diff --git a/domain-model.md b/domain-model.md
new file mode 100644
index 00000000..580c3342
--- /dev/null
+++ b/domain-model.md
@@ -0,0 +1,68 @@
+# Domain Model
+
+## Simplified user stories
+
+- [x] Must be able to add bagel to basket
+- [x] Must be able to remove bagel from basket
+- [x] Must be able to check if basket is full
+- [x] Must be able to change basket capacity
+- [x] Must be able to check if item exists in basket
+- [x] Warn when user removes non-existent item from basket
+- [x] Must be able to check total cost of items in basket
+- [x] Must be able to check cost of bagel before adding to basket
+- [x] Must be able to choose fillings for bagel
+- [x] Must be able to check cost of filling before adding to bagel order
+- [x] Must be able to add coffee to basket
+- [x] Must be able to check cost of coffee before adding to basket
+- [x] Must be able to add promotion to product
+
+
+## Methods
+
+### Product (Bagel, coffee, etc.)
+
+| Function Name  | Parameters               | Behavior                       | Returns      |
+|----------------|--------------------------|--------------------------------|--------------|
+| GetCost        | double cost              |                                |              |
+| SetCost        | double newCost           |                                |              |
+| AddPromo       | int amount, double price | Add a new promotion on product | void         |
+
+### Basket
+
+| Function Name            | Parameters             | Behavior                                        | Returns |
+|--------------------------|------------------------|-------------------------------------------------|---------|
+| Basket                   | int? capacity          | Constructor, sets capacity to cart              | void    |
+| Add                      | string SKU, int amount | Adds product to basket                          | void    |
+| Remove                   | string SKU, int amount |                                                 | void    |
+| SetCapacity              | int newCapacity        | Sets the new capacity of a basket               | void    |
+| [private] CheckDiscounts |                        |                                                 |         |
+| [private] CheckCapacity  |                        | Checks whether the basket can fit more products | bool    |
+| GetTotal                 |                        | Sets the new capacity of a basket               | double  |
+| Order                    |                        | Submits the bagel order                         | void    |
+| [override] ToString      |                        | Generates a string representation of cart       | string  |
+
+### BasketItem
+- Product
+- Amount
+
+### Inventory
+
+| Function Name | Parameters                  | Behavior                          | Returns |
+|---------------|-----------------------------|-----------------------------------|---------|
+| Add           | Product product, int amount |                                   |         |
+| Remove        | Product product, int amount |                                   |         |
+| GetProduct    | string SKU                  | Get product by SKU                | Product |
+| GetStock      |                             | Get stock of the specific product | int     |
+
+### Order
+
+| Function Name       | Parameters      | Behavior                                          | Returns |
+|---------------------|-----------------|---------------------------------------------------|---------|
+| Order               | List<OrderLine> | Constructor                                       | void    |
+| [override] ToString |                 | Generate string representation of order (receipt) | string  |
+
+### OrderLine
+- Product
+- Amount
+- Price
+- Discount
diff --git a/exercise.main/Basket.cs b/exercise.main/Basket.cs
new file mode 100644
index 00000000..98f2d499
--- /dev/null
+++ b/exercise.main/Basket.cs
@@ -0,0 +1,183 @@
+namespace exercise.main;
+
+public class Basket
+{
+    private int _capacity;
+    private List<BasketItem> _items;
+    
+    private readonly IInventory _inventory;
+    
+    public Basket(IInventory inventory, int capacity = 10)
+    {
+        _capacity = capacity;
+        _items = new List<BasketItem>();
+        _inventory = inventory;
+    }
+    public void Add(string SKU, int quantity)
+    {
+        // Do not allow overfilled bagel basket!
