using System;
using System.Data;

namespace BuildingTrees
{
  public class SlowTree
  {
    public SlowTree()
    {
    }

    public TreeNode LoadTree(DataView dataTree)
    {
      // Prepare the resulting rootnode
      TreeNode rootNode = null;

      // Loop through the dataview
      foreach (DataRowView dataNode in dataTree)
      {
        // Store the current record in typed variables
        int nodeID = (int)dataNode["NodeID"];
        int parentNodeID = (int)dataNode["ParentNodeID"];
        string text = dataNode["NodeText"].ToString();

        // Check if the current node is the rootnode
        if (nodeID == parentNodeID)
        {
          // Yes, so create the node, and start searching for it's child nodes
          rootNode = new TreeNode(nodeID, null);
          rootNode.Text = text;
          LoadChildNodes(rootNode, dataTree);
        }
      }

      // Return the result
      return rootNode;
    }

    private void LoadChildNodes(TreeNode parentNode, DataView dataTree)
    {
      // Loop throught the dataview
      foreach (DataRowView dataNode in dataTree)
      {
        // Store the current record in typed variables
        int nodeID = (int)dataNode["NodeID"];
        int parentNodeID = (int)dataNode["ParentNodeID"];
        string text = dataNode["NodeText"].ToString();

        // Check if the current node is not the root node, and if the current node is a child node of the supplied parent node
        if (nodeID != parentNodeID && parentNodeID == parentNode.ID)
        {
          // Yes, create the node and start searching for it's child nodes.
          TreeNode node = new TreeNode(nodeID, parentNode);
          node.Text = text;
          LoadChildNodes (node, dataTree);
        }
      }
    }
  }
}