using LiteCharms.Features.TechShop.Extensions;
using LiteCharms.Features.TechShop.Postgres;
using LiteCharms.Features.TechShop.ShoppingCarts.Models;

namespace LiteCharms.Features.TechShop.ShoppingCarts;

public class ShoppingCartService(IDbContextFactory<ShopDbContext> contextFactory)
{
    public async ValueTask<Result> AddItemToShoppingCartAsync(Guid shoppingCartId, Guid productPriceId, int quantity, CancellationToken cancellationToken = default)
    {
        try
        {
            using var context = await contextFactory.CreateDbContextAsync(cancellationToken);

            if (!await context.ProductPrices.AnyAsync(c => c.Id == productPriceId, cancellationToken))
                return Result.Fail($"Product item could not be found with id {productPriceId}");

            var cart = await context.ShoppingCarts.FirstOrDefaultAsync(c => c.Id == shoppingCartId, cancellationToken);

            if (cart is null)
                return Result.Fail($"Shopping cart could not be found with id {shoppingCartId}");

            if (cart.ShoppingCartItems?.Any(i => i.ProductPriceId == productPriceId) == true)
                return Result.Fail($"Item already in shopping cart with id {shoppingCartId}");

            context.ShoppingCartItems.Add(new Entities.ShoppingCartItem
            {
                ShoppingCartId = shoppingCartId,
                ProductPriceId = productPriceId,
                Quantity = quantity
            });

            return await context.SaveChangesAsync(cancellationToken) > 0
                ? Result.Ok()
                : Result.Fail($"Failed to add cart item with id {productPriceId}");
        }
        catch (Exception ex)
        {
            return Result.Fail(new Error(ex.Message).CausedBy(ex));
        }
    }

    public async ValueTask<Result> AddPackageToShoppingCartAsync(Guid shoppingCartId, Guid packageId, CancellationToken cancellationToken = default)
    {
        try
        {
            using var context = await contextFactory.CreateDbContextAsync(cancellationToken);

            if (!await context.Packages.AnyAsync(p => p.Id == packageId, cancellationToken))
                return Result.Fail($"Package cold not be found by ID {packageId}");

            var shoppingCart = await context.ShoppingCarts.FirstOrDefaultAsync(c => c.Id == shoppingCartId, cancellationToken);

            if (shoppingCart is null)
                return Result.Fail($"Shopping cart could not be found by ID {shoppingCartId}");

            if (!await context.ShoppingCartPackages.AnyAsync(cp => cp.ShoppingCartId == shoppingCartId, cancellationToken))
                return Result.Fail($"Package {packageId} is already in the cart");

            var newShoppingCartPackage = context.ShoppingCartPackages.Add(new Entities.ShoppingCartPackage
            {
                ShoppingCartId = shoppingCartId,
                PackageId = packageId
            });

            return await context.SaveChangesAsync(cancellationToken) > 0
                ? Result.Ok()
                : Result.Fail($"Could not add package of id {packageId} to shopping cart {shoppingCartId}");
        }
        catch (Exception ex)
        {
            return Result.Fail(new Error(ex.Message).CausedBy(ex));
        }
    }

    public async ValueTask<Result<Guid>> CreateShoppingCartAsync(Guid customerId, Guid orderId, CancellationToken cancellationToken = default)
    {
        try
        {
            using var context = await contextFactory.CreateDbContextAsync(cancellationToken);

            if (!await context.Customers.AnyAsync(c => c.Id == customerId, cancellationToken))
                return Result.Fail<Guid>($"Customer could not be found with id {customerId}");

            var cart = context.ShoppingCarts.Add(new Entities.ShoppingCart
            {
                CustomerId = customerId,
                OrderId = orderId
            });

            return await context.SaveChangesAsync(cancellationToken) > 0
                ? Result.Ok(cart.Entity.Id)
                : Result.Fail<Guid>($"Failed to create shopping cart for customer id {customerId}");
        }
        catch (Exception ex)
        {
            return Result.Fail<Guid>(new Error(ex.Message).CausedBy(ex));
        }
    }

    public async ValueTask<Result> EmptyShoppingCartAsync(Guid shoppingCartId, CancellationToken cancellationToken = default)
    {
        try
        {
            using var context = await contextFactory.CreateDbContextAsync(cancellationToken);

