@use 'sass:math';
@use 'sass:color';

@function _linear-channel($c) {
    $c: math.div($c, 255);

    @if $c <= 0.04045 {
        @return math.div($c, 12.92);
    }

    @return math.pow(math.div($c + 0.055, 1.055), 2.4);
}

@function luminance($color) {
    $r: _linear-channel(color.channel($color, 'red', $space: rgb));
    $g: _linear-channel(color.channel($color, 'green', $space: rgb));
    $b: _linear-channel(color.channel($color, 'blue', $space: rgb));

    @return 0.2126 * $r + 0.7152 * $g + 0.0722 * $b;
}

@function contrast($c1, $c2) {
    $l1: luminance($c1);
    $l2: luminance($c2);

    @if $l1 < $l2 {
        $tmp: $l1;
        $l1: $l2;
        $l2: $tmp;
    }

    @return math.div($l1 + 0.05, $l2 + 0.05);
}

@function wcag-required($level) {
    @if $level == AAA {
        @return 7;
    }

    @return 4.5;
}