Introduce ObjectDatabase.CalculateHistoryDivergence()

Fix #562

1 files changed, 11 insertions, 35 deletions

diff --git a/LibGit2Sharp/BranchTrackingDetails.cs b/LibGit2Sharp/BranchTrackingDetails.cs
index 0acce526..ad7153c8 100644
--- a/LibGit2Sharp/BranchTrackingDetails.cs
+++ b/LibGit2Sharp/BranchTrackingDetails.cs
@@ -1,5 +1,4 @@
-using LibGit2Sharp.Core;
-using LibGit2Sharp.Core.Compat;
+using System;
 
 namespace LibGit2Sharp
 {
@@ -8,10 +7,7 @@ namespace LibGit2Sharp
     /// </summary>
     public class BranchTrackingDetails
     {
-        private readonly Repository repo;
-        private readonly Branch branch;
-        private readonly Lazy<Tuple<int?, int?>> aheadBehind;
-        private readonly Lazy<Commit> commonAncestor;
+        private readonly HistoryDivergence historyDivergence;
 
         /// <summary>
         /// Needed for mocking purposes.
@@ -21,11 +17,13 @@ namespace LibGit2Sharp
 
         internal BranchTrackingDetails(Repository repo, Branch branch)
         {
-            this.repo = repo;
-            this.branch = branch;
+            if (!branch.IsTracking || branch.Tip == null || branch.TrackedBranch.Tip == null)
+            {
+                historyDivergence = new NullHistoryDivergence();
+                return;
+            }
 
-            aheadBehind = new Lazy<Tuple<int?, int?>>(ResolveAheadBehind);
-            commonAncestor = new Lazy<Commit>(ResolveCommonAncestor);
+            historyDivergence = repo.ObjectDatabase.CalculateHistoryDivergence(branch.Tip, branch.TrackedBranch.Tip);
         }
 
         /// <summary>
@@ -37,7 +35,7 @@ namespace LibGit2Sharp
         /// </summary>
         public virtual int? AheadBy
         {
-            get { return aheadBehind.Value.Item1; }
+            get { return historyDivergence.AheadBy; }
         }
 
         /// <summary>
@@ -49,7 +47,7 @@ namespace LibGit2Sharp
         /// </summary>
         public virtual int? BehindBy
         {
-            get { return aheadBehind.Value.Item2; }
+            get { return historyDivergence.BehindBy; }
         }
 
         /// <summary>
@@ -61,29 +59,7 @@ namespace LibGit2Sharp
         /// </summary>
         public virtual Commit CommonAncestor
         {
-            get { return commonAncestor.Value; }
-        }
-
-        private Tuple<int?, int?> ResolveAheadBehind()
-        {
-            return branch.IsTracking
-                       ? Proxy.git_graph_ahead_behind(repo.Handle, branch.TrackedBranch.Tip, branch.Tip)
-                       : new Tuple<int?, int?>(null, null);
-        }
-
-        private Commit ResolveCommonAncestor()
-        {
-            if (!branch.IsTracking)
-            {
-                return null;
-            }
-
-            if (branch.Tip == null || branch.TrackedBranch.Tip == null)
-            {
-                return null;
-            }
-
-            return repo.Commits.FindCommonAncestor(branch.Tip, branch.TrackedBranch.Tip);
+            get { return historyDivergence.CommonAncestor; }
         }
     }
 }