using System.Linq;
using System.Reflection;

using UnityEngine;
using UnityEngine.UIElements;

using UnityEditor;


namespace UnityEditor.VFX.UI
{
    static class VisualElementExtensions
    {
        static MethodInfo m_ValidateLayoutMethod;
        public static void InternalValidateLayout(this IPanel panel)
        {
            if (m_ValidateLayoutMethod == null)
                m_ValidateLayoutMethod = panel.GetType().GetMethod("ValidateLayout", BindingFlags.Instance | BindingFlags.FlattenHierarchy | BindingFlags.NonPublic | BindingFlags.Public);

            m_ValidateLayoutMethod.Invoke(panel, new object[] { });
        }

        static PropertyInfo m_OwnerPropertyInfo;

        public static GUIView InternalGetGUIView(this IPanel panel)
        {
            if (m_OwnerPropertyInfo == null)
                m_OwnerPropertyInfo = panel.GetType().GetProperty("ownerObject", BindingFlags.Instance | BindingFlags.FlattenHierarchy | BindingFlags.NonPublic | BindingFlags.Public);


            return (GUIView)m_OwnerPropertyInfo.GetValue(panel, new object[] { });
        }

        public static bool HasFocus(this VisualElement visualElement)
        {
            if (visualElement.panel == null) return false;

            return visualElement.panel.focusController.focusedElement == visualElement;
        }

        public static void AddStyleSheetPath(this VisualElement visualElement, string path)
        {
            var sheet = VFXView.LoadStyleSheet(path);
            if (sheet != null)
                visualElement.styleSheets.Add(sheet);
        }

        public static void AddStyleSheetPathWithSkinVariant(this VisualElement visualElement, string path)
        {
            visualElement.AddStyleSheetPath(path);
            //if (true)
            {
                visualElement.AddStyleSheetPath(path + "Dark");
            }
            /*else
            {
                visualElement.AddStyleSheetPath(path + "Light");
            }*/
        }

        public static void ResetPositionProperties(this VisualElement visualElement)
        {
            var style = visualElement.style;
            style.position = StyleKeyword.Null;
            style.marginLeft = StyleKeyword.Null;
            style.marginRight = StyleKeyword.Null;
            style.marginBottom = StyleKeyword.Null;
            style.marginTop = StyleKeyword.Null;
            style.left = StyleKeyword.Null;
            style.top = StyleKeyword.Null;
            style.right = StyleKeyword.Null;
            style.bottom = StyleKeyword.Null;
            style.width = StyleKeyword.Null;
            style.height = StyleKeyword.Null;
        }

        public static Vector2 GlobalToBound(this VisualElement visualElement, Vector2 position)
        {
            return visualElement.worldTransform.inverse.MultiplyPoint3x4(position);
        }

        public static Vector2 BoundToGlobal(this VisualElement visualElement, Vector2 position)
        {
            position = visualElement.worldTransform.MultiplyPoint3x4(position);

            return position;
        }
    }
}