feat: multi-tenancy database filters, duplicate username auth, and empty-state UX enhancements

MySupplyChain.API/Controllers/AuthController.cs

@@ -81,4 +81,23 @@ public async Task<IActionResult> DeleteAccount()
         await mediator.Send(new DeleteAccountCommand(userId));
         return NoContent();
     }
+
+    /// <summary>
+    /// Update user's username (display name)
+    /// </summary>
+    [Authorize]
+    [HttpPut("username")]
+    [ProducesResponseType(typeof(object), StatusCodes.Status200OK)]
+    [ProducesResponseType(StatusCodes.Status400BadRequest)]
+    [ProducesResponseType(StatusCodes.Status401Unauthorized)]
+    public async Task<ActionResult> UpdateUsername([FromBody] UpdateUsernameDto dto)
+    {
+        var userId = User.FindFirstValue(ClaimTypes.NameIdentifier);
+        if (string.IsNullOrEmpty(userId)) return Unauthorized();
+
+        var token = await mediator.Send(new MySupplyChain.Application.Auth.Commands.UpdateUsername.UpdateUsernameCommand(userId, dto.NewUsername));
+        return Ok(new { Token = token, Message = "Username updated successfully" });
+    }
 }
+
+public record UpdateUsernameDto(string NewUsername);

MySupplyChain.API/Program.cs

@@ -69,9 +69,13 @@
     });
 
     builder.Services.AddDataProtection();
+    builder.Services.AddHttpContextAccessor();
 
     builder.Services.AddIdentityCore<MySupplyChain.Domain.Entities.User>(options =>
     {
+        // Require unique emails for all accounts
+        options.User.RequireUniqueEmail = true;
+
         //Add spaces to the allowed user name characters
         options.User.AllowedUserNameCharacters = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-._@+ ";
 
@@ -149,23 +153,17 @@
     // ─── Seed Database ─────────────────────────────────────────────────────────
     if (!IsIntegrationTestRun)
     {
-        using (var scope = app.Services.CreateScope())
+        using var scope = app.Services.CreateScope();
+        var services = scope.ServiceProvider;
+        try
         {
-            var services = scope.ServiceProvider;
-            try
-            {
-                var context = services.GetRequiredService<MySupplyChain.Infrastructure.Persistence.ApplicationDbContext>();
-                await context.Database.MigrateAsync();
-
-                var seederLogger = services.GetRequiredService<ILogger<Program>>();
-                var csvPath = Path.Combine(app.Environment.ContentRootPath, "..", "data", "Retail-Supply-Chain-Sales-Dataset.csv");
-                await MySupplyChain.Infrastructure.Persistence.CsvDatabaseSeeder.SeedAsync(context, csvPath, seederLogger);
-            }
-            catch (Exception ex)
-            {
-                var seederLogger = services.GetRequiredService<ILogger<Program>>();
-                seederLogger.LogError(ex, "An error occurred while seeding the database.");
-            }
+            var context = services.GetRequiredService<MySupplyChain.Infrastructure.Persistence.ApplicationDbContext>();
+            await context.Database.MigrateAsync();
+        }
+        catch (Exception ex)
+        {
+            var seederLogger = services.GetRequiredService<ILogger<Program>>();
+            seederLogger.LogError(ex, "An error occurred while migrating the database.");
         }
     }
 

MySupplyChain.Application/Auth/Commands/DeleteAccount/DeleteAccountCommand.cs

@@ -9,8 +9,7 @@ public class DeleteAccountCommandHandler(IApplicationDbContext context, IAuthSer
 {
     public async Task Handle(DeleteAccountCommand request, CancellationToken cancellationToken)
     {
-        // 1. Wipe business data first
-        // In a real app, we'd filter these by UserId
+        // 1. Wipe business data first (scoped automatically by global query filters)
         context.SalesHistories.RemoveRange(context.SalesHistories);
         context.Orders.RemoveRange(context.Orders);
         context.Products.RemoveRange(context.Products);

MySupplyChain.Application/Auth/Commands/UpdateUsername/UpdateUsernameCommand.cs

@@ -0,0 +1,14 @@
+using MediatR;
+using MySupplyChain.Application.Common.Interfaces;
+
+namespace MySupplyChain.Application.Auth.Commands.UpdateUsername;
+
+public record UpdateUsernameCommand(string UserId, string NewUsername) : IRequest<string>;
+
+public class UpdateUsernameCommandHandler(IAuthService authService) : IRequestHandler<UpdateUsernameCommand, string>
+{
+    public async Task<string> Handle(UpdateUsernameCommand request, CancellationToken cancellationToken)
+    {
+        return await authService.UpdateUsernameAsync(request.UserId, request.NewUsername);
+    }
+}

MySupplyChain.Application/Auth/Commands/WipeUserData/WipeUserDataCommand.cs

@@ -1,5 +1,4 @@
 using MediatR;
-using Microsoft.EntityFrameworkCore;
 using MySupplyChain.Application.Common.Interfaces;
 
 namespace MySupplyChain.Application.Auth.Commands.WipeUserData;
@@ -10,8 +9,8 @@ public class WipeUserDataCommandHandler(IApplicationDbContext context) : IReques
 {
     public async Task Handle(WipeUserDataCommand request, CancellationToken cancellationToken)
     {
-        // In a real multi-tenant app, filter by UserId. 
-        // For this single-user demo/prototype, we wipe the global tables.
+        // The global query filters automatically scope these collections
+        // to the current authenticated user's data.
 
         context.SalesHistories.RemoveRange(context.SalesHistories);
         context.Orders.RemoveRange(context.Orders);

MySupplyChain.Application/Common/Interfaces/IAuthService.cs

@@ -26,6 +26,11 @@ public interface IAuthService
     /// </summary>
     Task DeleteAccountAsync(string userId);
 
