@use 'sass:list';
@use 'sass:meta';

/// Validates that the object's type matches any of the expected types.
/// @param {any} $obj The object to test
/// @param {List} $types The expected types
/// @return {String} null if no error, else the unexpected type.
@function validate-type($obj, $types...) {
  $result: meta.type-of($obj);
  // A zero-length list is the same as a zero-length map.
  @if ($result == list and list.index($types, map) and list.length($obj) == 0) {
    @return null;
  }
  @return if(list.index($types, $result), null, $result);
}

/// Validates that a list contains only values from the allowed list of values.
/// @param {List} $list The list to test
/// @param {List} $allowed The allowed values
/// @return {List} null if no error, else the list of non-allowed values.
@function validate-allowed-values($list, $allowed...) {
  $invalid: ();
  @each $element in $list {
    @if not list.index($allowed, $element) {
      $invalid: list.append($invalid, $element);
    }
  }
  @return if(list.length($invalid) > 0, $invalid, null);
}

/// Validates that a list contains all values from the required list of values.
/// @param {List} $list The list to test
/// @param {List} $required The required values
/// @return {List} null if no error, else the list of missing values.
@function validate-required-values($list, $required...) {
  $invalid: ();
  @each $element in $required {
    @if not list.index($list, $element) {
      $invalid: list.append($invalid, $element);
    }
  }
  @return if(list.length($invalid) > 0, $invalid, null);
}