Assignment 5 (Inventory Management System with Exception Handling)

InventoryManagementSystem/InventoryManagementSystem/IProductManager.cs

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+namespace InventoryManagementSystem
+{
+    public interface IProductManager
+    {
+        Product GetProductById(int productId);
+        List<Product> GetProducts();
+        void AddProduct(Product product);
+        void UpdateProduct(Product product);
+        void DeleteProduct(Product product);
+        void SellProduct(Product product, int quantity);
+    }
+}

InventoryManagementSystem/InventoryManagementSystem/InventoryManagementController.cs

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+namespace InventoryManagementSystem
+{
+    public class InventoryManagementController
+    {
+        private IProductManager manager;
+
+        public InventoryManagementController(IProductManager manager)
+        {
+            this.manager = manager;
+        }
+
+        public void Start()
+        {
+            Console.WriteLine("Welcome to Inventory Management System");
+            while (true)
+            {
+                DisplayMenu();
+                string choice = Console.ReadLine();
+                ProcessChoice(choice);
+            }
+        }
+
+        private void DisplayMenu()
+        {
+            Console.WriteLine("\nEnter operation to perform:");
+            Console.WriteLine("1. View Inventory");
+            Console.WriteLine("2. Add Product");
+            Console.WriteLine("3. Update Product");
+            Console.WriteLine("4. Delete Product");
+            Console.WriteLine("5. Sell Product");
+            Console.WriteLine("6. Exit");
+            Console.Write("Enter your choice: ");
+        }
+
+        private void ProcessChoice(string choice)
+        {
+            switch (choice)
+            {
+                case "1":
+                    ViewInventory();
+                    break;
+                case "2":
+                    AddProduct();
+                    break;
+                case "3":
+                    UpdateProduct();
+                    break;
+                case "4":
+                    DeleteProduct();
+                    break;
+                case "5":
+                    SellProduct();
+                    break;
+                case "6":
+                    Console.WriteLine("Exiting program...");
+                    Environment.Exit(0);
+                    break;
+                default:
+                    Console.WriteLine("Invalid choice! Please try again.");
+                    break;
+            }
+        }
+
+        private void ViewInventory()
+        {
+            try
+            {
+                var products = manager.GetProducts();
+                if (products.Count == 0)
+                {
+                    Console.WriteLine("\nInventory is empty!");
+                }
+                else
+                {
+                    Console.WriteLine("\nList of all Products:");
+                    foreach (var product in products)
+                    {
+                        Console.WriteLine($"ID: {product.Id}\nName: {product.Name}\nPrice: {product.Price}\nQuantity: {product.Quantity}\n");
+                    }
+                }
+            }
+            catch (Exception ex)
+            {
+                Console.WriteLine("Error: " + ex.Message);
+            }
+        }
+
+        private void AddProduct()
+        {
+            try
+            {
+                Console.WriteLine("\nEnter details of the product:");
+                Console.Write("ID: ");
+                int id = ReadIntFromConsole("ID");
+                Console.Write("Name: ");
+                string name = ReadStringFromConsole("Name");
+                Console.Write("Price: ");
+                double price = ReadDoubleFromConsole("Price");
+                Console.Write("Quantity: ");
+                int quantity = ReadIntFromConsole("Quantity");
+
+                manager.AddProduct(new Product { Id = id, Name = name, Price = price, Quantity = quantity });
+                Console.WriteLine("Product added successfully.");
+            }
+            catch (Exception ex)
+            {
+                Console.WriteLine("Error: " + ex.Message);
+            }
+        }
+
+        private void UpdateProduct()
+        {
+            try
+            {
+                Console.Write("\nEnter ID of the product to update: ");
+                int id = ReadIntFromConsole("ID");
+
+                var productToUpdate = manager.GetProductById(id);
+
+                Console.Write("New Name (press Enter to keep current): ");
+                string name = Console.ReadLine();
+                if (name == null)
+                {
+                    name = productToUpdate.Name;
+                }
+
+                Console.Write("New Price (press Enter to keep current): ");
+                string priceInput = Console.ReadLine();
+                double? price = null;
+                if (!string.IsNullOrWhiteSpace(priceInput))
+                {
+                    price = double.Parse(priceInput);
+                }
+                else
+                {
+                    price = productToUpdate.Price;
+                }
+
+                Console.Write("New Quantity (press Enter to keep current): ");
+                string quantityInput = Console.ReadLine();
+                int? quantity = null;
+                if (!string.IsNullOrWhiteSpace(quantityInput))
+                {
+                    quantity = int.Parse(quantityInput);
+                }
+                else
+                {
+                    quantity = productToUpdate.Quantity;
+                }
+
+                manager.UpdateProduct(new Product { Id = id, Name = name, Price = (double)price, Quantity = (int)quantity });
+                Console.WriteLine("Product updated successfully.");
+            }
+            catch (Exception ex)
+            {
+                Console.WriteLine("Error: " + ex.Message);
+            }
+        }
+
+        private void DeleteProduct()
+        {
+            try
+            {
+                Console.Write("\nEnter ID of the product to delete: ");
+                int id = ReadIntFromConsole("ID");
+
+                var product = manager.GetProductById(id);
+
+                manager.DeleteProduct(product);
+                Console.WriteLine("Product deleted successfully.");
+            }
+            catch (Exception ex)
+            {
+                Console.WriteLine("Error: " + ex.Message);
+            }
+        }
+
+        private void SellProduct()
+        {
+            try
+            {
+                Console.Write("\nEnter ID of the product to sell: ");
+                int id = ReadIntFromConsole("ID");
+                Console.Write("Enter quantity to sell: ");
+                int quantity = ReadIntFromConsole("Quantity");
+
+                var product = manager.GetProductById(id);
+
+                manager.SellProduct(product, quantity);
+                Console.WriteLine("Product sold successfully.");
+            }
+            catch (Exception ex)
+            {
+                Console.WriteLine("Error: " + ex.Message);
+            }
+        }
+
+        private int ReadIntFromConsole(string fieldName)
+        {
+            string input = Console.ReadLine();
+            if (!int.TryParse(input, out int result))
+            {
+                throw new ArgumentException($"{fieldName} must be an integer.");
+            }
+            return result;
+        }
+
+        private double ReadDoubleFromConsole(string fieldName)
+        {
+            string input = Console.ReadLine();
+            if (!double.TryParse(input, out double result))
+            {
+                throw new ArgumentException($"{fieldName} must be a valid number.");
+            }
+            return result;
+        }
+
+        private string ReadStringFromConsole(string fieldName)
+        {
+            string input = Console.ReadLine();
+            if (string.IsNullOrWhiteSpace(input))
+            {
+                throw new ArgumentException($"{fieldName} is required.");
+            }
+            return input;
+        }
+    }
+}

