?.getBoundingClientRect();
    burst(rect ? rect.left + rect.width / 2 : innerWidth / 2, rect ? rect.top : innerHeight * 0.7);
    count();
    showToast();
  }

  function rap() {
    clearInterval(rapTimer);
    const lines = [...document.querySelectorAll('#rapText span')];
    lines.forEach(line => line.classList.remove('active'));
    let index = 0;
    const next = () => {
      if (index < lines.length) lines[index++].classList.add('active');
      else clearInterval(rapTimer);
    };
    next();
    rapTimer = setInterval(next, 650);
    showToast('REPAS DONATUI — PUBLIKA PRAŠO BISO!');
  }

  function reunion(event) {
    clearInterval(twinTimer);
    const cards = [...document.querySelectorAll('.twin-card')];
    cards.forEach(card => card.classList.remove('active'));
    if (reduced.matches) cards.forEach(card => card.classList.add('active'));
    else {
      let index = 0;
      const next = () => {
        cards.forEach(card => card.classList.remove('active'));
        cards[index % cards.length].classList.add('active');
        index += 1;
        if (index > cards.length) clearInterval(twinTimer);
      };
      next();
      twinTimer = setInterval(next, 850);
    }
    const rect = event.currentTarget.getBoundingClientRect();
    burst(rect.left + rect.width / 2, rect.top);
    showToast('KĮŽ3 SKAITMENINIS REUNIONAS PALEISTAS!');
  }

  start.addEventListener('click', launch);
  encore.addEventListener('click', launch);
  rapButton.addEventListener('click', event => {
    rap();
    const rect = event.currentTarget.getBoundingClientRect();
    burst(rect.left + rect.width / 2, rect.top);
  });
  twinButton.addEventListener('click', reunion);
  addEventListener('resize', resize, { passive: true });
  resize();

  const observer = new IntersectionObserver(entries => {
    if (entries.some(entry => entry.isIntersecting)) {
      count();
      observer.disconnect();
    }
  }, { threshold: 0.3 });
  observer.observe(document.querySelector('.numbers'));
})();