components/LiteCharms.Features.MidrandBooks/Products/ProductService.cs

using LiteCharms.Features.MidrandBooks.Abstractions;
using LiteCharms.Features.MidrandBooks.Categories.Models;
using LiteCharms.Features.MidrandBooks.Extensions;
using LiteCharms.Features.MidrandBooks.Postgres;
using LiteCharms.Features.MidrandBooks.Products.Models;
using LiteCharms.Features.Models;

namespace LiteCharms.Features.MidrandBooks.Products;

public sealed class ProductService(IDbContextFactory<MidrandBooksDbContext> contextFactory) : IService
{
    public async ValueTask<Result> AddProductCategoryAsync(long productId, long categoryId, CancellationToken cancellationToken = default)
    {
        try
        {
            await using var context = await contextFactory.CreateDbContextAsync(cancellationToken);

            if (!await context.Products.AnyAsync(p => p.Id == productId && p.Enabled, cancellationToken))
                return Result.Fail("Product does not exist");

            if (!await context.Categories.AnyAsync(c => c.Id == categoryId && c.Enabled, cancellationToken))
                return Result.Fail("Category does not exist");

            if (await context.ProductCategories.AnyAsync(c => c.ProductId == productId && c.CategoryId == categoryId, cancellationToken))
                return Result.Fail("Category already assigned to product");

            context.ProductCategories.Add(new Entities.ProductCategory
            {
                ProductId = productId,
                CategoryId = categoryId,
            });

            return await context.SaveChangesAsync(cancellationToken) > 0
                ? Result.Ok()
                : Result.Fail("Could not add category to product");
        }
        catch (Exception ex)
        {
            return Result.Fail(new Error(ex.Message).CausedBy(ex));
        }
    }

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

            var categories = await context.ProductCategories.AsNoTracking()
                .Where(p => p.ProductId == productId)
                .OrderByDescending(o => o.Id)                
                .Select(p => p.Category)
                .ToArrayAsync(cancellationToken);

            return categories?.Length > 0
                ? Result.Ok(categories.Select(c => c!.ToModel()).ToArray())
                : Result.Fail<Category[]>("Failed to get product categories");

        }
        catch (Exception ex)
        {
            return Result.Fail(new Error(ex.Message).CausedBy(ex));
        }
    }

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

            var rowsDeleted = await context.ProductCategories
                .Where(p => p.ProductId == productId && p.CategoryId == categoryId)
                .ExecuteDeleteAsync(cancellationToken);

            return rowsDeleted > 0
                ? Result.Ok()
                : Result.Fail("No product categories were deleted");
        }
        catch (Exception ex)
        {
            return Result.Fail(new Error(ex.Message).CausedBy(ex));
        }
    }

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

            var rowsDeleted = await context.ProductCategories
                .Where(p => p.ProductId == productId)
                .ExecuteDeleteAsync(cancellationToken);

            return rowsDeleted > 0
                ? Result.Ok()
                : Result.Fail("No product categories were deleted");
        }
        catch (Exception ex)
        {
            return Result.Fail(new Error(ex.Message).CausedBy(ex));
        }
    }

    public async ValueTask<Result> UpdateProductPriceStatusAsync(long productPriceId, bool isEnabled, CancellationToken cancellationToken = default)
    {
        try
        {
            await using var context = await contextFactory.CreateDbContextAsync(cancellationToken);

            var rowsUpdated = await context.Prices
                .Where(p => p.Id == productPriceId)
                .ExecuteUpdateAsync(setters => setters
                    .SetProperty(p => p.Enabled, isEnabled)
                    .SetProperty(p => p.UpdatedAt, DateTime.UtcNow), cancellationToken);

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

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

            var rowsUpdated = await context.Products
                .Where(p => p.Id == productId)
                .ExecuteUpdateAsync(setters => setters
                    .SetProperty(p => p.Enabled, isEnabled)
                    .SetProperty(p => p.UpdatedAt, DateTime.UtcNow), cancellationToken);

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

    public async ValueTask<Result<Product[]>> SearchProductsAsync(ProductFilter filter, CancellationToken cancellationToken = default)
    {
        try
        {
            await using var context = await contextFactory.CreateDbContextAsync(cancellationToken);

            var query = context.Products
                .Include(i => i.Price)
                .AsQueryable();

            var cultureInfo = CultureInfo.InvariantCulture;

            if (!string.IsNullOrWhiteSpace(filter.Name))
                query = query.Where(p => EF.Functions.ILike(p.Name!, $"%{filter.Name}%"));

            if (!string.IsNullOrWhiteSpace(filter.Title))
                query = query.Where(p => EF.Functions.ILike(p.Name!, $"%{filter.Title}%"));

            if (!string.IsNullOrWhiteSpace(filter.Manufacturer))
                query = query.Where(p => EF.Functions.ILike(p.Metadata!.Manufacturer!, $"%{filter.Manufacturer}%"));

