Removed comments from function blocks

LiteCharms.Features.MidrandBooks.Tests/PaymentServiceFeatureTests.cs

@@ -0,0 +1,98 @@
+using LiteCharms.Features.MidrandBooks.Payments;
+using LiteCharms.Features.MidrandBooks.Payments.Models;
+using LiteCharms.Features.MidrandBooks.Tests.Common;
+
+namespace LiteCharms.Features.MidrandBooks.Tests;
+
+public sealed class PaymentServiceFeatureTests(Fixture fixture) : IClassFixture<Fixture>
+{
+    private readonly PaymentService paymentService = fixture.Services.GetRequiredService<PaymentService>();
+
+    [IntegrationFact]
+    public async Task CreateRefundAsync_ShouldReturn_ResultWithRefundId()
+    {
+        var request = new CreateRefund
+        {
+            Amount = 50,
+            OrderId = 2,
+            Type = RefundTypes.Partial,
+            Reason = "Returned damaged book",
+            Status = RefundStatus.Completed,            
+        };
+
+        var result = await paymentService.CreateRefundAsync(request, fixture.CancellationToken);
+
+        Assert.True(result.IsSuccess);
+        Assert.True(result.Value > 0);
+    }
+
+    [IntegrationFact]
+    public async Task WriteLedgerEntryAsync_ShouldReturn_ResultWithSuccess()
+    {
+        var request = new CreateLedgerEntry
+        {
+            CustomerId = 1,
+            OrderId = 1,
+            PaymentGatewayId = 1,
+            PaymentGatewayReference = "TEST REFERENCE",
+            PaymentId = 1,
+            Status = LedgerStatuses.Received,
+        };
+
+        var result = await paymentService.WriteLedgerEntryAsync(request, fixture.CancellationToken);
+
+        Assert.True(result.IsSuccess);
+    }
+
+    [IntegrationFact]
+    public async Task GetPaymentGatewayAsync_ShouldReturn_ResultWithPaymentGateway()
+    {
+        var result = await paymentService.GetPaymentGatewayAsync(1, fixture.CancellationToken);
+
+        Assert.True(result.IsSuccess);
+        Assert.NotNull(result.Value);
+    }
+
+    [IntegrationFact]
+    public async Task CreatePaymentGatewayAsync_ShouldReturn_ResultWithGatewayId()
+    {
+        var request = new CreatePaymentGateway
+        {
+            IsSandbox = true,
+            MerchantId = "10049307",
+            MerchantKey = "ju6navn0jcbf0",
+            Name = "Payfast",
+            Website = "https://sandbox.payfast.co.za/eng/process",
+        };
+
+        var result = await paymentService.CreatePaymentGatewayAsync(request, fixture.CancellationToken);
+
+        Assert.True(result.IsSuccess);
+        Assert.True(result.Value > 0);
+    }
+
+    [IntegrationFact]
+    public async Task CompletePaymentAsync_ShouldReturn_ResultWithSuccess()
+    {
+        var result = await paymentService.CompletePaymentAsync(1, PaymentStatuses.Paid, fixture.CancellationToken);
+
+        Assert.True(result.IsSuccess);
+    }
+
+    [IntegrationFact]
+    public async Task UpdatePaymentAsync_ShouldReturn_ResultWithSuccess()
+    {
+        var result = await paymentService.UpdatePaymentAsync(1, 200, fixture.CancellationToken);
+
+        Assert.True(result.IsSuccess);
+    }
+
+    [IntegrationFact]
+    public async Task CreatePaymentAsync_ShouldReturn_ResultWithPaymentId()
+    {
+        var result = await paymentService.CreatePaymentAsync(100, 1, "HASHEDID", fixture.CancellationToken);
+
+        Assert.True(result.IsSuccess);
+        Assert.True(result.Value > 0);
+    }
+}

LiteCharms.Features.MidrandBooks.Tests/ProductServiceFeatureTests.cs

@@ -9,6 +9,47 @@ public class ProductServiceFeatureTests(Fixture fixture, ITestOutputHelper outpu
 {
     private readonly ProductService productService = fixture.Services.GetRequiredService<ProductService>();
 