+        if (GetNumberOfItems() + quantity > _capacity)
+        {
+            throw new Exception("Basket is full");
+        }
+        
+        var item = Get(SKU);
+        
+        if (ReferenceEquals(item, null))
+        {
+            _items.Add(new BasketItem(SKU, quantity));
+            return;
+        }
+        
+        item.Quantity = quantity;
+    }
+    
+    public void Remove(string SKU, int quantity)
+    {
+        var item = Get(SKU);
+        // Check if nullable item is null or empty
+        
+        if (!ReferenceEquals(item, null))
+        {
+            Get(SKU).Quantity -= quantity;
+        }
+    }
+    
+    public BasketItem? Get(string SKU)
+    {
+        return _items.FirstOrDefault(x => x.SKU == SKU);
+    }
+    
+    public void SetCapacity(int capacity)
+    {
+        _capacity = capacity;
+    }
+    
+    public int GetCapacity()
+    {
+        return _capacity;
+    }
+    
+    private int GetNumberOfItems()
+    {
+        var numItems = 0;
+
+        foreach (var item in _items)
+        {
+            numItems += item.Quantity;
+        }
+
+        return numItems;
+    }
+    
+    public double GetTotal()
+    {
+        double total = 0;
+        
+        foreach (var item in _items)
+        {
+            var price = _inventory.GetProduct(item.SKU).GetPrice();
+            
+            total += price * item.Quantity;
+        }
+        
+        return total;
+    }
+    
+    public Order Order()
+    {
+        Order order = new Order();
+        Dictionary<string, double> discounts = CheckDiscounts();
+
+        foreach (var item in _items)
+        {
+            var product = _inventory.GetProduct(item.SKU);
+            order.Add(product, item.Quantity);
+        }
+
+        foreach (var discount in discounts)
+        {
+            order.AddModifier(discount.Key, 0, discount.Value * -1);
+        }
+        
+        return order;
+    }
+    
+    public override string ToString()
+    {
+        throw new NotImplementedException();
+    }
+    
+    private Dictionary<string, double> CheckDiscounts()
+    {
+        var discounts = new Dictionary<string, double>();
+        var numBagels = 0;
+        var numCoffees = 0;
+        var discount = 0.0;
+
+        foreach (var basketItem in _items)
+        {
+            if (basketItem.SKU.StartsWith("BGL"))
+            {
+                numBagels += basketItem.Quantity;
+            }
+            
+            if (basketItem.SKU.StartsWith("COF"))
+            {
+                numCoffees += basketItem.Quantity;
+            }
+        }
+
+        // Apply the 12 for 3.99 offer
+        var twelves = numBagels / 12;
+        discount = twelves * (12 * 0.49 - 3.99);
+        numBagels %= 12;
+        // Discount is only applied when more than 0
+        if (discount > 0)
+        {
+            discounts.Add("12 for 3.99", discount);
+        }
+
+        // Apply the 6 for 2.49 offer
+        var sixes = numBagels / 6;
+        discount = sixes * (6 * 0.49 - 2.49);
+        numBagels %= 6;
+        if (discount > 0)
+        {
+            discounts.Add("6 for 2.49", discount);
+        }
+
+        // Coffee deal. Not to be combined with other deals
+        var qualifyingMealDeals = Math.Min(numBagels, numCoffees);
+        discount = qualifyingMealDeals * 0.5;
+        if (discount > 0)
+        {
+            discounts.Add("Coffee and Bagel", discount);
+        }
+        
+        return discounts;
+    }
+    
+    private bool CheckCapacity(int numNewItems)
+    {
+        throw new NotImplementedException();
+    }
+
+    private BasketItem? Contains(string SKU)
+    {
+        return Contains(SKU, []);
+    }
+    
+    private BasketItem? Contains(string SKU, List<string> modifiers)
+    {
+        modifiers.Sort();
+        try
+        {
+            return _items.First(x => x.SKU == SKU && x.Modifiers.SequenceEqual(modifiers));
+        }
+        catch
+        {
+            return null;
+        }
+    }
+}
