class SortArray

class SortArray {
  
  /**
   * Sorts a structured array by the 'weight' element.
   *
   * Note that the sorting is by the 'weight' array element, not by the render
   * element property '#weight'.
   *
   * Callback for uasort().
   *
   * @param array $a
   *   First item for comparison. The compared items should be associative
   *   arrays that optionally include a 'weight' element. For items without a
   *   'weight' element, a default value of 0 will be used.
   * @param array $b
   *   Second item for comparison.
   *
   * @return int
   *   The comparison result for uasort().
   */
  public static function sortByWeightElement(array $a, array $b) {
    return static::sortByKeyInt($a, $b, 'weight');
  }
  
  /**
   * Sorts a structured array by '#weight' property.
   *
   * Callback for uasort().
   *
   * @param array $a
   *   First item for comparison. The compared items should be associative
   *   arrays that optionally include a '#weight' key.
   * @param array $b
   *   Second item for comparison.
   *
   * @return int
   *   The comparison result for uasort().
   */
  public static function sortByWeightProperty($a, $b) {
    return static::sortByKeyInt($a, $b, '#weight');
  }
  
  /**
   * Sorts a structured array by 'title' key (no # prefix).
   *
   * Callback for uasort().
   *
   * @param array $a
   *   First item for comparison. The compared items should be associative arrays
   *   that optionally include a 'title' key.
   * @param array $b
   *   Second item for comparison.
   *
   * @return int
   *   The comparison result for uasort().
   */
  public static function sortByTitleElement($a, $b) {
    return static::sortByKeyString($a, $b, 'title');
  }
  
  /**
   * Sorts a structured array by '#title' property.
   *
   * Callback for uasort().
   *
   * @param array $a
   *   First item for comparison. The compared items should be associative arrays
   *   that optionally include a '#title' key.
   * @param array $b
   *   Second item for comparison.
   *
   * @return int
   *   The comparison result for uasort().
   */
  public static function sortByTitleProperty($a, $b) {
    return static::sortByKeyString($a, $b, '#title');
  }
  
  /**
   * Sorts a string array item by an arbitrary key.
   *
   * @param array $a
   *   First item for comparison.
   * @param array $b
   *   Second item for comparison.
   * @param string $key
   *   The key to use in the comparison.
   *
   * @return int
   *   The comparison result for uasort().
   */
  public static function sortByKeyString($a, $b, $key) {
    $a_title = is_array($a) && isset($a[$key]) ? $a[$key] : '';
    $b_title = is_array($b) && isset($b[$key]) ? $b[$key] : '';
    return strnatcasecmp($a_title, $b_title);
  }
  
  /**
   * Sorts an integer array item by an arbitrary key.
   *
   * @param array $a
   *   First item for comparison.
   * @param array $b
   *   Second item for comparison.
   * @param string $key
   *   The key to use in the comparison.
   *
   * @return int
   *   The comparison result for uasort().
   */
  public static function sortByKeyInt($a, $b, $key) {
    $a_weight = is_array($a) && isset($a[$key]) ? $a[$key] : 0;
    $b_weight = is_array($b) && isset($b[$key]) ? $b[$key] : 0;
    return $a_weight <=> $b_weight;
  }

}