+    [IntegrationFact]
+    public async Task CheckProductStockAvailabilityAsync_ShouldReturn_ResultWithProductInventory()
+    {
+        var result = await productService.CheckProductStockAvailabilityAsync(1, 1, fixture.CancellationToken);
+
+        Assert.True(result.IsSuccess);
+        Assert.NotNull(result.Value);
+    }
+
+    [IntegrationFact]
+    public async Task ReserveProductInventoryAsync_ShouldReturn_ResultWithSuccess()
+    {
+        var request = new ReserveStock
+        {
+            ProductId = 1,
+            ProductPriceId = 1,
+            Reservation = 100,            
+        };
+
+        var result = await productService.ReserveProductInventoryAsync(request, fixture.CancellationToken);
+
+        Assert.True(result.IsSuccess);
+        Assert.True(result.Value > 0);
+    }
+
+    [IntegrationFact]
+    public async Task AllocateProductInventoryAsync_ShouldReturn_ResultWithSuccess()
+    {
+        var request = new AllocateStock
+        {
+            ProductId = 1, 
+            ProductPriceId = 1,
+            Allocation = 500,
+        };
+
+        var result = await productService.AllocateProductInventoryAsync(request, fixture.CancellationToken);
+
+        Assert.True(result.IsSuccess);
+        Assert.True(result.Value > 0);
+    }
+
     [IntegrationFact]
     public async Task AddProductCategoryAsync_ShouldReturn_ResultWithId()
     {

LiteCharms.Features.MidrandBooks/Abstractions/IService.cs

@@ -1,3 +0,0 @@
-namespace LiteCharms.Features.MidrandBooks.Abstractions;
-
-public interface IService;

LiteCharms.Features.MidrandBooks/AuthorBooks/BooksService.cs

@@ -1,4 +1,4 @@
-using LiteCharms.Features.MidrandBooks.Abstractions;
+using LiteCharms.Features.Abstractions;
 using LiteCharms.Features.MidrandBooks.AuthorBooks.Models;
 using LiteCharms.Features.MidrandBooks.Extensions;
 using LiteCharms.Features.MidrandBooks.Postgres;

LiteCharms.Features.MidrandBooks/Authors/AuthorService.cs

@@ -1,4 +1,4 @@
-using LiteCharms.Features.MidrandBooks.Abstractions;
+using LiteCharms.Features.Abstractions;
 using LiteCharms.Features.MidrandBooks.Authors.Models;
 using LiteCharms.Features.MidrandBooks.Extensions;
 using LiteCharms.Features.MidrandBooks.Postgres;

LiteCharms.Features.MidrandBooks/Categories/CategoryService.cs

@@ -1,4 +1,4 @@
-using LiteCharms.Features.MidrandBooks.Abstractions;
+using LiteCharms.Features.Abstractions;
 using LiteCharms.Features.MidrandBooks.Categories.Models;
 using LiteCharms.Features.MidrandBooks.Extensions;
 using LiteCharms.Features.MidrandBooks.Postgres;

LiteCharms.Features.MidrandBooks/Customers/CustomerService.cs

@@ -1,4 +1,4 @@
-using LiteCharms.Features.MidrandBooks.Abstractions;
+using LiteCharms.Features.Abstractions;
 using LiteCharms.Features.MidrandBooks.Customers.Models;
 using LiteCharms.Features.MidrandBooks.Extensions;
 using LiteCharms.Features.MidrandBooks.Postgres;

LiteCharms.Features.MidrandBooks/Extensions/Mappers.cs

@@ -6,11 +6,24 @@ using LiteCharms.Features.MidrandBooks.Orders.Models;
 using LiteCharms.Features.MidrandBooks.Pages.Models;
 using LiteCharms.Features.MidrandBooks.Payments.Models;
 using LiteCharms.Features.MidrandBooks.Products.Models;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
 
 namespace LiteCharms.Features.MidrandBooks.Extensions;
 
 public static class Mappers
 {
+    public static Refund ToModel(this Payments.Entities.Refund entity) => new()
+    {
+        CreatedAt = entity.CreatedAt,
+        Amount = entity.Amount,
+        Id = entity.Id,
+        OrderId = entity.OrderId,
+        Reason = entity.Reason,
+        Status = entity.Status,
+        Type = entity.Type,
+        UpdatedAt = entity.UpdatedAt,        
+    };
+
     public static PaymentLedger ToModel(this Payments.Entities.PaymentLedger entity) => new()
     {
         Id = entity.Id,

LiteCharms.Features.MidrandBooks/Extensions/Shop.cs

@@ -1,4 +1,4 @@
-using LiteCharms.Features.MidrandBooks.Abstractions;
+using LiteCharms.Features.Abstractions;
 
 namespace LiteCharms.Features.MidrandBooks.Extensions;
 

LiteCharms.Features.MidrandBooks/Orders/OrderService.cs

@@ -1,4 +1,4 @@
-using LiteCharms.Features.MidrandBooks.Abstractions;
+using LiteCharms.Features.Abstractions;
 using LiteCharms.Features.MidrandBooks.Extensions;
 using LiteCharms.Features.MidrandBooks.Orders.Models;
 using LiteCharms.Features.MidrandBooks.Postgres;

