Merge pull request SciSharp#1339 from iceljc/features/fix-frontier-order

fix frontier order

Author: iceljc

src/Infrastructure/BotSharp.Abstraction/Rules/Frontier.cs

@@ -31,11 +31,18 @@ public sealed class StackFrontier<T> : IFrontier<T>
 
     public void DrainTo(IFrontier<T> other)
     {
-        // Reverse so the item that was on top is added first and
-        // therefore ends up at the same "priority" position in the target.
-        var items = _stack.ToList();
-        items.Reverse();
-        _stack.Clear();
+        // Pop gives items in priority order (highest-weight first).
+        var items = new List<T>();
+        while (_stack.Count > 0)
+        {
+            items.Add(_stack.Pop());
+        }
+
+        if (other is StackFrontier<T>)
+        {
+            items.Reverse();
+        }
+
         foreach (var item in items)
         {
             other.Add(item);
@@ -58,9 +65,21 @@ public sealed class QueueFrontier<T> : IFrontier<T>
 
     public void DrainTo(IFrontier<T> other)
     {
+        // Dequeue gives items in priority order (highest-weight first).
+        var items = new List<T>();
         while (_queue.Count > 0)
         {
-            other.Add(_queue.Dequeue());
+            items.Add(_queue.Dequeue());
+        }
+
+        if (other is StackFrontier<T>)
+        {
+            items.Reverse();
+        }
+
+        foreach (var item in items)
+        {
+            other.Add(item);
         }
     }
 }

src/Infrastructure/BotSharp.Abstraction/Rules/RuleGraph.cs

@@ -121,20 +121,24 @@ public void AddEdge(RuleNode from, RuleNode to, EdgeItemPayload payload)
         }
     }
 
-    public IEnumerable<(RuleNode, RuleEdge)> GetParentNodes(RuleNode node)
+    public IEnumerable<(RuleNode, RuleEdge)> GetParentNodes(RuleNode node, bool ascending = false)
     {
-        return _edges.Where(e => e.To != null && e.To.Id.IsEqualTo(node.Id))
-                     .OrderByDescending(e => e.Weight)
-                     .Select(e => (e.From, e))
-                     .ToList();
+        var filtered = _edges.Where(e => e.To != null && e.To.Id.IsEqualTo(node.Id));
+        var ordered = ascending
+            ? filtered.OrderBy(e => e.Weight)
+            : filtered.OrderByDescending(e => e.Weight);
+
+        return ordered.Select(e => (e.From, e)).ToList();
     }
 
-    public IEnumerable<(RuleNode, RuleEdge)> GetChildrenNodes(RuleNode node)
+    public IEnumerable<(RuleNode, RuleEdge)> GetChildrenNodes(RuleNode node, bool ascending = false)
     {
-        return _edges.Where(e => e.From != null && e.From.Id.IsEqualTo(node.Id))
-                     .OrderByDescending(e => e.Weight)
-                     .Select(e => (e.To, e))
-                     .ToList();
+        var filtered = _edges.Where(e => e.From != null && e.From.Id.IsEqualTo(node.Id));
+        var ordered = ascending
+            ? filtered.OrderBy(e => e.Weight)
+            : filtered.OrderByDescending(e => e.Weight);
+
+        return ordered.Select(e => (e.To, e)).ToList();
     }
 
     public RuleGraphInfo GetGraphInfo()

src/Infrastructure/BotSharp.Core.Rules/Engines/RuleEngine.cs

@@ -211,11 +211,7 @@ private async Task ExecuteGraphTraversal(
             ? new QueueFrontier<(RuleNode, RuleEdge)>()
             : new StackFrontier<(RuleNode, RuleEdge)>();
 
-        // Seed the frontier with root's children
-        foreach (var child in graph.GetChildrenNodes(root))
-        {
-            frontier.Add(child);
-        }
+        EnqueueChildren(frontier, graph, root);
 
         while (frontier.Count > 0)
         {
@@ -345,7 +341,8 @@ private static void EnqueueChildren(
         RuleGraph graph,
         RuleNode parent)
     {
-        foreach (var child in graph.GetChildrenNodes(parent))
+        var sortAscending = frontier is StackFrontier<(RuleNode, RuleEdge)>;
+        foreach (var child in graph.GetChildrenNodes(parent, sortAscending))
         {
             frontier.Add(child);
         }