\ No newline at end of file
diff --git a/exercise.main/BasketItem.cs b/exercise.main/BasketItem.cs
new file mode 100644
index 00000000..9130442e
--- /dev/null
+++ b/exercise.main/BasketItem.cs
@@ -0,0 +1,15 @@
+namespace exercise.main;
+
+public class BasketItem
+{
+    public string SKU { get; set; }
+    public int Quantity { get; set; }
+    public List<string> Modifiers { get; set; }
+    
+    public BasketItem(string sku, int quantity)
+    {
+        SKU = sku;
+        Quantity = quantity;
+        Modifiers = new List<string>();
+    }
+}
\ No newline at end of file
diff --git a/exercise.main/Inventory.cs b/exercise.main/Inventory.cs
new file mode 100644
index 00000000..3aaee9d6
--- /dev/null
+++ b/exercise.main/Inventory.cs
@@ -0,0 +1,65 @@
+using System.Collections;
+
+namespace exercise.main;
+
+public class Inventory : IInventory, IEnumerable<KeyValuePair<Product, int>>
+{
+    private Dictionary<Product, int> _products;
+    
+    public Inventory()
+    {
+        _products = new Dictionary<Product, int>();
+    }
+    
+    public IEnumerator<KeyValuePair<Product, int>> GetEnumerator()
+    {
+        return _products.GetEnumerator();
+    }
+
+    IEnumerator IEnumerable.GetEnumerator()
+    {
+        return GetEnumerator();
+    }
+    
+    public void AddProduct(Product product, int quantity)
+    {
+        _products.Add(product, quantity);
+    }
+    
+    public void RemoveProduct(Product product, int quantity)
+    {
+        throw new NotImplementedException();
+    }
+    
+    public void SetStock(Product product, int quantity)
+    {
+        throw new NotImplementedException();
+    }
+    
+    public int GetStock(Product product)
+    {
+        throw new NotImplementedException();
+    }
+    
+    public Product GetProduct(string sku)
+    {
+        try
+        {
+            
+            return _products.First(p => p.Key.Sku == sku).Key;
+        }
+        catch (Exception e)
+        {
+            throw new Exception("Product not found", e);
+        }
+    }
+}
+
+public interface IInventory
+{
+    void AddProduct(Product product, int quantity);
+    void RemoveProduct(Product product, int quantity);
+    void SetStock(Product product, int quantity);
+    int GetStock(Product product);
+    Product GetProduct(string sku);
+}
\ No newline at end of file
diff --git a/exercise.main/Order.cs b/exercise.main/Order.cs
new file mode 100644
index 00000000..50d6278b
--- /dev/null
+++ b/exercise.main/Order.cs
@@ -0,0 +1,78 @@
+using System.Text;
+
+namespace exercise.main;
+
+public class Order
+{
+    private List<OrderLine> _orderLines;
+    private DateTime _date;
+    
+    public Order()
+    {
+        _orderLines = new List<OrderLine>();
+        _date = DateTime.Now;
+    }
+    
+    public override string ToString()
+    {
+        var sb = new StringBuilder();
+        
+        sb.AppendLine("------- Bob's Bagels -------\n");
+        sb.AppendLine($"    {_date}    \n");
+
+        
+        sb.AppendLine("Product         Amt Price");
+        
+        foreach (var orderLine in _orderLines)
+        {
+            sb.AppendLine($"{
+                FixedLengthString(orderLine.Product, 15)} " +
+                          $"{FixedLengthString(orderLine.Amount.ToString(), 2)} " +
+                          $"{FormatPrice(orderLine.Price)}");
+        }
+        
+        sb.AppendLine($"\n{"Total:", 18} {FormatPrice(Total())}");
+        
+        return sb.ToString();
+    }
+
+    public void Add(Product product, int amount)
+    {
+        _orderLines.Add(new OrderLine
+        {
+            Product = product.Name,
+            Amount = amount,
+            Price = product.GetPrice()
+        });
+    }
+    
+    public void AddModifier(string label, int amount, double price)
+    {
+        _orderLines.Add(new OrderLine
+        {
+            Product = label,
+            Amount = amount,
+            Price = price
+        });
+    }
+    
+    public double Total()
+    {
