Set default tank type based of order of preference

Source/Tanks/ModuleFuelTanks.cs

@@ -1,14 +1,13 @@
 using System;
 using System.Collections.Generic;
-using System.Collections;
-using System.Linq;
+using System.Reflection;
+using UniLinq;
 using UnityEngine;
+using UnityEngine.Profiling;
 
 using KSP.UI.Screens;
-using System.Reflection;
 using KSP.Localization;
 using ROUtils;
-using UnityEngine.Profiling;
 
 // ReSharper disable InconsistentNaming, CompareOfFloatsByEqualityOperator
 
@@ -57,6 +56,8 @@ public void ChooseTankDefinition()
         }
         private TankDefinitionSelectionGUI tankDefinitionSelectionGUI = null;
 
+        private bool onLoadFiredInEditor;
+
         // The total tank volume. This is prior to utilization
         public double totalVolume;
 
@@ -238,6 +239,8 @@ public override void OnLoad(ConfigNode node)
                 // Setup the mass
                 massDirty = true;
                 CalculateMass();
+
+                onLoadFiredInEditor = HighLogic.LoadedSceneIsEditor;
             }
             OnLoadRF(node);
         }
@@ -280,6 +283,7 @@ public override void OnStart(StartState state)
                 if (MFSSettings.previewAllLockedTypes)
                     GatherLockedTypesFromAllPossible();
                 InitializeTankType();
+                TrySetBestTankDef();
                 UpdateTankType(false);
                 InitUtilization();
                 Fields[nameof(utilization)].uiControlEditor.onFieldChanged += OnUtilizationChanged;
@@ -375,6 +379,21 @@ private void InitializeTankType()
             c.display = typesAvailable.Select(t => ConstructColoredTypeTitle(t)).ToArray();
         }
 
+        private void TrySetBestTankDef()
+        {
+            if (!onLoadFiredInEditor)
+            {
+                var match = typesAvailable
+                    .Where(t => t.orderOfPreference >= 0 && !lockedTypes.Contains(t))
+                    .OrderByDescending((e) => e.orderOfPreference)
+                    .FirstOrDefault();
+                if (match != null)
+                {
+                    type = match.name;
+                }
+            }
+        }
+
         private string ConstructColoredTypeTitle(TankDefinition def)
         {
             if (!MFSSettings.previewAllLockedTypes || HighLogic.LoadedScene == GameScenes.LOADING)

Source/Tanks/TankDefinition.cs

@@ -35,6 +35,13 @@ public class TankDefinition : IConfigNode
         [Persistent]
         public float maxUtilization = 0;
 
+        /// <summary>
+        /// When picking a new part from catalog, the definition with highest preference number will be set as the default type.
+        /// Use -1 to prevent a definition from being chosen. If all definitions have -1 then no preference-based override will happen.
+        /// </summary>
+        [Persistent]
+        public int orderOfPreference = -1;
+
         public Dictionary<string, FuelTank> tankList = new Dictionary<string, FuelTank>();
 
         public List<string> tags = new List<string>();