Visual Tree Node

using UnityEngine;
using System.Collections;
using System.Collections.Generic;
using UnityEngine.UI;
using UnityEngine.EventSystems;

/// <summary>
/// Node Behaviour representing a node. Assumes it's parent has a Layout Group.
/// </summary>
[RequireComponent(typeof(Image)),RequireComponent(typeof(VerticalLayoutGroup))]
public class NodeBehaviour : MonoBehaviour, IPointerDownHandler
{
    Node root_;

    /// <summary>
    /// Layout Group for child nodes. Will be a sibling of this NodeBehaviour's gameobject so
    /// the nodes can be offset from the left visually using padding
    /// </summary>
    VerticalLayoutGroup childrenLayout_ = null;

    public int indentSize_ = 10;
    public int indentLevel_ = 1;

    // Text object to represent the node. Created on awake
    GameObject textGO_;

    // Could be cached
    public Text text_ { get { return textGO_.GetComponent<Text>(); } }
    RectTransform rt_ { get { return GetComponent<RectTransform>(); } }
    VerticalLayoutGroup layout_ { get { return GetComponent<VerticalLayoutGroup>();  } }
    Image image_ { get { return GetComponent<Image>();  } }
    

    void Awake()
    { 
        // Create our text object and reparent it
        textGO_ = new GameObject("Node text", typeof(Text));
        text_.font = Resources.GetBuiltinResource<Font>("Arial.ttf");
        textGO_.transform.SetParent(transform, false);
        textGO_.transform.localPosition = Vector3.zero;
        // No expanding
        layout_.childForceExpandHeight = false;
        layout_.childForceExpandWidth = false;
    }


    // Populate our visuals and create the nodebehaviours for any children of this node
    public void BuildVisualTree()
    {
        textGO_.name = root_.name_ + " Text";
        text_.text = root_.name_;

        image_.sprite = null;
        image_.type = Image.Type.Sliced;

        Color color = Color.grey;
        color.a = .392f;
        image_.color = color;

        if (root_.children_.Count == 0)
            return;

        for (int i = 0; i < root_.children_.Count; ++i)
        {
            var behaviour = AddBehaviourNode(root_[i]);
            behaviour.BuildVisualTree();
        }


    }

    // Add a behaviour node as a child of this node, using the given node as the root for the new behaviour
    NodeBehaviour AddBehaviourNode( Node n )
    {
        if (childrenLayout_ == null)
            MakeChildrenLayout();

        var nodeGO = new GameObject(n.name_, typeof(NodeBehaviour));
        var nodeBehaviour = nodeGO.GetComponent<NodeBehaviour>();
       
        // Increment our indent level so children will be offset appropriately
        ++nodeBehaviour.indentLevel_;
        nodeBehaviour.root_ = n;

        // Reparent the new child node to the childrenLayout
        nodeGO.transform.SetParent(childrenLayout_.transform, false);



        return nodeBehaviour;
    }


    // Left click to collapse a node, right click to add a new child to the node
    public void OnPointerDown(PointerEventData eventData)
    {
        if( eventData.button == PointerEventData.InputButton.Left )
            if( childrenLayout_ != null )
                childrenLayout_.gameObject.SetActive(!childrenLayout_.gameObject.activeInHierarchy);

        if( eventData.button == PointerEventData.InputButton.Right )
        {
            var newNode = new Node(root_.name_ + "-> dynamic " + (root_.children_.Count - 1) );
            root_.children_.Add(newNode);

            var newBehaviour = AddBehaviourNode(newNode);
            newBehaviour.BuildVisualTree();
        }

    }

    void MakeChildrenLayout()
    {
        // Create the layout group for our children. Note that it's created as a sibling of this nodebehaviour.
        // That way we can use the padding of the childrenLayout and they will appear to be a sub-group of this
        childrenLayout_ = new GameObject(name + " childrenLayout", typeof(VerticalLayoutGroup)).GetComponent<VerticalLayoutGroup>();
        childrenLayout_.transform.SetParent(transform.parent, false);
        // Ensure the childrenLayout is directly below this Node Behaviour
        childrenLayout_.transform.SetSiblingIndex(transform.GetSiblingIndex() + 1);
        childrenLayout_.padding.left = indentLevel_ * indentSize_;
        childrenLayout_.childForceExpandHeight = false;
        childrenLayout_.childForceExpandWidth = false;
    }

    void PopulateNode(Node n, int count)
    {
        n.children_.Clear();
        for (int i = 0; i < count; ++i)
        {
            n.children_.Add(new Node(n.name_ + "->" + " child " + i));
        }

    }

    
    void PopulateRoot()
    {
        PopulateNode( root_, 3 );
        PopulateNode( root_[1], 2 );

        PopulateNode(root_[1], 3);

        PopulateNode(root_[1][1], 2);
    }

 

    [ContextMenu("RebuildVisualTree")]
    void RebuildTree()
    {
        if( childrenLayout_ != null )
            GameObject.DestroyImmediate(childrenLayout_);

        root_ = new Node("Root");

        PopulateRoot();

        BuildVisualTree();
    }
}

public class Node
{
    public Node(string name) { name_ = name; }
    public string name_;
    public List<Node> children_ = new List<Node>();
    public Node this[int i] { get { return children_[i]; } }
}