Enhance Hierarchy Population to Support Nodes with Multiple Parents

This commit refines the `populateSelectedNodeHierarchy` method in the `SkillTreeViewModel` to accurately represent nodes that possess multiple parent nodes, ensuring a comprehensive and non-redundant representation of the entire hierarchy leading back to the root nodes.

Modifications and Features:
- The method now employs recursion to traverse all possible paths back to the root nodes from a selected node, capturing every unique node in the hierarchies.
- A `Set` is utilized to monitor and ensure that each node is only added once to the `_selectedNodeHierarchy` list, eliminating the possibility of duplicates.
- The finalized `_selectedNodeHierarchy` list is constructed such that the root of the tree is the last item in the list, providing a more logical representation of the hierarchy.

These enhancements ensure a more accurate and efficient representation of the skill tree structure, particularly in scenarios where nodes have multiple parents, facilitating better navigation and interaction within the skill tree.

frontend/lib/viewmodels/skill_tree_viewmodel.dart

@@ -97,36 +97,40 @@ class SkillTreeViewModel extends ChangeNotifier {
     notifyListeners();
   }
 
+  // TODO: Do we want to continue testing other branches of tree if one branch side fails benchmarking?
   void populateSelectedNodeHierarchy(String startNodeId) {
-    // Initialize an empty list to hold the nodes in the hierarchy.
-    _selectedNodeHierarchy = [];
+    // Initialize an empty list to hold the nodes in all hierarchies.
+    _selectedNodeHierarchy = <SkillTreeNode>[];
 
-    // Find the starting node (the selected node) in the skill tree nodes list.
-    SkillTreeNode? currentNode =
-        _skillTreeNodes.firstWhere((node) => node.id == startNodeId);
+    // Initialize a set to keep track of nodes that have been added.
+    final addedNodes = <String>{};
 
-    // Loop through the tree to populate the hierarchy list.
-    // The loop will continue as long as there's a valid current node.
-    while (currentNode != null) {
-      // Add the current node to the hierarchy list.
-      _selectedNodeHierarchy!.add(currentNode);
+    // Start the recursive population of the hierarchy from the startNodeId.
+    recursivePopulateHierarchy(startNodeId, addedNodes);
+
+    // Notify listeners about the change in the selectedNodeHierarchy state.
+    notifyListeners();
+  }
 
-      // Find the parent node by looking through the skill tree edges.
-      // We find the edge where the 'to' field matches the ID of the current node.
-      SkillTreeEdge? parentEdge = _skillTreeEdges
-          .firstWhereOrNull((edge) => edge.to == currentNode?.id);
-
-      // If a parent edge is found, find the corresponding parent node.
-      if (parentEdge != null) {
-        // The 'from' field of the edge gives us the ID of the parent node.
-        // We find that node in the skill tree nodes list.
-        currentNode = _skillTreeNodes
-            .firstWhereOrNull((node) => node.id == parentEdge.from);
-      } else {
-        // If no parent edge is found, it means we've reached the root node.
-        // We set currentNode to null to exit the loop.
-        currentNode = null;
+  void recursivePopulateHierarchy(String nodeId, Set<String> addedNodes) {
+    // Find the current node in the skill tree nodes list.
+    final currentNode =
+        _skillTreeNodes.firstWhereOrNull((node) => node.id == nodeId);
+
+    // If the node is found and it hasn't been added yet, proceed with the population.
+    if (currentNode != null && addedNodes.add(currentNode.id)) {
+      // Find all parent edges for the current node.
+      final parentEdges =
+          _skillTreeEdges.where((edge) => edge.to == currentNode.id);
+
+      // For each parent edge found, recurse to the parent node.
+      for (final parentEdge in parentEdges) {
+        // Recurse to the parent node identified by the 'from' field of the edge.
+        recursivePopulateHierarchy(parentEdge.from, addedNodes);
       }
+
+      // After processing all parent nodes, add the current node to the list.
+      _selectedNodeHierarchy!.add(currentNode);
     }
   }
 
@@ -156,16 +160,14 @@ class SkillTreeViewModel extends ChangeNotifier {
     // Notify listeners
     notifyListeners();
 
-    // Populate benchmarkStatusList with reversed node hierarchy
-    final reversedSelectedNodeHierarchy =
-        List.from(_selectedNodeHierarchy!.reversed);
-    for (var node in reversedSelectedNodeHierarchy) {
+    // Populate benchmarkStatusList with node hierarchy
+    for (var node in _selectedNodeHierarchy!) {
       benchmarkStatusMap[node] = BenchmarkTaskStatus.notStarted;
     }
 
     try {
       // Loop through the nodes in the hierarchy
-      for (var node in reversedSelectedNodeHierarchy) {
+      for (var node in _selectedNodeHierarchy!) {
         benchmarkStatusMap[node] = BenchmarkTaskStatus.inProgress;
         notifyListeners();
 

frontend/lib/views/task_queue/task_queue_view.dart

@@ -11,19 +11,18 @@ class TaskQueueView extends StatelessWidget {
   Widget build(BuildContext context) {
     final viewModel = Provider.of<SkillTreeViewModel>(context);
 
-    // Reverse the node hierarchy
-    final reversedHierarchy =
-        viewModel.selectedNodeHierarchy?.reversed.toList() ?? [];
+    // Node hierarchy
+    final nodeHierarchy = viewModel.selectedNodeHierarchy ?? [];
 
     return Material(
       color: Colors.white,
       child: Stack(
         children: [
           // The list of tasks (tiles)
           ListView.builder(
-            itemCount: reversedHierarchy.length,
+            itemCount: nodeHierarchy.length,
             itemBuilder: (context, index) {
-              final node = reversedHierarchy[index];
+              final node = nodeHierarchy[index];
 
               // Choose the appropriate leading widget based on the task status
               Widget leadingWidget;