// scss原生并没有提供字符串的替换函数，需自己编写函数来实现这个功能
@function str-replace($string, $search, $replace) {
  $index: str-index($string, $search);

  @if $index {
    @return str-slice($string, 1, $index - 1) + $replace +
      str-replace(str-slice($string, $index + str-length($search)), $search, $replace);
  }

  @return $string;
}

// 把svg字符串编码成符合浏览器css规则的字符串
@function encode-svg($str) {
  @return str-replace($str, "#", "%23");
}

// A list of pre-calculated numbers of pow(divide((divide($value, 255) + .055), 1.055), 2.4). (from 0 to 255)
// stylelint-disable-next-line scss/dollar-variable-default, scss/dollar-variable-pattern
$_luminance-list: 0.0008 0.001 0.0011 0.0013 0.0015 0.0017 0.002 0.0022 0.0025 0.0027 0.003 0.0033 0.0037 0.004 0.0044
  0.0048 0.0052 0.0056 0.006 0.0065 0.007 0.0075 0.008 0.0086 0.0091 0.0097 0.0103 0.011 0.0116 0.0123 0.013 0.0137
  0.0144 0.0152 0.016 0.0168 0.0176 0.0185 0.0194 0.0203 0.0212 0.0222 0.0232 0.0242 0.0252 0.0262 0.0273 0.0284 0.0296
  0.0307 0.0319 0.0331 0.0343 0.0356 0.0369 0.0382 0.0395 0.0409 0.0423 0.0437 0.0452 0.0467 0.0482 0.0497 0.0513 0.0529
  0.0545 0.0561 0.0578 0.0595 0.0612 0.063 0.0648 0.0666 0.0685 0.0704 0.0723 0.0742 0.0762 0.0782 0.0802 0.0823 0.0844
  0.0865 0.0887 0.0908 0.0931 0.0953 0.0976 0.0999 0.1022 0.1046 0.107 0.1095 0.1119 0.1144 0.117 0.1195 0.1221 0.1248
  0.1274 0.1301 0.1329 0.1356 0.1384 0.1413 0.1441 0.147 0.15 0.1529 0.1559 0.159 0.162 0.1651 0.1683 0.1714 0.1746
  0.1779 0.1812 0.1845 0.1878 0.1912 0.1946 0.1981 0.2016 0.2051 0.2086 0.2122 0.2159 0.2195 0.2232 0.227 0.2307 0.2346
  0.2384 0.2423 0.2462 0.2502 0.2542 0.2582 0.2623 0.2664 0.2705 0.2747 0.2789 0.2831 0.2874 0.2918 0.2961 0.3005 0.305
  0.3095 0.314 0.3185 0.3231 0.3278 0.3325 0.3372 0.3419 0.3467 0.3515 0.3564 0.3613 0.3663 0.3712 0.3763 0.3813 0.3864
  0.3916 0.3968 0.402 0.4072 0.4125 0.4179 0.4233 0.4287 0.4342 0.4397 0.4452 0.4508 0.4564 0.4621 0.4678 0.4735 0.4793
  0.4851 0.491 0.4969 0.5029 0.5089 0.5149 0.521 0.5271 0.5333 0.5395 0.5457 0.552 0.5583 0.5647 0.5711 0.5776 0.5841
  0.5906 0.5972 0.6038 0.6105 0.6172 0.624 0.6308 0.6376 0.6445 0.6514 0.6584 0.6654 0.6724 0.6795 0.6867 0.6939 0.7011
  0.7084 0.7157 0.7231 0.7305 0.7379 0.7454 0.7529 0.7605 0.7682 0.7758 0.7835 0.7913 0.7991 0.807 0.8148 0.8228 0.8308
  0.8388 0.8469 0.855 0.8632 0.8714 0.8796 0.8879 0.8963 0.9047 0.9131 0.9216 0.9301 0.9387 0.9473 0.956 0.9647 0.9734
  0.9823 0.9911 1;

// Customize the light and dark text colors for use in our color contrast function.
$color-contrast-dark: #000 !default;
$color-contrast-light: #fff !default;