LiteCharms.Features.MidrandBooks/Pages/PageService.cs

@@ -1,4 +1,4 @@
-using LiteCharms.Features.MidrandBooks.Abstractions;
+using LiteCharms.Features.Abstractions;
 using LiteCharms.Features.MidrandBooks.Extensions;
 using LiteCharms.Features.MidrandBooks.Pages.Models;
 using LiteCharms.Features.MidrandBooks.Postgres;

LiteCharms.Features.MidrandBooks/Payments/Models/Records.cs

@@ -0,0 +1,53 @@
+namespace LiteCharms.Features.MidrandBooks.Payments.Models;
+
+public sealed record UpdateRefund
+{
+    public long OrderId { get; set; }
+
+    public RefundStatus Status { get; set; }
+
+    public string? Reason { get; set; }
+
+    public decimal Amount { get; set; }
+};
+
+public sealed record CreateRefund
+{
+    public long OrderId { get; set; }
+
+    public RefundTypes Type { get; set; }
+
+    public RefundStatus Status { get; set; }
+
+    public string? Reason { get; set; }
+
+    public decimal Amount { get; set; }
+}
+
+public sealed record CreateLedgerEntry
+{
+    public required LedgerStatuses Status { get; set; }
+
+    public required long OrderId { get; set; }
+
+    public required long PaymentId { get; set; }
+
+    public required long CustomerId { get; set; }
+
+    public string? PaymentGatewayReference { get; set; }
+
+    public long? PaymentGatewayId { get; set; }
+}
+
+public sealed record CreatePaymentGateway
+{
+    public required string? Name { get; set; }
+
+    public string? Website { get; set; }
+
+    public required string? MerchantId { get; set; }
+
+    public required string? MerchantKey { get; set; }
+
+    public bool IsSandbox { get; set; }
+}

LiteCharms.Features.MidrandBooks/Payments/PaymentService.cs

@@ -1,7 +1,265 @@
-using LiteCharms.Features.MidrandBooks.Abstractions;
+using LiteCharms.Features.Abstractions;
+using LiteCharms.Features.MidrandBooks.Extensions;
+using LiteCharms.Features.MidrandBooks.Payments.Models;
+using LiteCharms.Features.MidrandBooks.Postgres;
 
 namespace LiteCharms.Features.MidrandBooks.Payments;
 