            if (!string.IsNullOrWhiteSpace(filter.SerialNumber))
                query = query.Where(p => EF.Functions.ILike(p.Metadata!.SerialNumber!, $"%{filter.SerialNumber}%"));

            if (filter.MinPrice > 0)
                query = query.Where(p => p.Prices!.Any(pr => pr.Amount >= filter.MinPrice && pr.Amount <= filter.MaxPrice));

            var products = await query.AsNoTracking().Where(p => p.Enabled).ToListAsync(cancellationToken);

            return products?.Count > 0
                ? Result.Ok(products.Select(p => p.ToModel()).ToArray())
                : Result.Fail<Product[]>("No products found.");
        }
        catch (Exception ex)
        {
            return Result.Fail<Product[]>(new Error(ex.Message).CausedBy(ex));
        }
    }

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

            if (!await context.Products.AnyAsync(p => p.Id == productId, cancellationToken))
                return Result.Fail<long>($"Product with ID {productId} does not exist.");

            var existingPrices = await context.Prices.Where(p => p.ProductId == productId).ToListAsync(cancellationToken);

            if (existingPrices.Count > 0)
                foreach (var existingPrice in existingPrices)
                {
                    existingPrice.Enabled = false;
                    existingPrice.UpdatedAt = DateTime.UtcNow;
                    context.Prices.Update(existingPrice);
                }

            var price = context.Prices.Add(new Entities.ProductPrice
            {
                ProductId = productId,
                Amount = request.Amount,
                Discount = request.Discount,
                Enabled = true,
            });

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

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

            if (await context.Products.AnyAsync(p => p.Name == request.Name, cancellationToken))
                return Result.Fail<long>("A product with the same name already exists.");

            if (request.Metadata is not null)
                if (await context.Products.AnyAsync(p => p.Metadata!.SerialNumber == request.Metadata.SerialNumber, cancellationToken))
                    return Result.Fail<long>("A product with the same metadata already exists.");

            var product = context.Products.Add(new Entities.Product
            {
                UpdatedAt = DateTime.UtcNow,
                Type = request.Type,
                Name = request.Name,
                Summary = request.Summary,
                Description = request.Description,
                ImageUrl = request.ImageUrl,
                ThumbnailUrls = request.ThumbnailUrls,
                Metadata = request.Metadata,
                Enabled = true
            });

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

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

            var product = await context.Prices
                .AsNoTracking()
                .OrderByDescending(p => p.CreatedAt)
                    .ThenBy(p => p.UpdatedAt)
                .FirstOrDefaultAsync(p => p.ProductId == productId && p.Enabled, cancellationToken);

            return product is not null
                ? Result.Ok(product.ToModel())
                : Result.Fail<ProductPrice>(new Error($"No price found for product with ID {productId}"));

        }
        catch (Exception ex)
        {
            return Result.Fail<ProductPrice>(new Error(ex.Message).CausedBy(ex));
        }
    }

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

            var prices = await context.Prices.Where(p => p.ProductId == productId).ToListAsync(cancellationToken);

            return prices?.Count > 0
                ? prices.Select(p => p.ToModel()).ToArray()
                : Result.Fail<ProductPrice[]>(new Error($"No prices found for product with ID {productId}"));
        }
        catch (Exception ex)
        {
            return Result.Fail<ProductPrice[]>(new Error(ex.Message).CausedBy(ex));
        }
    }

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

            var product = await context.Products
                .Include(i => i.Price)
                .AsNoTracking().FirstOrDefaultAsync(p => p.Id == productId, cancellationToken);

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

    public async ValueTask<Result<Product[]>> GetProductsAsync(int offset, DateRange range, CancellationToken cancellationToken = default)
    {
        try
        {
            var fromDate = range.From.ToDateTime(TimeOnly.MinValue, DateTimeKind.Utc);
            var toDate = range.To.ToDateTime(TimeOnly.MaxValue, DateTimeKind.Utc);

            await using var context = await contextFactory.CreateDbContextAsync(cancellationToken);

            var products = await context.Products
                .AsNoTracking()
                .Include(p => p.Prices)
                .OrderByDescending(p => p.CreatedAt)
                    .ThenByDescending(p => p.UpdatedAt)
                .Where(p => p.CreatedAt >= fromDate && p.CreatedAt <= toDate)
                .Skip(offset)
                .Take(range.MaxRecords)
                .AsSplitQuery()
                .ToArrayAsync(cancellationToken);

            return products?.Length > 0
                ? Result.Ok(products.Select(p => p.ToModel()).ToArray())
                : Result.Fail<Product[]>(new Error("Failed to retrieve products."));
        }
        catch (Exception ex)
        {
            return Result.Fail<Product[]>(new Error(ex.Message).CausedBy(ex));
        }
    }
}