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

// Return opaque color
//
// opaque(#fff, rgba(0, 0, 0, 0.5)) => #808080
//
@function opaque($background, $foreground) {
    @return mix(rgba($foreground, 1), $background, opacity($foreground) * 100);
}

// Tint a color (mix with white)
//
@function tint-color($color, $weight) {
    @return change-color($color, $lightness: math.div((100% - $weight), 100%) * lightness($color) + $weight);
}

// Shade a color (mix with black)
//
@function shade-color($color, $weight) {
    @return change-color($color, $saturation: math.div(saturation($color) * (100% - $weight), 100%), $lightness: math.div(lightness($color) * (100% - $weight), 100%));
}

// Shade the color if the weight is positive, else tint it
//
@function shift-color($color, $weight) {
    @return if($weight > 0, shade-color($color, $weight), tint-color($color, -$weight));
}

// Generate a gradient background color with given colors array and gradient direction
//
// @param colors Colors to be added to the gradient
// @param direction The direction of the gradient
// @return A gradient color
//
@function gradient($colors, $direction: $gradient-direction) {
    @return linear-gradient($direction, unquote($colors));
}

// A list of pre-calculated numbers of pow(($value / 255 + .055) / 1.055, 2.4). (from 0 to 255)
//
// Source: https://github.com/twbs/bootstrap/blob/main/scss/_functions.scss
//
$linear-channel-values: 0 0.0003035269835488375 0.000607053967097675 0.0009105809506465125 0.00121410793419535 0.0015176349177441874 0.001821161901293025 0.0021246888848418626 0.0024282158683907 0.0027317428519395373 0.003035269835488375 0.003346535763899161 0.003676507324047436 0.004024717018496307 0.004391442037410293 0.004776953480693729 0.005181516702338386 0.005605391624202723 0.006048833022857054 0.006512090792594475 0.006995410187265387 0.007499032043226175 0.008023192985384994 0.008568125618069307 0.009134058702220787 0.00972121732023785 0.010329823029626936 0.010960094006488246 0.011612245179743885 0.012286488356915872 0.012983032342173012 0.013702083047289686 0.014443843596092545 0.01520851442291271 0.01599629336550963 0.016807375752887384 0.017641954488384078 0.018500220128379697 0.019382360956935723 0.0202885630566524 0.021219010376003555 0.022173884793387385 0.02315336617811041 0.024157632448504756 0.02518685962736163 0.026241221894849898 0.027320891639074894 0.028426039504420793 0.0295568344378088 0.030713443732993635 0.03189603307301153 0.033104766570885055 0.03433980680868217 0.03560131487502034 0.03688945040110004 0.0382043715953465 0.03954623527673284 0.04091519690685319 0.042311410620809675 0.043735029256973465 0.04518620438567554 0.046665086336880095 0.04817182422688942 0.04970656598412723 0.05126945837404324 0.052860647023180246 0.05448027644244237 0.05612849004960009 0.05780543019106723 0.0595112381629812 0.06124605423161761 0.06301001765316767 0.06480326669290577 0.06662593864377289 0.06847816984440017 0.07036009569659588 0.07227185068231748 0.07421356838014963 0.07618538148130785 0.07818742180518633 0.08021982031446832 0.0822827071298148 0.08437621154414882 0.08650046203654976 0.08865558628577294 0.09084171118340768 0.09305896284668745 0.0953074666309647 0.09758734714186246 0.09989872824711389 0.10224173308810132 0.10461648409110419 0.10702310297826761 0.10946171077829933 0.1119324278369056 0.11443537382697373 0.11697066775851084 0.11953842798834562 0.12213877222960187 0.12477181756095049 0.12743768043564743 0.1301364766903643 0.13286832155381798 0.13563332965520566 0.13843161503245183 0.14126329114027164 0.14412847085805777 0.14702726649759498 0.14995978981060856 0.15292615199615017 0.1559264637078274 0.1589608350608804 0.162029375639111 0.1651321945016676 0.16826940018969075 0.1714411007328226 0.17464740365558504 0.17788841598362912 0.18116424424986022 0.184474994500441 0.18782077230067787 0.19120168274079138 0.1946178304415758 0.19806931955994886 0.20155625379439707 0.20507873639031693 0.20863687014525575 0.21223075741405523 0.21586050011389926 0.2195261997292692 0.2232279573168085 0.22696587351009836 0.23074004852434915 0.23455058216100522 0.238397573812271 0.24228112246555486 0.24620132670783548 0.25015828472995344 0.25415209433082675 0.2581828529215958 0.26225065752969623 0.26635560480286247 0.2704977910130658 0.27467731206038465 0.2788942634768104 0.2831487404299921 0.2874408377269175 0.29177064981753587 0.2961382707983211 0.3005437944157765 0.3049873140698863 0.30946892281750854 0.31398871337571754 0.31854677812509186 0.32314320911295075 0.3277780980565422 0.33245153634617935 0.33716361504833037 0.3419144249086609 0.3467040563550296 0.35153259950043936 0.3564001441459435 0.3613067797835095 0.3662525955988395 0.3712376804741491 0.3762621229909065 0.38132601143253014 0.386429433787049 0.39157247774972326 0.39675523072562685 0.4019777798321958 0.4072402119017367 0.41254261348390375 0.4178850708481375 0.4232676699860717 0.4286904966139066 0.43415363617474895 0.4396571738409188 0.44520119451622786 0.45078578283822346 0.45641102318040466 0.4620769996544071 0.467783796112159 0.47353149614800955 0.4793201831008268 0.4851499400560704 0.4910208498478356 0.4969329950608704 0.5028864580325687 0.5088813208549338 0.5149176653765214 0.5209955732043543 0.5271151257058131 0.5332764040105052 0.5394794890121072 0.5457244613701866 0.5520114015120001 0.5583403896342679 0.5647115057049292 0.5711248294648731 0.5775804404296506 0.5840784178911641 0.5906188409193369 0.5972017883637634 0.6038273388553378 0.6104955708078648 0.6172065624196511 0.6239603916750761 0.6307571363461468 0.6375968739940326 0.6444796819705821 0.6514056374198242 0.6583748172794485 0.665387298282272 0.6724431569576875 0.6795424696330938 0.6866853124353135 0.6938717612919899 0.7011018919329731 0.7083757798916868 0.7156935005064807 0.7230551289219693 0.7304607400903537 0.7379104087727308 0.7454042095403874 0.7529422167760779 0.7605245046752924 0.768151147247507 0.7758222183174236 0.7835377915261935 0.7912979403326302 0.799102738014409 0.8069522576692516 0.8148465722161012 0.8227857543962835 0.8307698767746546 0.83879901174074 0.846873231509858 0.8549926081242338 0.8631572134541023 0.8713671191987972 0.8796223968878317 0.8879231178819663 0.8962693533742664 0.9046611743911496 0.9130986517934192 0.9215818562772946 0.9301108583754237 0.938685728457888 0.9473065367331999 0.9559733532492861 0.9646862478944651 0.9734452903984125 0.9822505503331171 0.9911020971138298 1;