-public sealed class PaymentService : IService
+public sealed class PaymentService(IDbContextFactory<MidrandBooksDbContext> contextFactory) : IService
 {
+    public async ValueTask<Result<Refund>> GetRefundAsync(long refundId, CancellationToken cancellationToken = default)
+    {
+        try
+        {
+            await using var context = await contextFactory.CreateDbContextAsync(cancellationToken);
+
+            var refund = await context.Refunds.AsNoTracking()
+                .FirstOrDefaultAsync(r => r.Id == refundId, cancellationToken);
+
+            return refund is not null
+                ? Result.Ok(refund.ToModel())
+                : Result.Fail<Refund>("Could not find refund");
+        }
+        catch (Exception ex)
+        {
+            return Result.Fail<Refund>(new Error(ex.Message).CausedBy(ex));
+        }
+    }
+
+    public async ValueTask<Result> UpdateRefundAsync(long refundId, UpdateRefund request, CancellationToken cancellationToken = default)
+    {
+        try
+        {
+            await using var context = await contextFactory.CreateDbContextAsync(cancellationToken);
+
+            if (!await context.Orders.AnyAsync(o => o.Id == request.OrderId, cancellationToken))
+                return Result.Fail("Order not found");
+
+            var updatedRows = await context.Refunds
+                .Where(r => r.Id == refundId && r.OrderId == request.OrderId)
+                .ExecuteUpdateAsync(setters => setters
+                    .SetProperty(r => r.Status, request.Status)
+                    .SetProperty(r => r.Reason, request.Reason)
+                    .SetProperty(r => r.UpdatedAt, DateTime.UtcNow)
+                    .SetProperty(r => r.Amount, request.Amount), cancellationToken);
+
+            return updatedRows > 0
+                ? Result.Ok()
+                : Result.Fail("Failed to update refund");
+        }
+        catch (Exception ex)
+        {
+            return Result.Fail(new Error(ex.Message).CausedBy(ex));
+        }
+    }
+
+    public async ValueTask<Result<long>> CreateRefundAsync(CreateRefund request, CancellationToken cancellationToken = default)
+    {
+        try
+        {
+            await using var context = await contextFactory.CreateDbContextAsync(cancellationToken);
+
+            var order = await context.Orders.AsNoTracking()
+                .FirstOrDefaultAsync(o => o.Id == request.OrderId
+                    && o.Status == OrderStatus.Completed, cancellationToken);
+
+            if (order is null) return Result.Fail("Order not found");
+
+            if (request.Amount > order.Total)
+                return Result.Fail<long>("Refund amount cannot be greater than order total");
+
+            var totalRefundsPaid = await context.Refunds
+                .Where(r => r.OrderId == request.OrderId)
+                .SumAsync(r => r.Amount, cancellationToken);
+
+            if (request.Amount > (order.Total - totalRefundsPaid))
+                return Result.Fail<long>("Refund amount exceeds amount available for refund");
+
+            var refund = context.Refunds.Add(new Entities.Refund
+            {
+                Amount = request.Amount,
+                CreatedAt = DateTime.UtcNow,
+                OrderId = request.OrderId,
+                Reason = request.Reason,
+                Status = request.Status,
+                Type = request.Type,
+            });
+
+            return await context.SaveChangesAsync(cancellationToken) > 0
+                ? Result.Ok(refund.Entity.Id)
+                : Result.Fail<long>("Failed to create refund");
+        }
+        catch (Exception ex)
+        {
+            return Result.Fail(new Error(ex.Message).CausedBy(ex));
+        }
+    }
+
+    public async ValueTask<Result> WriteLedgerEntryAsync(CreateLedgerEntry request, CancellationToken cancellationToken = default)
+    {
+        try
+        {
+            await using var context = await contextFactory.CreateDbContextAsync(cancellationToken);
+
+            if (!await context.Orders.AnyAsync(o => o.Id == request.OrderId, cancellationToken))
+                return Result.Fail("Order not found");
+
+            if (!await context.Customers.AnyAsync(o => o.Id == request.CustomerId, cancellationToken))
+                return Result.Fail("Customer not found");
+
+            if (!await context.Orders.AnyAsync(oc => oc.Id == request.OrderId && oc.CustomerId == request.CustomerId, cancellationToken))
+                return Result.Fail("Customer does not match the order");
+
+            if (!await context.Payments.AnyAsync(o => o.Id == request.PaymentId && o.OrderId == request.OrderId, cancellationToken))
+                return Result.Fail("Payment not found");
+
+            if (request.PaymentGatewayId is not null)
+                if (!await context.Gateways.AnyAsync(o => o.Id == request.PaymentGatewayId, cancellationToken))
+                    return Result.Fail("Gateway not found");
+
+            context.Ledger.Add(new Entities.PaymentLedger
+            {
+                CreatedAt = DateTime.UtcNow,
+                CustomerId = request.CustomerId,
+                OrderId = request.OrderId,
+                PaymentGatewayId = request.PaymentGatewayId,
+                PaymentGatewayReference = request.PaymentGatewayReference,
+                PaymentId = request.PaymentId,
+                Status = request.Status,
+            });
+
+            return await context.SaveChangesAsync(cancellationToken) > 0
