$direction: ltr !default;
$direction-values: (
  ltr: rtl,
  rtl: ltr,
  left: right,
  right: left
) !default;

@function direction($value) {
  @if $direction == rtl and map-has-key($direction-values, $value) {
    @return map-get($direction-values, $value);
  }

  @return $value;
}

@function direction-sides($values) {
  @if $direction == rtl and length($values) == 4 {
    @return nth($values, 1) nth($values, 4) nth($values, 3) nth($values, 2);
  }

  @return $values;
}

@function direction-corners($values) {
  @if $direction == rtl and length($values) > 1 {
    @if length($values) == 2 {
      @return nth($values, 2) nth($values, 1);
    } @else if length($values) == 3 {
      @return nth($values, 2) nth($values, 1) nth($values, 2) nth($values, 3);
    } @else {
      @return nth($values, 2) nth($values, 1) nth($values, 4) nth($values, 3);
    }
  }

  @return $values;
}

@function direction-if($condition, $if, $else: null) {
  @return if($direction == $condition, $if, $else);
}

@function direction-ltr($if, $else: null) {
  @return direction-if(ltr, $if, $else);
}

@function direction-rtl($if, $else: null) {
  @return direction-if(rtl, $if, $else);
}

@mixin direction {
  direction: $direction;
}

@mixin direction-if($condition) {
  @if $direction == $condition {
    @content;
  }
}

@mixin direction-ltr {
  @include direction-if(ltr) {
    @content;
  }
}

@mixin direction-rtl {
  @include direction-if(rtl) {
    @content;
  }
}