import { getRepository } from '@/lib/db/client';
import { ArticleEntity } from '@/lib/feature/article/article.entity';
import {
    ArticleModel,
    CreateArticleModel,
    PaginatedArticlesResult,
    UpdateArticleModel,
} from '@/lib/feature/article/article.model';
import { TypedResult, wrap } from '@/utils/types/results';
import { UUIDv4 } from '@/utils/types/uuid';

export const articleEntityToModel = (
    articleEntity: ArticleEntity
): ArticleModel => {
    return {
        id: articleEntity.id,
        title: articleEntity.title,
        slug: articleEntity.slug,
        description: articleEntity.description,
        coverImageUrl: articleEntity.coverImageUrl,
        content: articleEntity.content,
        authorId: articleEntity.authorId,
        externalId: articleEntity.externalId,
        createdAt: articleEntity.createdAt,
        updatedAt: articleEntity.updatedAt,
    };
};

/** Retrieves an article by its external ID. */
export const getArticleByExternalId: (
    externalId: UUIDv4
) => Promise<TypedResult<ArticleModel | null>> = wrap(
    async (externalId: UUIDv4): Promise<ArticleModel | null> => {
        const articleRepository = await getRepository(ArticleEntity);

        const articleEntity = await articleRepository.findOneBy({
            externalId: externalId,
        });

        if (!articleEntity) {
            return null;
        }

        return articleEntityToModel(articleEntity);
    }
);

/** Retrieves an article by its slug. */
export const getArticleBySlug: (
    slug: string
) => Promise<TypedResult<ArticleModel | null>> = wrap(
    async (slug: string): Promise<ArticleModel | null> => {
        const articleRepository = await getRepository(ArticleEntity);

        const articleEntity = await articleRepository.findOneBy({ slug });

        if (!articleEntity) {
            return null;
        }

        return articleEntityToModel(articleEntity);
    }
);

/** Retrieves all articles by a given author ID. */
export const getArticlesByAuthorId: (
    authorId: string
) => Promise<TypedResult<ArticleModel[]>> = wrap(
    async (authorId: string): Promise<ArticleModel[]> => {
        const articleRepository = await getRepository(ArticleEntity);

        const articleEntities = await articleRepository.findBy({ authorId });

        return articleEntities.map(articleEntityToModel);
    }
);

/** Retrieves a paginated list of articles ordered by creation date descending. */
export const getArticlesPaginated: (
    page?: number,
    pageSize?: number
) => Promise<TypedResult<PaginatedArticlesResult>> = wrap(
    async (
        page: number = 1,
        pageSize: number = 10
    ): Promise<PaginatedArticlesResult> => {
        const articleRepository = await getRepository(ArticleEntity);

        const [articleEntities, total] = await articleRepository.findAndCount({
            order: { createdAt: 'DESC' },
            skip: (page - 1) * pageSize,
            take: pageSize,
        });

        return {
            data: articleEntities.map(articleEntityToModel),
            total,
            page,
            pageSize,
            totalPages: Math.ceil(total / pageSize),
        };
    }
);

/** Saves a new article to the database. */
export const saveArticle: (
    article: CreateArticleModel
) => Promise<TypedResult<ArticleModel>> = wrap(
    async (article: CreateArticleModel): Promise<ArticleModel> => {
        const articleRepository = await getRepository(ArticleEntity);

        if (!article.authorId) {
            throw new Error('Author ID is required to save an article');
        }

        if (!!(await articleRepository.findOneBy({ slug: article.slug }))) {
            throw new Error(`Article with slug ${article.slug} already exists`);
        }

        const newArticle = articleRepository.create(article);
        return articleEntityToModel(await articleRepository.save(newArticle));
    }
);

/** Updates an existing article in the database. */
export const updateArticle: (
    articleId: string,
    article: UpdateArticleModel
) => Promise<TypedResult<ArticleModel>> = wrap(
    async (
        articleId: string,
        article: UpdateArticleModel
    ): Promise<ArticleModel> => {
        const articleRepository = await getRepository(ArticleEntity);

        const existingArticle = await articleRepository.findOneBy({
            id: articleId,
        });
        if (!existingArticle) {
            throw new Error(`Article with ID ${articleId} not found`);
        }

        if (!!article.title) existingArticle.title = article.title;
        if (!!article.slug) existingArticle.slug = article.slug;
        if (!!article.description)
            existingArticle.description = article.description;
        if (!!article.coverImageUrl)
            existingArticle.coverImageUrl = article.coverImageUrl;
        if (!!article.content) existingArticle.content = article.content;

        return articleEntityToModel(
            await articleRepository.save(existingArticle)
        );
    }
);

/** Deletes an article from the database. */
export const deleteArticle: (articleId: string) => Promise<TypedResult<void>> =
    wrap(async (articleId: string): Promise<void> => {
        const articleRepository = await getRepository(ArticleEntity);

        const existingArticle = await articleRepository.findOneBy({
            id: articleId,
        });
        if (!existingArticle) {
            throw new Error(`Article with ID ${articleId} not found`);
        }

        await articleRepository.remove(existingArticle);
    });