+                ? Result.Ok()
+                : Result.Fail("Failed to create ledger entry");
+        }
+        catch (Exception ex)
+        {
+            return Result.Fail(new Error(ex.Message).CausedBy(ex));
+        }
+    }
+
+    public async ValueTask<Result<PaymentGateway>> GetPaymentGatewayAsync(long paymentGatewayId, CancellationToken cancellationToken = default)
+    {
+        try
+        {
+            await using var context = await contextFactory.CreateDbContextAsync(cancellationToken);
+
+            var gateway = await context.Gateways.AsNoTracking().FirstOrDefaultAsync(g => g.Id == paymentGatewayId, cancellationToken);
+
+            return gateway is not null
+                ? Result.Ok(gateway.ToModel())
+                : Result.Fail<PaymentGateway>("Could not find gateway");
+        }
+        catch (Exception ex)
+        {
+            return Result.Fail<PaymentGateway>(new Error(ex.Message).CausedBy(ex));
+        }
+    }
+
+    public async ValueTask<Result<long>> CreatePaymentGatewayAsync(CreatePaymentGateway request, CancellationToken cancellationToken = default)
+    {
+        try
+        {
+            await using var context = await contextFactory.CreateDbContextAsync(cancellationToken);
+
+            if (await context.Gateways.AnyAsync(g => g.MerchantId == request.MerchantId && g.MerchantKey == request.MerchantKey, cancellationToken))
+                return Result.Fail<long>("A gateway with the same credentials already exists");
+
+            var gateway = context.Gateways.Add(new Entities.PaymentGateway
+            {
+                CreatedAt = DateTime.UtcNow,
+                Enabled = true,
+                IsSandbox = request.IsSandbox,
+                MerchantId = request.MerchantId,
+                MerchantKey = request.MerchantKey,
+                Name = request.Name,
+                Website = request.Website,
+                Passphrase = "N/A",
+            });
+
+            return await context.SaveChangesAsync(cancellationToken) > 0
+                ? Result.Ok(gateway.Entity.Id)
+                : Result.Fail<long>("Failed to create payment gateway");
+        }
+        catch (Exception ex)
+        {
+            return Result.Fail<long>(new Error(ex.Message).CausedBy(ex));
+        }
+    }
+
+    public async ValueTask<Result> CompletePaymentAsync(long paymentId, PaymentStatuses status, CancellationToken cancellationToken = default)
+    {
+        try
+        {
+            await using var context = await contextFactory.CreateDbContextAsync(cancellationToken);
+
+            if (status == PaymentStatuses.NotPaid)
+                return Result.Fail("Cannot finalise a payment using NotPaid status");
+
+            var updatedRecords = await context.Payments
+                .Where(p => p.Id == paymentId && p.Status != PaymentStatuses.Paid && p.Status != status)
+                .ExecuteUpdateAsync(setters => setters
+                    .SetProperty(u => u.Status, status)
+                    .SetProperty(u => u.UpdatedAt, DateTime.UtcNow), cancellationToken);
+
+            return updatedRecords > 0
+                ? Result.Ok()
+                : Result.Fail("Failed to update payment");
+        }
+        catch (Exception ex)
+        {
+            return Result.Fail(new Error(ex.Message).CausedBy(ex));
+        }
+    }
+
+    public async ValueTask<Result> UpdatePaymentAsync(long paymentId, decimal amount, CancellationToken cancellationToken = default)
+    {
+        try
+        {
+            await using var context = await contextFactory.CreateDbContextAsync(cancellationToken);
+
+            var updatedRecords = await context.Payments
+                .Where(p => p.Id == paymentId && p.Status == PaymentStatuses.NotPaid)
+                .ExecuteUpdateAsync(setters => setters
+                    .SetProperty(u => u.Amount, amount)
+                    .SetProperty(u => u.Status, PaymentStatuses.NotPaid)
+                    .SetProperty(u => u.UpdatedAt, DateTime.UtcNow), cancellationToken);
+
+            return updatedRecords > 0
+                ? Result.Ok()
+                : Result.Fail("Failed to update payment");
+        }
+        catch (Exception ex)
+        {
+            return Result.Fail(new Error(ex.Message).CausedBy(ex));
+        }
+    }
+
+    public async ValueTask<Result<long>> CreatePaymentAsync(decimal amount, long orderId, string reference, CancellationToken cancellationToken = default)
+    {
+        try
+        {
+            await using var context = await contextFactory.CreateDbContextAsync(cancellationToken);
+
+            if (await context.Payments.AnyAsync(p => p.OrderId == orderId && p.Amount == amount && p.Status != PaymentStatuses.Paid, cancellationToken))
+                return Result.Fail<long>("An order with the same amount already exists in the system");
+
+            var payment = context.Payments.Add(new Entities.Payment
+            {
+                CreatedAt = DateTime.UtcNow,
+                Amount = amount,
+                OrderId = orderId,
+                Reference = reference,
+                Status = PaymentStatuses.NotPaid,
+            });
+
+            return await context.SaveChangesAsync(cancellationToken) > 0
+                ? Result.Ok(payment.Entity.Id)
+                : Result.Fail<long>("Failed to make payment");
+        }
+        catch (Exception ex)
+        {
+            return Result.Fail<long>(new Error(ex.Message).CausedBy(ex));
+        }
+    }
 }

