From f3472063523fb0d98c86bc677ef104aefe1dc9ef Mon Sep 17 00:00:00 2001
From: Vivek Gawande <vivek040997@gmail.com>
Date: Wed, 20 Oct 2021 13:15:57 +0530
Subject: [PATCH] Add alert when price of any product reaches below target

---
 PCPartPriceTracker/MainWindow.xaml.cs             |  8 ++++++++
 ViewModels/Helpers/PriceReachedTargetEventArgs.cs | 12 ++++++++++++
 ViewModels/MainVM.cs                              | 15 +++++++++++++++
 3 files changed, 35 insertions(+)
 create mode 100644 ViewModels/Helpers/PriceReachedTargetEventArgs.cs

diff --git a/PCPartPriceTracker/MainWindow.xaml.cs b/PCPartPriceTracker/MainWindow.xaml.cs
index 5277be2..486eaf4 100644
--- a/PCPartPriceTracker/MainWindow.xaml.cs
+++ b/PCPartPriceTracker/MainWindow.xaml.cs
@@ -37,8 +37,16 @@ public MainWindow()
         {
             InitializeComponent();
             VM = (MainVM)FindResource("vm");
+            VM.OnProductPriceReachedBelowTarget += VM_OnProductPriceReachedBelowTarget;
             SetupAutoRefresh();
         }
+
+        private void VM_OnProductPriceReachedBelowTarget(object sender, ViewModels.Helpers.PriceReachedTargetEventArgs e)
+        {
+            MessageBox.Show("The following products have reached below your target price and are in stock: " + e.Products, "Target Price Reached!", 
+                MessageBoxButton.OK, MessageBoxImage.Information);
+        }
+
         private void SetupAutoRefresh()
         {
             refreshTimer = new Timer(e =>
diff --git a/ViewModels/Helpers/PriceReachedTargetEventArgs.cs b/ViewModels/Helpers/PriceReachedTargetEventArgs.cs
new file mode 100644
index 0000000..794b4fd
--- /dev/null
+++ b/ViewModels/Helpers/PriceReachedTargetEventArgs.cs
@@ -0,0 +1,12 @@
+namespace ViewModels.Helpers
+{
+    public class PriceReachedTargetEventArgs
+    {
+        public string Products { get; set; }
+
+        public PriceReachedTargetEventArgs(string products)
+        {
+            Products = products;
+        }
+    }
+}
\ No newline at end of file
diff --git a/ViewModels/MainVM.cs b/ViewModels/MainVM.cs
index 9de305b..eb5eaaf 100644
--- a/ViewModels/MainVM.cs
+++ b/ViewModels/MainVM.cs
@@ -11,6 +11,7 @@
 using System.Threading.Tasks;
 using ViewModels.Commands;
 using ViewModels.Factories;
+using ViewModels.Helpers;
 
 namespace ViewModels
 {
@@ -21,6 +22,7 @@ public class MainVM : INotifyPropertyChanged
 
         private bool _loading;
 
+
         public bool Loading
         {
             get { return _loading; }
@@ -31,6 +33,8 @@ public bool Loading
             }
         }
 
+        public event EventHandler<PriceReachedTargetEventArgs> OnProductPriceReachedBelowTarget;
+
         public event PropertyChangedEventHandler PropertyChanged;
 
         private ProductContext _context = new ProductContext();
@@ -66,6 +70,7 @@ public async Task RefreshPricesAsync()
             Loading = true;
             var products = await _context.Products.ToListAsync();
             var tasks = new List<Task<Product>>();
+            var productsBelowTarget = new List<Product>();
 
             foreach (Product product in products)
             {
@@ -79,7 +84,12 @@ public async Task RefreshPricesAsync()
                 var updatedProduct = updatedProducts.Where(p => p.Id == product.Id).SingleOrDefault();
                 product.Price = updatedProduct.Price;
                 product.InStock = updatedProduct.InStock;
+                if (product.Price <= product.TargetPrice && product.InStock)
+                {
+                    productsBelowTarget.Add(product);
+                }
             }
+
             await _context.SaveChangesAsync();
 
             Products.Clear();
@@ -88,6 +98,11 @@ public async Task RefreshPricesAsync()
                 Products.Add(product);
             }
             Loading = false;
+
+            if (productsBelowTarget.Count > 0)
+            {
+                OnProductPriceReachedBelowTarget.Invoke(this, new PriceReachedTargetEventArgs(string.Join(",", productsBelowTarget.Select(p => p.Name))));
+            }
         }
     }
 }