Refactor code structure for improved readability and maintainability

Repository/DeploymentGroupRepository.cs

@@ -30,10 +30,70 @@ namespace Microsoft.SelfService.Portal.Core.API.Repository
                 .Where(dg => dg.Id == Id).FirstOrDefault();
         }
 
-        public bool AddDeploymentGroupById(DeploymentGroupModel deploymentgroup)
+        public bool AddDeploymentGroupById(DeploymentGroupModel deploymentgroup, ICollection<Guid>? virtualMachineIds)
         {
+            if (deploymentgroup.Id == Guid.Empty)
+            {
+                deploymentgroup.Id = Guid.NewGuid();
+            }
+
+            var template = _context.Templates
+                .Include(existing => existing.TemplateCategory)
+                .ThenInclude(existing => existing.Service)
+                .FirstOrDefault(existing => existing.Id == deploymentgroup.TemplateId);
+
+            if (template == null)
+            {
+                return false;
+            }
+
+            var isCloudService = template.TemplateCategory.Service.IsCloudService;
+            var selectedVirtualMachineIds = (virtualMachineIds ?? Array.Empty<Guid>())
+                .Distinct()
+                .ToList();
+
+            if (!isCloudService && selectedVirtualMachineIds.Count == 0)
+            {
+                return false;
+            }
+
+            if (selectedVirtualMachineIds.Count > 0)
+            {
+                var existingVirtualMachineIds = _context.VirtualMachines
+                    .Where(existing => selectedVirtualMachineIds.Contains(existing.Id))
+                    .Select(existing => existing.Id)
+                    .ToHashSet();
+
+                if (existingVirtualMachineIds.Count != selectedVirtualMachineIds.Count)
+                {
+                    return false;
+                }
+            }
+
             _context.Add(deploymentgroup);
-            return SaveChanges();
+
+            if (!SaveChanges())
+            {
+                return false;
+            }
+
+            if (!isCloudService)
+            {
+                foreach (var virtualMachineId in selectedVirtualMachineIds)
+                {
+                    _context.Deployments.Add(new DeploymentModel
+                    {
+                        DeploymentGroupId = deploymentgroup.Id,
+                        VirtualMachineId = virtualMachineId,
+                        Status = QueueJobStatus.Pending,
+                        JSONData = "{}"
+                    });
+                }
+
+                return SaveChanges();
+            }
+
+            return true;
         }
 
         public bool DeleteDeploymentGroupById(DeploymentGroupModel deploymentgroup)