InventoryManagementSystem/InventoryManagementSystem/InventoryManagementExceptions.cs

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+namespace InventoryManagementSystem
+{
+    public class DuplicateProductException : Exception
+    {
+        public DuplicateProductException(string message) : base(message) { }
+    }
+
+    public class ProductNotFoundException : Exception
+    {
+        public ProductNotFoundException(string message) : base(message) { }
+    }
+
+    public class InsufficientQuantityException : Exception
+    {
+        public InsufficientQuantityException(string message) : base(message) { }
+    }
+
+    public class InvalidDataException : Exception
+    {
+        public InvalidDataException(string message) : base(message) { }
+    }
+}

InventoryManagementSystem/InventoryManagementSystem/InventoryManagementSystem.csproj

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+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net6.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+</Project>

InventoryManagementSystem/InventoryManagementSystem/InventoryManagementSystem.sln

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+
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio Version 17
+VisualStudioVersion = 17.9.34728.123
+MinimumVisualStudioVersion = 10.0.40219.1
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "InventoryManagementSystem", "InventoryManagementSystem.csproj", "{1B05856A-36E1-4658-8124-1209E781ECD8}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|Any CPU = Debug|Any CPU
+		Release|Any CPU = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{1B05856A-36E1-4658-8124-1209E781ECD8}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{1B05856A-36E1-4658-8124-1209E781ECD8}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{1B05856A-36E1-4658-8124-1209E781ECD8}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{1B05856A-36E1-4658-8124-1209E781ECD8}.Release|Any CPU.Build.0 = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(SolutionProperties) = preSolution
+		HideSolutionNode = FALSE
+	EndGlobalSection
+	GlobalSection(ExtensibilityGlobals) = postSolution
+		SolutionGuid = {105F8084-48FF-445A-A58B-982EB594CF11}
+	EndGlobalSection
+EndGlobal

InventoryManagementSystem/InventoryManagementSystem/Product.cs

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+namespace InventoryManagementSystem
+{
+    public class Product
+    {
+        public int Id { get; set; }
+        public string Name { get; set; }
+        public double Price { get; set; }
+        public int Quantity { get; set; }
+    }
+}

InventoryManagementSystem/InventoryManagementSystem/ProductManager.cs

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+namespace InventoryManagementSystem
+{
+    public class ProductManager : IProductManager
+    {
+        private readonly List<Product> productInventory = new List<Product>();
+
+        public Product GetProductById(int productId)
+        {
+            var product = productInventory.Find(p => p.Id == productId) ?? throw new ProductNotFoundException("Product with this ID not found.");
+            return product;
+        }
+
+        public List<Product> GetProducts()
+        {
+            return productInventory;
+        }
+
+        public void AddProduct(Product product)
+        {
+            if (productInventory.Exists(p => p.Id == product.Id))
+            {
+                throw new DuplicateProductException("Product with the same ID already exists.");
+            }
+
+            ValidateProductData(product);
+
+            productInventory.Add(product);
+        }
+
+        public void UpdateProduct(Product product)
+        {
+            var existingProduct = GetProductById(product.Id);
+            ValidateProductData(product);
+
+            existingProduct.Name = product.Name ?? existingProduct.Name;
+            existingProduct.Price = product.Price >= 0 ? product.Price : existingProduct.Price;
+            existingProduct.Quantity = product.Quantity >= 0 ? product.Quantity : existingProduct.Quantity;
+        }
+
+        public void DeleteProduct(Product product)
+        {
+            productInventory.Remove(product);
+        }
+
+        public void SellProduct(Product product, int quantity)
+        {
+            if (quantity <= 0)
+            {
+                throw new InvalidDataException("Invalid quantity. Quantity must be greater than zero.");
+            }
+
+            if (quantity > product.Quantity)
+            {
+                throw new InsufficientQuantityException("Insufficient quantity for sale.");
+            }
+
+            if (product.Quantity == 0)
+            {
+                throw new InsufficientQuantityException("Cannot sell. Product is out of stock.");
+            }
+
+            product.Quantity -= quantity;
+        }
+
+        private void ValidateProductData(Product product)
+        {
+            if (product.Price < 0)
+            {
+                throw new InvalidDataException("Price of product cannot be negative.");
+            }
+
+            if (product.Quantity < 0)
+            {
+                throw new InvalidDataException("Quantity cannot be negative.");
+            }
+        }
+    }
+}