bulma/sass/utilities/functions.scss

@function mergeColorMaps($bulma-colors, $custom-colors) {
  // We return at least Bulma's hard-coded colors
  $merged-colors: $bulma-colors;

  // We want a map as input
  @if type-of($custom-colors) == "map" {
    @each $name, $components in $custom-colors {
      // The color name should be a string
      // and the components either a single color
      // or a colors list with at least one element
      @if type-of($name) == "string" and (type-of($components) == "list" or type-of($components) == "color") and length($components) >= 1 {
        $color-base: null;
        $color-invert: null;
        $color-light: null;
        $color-dark: null;
        $value: null;

        // The param can either be a single color
        // or a list of 2 colors
        @if type-of($components) == "color" {
          $color-base: $components;
          $color-invert: findColorInvert($color-base);
          $color-light: findLightColor($color-base);
          $color-dark: findDarkColor($color-base);
        }
        @else if type-of($components) == "list" {
          $color-base: nth($components, 1);

          // If Invert, Light and Dark are provided
          @if length($components) > 3 {
            $color-invert: nth($components, 2);
            $color-light: nth($components, 3);
            $color-dark: nth($components, 4);

            // If only Invert and Light are provided
          }
          @else if length($components) > 2 {
            $color-invert: nth($components, 2);
            $color-light: nth($components, 3);
            $color-dark: findDarkColor($color-base);

            // If only Invert is provided
          }
          @else {
            $color-invert: nth($components, 2);
            $color-light: findLightColor($color-base);
            $color-dark: findDarkColor($color-base);
          }
        }

        $value: $color-base, $color-invert, $color-light, $color-dark;

        // We only want to merge the map if the color base is an actual color
        @if type-of($color-base) == "color" {
          // We merge this colors elements as map with Bulma's colors map
          // (we can override them this way, no multiple definition for the same name)
          // $merged-colors: map_merge($merged-colors, ($name: ($color-base, $color-invert, $color-light, $color-dark)))
          $merged-colors: map_merge($merged-colors, ($name: $value));
        }
      }
    }
  }

  @return $merged-colors;
}

@function powerNumber($number, $exp) {
  $value: 1;

  @if $exp > 0 {
    @for $i from 1 through $exp {
      $value: $value * $number;
    }
  }
  @else if $exp < 0 {
    @for $i from 1 through -$exp {
      $value: divide($value, $number);
    }
  }

  @return $value;
}

@function colorLuminance($color) {
  @if type-of($color) != "color" {
    @return 0.55;
  }

  $color-rgb: ("red": red($color), "green": green($color), "blue": blue($color));

  @each $name, $value in $color-rgb {
    $adjusted: 0;
    $value: divide($value, 255);

    @if $value < 0.03928 {
      $value: divide($value, 12.92);
    }
    @else {
      $value: divide($value + 0.055, 1.055);
      $value: powerNumber($value, 2);
    }

    $color-rgb: map-merge($color-rgb, ($name: $value));
  }

  @return map-get($color-rgb, "red") * 0.2126 + map-get($color-rgb, "green") * 0.7152 + map-get($color-rgb, "blue") * 0.0722;
}

@function findColorInvert($color) {
  @if colorLuminance($color) > 0.55 {
    @return rgba(#000, 0.7);
  }
  @else {
    @return #fff;
  }
}

@function findLightColor($color, $l: 96%) {
  @if type-of($color) == "color" {
    $l: 96%;

    @if lightness($color) > 96% {
      $l: lightness($color);
    }

    @return change-color($color, $lightness: $l);
  }

  @return $background;
}

@function findDarkColor($color, $base-l: 29%) {
  @if type-of($color) == "color" {
    $luminance: colorLuminance($color);
    $luminance-delta: 0.53 - $luminance;
    $target-l: round($base-l + $luminance-delta * 53);

    @return change-color($color, $lightness: max($base-l, $target-l));
  }

  @return $text-strong;
}

@function bulmaRgba($color, $alpha) {
  @if type-of($color) != "color" {
    @return $color;
  }

  @return rgba($color, $alpha);
}

@function bulmaDarken($color, $amount) {
  @if type-of($color) != "color" {
    @return $color;
  }

  @return darken($color, $amount);
}

@function bulmaLighten($color, $amount) {
  @if type-of($color) != "color" {
    @return $color;
  }

  @return lighten($color, $amount);
}

// Custom divide function by @mdo from https://github.com/twbs/bootstrap/pull/34245
// Replaces old slash division deprecated in Dart Sass
@function divide($dividend, $divisor, $precision: 10) {
  $sign: if($dividend > 0 and $divisor > 0, 1, -1);
  $dividend: abs($dividend);
  $divisor: abs($divisor);
  $quotient: 0;
  $remainder: $dividend;

  @if $dividend == 0 {
    @return 0;
  }

  @if $divisor == 0 {
    @error "Cannot divide by 0";
  }

  @if $divisor == 1 {
    @return $dividend;
  }

  @while $remainder >= $divisor {
    $quotient: $quotient + 1;
    $remainder: $remainder - $divisor;
  }

  @if $remainder > 0 and $precision > 0 {
    $remainder: divide($remainder * 10, $divisor, $precision - 1) * 0.1;
  }

  @return ($quotient + $remainder) * $sign;
}