// Hydrogen / Sass Functions

@function squareRoot ($h2-r) {
  $h2-x0: 1;
  $h2-x1: $h2-x0;

  @for $h2-i from 1 through 10 {
    $h2-x1: $h2-x0 - ($h2-x0 * $h2-x0 - abs($h2-r)) / (2 * $h2-x0);
    $h2-x0: $h2-x1;
  }

  @return $h2-x1;
}

$h2-red-magic-number: 241;
$h2-green-magic-number: 691;
$h2-blue-magic-number: 68;
$h2-brightness-divisor: $h2-red-magic-number + $h2-green-magic-number + $h2-blue-magic-number;

@function brightness($h2-color) {
  // Extract color components
  $h2-red-component: red($h2-color);
  $h2-green-component: green($h2-color);
  $h2-blue-component: blue($h2-color);
  // Calculate a brightness value in 3d color space between 0 and 255
  $h2-number: squareRoot((($h2-red-component * $h2-red-component * $h2-red-magic-number) + ($h2-green-component * $h2-green-component * $h2-green-magic-number) + ($h2-blue-component * $h2-blue-component * $h2-blue-magic-number)) / $h2-brightness-divisor);
  // Convert to percentage and return
  @return 100% * $h2-number / 255;
}

@function contrasting-color($h2-color, $h2-light, $h2-dark) {
  @if brightness($h2-color) < 65% {
    @return $h2-light;
  } @else {
    @return $h2-dark;
  }
}