// Gutter Syntax
// =============

// Gutters
// -------
// Set gutters on an element.
// - [$span]   : <settings>
@mixin gutters(
  $span: $susy
) {
  $span: parse-gutters($span);
  $gutters: get-gutters($span);
  $output: (
    before: map-get($gutters, before),
    after: map-get($gutters, after),
    flow: susy-get(flow, $span),
  );

  @if is-inside($span) {
    @include padding-output($output...);
  } @else {
    @include margin-output($output...);
  }
}

@mixin gutter(
  $span: $susy
) {
  @include gutters($span);
}

// Gutter
// ------
// Return the width of a gutter.
// - [$span]   : <settings>
@function gutter(
  $span: $susy
) {
  $span: parse-gutters($span);

  $gutters: get-gutters($span);
  $gutters: map-get($gutters, before) or map-get($gutters, after);

  @return $gutters;
}

@function gutters(
  $span: $susy
) {
  @return gutter($span);
}

// Get Gutter Width
// ----------------
// Return gutter width.
// - [$context]: <context>
@function get-gutter-width(
  $context: $susy
) {
  $context  : parse-gutters($context);
  $gutters  : susy-get(gutters, $context);
  $gutter   : susy-get(gutter-override, $context);

  @if $gutters and ($gutters > 0) and not $gutter {
    $column-width: susy-get(column-width, $context);
    @if $column-width and gutter-math($context) == static {
      $gutter: $gutters * $column-width;
    } @else {
      $columns  : susy-get(columns, $context);
      $spread   : if(is-split($context), wide, susy-get(spread, $context));
      $gutter   : percentage($gutters / column-sum($columns, $gutters, $spread));
    }
  }

  $gutter: if($gutter == 'no-gutters' or $gutter == 'no-gutter', null, $gutter);

  @return $gutter;
}

// Get Gutters
// -----------
// Return before and after gutter values.
// - [$context]: <context>
@function get-gutters(
  $context: $susy
) {
  $context          : parse-gutters($context);
  $gutter-position  : susy-get(gutter-position, $context);
  $gutter           : get-gutter-width($context);
  $return           : (before: null, after: null);

  @if is-split($context) and $gutter {
    $gutter: $gutter / 2;
    $return: map-merge($return, (before: $gutter, after: $gutter));
  } @else {
    $return: map-merge($return, ($gutter-position: $gutter));
  }

  @return $return;
}

// Is Inside
// ---------
// Returns true if gutters are inside.
// $context: <context>
@function is-inside(
  $context
) {
  $inside: inside inside-static;
  $gutter-position: susy-get(gutter-position, $context);

  @return if(index($inside, $gutter-position), true, false);
}

// Is Split
// --------
// Returns true if gutters are split.
// $context: <context>
@function is-split(
  $context
) {
  $split: split inside inside-static;
  $gutter-position: susy-get(gutter-position, $context);

  @return if(index($split, $gutter-position), true, false);
}

// Gutter Math
// -----------
// Return the math to use for gutter calculations
// $context: <context>
@function gutter-math(
  $context: $susy
) {
  $return   : susy-get(math, $context);
  $return   : if(susy-get(gutter-position, $context) == inside-static, static, $return);

  @return $return;
}