Stopped double adding edges

SeeGitApp/Models/CommitEdge.cs

@@ -6,9 +6,56 @@ namespace SeeGit
     [DebuggerDisplay("{Source.Sha}..{Target.Sha}")]
     public class CommitEdge : Edge<CommitVertex>
     {
+        private string _id;
+
         public CommitEdge(CommitVertex child, CommitVertex parent)
             : base(child, parent)
         {
         }
+
+        public string Id
+        {
+            get
+            {
+                if (_id == null)
+                {
+                    if (Source != null)
+                    {
+                        _id = Source.Sha;
+                    }
+                    _id += "..";
+                    if (Target != null)
+                    {
+                        _id += Target.Sha;
+                    }
+                }
+                return _id;
+            }
+        }
+
+        public override bool Equals(object obj)
+        {
+            if (ReferenceEquals(null, obj)) return false;
+            if (ReferenceEquals(this, obj)) return true;
+            if (obj.GetType() != typeof (CommitEdge)) return false;
+            return Equals((CommitEdge)obj);
+        }
+
+        public bool Equals(CommitEdge other)
+        {
+            if (ReferenceEquals(null, other)) return false;
+            if (ReferenceEquals(this, other)) return true;
+            return Equals(other.Source, other.Target);
+        }
+
+        public override int GetHashCode()
+        {
+            unchecked
+            {
+                int result = (Target != null ? Target.GetHashCode() : 0);
+                result = (result*397) ^ (Source != null ? Source.GetHashCode() : 0);
+                return result;
+            }
+        }
     }
 }

SeeGitApp/Models/RepositoryGraph.cs

@@ -4,5 +4,6 @@ namespace SeeGit
 {
     public class RepositoryGraph : BidirectionalGraph<CommitVertex, CommitEdge>
     {
+        public string LayoutAlgorithmType { get; set; }
     }
 }

SeeGitApp/Models/RepositoryGraphBuilder.cs

@@ -9,6 +9,7 @@ public class RepositoryGraphBuilder : IRepositoryGraphBuilder
         private readonly RepositoryGraph _graph = new RepositoryGraph();
         private readonly Repository _repository;
         private readonly Dictionary<string, CommitVertex> _vertices = new Dictionary<string, CommitVertex>();
+        private readonly Dictionary<string, CommitEdge> _edges = new Dictionary<string, CommitEdge>();
 
         public RepositoryGraphBuilder(string gitRepositoryPath)
         {
@@ -36,6 +37,15 @@ public RepositoryGraph Graph()
                 _graph.Clear();
                 return _graph;
             }
+
+            foreach (var vertice in _vertices.Values)
+            {
+                if (vertice.Branches.Any())
+                {
+                    vertice.Branches.Clear();
+                }
+            }
+
             AddCommitsToGraph(commits.First(), null);
 
             foreach (var branch in _repository.Branches.Where(branch => branch.Commits.Any()))
@@ -45,6 +55,10 @@ public RepositoryGraph Graph()
                 commit.Branches.Add(branch.Name);
                 AddCommitsToGraph(firstCommit, null);
             }
+            if (_vertices.Count > 1)
+            {
+                _graph.LayoutAlgorithmType = "EfficientSugiyama";
+            }
 
             return _graph;
         }
@@ -55,7 +69,12 @@ private void AddCommitsToGraph(Commit commit, CommitVertex childVertex)
             _graph.AddVertex(commitVertex);
             if (childVertex != null)
             {
-                _graph.AddEdge(new CommitEdge(childVertex, commitVertex));
+                var edge = new CommitEdge(childVertex, commitVertex);
+                if (!_edges.ContainsKey(edge.Id))
+                {
+                    _graph.AddEdge(edge);
+                    _edges.Add(edge.Id, edge);
+                }
             }
 
             foreach (var parent in commit.Parents)
@@ -66,7 +85,7 @@ private void AddCommitsToGraph(Commit commit, CommitVertex childVertex)
 
         private CommitVertex GetCommitVertex(Commit commit)
         {
-            CommitVertex commitVertex = null;
+            CommitVertex commitVertex;
             if (!_vertices.TryGetValue(commit.Sha, out commitVertex))
             {
                 commitVertex = new CommitVertex(commit.Sha, commit.MessageShort) {Description = commit.Message};

SeeGitApp/ViewModels/MainWindowViewModel.cs

@@ -7,29 +7,39 @@ public class MainWindowViewModel : INotifyPropertyChanged
     {
         private RepositoryGraph _graph;
         private readonly IRepositoryGraphBuilder _graphBuilder;
+        private string layoutAlgorithmType = "Tree";
 
         public MainWindowViewModel(IRepositoryGraphBuilder graphBuilder, string repositoryPath)
         {
             _graphBuilder = graphBuilder;
             RepositoryPath = repositoryPath;
             Graph = _graphBuilder.Graph();
             LayoutAlgorithmType = "Tree";
-                // Tree, LinLog, KK, ISOM, EfficientSugiyama, FR, CompoundFDP, BoundedFR, Circular
+            // Tree, LinLog, KK, ISOM, EfficientSugiyama, FR, CompoundFDP, BoundedFR, Circular
         }
 
-        public string LayoutAlgorithmType { get; private set; }
+        public string LayoutAlgorithmType
+        {
+            get { return layoutAlgorithmType; }
+            set
+            {
+                layoutAlgorithmType = value;
+                NotifyPropertyChanged("LayoutAlgorithmType");
+            }
+        }
 
         public RepositoryGraph Graph
         {
             get { return _graph; }
             set
             {
                 _graph = value;
+                LayoutAlgorithmType = _graph.LayoutAlgorithmType;
                 NotifyPropertyChanged("Graph");
             }
         }
 
-        public string RepositoryPath { get; private set;}
+        public string RepositoryPath { get; private set; }
 
         public void Refresh()
         {