// The contrast ratio to reach against white, to determine if color changes from "light" to "dark". Acceptable values for WCAG 2.0 are 3, 4.5 and 7.
// See https://www.w3.org/TR/WCAG20/#visual-audio-contrast-contrast
$min-contrast-ratio: 4.5 !default;

@function color-contrast(
  $background,
  $color-contrast-dark: $color-contrast-dark,
  $color-contrast-light: $color-contrast-light,
  $min-contrast-ratio: $min-contrast-ratio
) {
  $foregrounds: $color-contrast-light, $color-contrast-dark, $s-white, $s-black;
  $max-ratio: 0;
  $max-ratio-color: null;

  @each $color in $foregrounds {
    $contrast-ratio: contrast-ratio($background, $color);
    @if $contrast-ratio > $min-contrast-ratio {
      @return $color;
    } @else if $contrast-ratio > $max-ratio {
      $max-ratio: $contrast-ratio;
      $max-ratio-color: $color;
    }
  }

  @warn "Found no color leading to #{$min-contrast-ratio}:1 contrast ratio against #{$background}...";

  @return $max-ratio-color;
}

@function contrast-ratio($background, $foreground: $color-contrast-light) {
  $l1: luminance($background);
  $l2: luminance(opaque($background, $foreground));

  @return if($l1 > $l2, divide($l1 + 0.05, $l2 + 0.05), divide($l2 + 0.05, $l1 + 0.05));
}

// 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) {
  $rgb: (
    "r": red($color),
    "g": green($color),
    "b": blue($color),
  );

  @each $name, $value in $rgb {
    $value: if(divide($value, 255) < 0.03928, divide(divide($value, 255), 12.92), nth($_luminance-list, $value + 1));
    $rgb: map-merge(
      $rgb,
      (
        $name: $value,
      )
    );
  }

  @return (map-get($rgb, "r") * 0.2126) + (map-get($rgb, "g") * 0.7152) + (map-get($rgb, "b") * 0.0722);
}

// Return opaque color
// opaque(#fff, rgba(0, 0, 0, .5)) => #808080
@function opaque($background, $foreground) {
  @return mix(rgba($foreground, 1), $background, opacity($foreground) * 100);
}

@function divide($dividend, $divisor, $precision: 10) {
  $sign: if($dividend > 0 and $divisor > 0 or $dividend < 0 and $divisor < 0, 1, -1);
  $dividend: abs($dividend);
  $divisor: abs($divisor);
  @if $dividend == 0 {
    @return 0;
  }
  @if $divisor == 0 {
    @error "Cannot divide by 0";
  }
  $remainder: $dividend;
  $result: 0;
  $factor: 10;
  @while ($remainder > 0 and $precision >= 0) {
    $quotient: 0;
    @while ($remainder >= $divisor) {
      $remainder: $remainder - $divisor;
      $quotient: $quotient + 1;
    }
    $result: $result * 10 + $quotient;
    $factor: $factor * 0.1;
    $remainder: $remainder * 10;
    $precision: $precision - 1;
    @if ($precision < 0 and $remainder >= $divisor * 5) {
      $result: $result + 1;
    }
  }
  $result: $result * $factor * $sign;
  $dividend-unit: unit($dividend);
  $divisor-unit: unit($divisor);
  $unit-map: (
    "px": 1px,
    "rem": 1rem,
    "em": 1em,
    "%": 1%,
  );
  @if ($dividend-unit != $divisor-unit and map-has-key($unit-map, $dividend-unit)) {
    $result: $result * map-get($unit-map, $dividend-unit);
  }
  @return $result;
}

// scss-docs-start color-functions
// Tint a color: mix a color with white
@function tint-color($color, $weight) {
  @return mix(white, $color, $weight);
}

// Shade a color: mix a color with black
@function shade-color($color, $weight) {
  @return mix(black, $color, $weight);
}

// 把一个数四舍五入到指定位数小数
@function tofixed($n, $digits: 0) {
  @return math.div(round($n * math.pow(10, $digits)), math.pow(10, $digits));
}