+        return _orderLines.Sum(ol => ol.Price * Math.Max(1, ol.Amount));
+    }
+    
+    private string FixedLengthString(string value, int length)
+    {
+        return value.PadRight(length).Substring(0, length);
+    }
+    
+    private string FormatPrice(double price)
+    {
+        if (price < 0)
+        {
+            return $"(€{price.ToString("F2")})";
+        }
+
+        return $" €{price.ToString("F2")}";
+    }
+}
\ No newline at end of file
diff --git a/exercise.main/OrderLine.cs b/exercise.main/OrderLine.cs
new file mode 100644
index 00000000..59137b49
--- /dev/null
+++ b/exercise.main/OrderLine.cs
@@ -0,0 +1,9 @@
+namespace exercise.main;
+
+public class OrderLine
+{
+    public string Product { get; set; }
+    public int Amount { get; set; }
+    public double Price { get; set; }
+    public double Discount { get; set; }
+}
\ No newline at end of file
diff --git a/exercise.main/Product.cs b/exercise.main/Product.cs
new file mode 100644
index 00000000..8c08227b
--- /dev/null
+++ b/exercise.main/Product.cs
@@ -0,0 +1,56 @@
+namespace exercise.main;
+
+public class Product
+{
+    public string Sku { get; set; }
+    public string Name { get; set; }
+    public double Price { get; set; }
+    public Dictionary<int, double> Promotions { get; }
+    public List<ProductModification> AllowedModifications { get; set; }
+    public List<string> Modifications { get; set; }
+
+    
+    public Product(string sku, string name, double price)
+    {
+        Sku = sku;
+        Name = name;
+        Price = price;
+        Promotions = new Dictionary<int, double>();
+        AllowedModifications = new List<ProductModification>();
+    }
+    
+    public double GetPrice()
+    {
+        return Price;
+    }
+    
+    public void SetPrice(double price)
+    {
+        if (price <= 0)
+        {
+            throw new Exception("Price must be greater than 0");
+        }
+        
+        Price = price;
+    }
+    
+    public void AddModification(ProductModification modification)
+    {
+        // Checks if the modification SKU is allowed, then add and sort
+        if (AllowedModifications.Any(m => m.Sku == modification.Sku))
+        {
+            Modifications.Add(modification.Sku);
+        }
+    }
+    
+    public void AddPromotion(int quantity, double price)
+    {
+        if (quantity > 0 && price > 0)
+        {
+            Promotions.Add(quantity, price);
+            return;
+        }
+        
+        throw new Exception("Invalid promotion. Quantity and promotional price must be greater than 0");
+    }
+}
\ No newline at end of file
diff --git a/exercise.main/ProductModification.cs b/exercise.main/ProductModification.cs
new file mode 100644
index 00000000..228e0f85
--- /dev/null
+++ b/exercise.main/ProductModification.cs
@@ -0,0 +1,8 @@
+namespace exercise.main;
+
+public class ProductModification : Product
+{
+    public ProductModification(string sku, string name, double price) : base(sku, name, price)
+    {
+    }
+}
\ No newline at end of file
diff --git a/exercise.main/Startup.cs b/exercise.main/Startup.cs
new file mode 100644
index 00000000..fa7e16a4
--- /dev/null
+++ b/exercise.main/Startup.cs
@@ -0,0 +1,11 @@
+using Microsoft.Extensions.DependencyInjection;
+
+namespace exercise.main;
+
+public class Startup
+{
+    public void ConfigureServices(IServiceCollection services)
+    {
+        services.AddSingleton<IInventory, Inventory>();
+    }
+}
\ No newline at end of file
diff --git a/exercise.main/exercise.main.csproj b/exercise.main/exercise.main.csproj
index fd4bd08d..eaaf31f1 100644
--- a/exercise.main/exercise.main.csproj
+++ b/exercise.main/exercise.main.csproj
@@ -7,4 +7,8 @@
     <Nullable>enable</Nullable>
   </PropertyGroup>
 
+  <ItemGroup>
+    <PackageReference Include="Microsoft.Extensions.Hosting" Version="9.0.0" />
+  </ItemGroup>
+
 </Project>
diff --git a/exercise.tests/BasketTest.cs b/exercise.tests/BasketTest.cs
new file mode 100644
index 00000000..1e77d12e
--- /dev/null
+++ b/exercise.tests/BasketTest.cs
@@ -0,0 +1,45 @@
