// Bleed Syntax
// ============

// Bleed
// -----
// Add negative margins, and equal positive padding to create bleed.
// - $bleed  : <span>
@mixin bleed(
  $bleed: 0 gutter()
) {
  $inspect  : $bleed;
  $output   : get-bleed($bleed);

  @if susy-get(global-box-sizing) != content-box {
    $output: map-merge((box-sizing: content-box), $output);
  }

  @include susy-inspect(bleed, $inspect);
  @include output($output);
}


// Bleed-x
// -------
// Shortcut for horizontal bleed.
// - $bleed  : <span>
@mixin bleed-x(
  $bleed: gutter()
) {
  $bleed  : parse-span($bleed);
  $trbl   : susy-get(span, $bleed);

  @if length($trbl) == 1 {
    $bleed: map-merge($bleed, (span: 0 nth($trbl, 1)));
  } @else if length($trbl) == 2 {
    $bleed: map-merge($bleed, (span: 0 nth($trbl, 2) 0 nth($trbl, 1)));
  } @else {
    @warn 'bleed-x only takes 2 lengths, but #{length($trbl)} were passed.';
  }

  @include bleed($bleed);
}


// Bleed-y
// -------
// Shortcut for vertical bleed.
// - $bleed  : <span>
@mixin bleed-y(
  $bleed: if(function-exists(rhythm), rhythm(1), 1em)
) {
  $bleed  : parse-span($bleed);
  $trbl   : susy-get(span, $bleed);

  @if length($trbl) == 1 {
    $bleed: map-merge($bleed, (span: nth($trbl, 1) 0));
  } @else if length($trbl) == 2 {
    $bleed: map-merge($bleed, (span: nth($trbl, 1) 0 nth($trbl, 2) 0));
  } @else {
    @warn 'bleed-y only takes 2 lengths, but #{length($trbl)} were passed.';
  }

  @include bleed($bleed);
}


// Get Bleed
// ---------
// Return bleed output values
// - $bleed: <span>
@function get-bleed(
  $bleed
) {
  $bleed    : map-merge((spread: wide), parse-span($bleed));
  $trbl     : susy-get(span, $bleed);
  $short    : null;
  $output   : ();

  @for $i from 1 through length($trbl) {
    $this: nth($trbl, $i);
    $new: ();
    $margin: null;
    $padding: null;
    $padding-x: null;

    @if $this > 0 {
      $this: map-merge($bleed, (span: $this));
      $margin: span($this);
      $padding: $margin;
      $padding-x: $padding;
    }

    @if $margin and $margin > 0 {
      $margin: - $margin;

      @if is-inside($this) {
        $gutter: gutter($this);
        $join: if($gutter and comparable($padding, $gutter), true, false);
        $padding-x: if($join and $padding > 0, $padding + $gutter, $padding);
      }
    }

    @if $i == 1 {
      $new: (
        margin-top: $margin,
        padding-top: $padding,
        margin-right: $margin,
        padding-right: $padding-x,
        margin-bottom: $margin,
        padding-bottom: $padding,
        margin-left: $margin,
        padding-left: $padding-x,
      );
    } @else if $i == 2 {
      $new: (
        margin-right: $margin,
        padding-right: $padding-x,
        margin-left: $margin,
        padding-left: $padding-x,
      );
    } @else if $i == 3 {
      $new: (
        margin-bottom: $margin,
        padding-bottom: $padding,
      );
    } @else if $i == 4 {
      $new: (
        margin-left: $margin,
        padding-left: $padding-x,
      );
    }

    $output: map-merge($output, $new);
  }

  @each $prop, $value in $output {
    $output: if($value == 0, map-merge($output, ($prop: null)), $output);
  }

  @return bleed-shorthand($output);
}

// Bleed Shorthand
// ---------------
// Convert bleed output into shorthand when possible.
// - $bleed: <output map>
@function bleed-shorthand(
  $bleed
) {
  $margin: ();
  $padding: ();
  $return: ();

  @each $key, $value in $bleed {
    @if str-index($key, margin) {
      $margin: map-merge($margin, ($key: $value));
    } @else if str-index($key, padding) > 0 {
      $padding: map-merge($padding, ($key: $value));
    }
  }

  $props: (
    margin: $margin,
    padding: $padding,
  );

  @each $name, $map in $props {
    $four: if(length(map-keys($map)) == 4, true, false);
    $null: if(index(map-values($map), null), true, false);

    @if $four and not($null) {
      $top: map-get($map, '#{$name}-top');
      $right: map-get($map, '#{$name}-right');
      $bottom: map-get($map, '#{$name}-bottom');
      $left: map-get($map, '#{$name}-left');

      $tb: if($top == $bottom, $top, null);
      $rl: if($right == $left, $right, null);
      $all: if($tb == $rl, $tb, null);

      $new: if($all, $all, null);

      @if not($new) {
        @if $tb and $rl {
          $new: $tb $rl;
        } @else if $rl {
          $new: $top $rl $bottom;
        } @else {
          $new: $top $right $bottom $left;
        }
      }

      $return: map-merge($return, ($name: $new));
    } @else {
      $return: map-merge($return, $map);
    }
  }

  @return $return;
}