LiteCharms.Features.MidrandBooks/Products/Models/Records.cs

@@ -2,6 +2,24 @@
 
 namespace LiteCharms.Features.MidrandBooks.Products.Models;
 
+public sealed record ReserveStock
+{
+    public required long ProductId { get; set; }
+
+    public required long ProductPriceId { get; set; }
+
+    public int Reservation { get; set; }
+}
+
+public sealed record AllocateStock
+{
+    public required long ProductId { get; set; }
+
+    public required long ProductPriceId { get; set; }
+
+    public int Allocation { get; set; }
+}
+
 public sealed record CreateProduct
 {
     public required ProductTypes Type { get; set; }

LiteCharms.Features.MidrandBooks/Products/ProductService.cs

@@ -1,14 +1,132 @@
-using LiteCharms.Features.MidrandBooks.Abstractions;
+using LiteCharms.Features.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;
+using Org.BouncyCastle.Asn1.Ocsp;
 
 namespace LiteCharms.Features.MidrandBooks.Products;
 
 public sealed class ProductService(IDbContextFactory<MidrandBooksDbContext> contextFactory) : IService
 {
+    public async ValueTask<Result<ProductInventory>> CheckProductStockAvailabilityAsync(long productId, long productPriceId, CancellationToken cancellationToken = default)
+    {
+        try
+        {
+            await using var context = await contextFactory.CreateDbContextAsync(cancellationToken);
+
+            var inventory = await context.Inventories
+                .AsNoTracking()
+                .Where(i => i.ProductPriceId == productPriceId && i.ProductId == productId)
+                .OrderByDescending(o => o.Id)
+                .FirstOrDefaultAsync(cancellationToken);
+
+            return inventory is not null
+                ? Result.Ok(inventory.ToModel())
+                : Result.Fail<ProductInventory>("Product sold out");
+        }
+        catch (Exception ex)
+        {
+            return Result.Fail<ProductInventory>(new Error(ex.Message).CausedBy(ex));
+        }
+    }
+
+    public async ValueTask<Result<long>> ReserveProductInventoryAsync(ReserveStock request, CancellationToken cancellationToken = default)
+    {
+        try
+        {
+            await using var context = await contextFactory.CreateDbContextAsync(cancellationToken);
+
+            var oldInventory = await context.Inventories
+                .AsNoTracking()
+                .Where(i => i.ProductPriceId == request.ProductPriceId && i.ProductId == request.ProductId)
+                .OrderByDescending(o => o.Id)
+                .FirstOrDefaultAsync(cancellationToken);
+
+            var newAllocation = 0;
+            var newReservation = 0;
+
+            if (oldInventory is not null)
+            {
+                newAllocation = oldInventory.TotalAllocated;
+                newReservation = oldInventory.TotalReserved + request.Reservation;
+            }
+            else
+            {
+                newAllocation = 0;
+                newReservation = request.Reservation;
+            }
+
+            if (newAllocation - newReservation < 0)
+                return Result.Fail<long>("Allocation failure: The requested book quantity exceeds current physical inventory availability.");
+
+            var inventory = context.Inventories.Add(new Entities.ProductInventory
+            {
+                CreatedAt = DateTime.UtcNow,
+                ProductId = request.ProductId,
+                ProductPriceId = request.ProductPriceId,
+                Status = InventoryStatuses.Reserved,
+                TotalAllocated = newAllocation,
+                TotalReserved = newReservation,
+            });
+
+            return await context.SaveChangesAsync(cancellationToken) > 0
+                ? Result.Ok(inventory.Entity.Id)
+                : Result.Fail<long>("Failed to create inventory entry");
+        }
+        catch (Exception ex)
+        {
+            return Result.Fail<long>(new Error(ex.Message).CausedBy(ex));
+        }
+    }
+
+    public async ValueTask<Result<long>> AllocateProductInventoryAsync(AllocateStock request, CancellationToken cancellationToken = default)
+    {
+        try
+        {
+            await using var context = await contextFactory.CreateDbContextAsync(cancellationToken);
+
+            var oldInventory = await context.Inventories
+                .AsNoTracking()
+                .Where(i => i.ProductPriceId == request.ProductPriceId && i.ProductId == request.ProductId)
+                .OrderByDescending(o => o.Id)
+                .FirstOrDefaultAsync(cancellationToken);
+
+            var newAllocation = 0;
+            var newReservation = 0;
+
+            if (oldInventory is not null)
+            {
+                newAllocation = oldInventory.TotalAllocated + request.Allocation;
+                newReservation = oldInventory.TotalReserved;
+            }
+            else
+            {
+                newAllocation = request.Allocation;
+                newReservation = 0;
+            }
+
+            var inventory = context.Inventories.Add(new Entities.ProductInventory
+            {
+                CreatedAt = DateTime.UtcNow,
+                ProductId = request.ProductId,
+                ProductPriceId = request.ProductPriceId,
+                Status = InventoryStatuses.Adjustment,
+                TotalAllocated = newAllocation,
+                TotalReserved = newReservation,
+            });
+
+            return await context.SaveChangesAsync(cancellationToken) > 0
+                ? Result.Ok(inventory.Entity.Id)
+                : Result.Fail<long>("Failed to create inventory entry");
+        }
+        catch (Exception ex)
+        {
+            return Result.Fail<long>(new Error(ex.Message).CausedBy(ex));
+        }
+    }
+
     public async ValueTask<Result> AddProductCategoryAsync(long productId, long categoryId, CancellationToken cancellationToken = default)
     {
         try