+using exercise.main;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace exercise.tests;
+
+[TestFixture]
+public class BasketTest
+{
+    private Basket _basket;
+    private Inventory _inventory;
+    
+    [SetUp]
+    public void Setup()
+    {
+        _inventory = new Inventory();
+        Seed.AddData(out _inventory);
+        _basket = new Basket(_inventory);
+    }
+    
+    [TestCase("BGLO", 1, 0.49)]
+    [TestCase("BGLP", 1, 0.39)]
+    [TestCase("BGLP", 3, 1.17)]
+    [TestCase("COFC", 1, 1.29)]
+
+    public void TestAdd(string sku, int quantity, double total)
+    {
+        _basket.Add(sku, quantity);
+        Assert.AreEqual(total, _basket.GetTotal());
+    }
+    
+    [Test]
+    public void TestRemove()
+    {
+        _basket.Add("BGLO", 1);
+        _basket.Remove("BGLO", 1);
+        Assert.AreEqual(0, _basket.GetTotal());
+    }
+    
+    [Test]
+    public void TestSetCapacity()
+    {
+        _basket.SetCapacity(5);
+        Assert.AreEqual(5, _basket.GetCapacity());
+    }
+}
\ No newline at end of file
diff --git a/exercise.tests/OrderTest.cs b/exercise.tests/OrderTest.cs
new file mode 100644
index 00000000..550ec289
--- /dev/null
+++ b/exercise.tests/OrderTest.cs
@@ -0,0 +1,47 @@
+using exercise.main;
+
+namespace exercise.tests;
+
+[TestFixture]
+public class OrderTest
+{
+    private Inventory _inventory;
+    
+    [SetUp]
+    public void Setup()
+    {
+        _inventory = new Inventory();
+        
+        Seed.AddData(out _inventory);
+    }
+    
+    [Test]
+    public void TestOrder()
+    {
+        var _basket = new Basket(_inventory);
+        
+        _basket.Add("BGLO", 3);
+        _basket.Add("COFB", 1);
+        var order = _basket.Order();
+        
+        Console.WriteLine(order);
+        
+        Assert.IsNotEmpty(order.ToString());
+    }
+    
+    [Test]
+    public void TestDiscounts()
+    {
+        var _basket = new Basket(_inventory);
+        
+        _basket.SetCapacity(20);
+        
+        _basket.Add("BGLO", 14);
+        _basket.Add("COFB", 1);
+        var order = _basket.Order();
+        
+        Console.WriteLine(order);
+        
+        Assert.IsNotEmpty(order.ToString());
+    }
+}
\ No newline at end of file
diff --git a/exercise.tests/ProductModificationTest.cs b/exercise.tests/ProductModificationTest.cs
new file mode 100644
index 00000000..6f73cd43
--- /dev/null
+++ b/exercise.tests/ProductModificationTest.cs
@@ -0,0 +1,39 @@
+using exercise.main;
+
+namespace exercise.tests;
+
+[TestFixture]
+public class ProductModificationTest
+{
+    private static Product _product;
+    
+    [SetUp]
+    public void Setup()
+    {
+        _product = new Product("SKU0", "Test Product", 10.99);
+        _product.AllowedModifications
+            .Add(new ProductModification("MOD1", "Test Modification", 9.99));
+    }
+    
+    [Test]
+    public void ProductModConstructorTest()
+    {
+        Assert.That(_product.AllowedModifications.First().Sku, Is.EqualTo("MOD1"));
+        Assert.That(_product.AllowedModifications.First().Name, Is.EqualTo("Test Modification"));
+        Assert.That(_product.AllowedModifications.First().Price, Is.EqualTo(9.99));
+    }
+    
+    [Test]
+    public void ProductModGetPriceTest()
+    {
+        // Checks total price of product and modification
+        Assert.That(_product.GetPrice(), Is.EqualTo(20.99));
+    }
+    
+    [Test]
+    public void ProductSetPriceTest()
+    {
+        _product.SetPrice(8.99);
+        Assert.That(_product.AllowedModifications.First().GetPrice(), Is.EqualTo(8.99));
+    }
+}
\ No newline at end of file
diff --git a/exercise.tests/ProductTest.cs b/exercise.tests/ProductTest.cs
new file mode 100644
index 00000000..a689cbb9
--- /dev/null
+++ b/exercise.tests/ProductTest.cs
@@ -0,0 +1,56 @@
+using exercise.main;
+
+namespace exercise.tests;
+
+[TestFixture]
+public class ProductTest
+{
+    private static Product _product;
+    
+    [SetUp]
+    public void Setup()
+    {
+        _product = new Product("SKU0", "Test Product", 10.99);
