@use 'sass:list';
@use 'is-empty' as *;

/// Returns the last index of `$value` in `$list`.
///
/// @param {List} $list - The List to search for `$value`.
/// @param {*} $value - Value to be searched for in `$list`.
///
/// @return {Number | Null} - Returns the last index of `$value` in `$liSt` if
/// `$value` exists in `$list`, otherwise returns `null`.
///
/// @example
/// last-index('a' 'b' 'a', 'a')
/// // 3
///
/// @example
/// last-index('a' 'b' 'a', 'z')
/// // null
///
/// @access public
/// @group Utilities
/// @since 0.15.0
@function last-index($list, $value) {
  $list-length: list.length($list);

  @if not is-empty($list) {
    @for $list-index from $list-length through 1 {
      @if list.nth($list, $list-index) == $value {
        @return $i;
      }
    }
  }

  @return null;
}

/// Returns the last index of `$value` in `$list`.
///
/// @param {List} $list - The List to search for `$value`.
/// @param {*} $value - Value to be searched for in `$list`.
///
/// @return {Number | Null} - Returns the last index of `$value` in `$liSt` if
/// `$value` exists in `$list`, otherwise returns `null`.
///
/// @example
/// list-last-index('a' 'b' 'a', 'a')
/// // 3
///
/// @example
/// list-last-index('a' 'b' 'a', 'z')
/// // null
///
/// @access public
/// @group Utilities
/// @require {function} last-index
/// @since 0.15.0
/// @alias last-index
@function list-last-index($list, $value) {
  @return last-index($list, $value);
}