LiteCharms.Features/Abstractions/IService.cs

@@ -0,0 +1,3 @@
+namespace LiteCharms.Features.Abstractions;
+
+public interface IService;

LiteCharms.Features/Extensions/Hash.cs

@@ -1,13 +1,23 @@
-namespace LiteCharms.Features.Extensions;
+using LiteCharms.Features.Hasher;
+using LiteCharms.Features.Hasher.Configuration;
+
+namespace LiteCharms.Features.Extensions;
 
 public static class Hash
 {
-    public static readonly Func<string?, string?> StringToSha256Hash = (input) => 
-        Convert.ToHexString(SHA256.HashData(Encoding.UTF8.GetBytes(input!)));
+    public const string HasherConfigSectionName = "HasherSettings";
 
-    public static readonly Func<Stream, string?> StreamToSha256Hash = (stream) =>
-        Convert.ToHexString(SHA256.HashData(stream));
+    public static IServiceCollection AddHashServices(this IServiceCollection services, IConfiguration configuration)
+    {
+        services.Configure<HasherSettings>(configuration.GetSection(HasherConfigSectionName));
 
-    public static readonly Func<byte[], string?> BytesToSha256Hash = (bytes) =>
-        Convert.ToHexString(SHA256.HashData(bytes));
-}
+        var settings = configuration.GetSection(HasherConfigSectionName).Get<HasherSettings>();
+
+        services.AddSingleton<IHashids>(_ =>
+            new Hashids(settings!.Salt, minHashLength: settings.MinHashLength));
+
+        services.AddSingleton<HashService>();
+
+        return services;
+    }
+}

LiteCharms.Features/Hasher/Configuration/HasherSettings.cs

@@ -0,0 +1,10 @@
+namespace LiteCharms.Features.Hasher.Configuration;
+
+public sealed class HasherSettings
+{
+    public string? Salt { get; set; }
+
+    public int MinHashLength { get; set; }
+
+    public string? PayfastPassphrase { get; set; }
+}

