(function () {
  var COLORS = ['#11b3be','#ff6b9d','#ffd93d','#6bcb77','#4d96ff','#ff6b35','#c77dff','#ff9f43','#54a0ff','#ff6348'];

  var SVG_NS = 'http://www.w3.org/2000/svg';
  function makeBalloon(color, size) {
    var svg = document.createElementNS(SVG_NS, 'svg');
    svg.setAttribute('viewBox', '0 0 50 82');
    svg.setAttribute('width', size);
    svg.setAttribute('height', Math.round(size * 1.64));

    var body = document.createElementNS(SVG_NS, 'ellipse');
    body.setAttribute('cx', '25'); body.setAttribute('cy', '26');
    body.setAttribute('rx', '21'); body.setAttribute('ry', '25');
    body.setAttribute('fill', color); body.setAttribute('opacity', '0.88');

    var shine = document.createElementNS(SVG_NS, 'ellipse');
    shine.setAttribute('cx', '18'); shine.setAttribute('cy', '16');
    shine.setAttribute('rx', '7'); shine.setAttribute('ry', '5');
    shine.setAttribute('fill', 'white'); shine.setAttribute('opacity', '0.25');
    shine.setAttribute('transform', 'rotate(-20 18 16)');

    var knot = document.createElementNS(SVG_NS, 'path');
    knot.setAttribute('d', 'M25 51 Q27.5 55.5 25 58.5 Q22.5 55.5 25 51Z');
    knot.setAttribute('fill', color); knot.setAttribute('opacity', '0.88');

    var str = document.createElementNS(SVG_NS, 'path');
    str.setAttribute('d', 'M25 58.5 Q20 68 25 80');
    str.setAttribute('stroke', '#999'); str.setAttribute('stroke-width', '1.2');
    str.setAttribute('fill', 'none'); str.setAttribute('opacity', '0.7');

    svg.appendChild(body);
    svg.appendChild(shine);
    svg.appendChild(knot);
    svg.appendChild(str);
    return svg;
  }

  var active = false;

  function attach() {
    var el = document.getElementById('bpb-copyright');
    if (!el) return;
    el.addEventListener('click', function () {
      if (active) return;
      launch();
    });
  }

  // Footer is injected by nav.js — wait for it
  if (document.readyState === 'loading') {
    document.addEventListener('DOMContentLoaded', attach);
  } else {
    attach();
  }

  function launch() {
    active = true;

    var container = document.createElement('div');
    Object.assign(container.style, {
      position:      'fixed',
      inset:         '0',
      pointerEvents: 'none',
      zIndex:        '9',
      overflow:      'hidden',
    });
    document.body.insertBefore(container, document.body.firstChild);

    var count = 22;
    for (var i = 0; i < count; i++) {
      (function (idx) {
        var delay   = idx * 130 + Math.random() * 150;
        setTimeout(function () {
          var color   = COLORS[Math.floor(Math.random() * COLORS.length)];
          var size    = 38 + Math.random() * 32;
          var leftPct = 3 + Math.random() * 94;
          var sway    = Math.random() * 40 - 20;
          var tilt    = Math.random() * 24 - 12;
          var dur     = 4500 + Math.random() * 3500;
          var rise    = window.innerHeight + size * 2;

          var wrap = document.createElement('div');
          Object.assign(wrap.style, {
            position: 'absolute',
            bottom:   (-size * 1.64 - 10) + 'px',
            left:     leftPct + '%',
          });
          wrap.appendChild(makeBalloon(color, size));
          container.appendChild(wrap);

          wrap.animate([
            { transform: 'translateX(0px)          translateY(0px)    rotate(' + tilt + 'deg)',    opacity: 0 },
            { transform: 'translateX(0px)          translateY(0px)    rotate(' + tilt + 'deg)',    opacity: 1,   offset: 0.06 },
            { transform: 'translateX(' + sway + 'px) translateY(' + (-rise * 0.5) + 'px) rotate(' + (-tilt * 0.3) + 'deg)', opacity: 1, offset: 0.5 },
            { transform: 'translateX(' + (-sway) + 'px) translateY(' + (-rise) + 'px) rotate(' + (-tilt * 0.6) + 'deg)', opacity: 0 },
          ], {
            duration: dur,
            easing:   'cubic-bezier(0.25, 0.46, 0.45, 0.94)',
            fill:     'forwards',
          });
        }, delay);
      })(i);
    }

    setTimeout(function () {
      container.remove();
      active = false;
    }, 14000);
  }
})();