@use 'sass:list';
@use 'sass:string';
@use 'equals-false' as *;
@use 'equals-true' as *;
@use 'is-alias' as *;
@use 'is-length' as *;
@use 'is-percentage' as *;
@use 'is-string' as *;
@use 'resolve-alias' as *;

/// Checks if a value is a position/offset, which is defined as either a length,
/// a percentage, or one of the following keyword values: `center`, `top`, `right`,
/// `bottom`, or `left`. This is useful when writing mixins that use properties
/// such as `transform-origin`, which has a 1-3 value syntax where the first
/// two values must be a position/offset.
///
/// @param {*} $value - A value to be checked.
/// @param {Bool | String } $allow-aliases [false] - If `true`, the function
/// will return true if the `$value` is an alias for a position/offset, not
/// just for exact matches. For example, if this is set to true, the function
/// will return true for a $value of `btm` as well as `bottom`. This parameter
/// also accepts a number of string values such as a `aliases`, `alias`, `allow`,
/// and `allow-alias`.
/// @param {Bool} $include-center [true] - Pass true to include the `'center'`
/// position/offset. Pass `false` or `null` to not include center.
///
/// @return {Bool} True if $value is a position, false if it is not.
///
/// @access public
/// @group Utilities
/// @require {function} equals-false
/// @require {function} equals-true
/// @require {function} is-alias
/// @require {function} is-length
/// @require {function} is-percentage
/// @require {function} is-string
/// @require {function} resolve-alias
@function is-position($value, $allow-aliases: false, $include-center: true) {
  $positions: ('top' 'right' 'bottom' 'left');

  @if equals-true($include-center) {
    $positions: list.append($positions, 'center')
  }

  @if is-string($value) {
    $value: string.to-lower-case($value);
  }

  @if $allow-aliases and is-string($allow-aliases) {
    $allow-aliases: string.to-lower-case($allow-aliases);
  }

  @if equals-true($allow-aliases) or
      $allow-aliases == 'aliases' or
      $allow-aliases == 'alias' or
      $allow-aliases == 'allow' or
      $allow-aliases == 'allow-aliases' or
      $allow-aliases == 'allow aliases' or
      $allow-aliases == 'allowaliases' or
      $allow-aliases == 'allow-alias' or
      $allow-aliases == 'allow alias' or
      $allow-aliases == 'allowalias'
  {
    @if is-string($value) {
      $value: resolve-alias($value);
    }
  } @else if not equals-false($allow-aliases) and
      not is-alias('none', $allow-aliases) and
      $allow-aliases != 'no'
  {
    @warn 'Unknown $allow-aliases value of of #{meta.inspect($allow-aliases)} '
        'passed to the [ is-position() ] function. This value should be either '
        '`true` (or `aliases`, `alias`, `allow`) or `false` (or `none` or `no`). ' +
        'Assuming the default value of `false`.';
  }

  @return (
    is-length($value) or is-percentage($value) or
      list.index($positions, $value) != null
  );
}

/// Checks if a value is a position/offset, which is defined as either a length,
/// a percentage, or one of the following keyword values: `center`, `top`, `right`,
/// `bottom`, or `left`. This is useful when writing mixins that use properties
/// such as `transform-origin`, which has a 1-3 value syntax where the first
/// two values must be a position/offset.
///
/// @param {*} $value - A value to be checked.
/// @param {Bool | String } $allow-aliases [false] - If `true`, the function
/// will return true if the `$value` is an alias for a position/offset, not
/// just for exact matches. For example, if this is set to true, the function
/// will return true for a $value of `btm` as well as `bottom`. This parameter
/// also accepts a number of string values such as a `aliases`, `alias`, `allow`,
/// and `allow-alias`.
///
/// @return {Bool} True if $value is a position, false if it is not.
///
/// @access public
/// @group Utilities
/// @require {function} equals-false
/// @require {function} equals-true
/// @require {function} is-alias
/// @require {function} is-length
/// @require {function} is-percentage
/// @require {function} resolve-alias
///
/// @alias is-position
@function is-offset($value, $allow-aliases: false) {
  @return is-position($value, $allow-aliases);
}