<?php

namespace App\Set\UseCases\ReorderSets;

use App\Exceptions\BadRequestException;
use App\Set\Set;
use App\Set\SetRepository;

class ReorderSets
{
    public function __construct(private SetRepository $setRepository)
    {
    }

    /**
     * @return Set[]
     * @throws BadRequestException
     */
    public function execute(ReorderSetsRequest $request): array
    {
        if ($request->setIds === null) {
            throw new BadRequestException('setIds is required');
        }

        $setIds = $this->validatedSetIds($request->setIds);
        $existingSetIds = $this->setIds($this->setRepository->getAll());

        $this->validateNoDuplicateIds($setIds);
        $this->validateAllIdsAreSets($setIds, $existingSetIds);
        $this->validateEverySetWasSubmitted($setIds, $existingSetIds);

        return $this->setRepository->reorder($setIds);
    }

    /**
     * @param mixed[] $setIds
     * @return int[]
     * @throws BadRequestException
     */
    private function validatedSetIds(array $setIds): array
    {
        $validatedSetIds = [];
        foreach ($setIds as $setId) {
            if (! is_int($setId)) {
                throw new BadRequestException(
                    'setIds must contain integers',
                );
            }

            $validatedSetIds[] = $setId;
        }

        return $validatedSetIds;
    }

    /**
     * @param int[] $setIds
     * @throws BadRequestException
     */
    private function validateNoDuplicateIds(array $setIds): void
    {
        $seenSetIds = [];
        foreach ($setIds as $setId) {
            if (isset($seenSetIds[$setId])) {
                throw new BadRequestException(
                    'Set order contains duplicate ids',
                );
            }

            $seenSetIds[$setId] = true;
        }
    }

    /**
     * @param int[] $setIds
     * @param int[] $existingSetIds
     * @throws BadRequestException
     */
    private function validateAllIdsAreSets(
        array $setIds,
        array $existingSetIds,
    ): void {
        $existingSetIdsById = [];
        foreach ($existingSetIds as $existingSetId) {
            $existingSetIdsById[$existingSetId] = true;
        }

        foreach ($setIds as $setId) {
            if (! isset($existingSetIdsById[$setId])) {
                throw new BadRequestException(
                    'Set order contains invalid set',
                );
            }
        }
    }

    /**
     * @param int[] $setIds
     * @param int[] $existingSetIds
     * @throws BadRequestException
     */
    private function validateEverySetWasSubmitted(
        array $setIds,
        array $existingSetIds,
    ): void {
        if (count($setIds) === count($existingSetIds)) {
            return;
        }

        throw new BadRequestException(
            'Set order must include every set',
        );
    }

    /**
     * @param Set[] $sets
     * @return int[]
     */
    private function setIds(array $sets): array
    {
        $setIds = [];
        foreach ($sets as $set) {
            $setIds[] = $set->getId();
        }

        return $setIds;
    }
}