add depreciation calculation

Controllers/VehicleController.cs

@@ -1336,19 +1336,36 @@ namespace CarCareTracker.Controllers
             if (!string.IsNullOrWhiteSpace(vehicleHistory.VehicleData.PurchaseDate))
             {
                 var endDate = vehicleHistory.VehicleData.SoldDate;
+                int daysOwned = 0;
                 if (string.IsNullOrWhiteSpace(endDate))
                 {
                     endDate = DateTime.Now.ToShortDateString();
                 }
                 try
                 {
-                    vehicleHistory.DaysOwned = (DateTime.Parse(endDate) - DateTime.Parse(vehicleHistory.VehicleData.PurchaseDate)).Days.ToString("N0");
+                    daysOwned = (DateTime.Parse(endDate) - DateTime.Parse(vehicleHistory.VehicleData.PurchaseDate)).Days;
+                    vehicleHistory.DaysOwned = daysOwned.ToString("N0");
                 }
                 catch (Exception ex)
                 {
                     _logger.LogError(ex.Message);
                     vehicleHistory.DaysOwned = string.Empty;
                 }
+                //calculate depreciation
+                var totalDepreciation = vehicleHistory.VehicleData.PurchasePrice - vehicleHistory.VehicleData.SoldPrice;
+                //we only calculate depreciation if a sold price is provided.
+                if (totalDepreciation != default && vehicleHistory.VehicleData.SoldPrice != default)
+                {
+                    vehicleHistory.TotalDepreciation = totalDepreciation;
+                    if (daysOwned != default)
+                    {
+                        vehicleHistory.DepreciationPerDay = Math.Abs(totalDepreciation / daysOwned);
+                    }
+                    if (distanceTraveled != default)
+                    {
+                        vehicleHistory.DepreciationPerMile = Math.Abs(totalDepreciation / distanceTraveled);
+                    }
+                }
             }
             List<GenericReportModel> reportData = new List<GenericReportModel>();
             var serviceRecords = _serviceRecordDataAccess.GetServiceRecordsByVehicleId(vehicleId);

Models/Report/VehicleHistoryViewModel.cs

@@ -13,5 +13,8 @@
         public decimal TotalCostPerMile { get; set; }
         public decimal TotalGasCostPerMile { get; set; }
         public string DistanceUnit { get; set; }
+        public decimal TotalDepreciation { get; set; }
+        public decimal DepreciationPerDay { get; set; }
+        public decimal DepreciationPerMile { get; set; }
     }
 }

Views/Vehicle/_VehicleHistory.cshtml

@@ -62,6 +62,30 @@
         </div>
     </div>
     <hr />
+    @if (Model.TotalDepreciation != default)
+    {
+            <div class="row">
+                <div class="col-3">
+                    @(Model.TotalDepreciation > 0 ? translator.Translate(userLanguage, "Depreciation") : translator.Translate(userLanguage, "Appreciation"))
+                </div>
+                <div class="col-3">
+                    <span><i class="bi @(Model.TotalDepreciation > 0 ? "bi-graph-down-arrow" : "bi-graph-up-arrow") me-2"></i>@Math.Abs(Model.TotalDepreciation).ToString("C")</span>
+                </div>
+                @if (Model.DepreciationPerDay != default)
+                {
+                    <div class="col-3">
+                        <span><i class="bi bi-calendar-event me-2"></i>@($"{Model.DepreciationPerDay.ToString("C")}/{translator.Translate(userLanguage, "day")}")</span>
+                    </div>
+                }
+                @if (Model.DepreciationPerMile != default)
+                {
+                    <div class="col-3">
+                        <span><i class="bi bi-speedometer me-2"></i>@($"{Model.DepreciationPerMile.ToString("C")}/{Model.DistanceUnit}")</span>
+                    </div>
+                }
+            </div>
+        <hr />
+    }
     <div class="row">
         <div class="col-12">
             <table class="table table-hover">