components/LiteCharms.Features.MidrandBooks/AuthorBooks/BooksService.cs

using LiteCharms.Features.MidrandBooks.Abstractions;
using LiteCharms.Features.MidrandBooks.AuthorBooks.Models;
using LiteCharms.Features.MidrandBooks.Extensions;
using LiteCharms.Features.MidrandBooks.Postgres;

namespace LiteCharms.Features.MidrandBooks.AuthorBooks;

public sealed class BooksService(IDbContextFactory<MidrandBooksDbContext> contextFactory) : IService
{
    public async ValueTask<Result> UpdateBookStatusAsync(long bookId, bool isEnabled, CancellationToken cancellationToken = default)
    {
        try
        {
            await using var context = await contextFactory.CreateDbContextAsync(cancellationToken);

            var rowsUpdated = await context.Books
                .Where(b => b.Id == bookId)
                .ExecuteUpdateAsync(setters => setters
                    .SetProperty(b => b.Enabled, isEnabled)
                    .SetProperty(b => b.UpdatedAt, DateTime.UtcNow), cancellationToken);

            return rowsUpdated > 0
                ? Result.Ok()
                : Result.Fail(new Error($"Book with ID {bookId} not found"));
        }
        catch (Exception ex)
        {
            return Result.Fail(new Error(ex.Message).CausedBy(ex));
        }
    }

    public async ValueTask<Result<long>> CreateBookAsync(long authorId, long productId, CancellationToken cancellationToken = default)
    {
        try
        {
            await using var context = await contextFactory.CreateDbContextAsync(cancellationToken);

            if(!await context.Authors.AnyAsync(a => a.Id == authorId, cancellationToken))
                return Result.Fail<long>("Author not found.");

            if (!await context.Products.AnyAsync(p => p.Id == productId, cancellationToken))
                return Result.Fail<long>("Product not found.");

            var book = context.Books.Add(new Entities.AuthorBook
            {
                CreatedAt = DateTime.UtcNow,
                AuthorId = authorId,
                ProductId = productId                
            });

            return await context.SaveChangesAsync(cancellationToken) > 0
                ? Result.Ok(book.Entity.Id)
                : Result.Fail<long>("Failed to create book.");
        }
        catch (Exception ex)
        {
            return Result.Fail<long>(new Error(ex.Message).CausedBy(ex));
        }
    }

    public async ValueTask<Result<AuthorBook>> GetBookAsync(long bookId, CancellationToken cancellationToken = default)
    {
        try
        {
            await using var context = await contextFactory.CreateDbContextAsync(cancellationToken);

            var book = await context.Books
                .AsNoTracking()
                .Include(b => b.Author)
                .Include(b => b.Product)
                    .ThenInclude(b => b!.Prices)
                .Include(b => b.Pages)
                .FirstOrDefaultAsync(b => b.Id == bookId, cancellationToken);

            return book is null 
                ? Result.Fail<AuthorBook>(new Error($"Book with ID {bookId} not found")) 
                : Result.Ok(book.ToModel());
        }
        catch (Exception ex)
        {
            return Result.Fail<AuthorBook>(new Error(ex.Message).CausedBy(ex));
        }
    }

    public async ValueTask<Result<AuthorBook[]>> GetBooksByAuthorAsync(long authorId, CancellationToken cancellationToken = default)
    {
        try
        {
            await using var context = await contextFactory.CreateDbContextAsync(cancellationToken);

            if(!await context.Authors.AnyAsync(a => a.Id == authorId, cancellationToken))
                return Result.Fail<AuthorBook[]>(new Error($"Author with ID {authorId} not found"));

            var books = await context.Books
                .AsNoTracking()
                .Include(b => b.Author)
                .Include(b => b.Product)
                    .ThenInclude(b => b.Prices)
                .OrderByDescending(b => b.CreatedAt)
                .Where(b => b.AuthorId == authorId)
                .ToListAsync(cancellationToken);

            return books?.Count > 0
                ? Result.Ok(books.Select(b => b.ToModel()).ToArray())
                : Result.Fail<AuthorBook[]>(new Error($"No books found for author with ID {authorId}"));
        }
        catch (Exception ex)
        {
            return Result.Fail<AuthorBook[]>(new Error(ex.Message).CausedBy(ex));
        }
    }

    public async ValueTask<Result<AuthorBook[]>> GetPublishedBooksAsync(int offset, int limit, CancellationToken cancellationToken = default)
    {
        try
        {
            await using var context = await contextFactory.CreateDbContextAsync(cancellationToken);

            var books = await context.Books
                .AsNoTracking()
                .Include(b => b.Author)
                .Include(b => b.Product)
                    .ThenInclude(b => b!.Prices)
                .Include(b => b.Pages)
                .Where(b => b.Enabled && b.Product!.Enabled && b.Author!.Enabled)
                .OrderByDescending(b => b.Ranking)
                    .ThenByDescending(b => b.Ranking)
                    .ThenByDescending(b => b.CreatedAt)
                    .ThenByDescending(b => b.UpdatedAt)
                .Skip(offset).Take(limit)
                .AsSplitQuery()
                .ToArrayAsync(cancellationToken);

            return books?.Length > 0
                ? Result.Ok(books.Select(b => b.ToModel()).ToArray())
                : Result.Fail<AuthorBook[]>(new Error("No published books found."));
        }
        catch (Exception ex)
        {
            return Result.Fail<AuthorBook[]>(new Error(ex.Message).CausedBy(ex));
        }
    }
}