_functions.scss

/**
 * Functions for z-index management
 *
 * @author      paul 
 * @package     z-manager
 * @date        25/11/15
 */

/**
 * Spin through the z-indexes and get the highest value
 *
 * @return int
 */
@function z-index-manager-highest(){

  $highest: 0;

  @each $layer, $z-index in $z-indexes {

	@if( $z-index > $highest ){

	  $highest: $z-index;
	}
  }

  @return $highest;
};

/**
 * Spin through the z-indexes and get the lowest value
 *
 * @return int
 */
@function z-index-manager-lowest(){

  $lowest: 999999999;

  @each $layer, $z-index in $z-indexes {

	@if( $z-index < $lowest ){

	  $lowest: $z-index;
	}
  }

  @return $lowest;
};

/**
 * Get the z-dex of a layer
 *
 * @param $target {string} layer name
 */
@function z-index-manager-get( $target ){

  @return map-get( $z-indexes, $target );
}

/**
 * Work out the z-index for an element.
 * By default will assume we want to get the value above the layer target.
 *
 * Example:
 *	z-index-manager( 'modal' ); // 25
 *
 * @param $target {string} layer target.
 * @param $insert-above {boolean} get the z-index valuer of above or below the layer target. Set to false to insert below.
 * @param $layer {string} if specified will store the new layer in our
 *
 * @return {int}
 */
@function z-index-manager( $target, $insert-above: true, $layer: '' ){

  $new-z-index: auto;
  $target-z-index: 1;

  // Get our target from the map of layers
  @if map-has-key( $z-indexes, $target ){

	$target-z-index: z-index-manager-get( $target );

	@if( $insert-above ){

	  $new-z-index: $target-z-index + $z-index-buffer;
	}

	@else {

	  $new-z-index: $target-z-index - $z-index-buffer;
	}
  }

  // Mapped layer not found test for all layers
  @elseif( $target == '*' ){

	@if( $insert-above ){

	  $new-z-index: z-index-manager-highest() + 1;
	}

	@else {

	  $new-z-index: z-index-manager-lowest() - 1;
	}
  }

  // Save the layer if layer name is specified.
  @if( $layer ){

	$z-indexes: map-merge( $z-indexes, ( $layer: $new-z-index ) ) !global;
  }

  @return $new-z-index;
}