From 1debac950598d755d0f9bb4b1982c497fdd4e546 Mon Sep 17 00:00:00 2001
From: KharchenkoVV <vv.harchenko@autodrilling.ru>
Date: Thu, 2 Sep 2021 10:13:20 +0500
Subject: [PATCH] Fixed exception with .ElementAt(0) call at empty collection

---
 .../Services/WellOperationsStatService.cs     | 38 +++++++++++--------
 1 file changed, 22 insertions(+), 16 deletions(-)

diff --git a/AsbCloudInfrastructure/Services/WellOperationsStatService.cs b/AsbCloudInfrastructure/Services/WellOperationsStatService.cs
index 0798c683..f670e045 100644
--- a/AsbCloudInfrastructure/Services/WellOperationsStatService.cs
+++ b/AsbCloudInfrastructure/Services/WellOperationsStatService.cs
@@ -470,24 +470,30 @@ namespace AsbCloudInfrastructure.Services
 
         private static IEnumerable<OperationParams> MakeOperationsExt(IEnumerable<WellOperation> operations)
         {
-            var sortedOperations = operations.OrderBy(o => o.StartDate);
-            var count = operations.Count();
-            var ops = new List<OperationParams>(count);
-            var item = operations.ElementAt(0);
-            var wellDepth = item.WellDepth;
-            var pre = new OperationParams(item);
-            var current = new OperationParams(item);
-            for (int i = 1; i < count; i++)
+            var ops = new List<OperationParams>();
+
+            if (operations.Any())
             {
-                item = operations.ElementAt(i);
-                current = new OperationParams(item){ WellDepth = Helper.Max(wellDepth, item.WellDepth) };
-                pre.DeltaDepth = current.WellDepth - wellDepth;
-                wellDepth = current.WellDepth;
-                pre.Hours = (current.Start - pre.Start).TotalHours;
-                ops.Add(pre);
-                pre = current;
+                var sortedOperations = operations.OrderBy(o => o.StartDate);
+                var count = operations.Count();
+                ops = new List<OperationParams>(count);
+                var item = operations.ElementAt(0);
+                var wellDepth = item.WellDepth;
+                var pre = new OperationParams(item);
+                var current = new OperationParams(item);
+                for (int i = 1; i < count; i++)
+                {
+                    item = operations.ElementAt(i);
+                    current = new OperationParams(item) { WellDepth = Helper.Max(wellDepth, item.WellDepth) };
+                    pre.DeltaDepth = current.WellDepth - wellDepth;
+                    wellDepth = current.WellDepth;
+                    pre.Hours = (current.Start - pre.Start).TotalHours;
+                    ops.Add(pre);
+                    pre = current;
+                }
+                ops.Add(current);
             }
-            ops.Add(current);
+
             return ops;
         }
     }