<?php

namespace App\Post\UseCases\SetFeaturedPost;

use App\Exceptions\BadRequestException;
use App\Exceptions\ForbiddenException;
use App\Post\Post;
use App\Post\PostRepository;
use DomainException;

class SetFeaturedPost
{
    private const VALID_SLOTS = [1, 2];

    public function __construct(
        private PostRepository $postRepo,
    ) {}

    /**
     * @throws BadRequestException
     * @throws ForbiddenException
     * @throws DomainException
     */
    public function execute(SetFeaturedPostRequest $request): Post
    {
        if (! $request->requesterIsAdmin) {
            throw new ForbiddenException(
                'only admins can feature a post'
            );
        }
        if ($request->postId <= 0) {
            throw new BadRequestException('postId must be positive');
        }
        if (! in_array($request->slot, self::VALID_SLOTS, true)) {
            throw new BadRequestException(
                'slot must be 1 or 2'
            );
        }

        $post = $this->postRepo->find($request->postId);
        if ($post === null) {
            throw new DomainException('post not found');
        }

        $existingInSlot = $this->postRepo->findByFeatureSlot($request->slot);
        if (
            $existingInSlot !== null
            && $existingInSlot->getId() !== $post->getId()
        ) {
            $this->postRepo->update(new Post(
                id: $existingInSlot->getId(),
                userId: $existingInSlot->getUserId(),
                title: $existingInSlot->getTitle(),
                body: $existingInSlot->getBody(),
                createdAt: $existingInSlot->getCreatedAt(),
                featureSlot: null,
            ));
        }

        return $this->postRepo->update(new Post(
            id: $post->getId(),
            userId: $post->getUserId(),
            title: $post->getTitle(),
            body: $post->getBody(),
            createdAt: $post->getCreatedAt(),
            featureSlot: $request->slot,
        ));
    }
}