// @category  utilities/spacing

// abstract spacing calculations
// @function  _spacing
// @private
// @param     $unit {Number} unit of measurement
// @param     $direction {String} [horizontal|vertical] spacing
// @param     $abuse {Bool} @see _getUnit
// @return    {String} the calculated spacing
@function _spacing($unit: nil, $direction: horizontal, $abuse: false) {
  @if $unit == nil {
    @return nil;
  }
  $unit: _getUnit($unit, $abuse);
  $spacing: if($direction == vertical, $CONFIG_VERTICAL_SPACING, $CONFIG_HORIZONTAL_SPACING);
  @return ($unit * $spacing);
}

// horizonatl spacing calculations
// @function  horizontal-spacing
// @param     $unit {Number} unit of measurement
// @param     $abuse {Bool} @see _getUnit
// @return    {String} the calculated horizontal spacing
@function horizontal-spacing($unit, $abuse: false) {
  @return _spacing($unit, $abuse: $abuse);
}

// vertical spacing calculations
// @function  vertical-spacing
// @param     $unit {Number} unit of measurement
// @param     $abuse {Bool} @see _getUnit
// @return    {String} the calculated vertical spacing
@function vertical-spacing($unit, $abuse: false) {
  @return _spacing($unit, $direction: vertical, $abuse: $abuse);
}

// generate the vertical spacing offset
// @mixin     vertical-spacing
// @param     $list {List} the list of units e.g. (1) => $top:1 $bottom:1; (1 0) => $top:1 $bottom:0;
// @param     $top {Number} the units to offset from the top
// @param     $bottom {Number} the units to offset from the bottom
// @param     $method {String} [margin|padding] offset method
// @param     $abuse {Bool} @see _getUnit
@mixin vertical-spacing($list: false, $top: nil, $bottom: nil, $method: false, $abuse: false) {
  $list: get-collection($list, ($top $bottom), $min: 2);
  @include _spacing($list, vertical, $method: $method, $abuse: $abuse);
}
// generate the horizontal spacing offset
// @mixin     horizontal-spacing
// @param     $list {List} the list of units e.g. (1) => $left:1 $right:1; (1 0) => $left:1 $right:0;
// @param     $left {Number} the units to offset from the left
// @param     $right {Number} the units to offset from the right
// @param     $method {String} [margin|padding] offset method
// @param     $abuse {Bool} @see _getUnit
@mixin horizontal-spacing($list: false, $left: nil, $right: nil, $method: false, $abuse: false) {
  $list: get-collection($list, ($left $right), $min: 2);
  @include _spacing($list, $method: $method, $abuse: $abuse);
}

// generate the spacing output
// @mixin     spacing
// @private
// @param     $units {List} the list of units e.g. (1) => $left:1 $right:1; (1 0) => $left:1 $right:0;
// @param     $method {String} [margin|padding] offset method
// @param     $abuse {Bool} @see _getUnit
@mixin _spacing($units, $direction: horizontal, $method: false, $abuse: false) {
  @if(not $method) {
    $method: $CONFIG_SPACING_METHOD;
  }
  @if($direction == vertical) {
    @include if-set(#{$method}-top,    vertical-spacing(nth($units,1), $abuse: $abuse), $ignore: nil);
    @include if-set(#{$method}-bottom, vertical-spacing(nth($units,2), $abuse: $abuse), $ignore: nil);
  }
  @else {
    @include if-set(#{$method}-#{rtl(left)},   horizontal-spacing(nth($units,1), $abuse: $abuse), $ignore: nil);
    @include if-set(#{$method}-#{rtl(right)},  horizontal-spacing(nth($units,2), $abuse: $abuse), $ignore: nil);
  }
}