@use 'variables' as *;
@use 'sass:map';
@use 'sass:list';
@use 'sass:string';

/// Get the difference between two lists.
/// @access private
/// @param {List} $list1 - The source list.
/// @param {List} $list2 - The list to check against the source list.
/// @return {List} - A list containing the diff items.
@function list-diff($list1, $list2) {
    $result: ();

    @each $item in $list1 {
        @if not list.index($list2, $item) {
            $result: list.append($result, $item, comma);
        }
    }

    @return $result;
}

/// @group Utilities
/// @author <a href="https://github.com/simeonoff" target="_blank">Simeon Simeonoff</a>
/// @access private
@function is-used($component, $checklist) {
    $used: true;

    @if list.index($checklist, $component) {
        $deps: map.get($components, $component, 'usedBy');
        $excluded: ();

        @each $item in $checklist {
            @if list.index($deps, $item) {
                $excluded: list.append($excluded, $item);
            }
        }

        $used: list.length($deps) != list.length($excluded);

        @if not($used) {
            $dropped-themes: list.append($dropped-themes, $component) !global;
        } @else {
            $remaining: list-diff($deps, $excluded);

            @warn string.unquote('You\'ve opted to exclude the "#{$component}" theme but it was held back as the following components depend on it: "#{$remaining}".');
        }
    }

    @return $used;
}

/// Test if a component, or list of components is in the list of known components.
/// @access private
/// @param {String|List} $items - The components list to check in.
/// @return {List} - The list of passed items.
@function is-component($items) {
    $register: map.keys($components);
    @each $item in $items {
        @if not(list.index($register, $item)) {
            @warn string.unquote('Can\'t exclude "#{$item}" because it is not in the list of known components.');
        }
    }
    @return $items;
}