using UnityEditor.Experimental.GraphView;
using UnityEngine.UIElements;
using UnityEditor;
using UnityEngine;
using System;

namespace GraphProcessor
{
	public abstract class PinnedElementView : GraphElement
	{
		protected PinnedElement	pinnedElement;
		protected VisualElement	root;
		protected VisualElement	content;
		protected VisualElement	header;

		protected event Action	onResized;

		VisualElement			main;
		Label					titleLabel;
		bool					_scrollable;
		ScrollView				scrollView;

        static readonly string	pinnedElementStyle = "GraphProcessorStyles/PinnedElementView";
        static readonly string	pinnedElementTree = "GraphProcessorElements/PinnedElement";

        public override string title
        {
            get { return titleLabel.text; }
            set { titleLabel.text = value; }
        }

        protected bool scrollable
        {
            get
            {
                return _scrollable;
            }
            set
            {
                if (_scrollable == value)
                    return;

                _scrollable = value;

                style.position = Position.Absolute;
                if (_scrollable)
                {
                    content.RemoveFromHierarchy();
                    root.Add(scrollView);
                    scrollView.Add(content);
                    AddToClassList("scrollable");
                }
                else
                {
					scrollView.RemoveFromHierarchy();
					content.RemoveFromHierarchy();
					root.Add(content);
                    RemoveFromClassList("scrollable");
                }
            }
        }

		public PinnedElementView()
		{
            var tpl = Resources.Load<VisualTreeAsset>(pinnedElementTree);
            styleSheets.Add(Resources.Load<StyleSheet>(pinnedElementStyle));

            main = tpl.CloneTree();
            main.AddToClassList("mainContainer");
			scrollView = new ScrollView(ScrollViewMode.VerticalAndHorizontal);

            root = main.Q("content");

            header = main.Q("header");

            titleLabel = main.Q<Label>(name: "titleLabel");
            content = main.Q<VisualElement>(name: "contentContainer");

            hierarchy.Add(main);

            capabilities |= Capabilities.Movable | Capabilities.Resizable;
            style.overflow = Overflow.Hidden;

            ClearClassList();
            AddToClassList("pinnedElement");

            this.AddManipulator(new Dragger { clampToParentEdges = true });

            scrollable = false;

            hierarchy.Add(new Resizer(() => onResized?.Invoke()));

            RegisterCallback<DragUpdatedEvent>(e =>
            {
                e.StopPropagation();
            });

			title = "PinnedElementView";
		}

		public void InitializeGraphView(PinnedElement pinnedElement, BaseGraphView graphView)
		{
			this.pinnedElement = pinnedElement;
			SetPosition(pinnedElement.position);

			onResized += () => {
				pinnedElement.position.size = layout.size;
			};

			RegisterCallback<MouseUpEvent>(e => {
				pinnedElement.position.position = layout.position;
			});

			Initialize(graphView);
		}

		public void ResetPosition()
		{
			pinnedElement.position = new Rect(Vector2.zero, PinnedElement.defaultSize);
			SetPosition(pinnedElement.position);
		}

		protected abstract void Initialize(BaseGraphView graphView);

		~PinnedElementView()
		{
			Destroy();
		}

		protected virtual void Destroy() {}
	}
}