<?php

declare(strict_types=1);

namespace App\Form\ChoiceLoader;

use App\Form\Model\RoomSelectionDto;
use Symfony\Component\Form\ChoiceList\ChoiceListInterface;
use Symfony\Component\Form\ChoiceList\Factory\ChoiceListFactoryInterface;
use Symfony\Component\Form\ChoiceList\Loader\ChoiceLoaderInterface;

/**
 * Choice loader for participant room assignments.
 *
 * Generates room choices for each participant from all selected room types
 * in Step 1, regardless of current capacity or assignments. Capacity conflicts
 * are automatically resolved by the field handler through intelligent
 * auto-unassignment when needed.
 */
class ParticipantRoomChoiceLoader implements ChoiceLoaderInterface
{
    private ?ChoiceListInterface $choiceList = null;

    /**
     * @param RoomSelectionDto[] $selectedRooms the rooms selected in the previous step
     */
    public function __construct(
        private readonly ChoiceListFactoryInterface $factory,
        private readonly array $selectedRooms,
    ) {
    }

    public function loadChoiceList(?callable $value = null): ChoiceListInterface
    {
        if (null === $this->choiceList) {
            $choices = $this->generateRoomChoicesForParticipant();
            $this->choiceList = $this->factory->createListFromChoices($choices, $value);
        }

        return $this->choiceList;
    }

    public function loadChoicesForValues(array $values, ?callable $value = null): array
    {
        if (empty($values)) {
            return [];
        }

        return $this->loadChoiceList($value)->getChoicesForValues($values);
    }

    public function loadValuesForChoices(array $choices, ?callable $value = null): array
    {
        if (empty($choices)) {
            return [];
        }

        return $this->loadChoiceList($value)->getValuesForChoices($choices);
    }

    /**
     * Generates room choices for the specific participant.
     *
     * Always includes all selected rooms from Step 1 regardless of current capacity.
     * Capacity conflicts are handled by the field handler during assignment.
     *
     * @return array<string, int>
     */
    private function generateRoomChoicesForParticipant(): array
    {
        $participantRoomChoices = [];

        foreach ($this->selectedRooms as $roomSelection) {
            // Always include all selected rooms - capacity conflicts handled in field handler
            $participantRoomChoices[$roomSelection->roomLabel] = $roomSelection->roomId;
        }

        return $participantRoomChoices;
    }
}