            if (!await context.ShoppingCarts.AnyAsync(c => c.Id == shoppingCartId, cancellationToken))
                return Result.Fail($"Shopping could not be found with id {shoppingCartId}");

            if (await context.ShoppingCartItems.CountAsync(i => i.ShoppingCartId == shoppingCartId, cancellationToken) == 0)
                return Result.Ok();

            var cartItems = await context.ShoppingCartItems.Where(i => i.ShoppingCartId == shoppingCartId).ToListAsync(cancellationToken);

            context.RemoveRange(cartItems);

            return await context.SaveChangesAsync(cancellationToken) > 0
                ? Result.Ok()
                : Result.Fail($"Could not empty cart with id {shoppingCartId}");
        }
        catch (Exception ex)
        {
            return Result.Fail(new Error(ex.Message).CausedBy(ex));
        }
    }

    public async ValueTask<Result<ShoppingCart[]>> GetCustomerShoppingCartsAsync(Guid customerId, CancellationToken cancellationToken = default)
    {
        try
        {
            using var context = await contextFactory.CreateDbContextAsync(cancellationToken);

            if (!await context.Customers.AnyAsync(c => c.Id == customerId, cancellationToken))
                return Result.Fail<ShoppingCart[]>(new Error($"Customer with Id {customerId} does not exist."));

            var shoppingCarts = await context.ShoppingCarts.Where(sc => sc.CustomerId == customerId).ToArrayAsync(cancellationToken);

            return shoppingCarts?.Length > 0
                ? Result.Ok(shoppingCarts.Select(c => c.ToModel()).ToArray())
                : Result.Fail<ShoppingCart[]>(new Error($"No shopping carts found for customer with Id {customerId}."));
        }
        catch (Exception ex)
        {
            return Result.Fail<ShoppingCart[]>(new Error(ex.Message).CausedBy(ex));
        }
    }

    public async ValueTask<Result<ShoppingCart>> GetShoppingCartAsync(Guid shoppingCartId, CancellationToken cancellationToken = default)
    {
        try
        {
            using var context = await contextFactory.CreateDbContextAsync(cancellationToken);

            var cart = await context.ShoppingCarts.AsNoTracking().FirstOrDefaultAsync(c => c.Id == shoppingCartId, cancellationToken);

            return cart is not null
                ? Result.Ok(cart.ToModel())
                : Result.Fail<ShoppingCart>($"Failed to find shopping cart with id {shoppingCartId}");
        }
        catch (Exception ex)
        {
            return Result.Fail<ShoppingCart>(new Error(ex.Message).CausedBy(ex));
        }
    }

    public async ValueTask<Result<ShoppingCartItem[]>> GetShoppingCartItemsAsync(Guid shoppingCartId, CancellationToken cancellationToken = default)
    {
        try
        {
            using var context = await contextFactory.CreateDbContextAsync(cancellationToken);

            if (!await context.ShoppingCarts.AnyAsync(i => i.Id == shoppingCartId, cancellationToken))
                return Result.Fail($"Shopping cart could not be found with id {shoppingCartId}");

            var items = await context.ShoppingCartItems.AsNoTracking()
                .Where(i => i.ShoppingCartId == shoppingCartId).ToArrayAsync(cancellationToken);

            return items?.Length > 0
                ? Result.Ok(items.Select(i => i.ToModel()).ToArray())
                : Result.Fail<ShoppingCartItem[]>($"Failed to retrieve shopping cart items with id {shoppingCartId}");
        }
        catch (Exception ex)
        {
            return Result.Fail<ShoppingCartItem[]>(new Error(ex.Message).CausedBy(ex));
        }
    }

    public async ValueTask<Result<ShoppingCartPackage[]>> GetShoppingCartPackagesAsync(Guid shoppingCartId, CancellationToken cancellationToken = default)
    {
        try
        {
            using var context = await contextFactory.CreateDbContextAsync(cancellationToken);

            if (!await context.ShoppingCarts.AnyAsync(c => c.Id == shoppingCartId, cancellationToken))
                return Result.Fail($"Shopping cart could not be found by ID {shoppingCartId}");