// Return WCAG2.0 relative luminance
//
// See https://www.w3.org/WAI/GL/wiki/Relative_luminance
// See https://www.w3.org/TR/WCAG20-TECHS/G17.html#G17-tests
//
@function luminance($color) {
    $red: list.nth($linear-channel-values, color.red($color) + 1);
    $green: list.nth($linear-channel-values, color.green($color) + 1);
    $blue: list.nth($linear-channel-values, color.blue($color) + 1);

    @return 0.2126 * $red + 0.7152 * $green + 0.0722 * $blue;
}

// Calculate contrast ratio between background and foreground
//
// Source: https://www.w3.org/TR/WCAG20-TECHS/G17.html#G17-tests
//
@function contrast-ratio($background, $foreground) {
    $backgroundLuminance: luminance($background) + 0.05;
    $foregroundLuminance: luminance($foreground) + 0.05;

    @return math.div(math.max($backgroundLuminance, $foregroundLuminance), math.min($backgroundLuminance, $foregroundLuminance));
}

// Get contrast text color for a background color by calculating the luminance
// of the given input color. If the given color is dark, return a light text color, otherwise if the current variant
// color is light, return a dark text color.
//
// @param color Text background color
// @return Contrasting text color
//
@function contrast-color-simple($background, $contrast-color-for-light-background: $contrast-color-for-light-background, $contrast-color-for-dark-background: $contrast-color-for-dark-background) {
    $lightContrast: contrast-ratio($background, $contrast-color-for-dark-background);
    $darkContrast: contrast-ratio($background, $contrast-color-for-light-background);

    @if ($lightContrast > $darkContrast) {
        @return var(--contrast-color-for-dark-background);
    } @else {
        @return var(--contrast-color-for-light-background);
    }
}

// Get contrast text color for a background color by calculating the contrast between the background and the foreground.
// If the given color is dark, return a light text color, otherwise if the current variant
// color is light, return a dark text color.
//
// @param color Text background color
// @return Contrasting text color
//
@function contrast-color($background, $contrast-color-for-light-background: $contrast-color-for-light-background, $contrast-color-for-dark-background: $contrast-color-for-dark-background, $min-contrast-ratio: $min-contrast-ratio) {
    $foregrounds: (
        'contrast-color-for-dark-background': $contrast-color-for-dark-background,
        'contrast-color-for-light-background': $contrast-color-for-light-background,
    );
    $max-ratio: 0;
    $max-ratio-color: null;

    @each $color-name, $color in $foregrounds {
        $contrast-ratio: contrast-ratio($background, $color);

        @if $contrast-ratio > $min-contrast-ratio {
            @return var(--#{$color-name});
        } @else if $contrast-ratio > $max-ratio {
            $max-ratio: $contrast-ratio;
            $max-ratio-color: var(--#{$color-name});
        }
    }

    @return $max-ratio-color;
}