LiteCharms.Features/Hasher/HashService.cs

@@ -0,0 +1,112 @@
+using LiteCharms.Features.Abstractions;
+using LiteCharms.Features.Hasher.Configuration;
+
+namespace LiteCharms.Features.Hasher;
+
+public sealed partial class HashService(IHashids hasher, IOptions<HasherSettings> options) : IService
+{
+    private readonly HasherSettings settings = options.Value;
+
+    [System.Text.RegularExpressions.GeneratedRegex(@"\A\b[0-9a-fA-F]+\b\Z")]
+    private static partial System.Text.RegularExpressions.Regex HexHashRegex();
+
+    public static readonly Func<string?, string?> StringToSha256Hash = (input) =>
+       string.IsNullOrEmpty(input) ? null : Convert.ToHexString(SHA256.HashData(Encoding.UTF8.GetBytes(input)));
+
+    public static readonly Func<Stream, string?> StreamToSha256Hash = (stream) =>
+        stream is null ? null : Convert.ToHexString(SHA256.HashData(stream));
+
+    public static readonly Func<byte[], string?> BytesToSha256Hash = (bytes) =>
+        bytes is null ? null : Convert.ToHexString(SHA256.HashData(bytes));
+        
+    public static Result<string> ComputeMd5Hash(string input)
+    {
+        if (string.IsNullOrEmpty(input))
+            return Result.Fail<string>("Input content cannot be null or empty for MD5 processing.");
+
+        byte[] bytes = MD5.HashData(Encoding.UTF8.GetBytes(input));
+        return Result.Ok(Convert.ToHexString(bytes).ToLowerInvariant()); 
+    }
+
+    public Result<bool> VerifyPayfastWebhookSignature(IDictionary<string, string> incomingFormData, string incomingSignature)
+    {
+        try
+        {
+            if (string.IsNullOrWhiteSpace(incomingSignature))
+                return Result.Fail<bool>("Validation failed: Missing signature string parameter.");
+
+            var sortedFields = incomingFormData
+                .Where(field => field.Key != "signature")
+                .OrderBy(field => field.Key)
+                .Select(field => $"{field.Key}={Uri.EscapeDataString(field.Value).Replace("%20", "+")}");
+
+            string payload = string.Join("&", sortedFields);
+
+            if (!string.IsNullOrWhiteSpace(settings.PayfastPassphrase))
+                payload += $"&passphrase={Uri.EscapeDataString(settings.PayfastPassphrase).Replace("%20", "+")}";
+
+            var localHashResult = ComputeMd5Hash(payload);
+
+            if (!localHashResult.IsSuccess)
+                return Result.Fail<bool>(localHashResult.Errors);
+
+            bool isValid = string.Equals(localHashResult.Value, incomingSignature, StringComparison.OrdinalIgnoreCase);
+
+            return Result.Ok(isValid);
+        }
+        catch (Exception ex)
+        {
+            return Result.Fail<bool>(new Error("An error occurred during MD5 verification loop.").CausedBy(ex));
+        }
+    }
+
+    public Result<string> HashEncodeHex(string input) => string.IsNullOrWhiteSpace(input) || !HexHashRegex().IsMatch(input)
+        ? Result.Fail<string>("Input must be a valid hexadecimal string.")
+        : Result.Ok(hasher.EncodeHex(input));
+
+    public Result<string> HashEncodeIntId(int id) => id < 0
+        ? Result.Fail<string>("Id cannot be negative.")
+        : Result.Ok(hasher.Encode(id));
+
+    public Result<string> HashEncodeLongId(long id) => id < 0
+        ? Result.Fail<string>("Id cannot be negative.")
+        : Result.Ok(hasher.EncodeLong(id));
+
+    public Result<int> DecodeIntIdHash(string hash)
+    {
+        if (string.IsNullOrWhiteSpace(hash)) return Result.Fail<int>("Invalid token layout.");
+
+        int[] decoded = hasher.Decode(hash);
+
+        return decoded.Length == 1 ? Result.Ok(decoded[0]) : Result.Fail<int>("Invalid or modified Int hash token.");
+    }
+
+    public Result<long> DecodeLongIdHash(string hash)
+    {
+        if (string.IsNullOrWhiteSpace(hash)) return Result.Fail<long>("Invalid token layout.");
+
+        long[] decoded = hasher.DecodeLong(hash);
+
+        return decoded.Length == 1 ? Result.Ok(decoded[0]) : Result.Fail<long>("Invalid or modified Long hash token.");
+    }
+
+    public Result<string> DecodeHexHash(string hex)
+    {
+        try
+        {
+            string decoded = hasher.DecodeHex(hex);
+
+            return string.IsNullOrEmpty(decoded)
+                ? Result.Fail<string>("Invalid or corrupted hex hash.")
+                : Result.Ok(decoded);
+        }
+        catch (FormatException fex)
+        {
+            return Result.Fail<string>(new Error("Invalid hash structure.").CausedBy(fex));
+        }
+        catch (Exception ex)
+        {
+            return Result.Fail<string>(new Error(ex.Message).CausedBy(ex));
+        }
+    }
+}

LiteCharms.Features/LiteCharms.Features.csproj

@@ -31,6 +31,7 @@
 
   <!-- Quartz Scheduler-->
   <ItemGroup>    
+    <PackageReference Include="Hashids.net" Version="1.7.0" />    
     <PackageReference Include="Meziantou.Analyzer" Version="3.0.96">
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
@@ -146,6 +147,7 @@
 
   <!-- Shared Usings -->
   <ItemGroup>
+    <Using Include="HashidsNet" />
     <Using Include="System.Globalization" />
     <Using Include="Microsoft.AspNetCore.Builder" />
     <Using Include="Microsoft.Extensions.Hosting" />

LiteCharms.Features/S3/Abstractions/S3ServiceBase.cs

@@ -1,4 +1,4 @@
-using static LiteCharms.Features.Extensions.Hash;
+using LiteCharms.Features.Hasher;
 
 namespace LiteCharms.Features.S3.Abstractions;
 
@@ -26,7 +26,7 @@ public abstract class S3ServiceBase(IAmazonS3 amazonS3)
 
             stream.Seek(0, SeekOrigin.Begin);
 
-            var fileHash = StreamToSha256Hash(stream);
+            var fileHash = HashService.StreamToSha256Hash(stream);
 
             if(string.IsNullOrWhiteSpace(fileHash))
                 return Result.Fail<string>("Failed to compute file hash.");
@@ -39,7 +39,7 @@ public abstract class S3ServiceBase(IAmazonS3 amazonS3)
                 Key = fileKey,
                 InputStream = stream,
                 ContentType = contentType,
-                UseChunkEncoding = false
+                UseChunkEncoding = false,
             };
 
             stream.Seek(0, SeekOrigin.Begin);