+    /// <summary>
+    /// Updates the user's username and returns a new JWT token
+    /// </summary>
+    Task<string> UpdateUsernameAsync(string userId, string newUsername);
+
     string GenerateJwtToken(User user);
 }
 

MySupplyChain.Application/Orders/Queries/GetOrders/GetOrdersQuery.cs

@@ -21,7 +21,7 @@ public async Task<IEnumerable<OrderDto>> Handle(GetOrdersQuery request, Cancella
             Id = o.Id,
             OrderNumber = o.OrderNumber,
             Date = o.OrderDate.ToString("MMM dd, HH:mm"),
-            Customer = o.Customer.Name,
+            Customer = o.Customer?.Name ?? "Unknown Customer",
             Items = o.Items.Sum(i => i.Quantity),
             Status = o.Status.ToString().ToLower(),
             Total = o.TotalAmount.ToString("C")

MySupplyChain.Application/SalesHistories/Commands/ImportSalesHistory/ImportSalesHistoryCommandHandler.cs

@@ -2,7 +2,6 @@
 using CsvHelper.Configuration;
 using MediatR;
 using Microsoft.EntityFrameworkCore;
-using MySupplyChain.Application.Common.Exceptions;
 using MySupplyChain.Application.Common.Interfaces;
 using MySupplyChain.Domain.Entities;
 using System.Globalization;
@@ -19,7 +18,7 @@ public async Task<ImportSummaryDto> Handle(ImportSalesHistoryCommand request, Ca
         // Harden cache against duplicate SKUs in DB
         // We fetch the list first to avoid untranslatable GroupBy issues in EF Core
         var productsList = await context.Products
-            .Where(p => p.Sku != null && p.Sku != "")
+            .Where(p => p.Sku != "")
             .ToListAsync(cancellationToken);
 
         var productsCache = productsList
@@ -28,7 +27,7 @@ public async Task<ImportSummaryDto> Handle(ImportSalesHistoryCommand request, Ca
 
         // Cache customers by email to avoid duplicates
         var customersList = await context.Customers
-            .Where(c => c.Email != null)
+            .Where(c => c.Email != "")
             .ToListAsync(cancellationToken);
 
         var customersCache = customersList
@@ -89,7 +88,10 @@ public async Task<ImportSummaryDto> Handle(ImportSalesHistoryCommand request, Ca
                     if (!string.IsNullOrEmpty(request.ProductPriceColumn) && headers.Contains(request.ProductPriceColumn))
                     {
                         var priceStr = csv.GetField<string>(request.ProductPriceColumn);
-                        decimal.TryParse(priceStr, out price);
+                        if (!decimal.TryParse(priceStr, out price))
+                        {
+                            price = 0m;
+                        }
                     }
 
                     product = new Product

MySupplyChain.Benchmarks/Program.cs

@@ -88,14 +88,14 @@ public async Task<ForecastResult> Forecast_Fallback()
     private static float[] GenerateSeries(Random rng, int count)
     {
         var series = new float[count];
-        float base_ = 50f;
+        var baseValue = 50f;
         for (int i = 0; i < count; i++)
         {
             // Trend + weekly seasonality + noise
-            base_ += rng.NextSingle() * 0.2f - 0.1f;
+            baseValue += rng.NextSingle() * 0.2f - 0.1f;
             var seasonal = 5f * MathF.Sin(2f * MathF.PI * i / 7f);
             var noise = (float)(rng.NextDouble() * 4 - 2);
-            series[i] = MathF.Max(0, base_ + seasonal + noise);
+            series[i] = MathF.Max(0, baseValue + seasonal + noise);
         }
         return series;
     }

MySupplyChain.Domain/Entities/EntityBase.cs

@@ -1,28 +1,33 @@
-/*
- * Author: Austin Chima
- * Base class for all domain entities.
- */
-
-namespace MySupplyChain.Domain.Entities;
-
-/// <summary>
-/// Abstract base class for all domain entities with common properties
-/// </summary>
-
-public abstract class EntityBase
-{
-    /// <summary>
-    /// Unique identifier for the entity
-    /// </summary>
-    public int Id { get; set; }
-
-    /// <summary>
-    /// When the entity was created (UTC)
-    /// </summary>
-    public DateTime CreatedAt { get; set; } = DateTime.UtcNow;
-
-    /// <summary>
-    /// When the entity was last updated (UTC)
-    /// </summary>
-    public DateTime? UpdatedAt { get; set; }
-}
+/*
+ * Author: Austin Chima
+ * Base class for all domain entities.
+ */
+
+namespace MySupplyChain.Domain.Entities;
+
+/// <summary>
+/// Abstract base class for all domain entities with common properties
+/// </summary>
+
+public abstract class EntityBase
+{
+    /// <summary>
+    /// Unique identifier for the entity
+    /// </summary>
+    public int Id { get; set; }
+
+    /// <summary>
+    /// When the entity was created (UTC)
+    /// </summary>
+    public DateTime CreatedAt { get; set; } = DateTime.UtcNow;
+
+    /// <summary>
+    /// When the entity was last updated (UTC)
+    /// </summary>
+    public DateTime? UpdatedAt { get; set; }
+
+    /// <summary>
+    /// The owner user identifier for multi-tenancy
+    /// </summary>
+    public string? UserId { get; set; }
+}

MySupplyChain.Domain/Entities/Order.cs

@@ -10,6 +10,6 @@ public class Order : EntityBase
     public OrderStatus Status { get; set; }
     public decimal TotalAmount { get; set; }
 
-    public Customer Customer { get; set; } = null!;
+    public Customer? Customer { get; set; } = null!;
     public ICollection<OrderItem> Items { get; set; } = new List<OrderItem>();
 }