Add discount support for institution contract extensions

- Introduce DiscountPercentage and DiscountAmount fields to contract creation and payment models
- Implement discount calculation logic in repository
- Add SetDiscountForExtension API endpoint and related request/response models
- Update contract creation and extension flows to handle discounts

CompanyManagment.EFCore/Repository/InstitutionContractRepository.cs

@@ -1870,6 +1870,51 @@ public class InstitutionContractRepository : RepositoryBase<long, InstitutionCon
             .FirstOrDefaultAsync(x => x.PublicId == id);
     }
 
+    public InstitutionContractExtensionPaymentResponse CalculateDiscount(InstitutionContractSetDiscountRequest request)
+    {
+        var baseAmount = request.PaymentAmount;
+        var discountAmount = (baseAmount * request.DiscountPercentage) / 100;
+        var paymentAmount = baseAmount - discountAmount;
+        var taxAmount = paymentAmount * 0.10;
+        var totalAmount = paymentAmount + taxAmount;
+        InstitutionContractPaymentMonthlyViewModel monthlyPayment = null;
+        InstitutionContractPaymentOneTimeViewModel oneTimePayment = null;
+        
+        if (request.IsInstallment)
+        {
+            monthlyPayment = new InstitutionContractPaymentMonthlyViewModel()
+            {
+                TotalAmount = totalAmount.ToMoney(),
+                PaymentAmount = paymentAmount.ToMoney(),
+                Tax = taxAmount.ToMoney(),
+                DiscountedAmount = discountAmount.ToMoney(),
+                DiscountPercetage = request.DiscountPercentage,
+                Installments = InstitutionMonthlyInstallmentCaculation((int)request.Duration,
+                    totalAmount, DateTime.Now.ToFarsi())
+            };
+        }
+        else
+        {
+            oneTimePayment =  new InstitutionContractPaymentOneTimeViewModel()
+            {
+                TotalAmount = totalAmount.ToMoney(),
+                PaymentAmount = paymentAmount.ToMoney(),
+                Tax = taxAmount.ToMoney(),
+                DiscountedAmount = discountAmount.ToMoney(),
+                DiscountPercetage = request.DiscountPercentage
+            };
+        }
+        
+        if (discountAmount > baseAmount)
+            throw new BadRequestException("مقدار تخفیف نمی‌تواند بیشتر از مبلغ کل باشد");
+
+        return new InstitutionContractExtensionPaymentResponse()
+        {
+            Monthly = monthlyPayment,
+            OneTime = oneTimePayment
+        };
+    }
+
     #region Extension
 
     public async Task<InstitutionContractExtensionInquiryResult> GetExtensionInquiry(long previousContractId)
@@ -2177,6 +2222,58 @@ public class InstitutionContractRepository : RepositoryBase<long, InstitutionCon
         return res;
     }
 
+    public async Task<InstitutionContractExtensionPaymentResponse> SetDiscountForExtension(InstitutionContractSetDiscountForExtensionRequest request)
+    {
+        
+        if (request.DiscountPercentage <= 0)
+            throw new BadRequestException("مقدار تخفیف نمی‌تواند برابر یا کمتر از صفر باشد");
+        var institutionTemp = await _institutionExtensionTemp.Find(x => x.Id == request.TempId)
+            .FirstOrDefaultAsync();
+        if (institutionTemp == null)
+        {
+            throw new BadRequestException("اطلاعات وارد شده نامعتبر است");
+        }
+
+        if (request.IsInstallment)
+        {
+            if(institutionTemp.MonthlyPayment.DiscountPercetage>0)
+                throw new BadRequestException("تخفیف قبلا برای این قرارداد اعمال شده است");
+        }
+        else
+        {
+            if(institutionTemp.OneTimePayment.DiscountPercetage>0)
+                throw new BadRequestException("تخفیف قبلا برای این قرارداد اعمال شده است");
+        }
+        
+        var calculateRequest = new InstitutionContractSetDiscountRequest()
+        {
+            Duration = institutionTemp.Duration.Value,
+            PaymentAmount = request.PaymentAmount,
+            DiscountPercentage = request.DiscountPercentage,
+            IsInstallment = request.IsInstallment
+        };
+        var res = CalculateDiscount(calculateRequest);
+
+        //این به این دلیل هست که متد caclulate discount یکی از مقادیر رو پر میکنه و ما نیاز داریم هر دو مقدار رو داشته باشیم
+        if (request.IsInstallment)
+        {
+            res.OneTime = institutionTemp.OneTimePayment;
+        }
+        else
+        {
+            res.Monthly = institutionTemp.MonthlyPayment;
+        }
+        institutionTemp.SetAmountAndDuration(institutionTemp.Duration.Value, res.Monthly, res.OneTime);
+        await _institutionExtensionTemp.ReplaceOneAsync(x => x.Id == institutionTemp.Id,
+            institutionTemp);
+
+        return new()
+        {
+            OneTime = institutionTemp.OneTimePayment,
+            Monthly = institutionTemp.MonthlyPayment
+        };
+    }
+
     public async Task<OperationResult> ExtensionComplete(InstitutionContractExtensionCompleteRequest request)
     {
         var institutionContractTemp = await _institutionExtensionTemp.Find(x => x.Id == request.TemporaryId)
@@ -2321,7 +2418,7 @@ public class InstitutionContractRepository : RepositoryBase<long, InstitutionCon
             previousInstitutionContract.Description,
             "NotOfficial", "JobRelation", hasValueAddedTax,
             payment.Tax.MoneyToDouble(), [],
-            request.LawId);
+            request.LawId,payment.DiscountPercetage,payment.DiscountedAmount.MoneyToDouble());
 
         await CreateAsync(entity);
         await SaveChangesAsync();