/// Transforms shorthand that can range from 1-to-4 values to be 4 values.
///
/// @argument {list} $shorthand
///
/// @example scss
///   .element {
///     margin: _unpack-shorthand(1em 2em);
///   }
///
///   // CSS Output
///   .element {
///     margin: 1em 2em 1em 2em;
///   }
///
/// @access private

@function _unpack-shorthand($shorthand) {
  @if length($shorthand) == 1 {
    @return nth($shorthand, 1) nth($shorthand, 1) nth($shorthand, 1) nth($shorthand, 1);
  } @else if length($shorthand) == 2 {
    @return nth($shorthand, 1) nth($shorthand, 2) nth($shorthand, 1) nth($shorthand, 2);
  } @else if length($shorthand) == 3 {
    @return nth($shorthand, 1) nth($shorthand, 2) nth($shorthand, 3) nth($shorthand, 2);
  } @else {
    @return $shorthand;
  }
}

/// hide-visually mixin from Bourbon < https://bourbon.io >
/// 
/// Hides an element visually while still allowing the content to be accessible
/// to assistive technology, e.g. screen readers. Passing `unhide` will reverse
/// the affects of the hiding, which is handy for showing the element on focus,
/// for example.
///
/// @link https://goo.gl/Vf1TGn
///
/// @argument {string} $toggle [hide]
///   Accepts `hide` or `unhide`. `unhide` reverses the affects of `hide`.
///
/// @example scss
///   .element {
///     @include hide-visually;
///
///     &:active,
///     &:focus {
///       @include hide-visually("unhide");
///     }
///   }
///
///   // CSS Output
///   .element {
///     border: 0;
///     clip: rect(1px, 1px, 1px, 1px);
///     clip-path: inset(100%);
///     height: 1px;
///     overflow: hidden;
///     padding: 0;
///     position: absolute;
///     width: 1px;
///   }
///
///   .hide-visually:active,
///   .hide-visually:focus {
///     clip: auto;
///     clip-path: none;
///     height: auto;
///     overflow: visible;
///     position: static;
///     width: auto;
///   }
///
/// @since 5.0.0

@mixin hide-visually($toggle: "hide") {
  @if not index("hide" "unhide", $toggle) {
    @error "`#{$toggle}` is not a valid value for the `$toggle` argument in " +
      "the `hide-visually` mixin. Must be either `hide` or `unhide`.";
  } @else if $toggle == "hide" {
    border: 0;
    clip: rect(1px, 1px, 1px, 1px);
    clip-path: inset(100%);
    height: 1px;
    overflow: hidden;
    padding: 0;
    position: absolute;
    white-space: nowrap;
    width: 1px;
  } @else if $toggle == "unhide" {
    clip: auto;
    clip-path: none;
    height: auto;
    overflow: visible;
    position: static;
    white-space: inherit;
    width: auto;
  }
}

/// Provides a concise, one-line method for setting an element’s positioning
/// properties: `position`, `top`, `right`, `bottom` and `left`. Use a `null`
/// value to “skip” an edge of the box.
///
/// @argument {string} $position
///   A CSS position value.
///
/// @argument {list} $box-edge-values
///   List of lengths; accepts CSS shorthand.
///
/// @example scss
///   .element {
///     @include position(relative, 0 null null 10em);
///   }
///
///   // CSS Output
///   .element {
///     left: 10em;
///     position: relative;
///     top: 0;
///   }
///
/// @example scss
///   .element {
///     @include position(absolute, 0);
///   }
///
///   // CSS Output
///   .element {
///     position: absolute;
///     top: 0;
///     right: 0;
///     bottom: 0;
///     left: 0;
///   }
///
/// @require {function} _is-length
///
/// @require {function} _unpack-shorthand

@mixin position(
  $position,
  $box-edge-values
) {
  $box-edge-values: _unpack-shorthand($box-edge-values);
  $offsets: (
    "top": nth($box-edge-values, 1),
    "right": nth($box-edge-values, 2),
    "bottom": nth($box-edge-values, 3),
    "left": nth($box-edge-values, 4),
  );

  position: $position;

  @each $offset, $value in $offsets {
    @if _is-length($value) {
      #{$offset}: $value;
    }
  }
}

@mixin circle($size, $display) {
  width: $size;
  height: $size;
  display: $display;
  -webkit-border-radius: $size/2;
  -moz-border-radius: $size/2;
  border-radius: $size/2;
}

// box-shadow
// top and left are  the anchor point from where to start moving the shadow
@mixin box-shadow($top, $left, $blur, $color, $inset: false) {
    @if unitless($top) or unitless($left) or unitless($blur) {
        $top: $top * 1px;
        $left: $left * 1px;
        $blur: $blur * 1px;
    }
    @if $inset {
        -webkit-box-shadow:inset $top $left $blur $color;
        -moz-box-shadow:inset $top $left $blur $color;
        box-shadow:inset $top $left $blur $color;
    } @else {
        -webkit-box-shadow: $top $left $blur $color;
        -moz-box-shadow: $top $left $blur $color;
        box-shadow: $top $left $blur $color;
    }
}