+    }
+    
+    [Test]
+    public void ProductConstructorTest()
+    {
+        Assert.That(_product.Sku, Is.EqualTo("SKU0"));
+        Assert.That(_product.Name, Is.EqualTo("Test Product"));
+        Assert.That(_product.Price, Is.EqualTo(10.99));
+        Assert.IsEmpty(_product.Promotions);
+        Assert.IsEmpty(_product.AllowedModifications);
+    }
+    
+    [Test]
+    public void ProductGetPriceTest()
+    {
+        Assert.That(_product.GetPrice(), Is.EqualTo(10.99));
+    }
+    
+    [TestCase(9.9)]
+    [TestCase(0.01)]
+    [TestCase(double.MaxValue)]
+
+    public void ProductSetPriceTest(double newPrice)
+    {
+        _product.SetPrice(newPrice);
+        Assert.That(_product.GetPrice(), Is.EqualTo(newPrice));
+    }
+    
+    [TestCase(0)]
+    [TestCase(-1.0)]
+    [TestCase(double.MinValue)]
+    public void ProductSetNegativePriceTest(double newPrice)
+    {
+        Assert.Throws<Exception>(() => _product.SetPrice(newPrice));
+    }
+    
+    [Test]
+    public void ProductAddPromotionTest()
+    {
+        _product.AddPromotion(2, 15.99);
+        Assert.That(_product.Promotions.First().Value, Is.EqualTo(15.99));
+    }
+}
\ No newline at end of file
diff --git a/exercise.tests/Seed.cs b/exercise.tests/Seed.cs
new file mode 100644
index 00000000..2c5519a2
--- /dev/null
+++ b/exercise.tests/Seed.cs
@@ -0,0 +1,37 @@
+using exercise.main;
+
+namespace exercise.tests;
+
+public class Seed
+{
+    public static void AddData(out Inventory inventory)
+    {
+        inventory = new Inventory();
+        inventory.AddProduct(new Product("BGLO", "Onion Bagel", 0.49), 10);
+        inventory.AddProduct(new Product("BGLP", "Plain Bagel", 0.39), 10);
+        inventory.AddProduct(new Product("BGLE", "Everything Bagel", 0.49), 10);
+        inventory.AddProduct(new Product("BGLS", "Sesame Bagel", 0.49), 10);
+        inventory.AddProduct(new Product("COFB", "Black Coffee", 	0.99), 10);
+        inventory.AddProduct(new Product("COFW", "White Coffee", 1.19), 10);
+        inventory.AddProduct(new Product("COFC", "Capuccino", 1.29), 10);
+        inventory.AddProduct(new Product("COFL", "Latte", 1.29), 10);
+        
+        ProductModification filb = new ProductModification("FILB", "Bacon", 0.12);
+        ProductModification file = new ProductModification("FILE", "Egg", 0.12);
+        ProductModification filc = new ProductModification("FILC", "Cheese", 0.12);
+        ProductModification filx = new ProductModification("FILX", "Cream Cheese", 0.12);
+        ProductModification fils = new ProductModification("FILS", "Smoked Salmon", 0.12);
+        ProductModification filh = new ProductModification("FILH", "Ham", 0.12);
+        
+        List<ProductModification> modifications = new List<ProductModification> { filb, file, filc, filx, fils, filh };
+
+        foreach (KeyValuePair<Product, int> inventoryItem in inventory)
+        {
+            var product = inventoryItem.Key;
+            if (product.Sku.StartsWith("BGL"))
+            {
+                product.AllowedModifications = modifications;
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/exercise.tests/UnitTest1.cs b/exercise.tests/UnitTest1.cs
index 7bdb8968..5585b540 100644
--- a/exercise.tests/UnitTest1.cs
+++ b/exercise.tests/UnitTest1.cs
@@ -1,10 +1,15 @@
+using exercise.main;
+
 namespace exercise.tests;
 
 public class Tests
 {
+    protected static Inventory inventory;
     [SetUp]
     public void Setup()
     {
+        inventory = new Inventory();
+        Seed.AddData(out inventory);
     }
 
     [Test]
diff --git a/exercise.tests/exercise.tests.csproj b/exercise.tests/exercise.tests.csproj
index 9fed8e17..a3a97d4f 100644
--- a/exercise.tests/exercise.tests.csproj
+++ b/exercise.tests/exercise.tests.csproj
@@ -17,4 +17,8 @@
     <PackageReference Include="coverlet.collector" Version="6.0.0" />
   </ItemGroup>
 
+  <ItemGroup>
+    <ProjectReference Include="..\exercise.main\exercise.main.csproj" />
+  </ItemGroup>
+
 </Project>