            var packages = await context.ShoppingCartPackages.AsNoTracking()
                .OrderByDescending(o => o.CreatedAt)
                .Where(cp => cp.ShoppingCartId == shoppingCartId)
                .ToArrayAsync(cancellationToken);

            return packages?.Length > 0
                ? Result.Ok(packages.Select(p => p.ToModel()).ToArray())
                : Result.Fail($"Could not find packaged in shopping cart by ID {shoppingCartId}");
        }
        catch (Exception ex)
        {
            return Result.Fail<ShoppingCartPackage[]>(new Error(ex.Message).CausedBy(ex));
        }
    }

    public async ValueTask<Result> RemovePackageFromShoppingCartAsync(Guid shoppingCartId, Guid shoppingCartPackageId, CancellationToken cancellationToken = default)
    {
        try
        {
            using var context = await contextFactory.CreateDbContextAsync(cancellationToken);

            if (!await context.ShoppingCarts.AnyAsync(c => c.Id == shoppingCartId, cancellationToken))
                return Result.Fail($"Shopping cart could not be found by ID {shoppingCartId}");

            if (!await context.ShoppingCartPackages.AnyAsync(p => p.Id == shoppingCartPackageId, cancellationToken))
                return Result.Fail($"Shopping cart package {shoppingCartPackageId} is not in the shopping cart {shoppingCartId}");

            var shoppingCartPackage = await context.ShoppingCartPackages.FirstOrDefaultAsync(cp => cp.Id == shoppingCartPackageId, cancellationToken);

            if (shoppingCartPackage is null)
                return Result.Ok();

            context.ShoppingCartPackages.Remove(shoppingCartPackage!);

            return await context.SaveChangesAsync(cancellationToken) > 0
                ? Result.Ok()
                : Result.Fail($"Could remove package of id {shoppingCartPackageId} from shopping cart {shoppingCartId}");
        }
        catch (Exception ex)
        {
            return Result.Fail(new Error(ex.Message).CausedBy(ex));
        }
    }

    public async ValueTask<Result> RemoveShoppingCartItemAsync(Guid shoppingCartId, Guid shoppingCartItemId, CancellationToken cancellationToken = default)
    {
        try
        {
            using var context = await contextFactory.CreateDbContextAsync(cancellationToken);

            if (!await context.ProductPrices.AnyAsync(c => c.Id == shoppingCartItemId, cancellationToken))
                return Result.Fail($"Product item could not be found with id {shoppingCartItemId}");

            var cart = await context.ShoppingCarts.FirstOrDefaultAsync(c => c.Id == shoppingCartId, cancellationToken);

            if (cart is null)
                return Result.Fail($"Shopping cart item could not be found with id {shoppingCartId}");

            var item = await context.ShoppingCartItems.FirstOrDefaultAsync(i => i.Id == shoppingCartItemId, cancellationToken);

            if (item is null) return Result.Ok();

            context.ShoppingCartItems.Remove(item);

            return await context.SaveChangesAsync(cancellationToken) > 0
                ? Result.Ok()
                : Result.Fail($"Failed to remove shopping cart item with id {shoppingCartItemId}");
        }
        catch (Exception ex)
        {
            return Result.Fail(new Error(ex.Message).CausedBy(ex));
        }
    }

    public async ValueTask<Result> UpdateShoppingCartItemAsync(Guid shoppingCartId, Guid shoppingCartItemId, int quantity, CancellationToken cancellationToken = default)
    {
        try
        {
            using var context = await contextFactory.CreateDbContextAsync(cancellationToken);

            if (!await context.ShoppingCarts.AnyAsync(c => c.Id == shoppingCartId, cancellationToken))
                return Result.Fail($"Shopping could not be found with id {shoppingCartId}");

            var item = await context.ShoppingCartItems.FirstOrDefaultAsync(i => i.ShoppingCartId == shoppingCartId, cancellationToken);

            if (item is null)
                return Result.Fail($"Shopping cart item could not be found with id {shoppingCartItemId}");

            item.Quantity = quantity;
            item.UpdatedAt = DateTime.UtcNow;

            return await context.SaveChangesAsync(cancellationToken) > 0
                ? Result.Ok()
                : Result.Fail($"Failed to update cart item quntity");
        }
        catch (Exception ex)
        {
            return Result.Fail(new Error(ex.Message).CausedBy(ex));
        }
    }
}