@use "sass:math";
@use "sass:meta";
@use "sass:list";

/// 单位转换
/// @function strip-unit($value)
/// @function compare-unit($values...)
/// @function join-unit($value, $unit)
/// @function add-unit($value, $unit)
/// @function px2rem($value, $base)
/// @function px2em($value, $base)
/// -----------------------------------------------------

/// 基础字体大小
$_base-font-size: 16px !default;

/// 去除单位
/// @param {number} $value 值
/// @return {number} 去除单位后的值
/// -----------------------------------------------------
@function strip-unit($value) {
  @return math.div($value, $value * 0 + 1);
}

/// 比较多个值的单位是否相等
/// @param {number} $value 值
/// @return {boolean} 是否相等
/// -----------------------------------------------------
@function compare-unit($values...) {
  $unit: math.unit(list.nth($values, 1));
  $equal: true;

  @each $value in $values {
    @if math.unit($value) != $unit {
      $equal: false;
    }
  }

  @return $equal;
}

/// 合并单位, 返回 number或 string
/// @param {number} $value 值
/// @param {string | number} $unit 单位, .e.g: ['px', 1px]
/// @return {string | number} $unit是number时返回number，否则返回string
/// -----------------------------------------------------
@function join-unit($value, $unit: px) {
  $_valueUnit: math.unit($value);
  $_unit: if(meta.type-of($unit) == number, math.unit($unit), $unit);

  @if $_valueUnit != '' {
    @if $_valueUnit != $_unit {
      @warn '[join-unit]: Parameter units are different.';
    }
    @return $value;
  } @else {
    @if meta.type-of($unit) == number {
      @return $value * $unit;
    }
    @return $value + $unit;
  }
}

/// 添加单位，返回合并后的数值
/// @param {number} $value 值
/// @param {string | number} $unit 单位, .e.g: ['px', 1px]
/// @return {number}
/// -----------------------------------------------------
@function add-unit($value, $unit: px) {
  $valueUnit: math.unit($value);
  @if $valueUnit != '' {
    @if math.unit($value) != $unit {
      @warn '[add-unit]: Parameter units are different.';
    }
    @return $value;
  } @else {
    @if meta.type-of($unit) == number {
      @return $value * $unit;
    } @else {
      @if $unit == 'px' {
        @return $value * 1px;
      } @else if $unit == 'em' {
        @return $value * 1em;
      } @else if $unit == 'rem' {
        @return $value * 1rem;
      } @else if $unit == '%' {
        @return $value * 1%;
      } @else {
        @warn "[add-unit]: Unsupported unit: #{$unit}.";
        @return $value;
      }
    }
  }
}

/// 将 px 转换为 rem
/// @param {number} $value 值
/// @param {number} $base 基准值
/// @return {number}
/// -----------------------------------------------------
@function px2rem($value, $base: $_base-font-size) {
  @if math.unit($value) == 'rem' {
    @return $value;
  }

  @if math.unit($value) != px or math.unit($base) != px {
    @error '[px2rem]: The unit must be `px`.';
  }

  @return math.div($value, $base) * 1rem;
}

/// 将 px 转换为 em
/// @param {number} $value 值
/// @param {number} $base 基准值
/// @return {number}
/// -----------------------------------------------------
@function px2em($value, $base: $_base-font-size) {
  @if math.unit($value) == 'em' {
    @return $value;
  }

  @if math.unit($value) != px or math.unit($base) != px {
    @error '[px2rem]: The unit must be `px`.';
  }

  @return math.div($value, $base) * 1em;
}