(function(){
  function parseColor(hex) {
    if (!hex) return [255, 255, 255];
    let c = hex.replace('#', '');
    if (c.length === 3) c = c.split('').map(x => x + x).join('');
    const num = parseInt(c, 16);
    return [(num >> 16) & 255, (num >> 8) & 255, num & 255];
  }

  const toHex = v => v.toString(16).padStart(2, '0');

  function hexToRgba(hex, a = 1) {
    const [r, g, b] = parseColor(hex);
    return `rgba(${r},${g},${b},${a})`;
  }

  function getContrastColor(hex) {
    const [r, g, b] = parseColor(hex);
    const yiq = (r * 299 + g * 587 + b * 114) / 1000;
    return yiq >= 128 ? '#000' : '#fff';
  }

  function lightenColor(hex, p) {
    const [r, g, b] = parseColor(hex).map(v =>
      Math.min(255, Math.round(v + (255 - v) * p))
    );
    return '#' + [r, g, b].map(toHex).join('');
  }

  function getHumanDiff(d1, d2) {
    let start = d1 < d2 ? d1 : d2;
    let end   = d1 < d2 ? d2 : d1;

    let years  = end.getUTCFullYear()  - start.getUTCFullYear();
    let months = end.getUTCMonth()     - start.getUTCMonth();
    let days   = end.getUTCDate()      - start.getUTCDate();

    if (days < 0) {
      months--;
      let prevMonthDays = new Date(Date.UTC(
        end.getUTCFullYear(),
        end.getUTCMonth(), 0
      )).getUTCDate();
      days += prevMonthDays;
    }
    if (months < 0) {
      years--;
      months += 12;
    }

    let aligned = new Date(Date.UTC(
      start.getUTCFullYear() + years,
      start.getUTCMonth()     + months,
      start.getUTCDate()      + days,
      start.getUTCHours(),
      start.getUTCMinutes(),
      start.getUTCSeconds()
    ));
    let diffMs = end.getTime() - aligned.getTime();

    if (diffMs < 0) {
      diffMs += 24 * 3600e3;
      if (days > 0) {
        days--;
      } else {
        months--;
        if (months < 0) {
          years--;
          months += 12;
        }
        days = new Date(Date.UTC(
          end.getUTCFullYear(),
          end.getUTCMonth(), 0
        )).getUTCDate();
      }
    }

    let hours   = Math.floor(diffMs / 3600e3); diffMs -= hours * 3600e3;
    let minutes = Math.floor(diffMs /   60e3); diffMs -= minutes *   60e3;
    let seconds = Math.floor(diffMs /    1e3);

    return { years, months, days, hours, minutes, seconds };
  }

  window.Utils = {
    parseColor,
    hexToRgba,
    getContrastColor,
    lightenColor,
    getHumanDiff
  };
})();