//** Susy Grid **//

// Variables -----------------------------------------------------------------

// Your basic settings for the grid.
// Override these in base.sass to customize your site.
$total-cols         : 12            !default;
$col-width          : 4em           !default;
$gutter-width       : 1em           !default;
$side-gutter-width  : $gutter-width !default;

// Controls for right-to-left or bi-directional sites.
// You can override these case-by-case as needed for bi-directional sites.
$from-direction     : left          !default;

// Sets the direction that +omega elements are floated by deafult.
$omega-float        : opposite-position($from-direction)    !default;

// Functions -----------------------------------------------------------------

// Return the width of 'n' columns plus 'n - 1' gutters 
// plus page padding in non-nested contexts
@function columns-width(
  $n: false
) {
  $sg: 0;
  @if not $n {
    $n: $total-cols;
    $sg: $side-gutter-width;
  }
  $columns-width: ($n*$col-width) + (ceil($n - 1)*$gutter-width) + ($sg*2);
  @return $columns-width;
}

// Return the percentage for the target in a given context
@function percent-width(
  $t,
  $c
) {
  $perc: ($t / $c) * 100%;
  @return $perc;
}

// Return the percentage width of 'n' columns in a context of 'c'
@function columns(
  $n, 
  $c: false
) {
  $columns: percent-width(columns-width($n), columns-width($c));
  @return $columns;
}

// Return the percentage width of a single gutter in a context of 'c'
@function gutter(
  $c: false
) {
  $gutter: percent-width($gutter-width, columns-width($c));
  @return $gutter;
}

// Return the percentage width of a single side gutter in a context of 'c'
@function side-gutter(
  $c: false
) {
  $side-gutter: percent-width($side-gutter-width, columns-width($c));
  @return $side-gutter;
}

// Return the percentage width of a single column in a context of 'c'
@function column(
  $c: false
) {
  $column: percent-width($col-width, columns-width($c));
  @return $column;
}

// Base Mixin ----------------------------------------------------------------

// Set +container() on the outer grid-containing element(s).
@mixin container() {
  @include pie-clearfix;
  margin: auto;
  width: columns-width();
  max-width: 100%;
}

// Column Mixins -------------------------------------------------------------

// Set +columns() on any column element, even nested ones.
// The first agument [required] is the number of columns to span.
// The second argument is the context (columns spanned by parent).
//  - Context is required on any nested elements.
//  - Context MUST NOT be declared on a top-level element.
// By default a grid-column is floated left with a right gutter.
//  - Override those with +float("right"), +alpha or +omega
@mixin columns(
  $n, 
  $context  : false, 
  $from     : $from-direction
) {
  $to   : opposite-position($from);
  // the column is floated left
  @include float($from);
  // the width of the column is set as a percentage of the context
  width: columns($n, $context);
  // the right gutter is added as a percentage of the context
  margin-#{$to}: gutter($context); 
}

// Set +un-column to reset a column element to default block behavior
@mixin un-column(
  $from : $from-direction
) {
  $to   : opposite-position($from);
  float: none;
  display: block;
  width: auto;
  margin-#{$to}: auto;  
}

// Set +full on an element that will span it's entire context.
// There is no need for +columns, +alpha or +omega on a +full element.
@mixin full(
  $nested: false
) {
  clear: both;
  @if not $nested {
    margin: {
      left: side-gutter();
      right: side-gutter();      
    }
  } 
}

// Padding Mixins ------------------------------------------------------------

// Set +prefix() on any element to add empty colums as padding 
// before or after.
@mixin prefix(
  $n, 
  $context  : false, 
  $from     : $from-direction
) {
  padding-#{$from}: columns($n, $context) + gutter($context); 
}

@mixin suffix(
  $n, 
  $context  : false, 
  $from     : $from-direction
) {
  $to       : opposite-position($from);
  padding-#{$to}: columns($n, $context) + gutter($context); 
}

// Set as a shortcut for both prefix and suffix.
@mixin pad(
  $p    : false, 
  $s    : false, 
  $c    : false, 
  $from : $from-direction
) {
  @if $p {
    @include prefix($p, $c, $from); 
  } 
  @if $s {
    @include suffix($s, $c, $from); 
  } 
}

// Alpha & Omega Mixins ------------------------------------------------------

// Set +alpha on any element spanning the first column in non-nested 
// context to take side-gutters into account. Recommended that you pass 
// the actual nested contexts (when nested) rather than a true/false 
// argument for the sake of consistency. Effect is the same.
@mixin alpha(
  $nested : false, 
  $from   : $from-direction
) {
  @if not $nested {
    margin-#{$from}: side-gutter();
  } @else {
    @warn "The alpha mixin is not needed in a nested context";
  }
}

// Set +omega() on the last element of a row, in order to take side-gutters
// and the page edge into account. Set the $nested argument for nested 
// columns. It is recommended that you pass the actual nested context when 
// nested, rather than a true/false argument, for the sake of consistency. 
// Effect is the same.
@mixin omega(
  $nested : false, 
  $from   : $from-direction
) {
  $to     : opposite-position($from);
  $hack   : opposite-position($omega-float);
  $sg     : 0;
  @if not $nested {
    $sg: side-gutter(); 
  }
  @include float($omega-float);
  margin-#{$to}: $sg;
  @if $legacy-support-for-ie6 or $legacy-support-for-ie7 {
    #margin-#{$hack}: - $gutter-width;
  }
}