using UnityEngine.EventSystems;

namespace UnityEngine.UI
{
    [AddComponentMenu("Layout/Layout Element", 140)]
    [RequireComponent(typeof(RectTransform))]
    [ExecuteInEditMode]
    public class LayoutElement : UIBehaviour, ILayoutElement, ILayoutIgnorer
    {
        [SerializeField] private bool m_IgnoreLayout = false;
        [SerializeField] private float m_MinWidth = -1;
        [SerializeField] private float m_MinHeight = -1;
        [SerializeField] private float m_PreferredWidth = -1;
        [SerializeField] private float m_PreferredHeight = -1;
        [SerializeField] private float m_FlexibleWidth = -1;
        [SerializeField] private float m_FlexibleHeight = -1;
        [SerializeField] private int m_LayoutPriority = 1;


        public virtual bool ignoreLayout { get { return m_IgnoreLayout; } set { if (SetPropertyUtility.SetStruct(ref m_IgnoreLayout, value)) SetDirty(); } }

        public virtual void CalculateLayoutInputHorizontal() {}
        public virtual void CalculateLayoutInputVertical() {}
        public virtual float minWidth { get { return m_MinWidth; } set { if (SetPropertyUtility.SetStruct(ref m_MinWidth, value)) SetDirty(); } }
        public virtual float minHeight { get { return m_MinHeight; } set { if (SetPropertyUtility.SetStruct(ref m_MinHeight, value)) SetDirty(); } }
        public virtual float preferredWidth { get { return m_PreferredWidth; } set { if (SetPropertyUtility.SetStruct(ref m_PreferredWidth, value)) SetDirty(); } }
        public virtual float preferredHeight { get { return m_PreferredHeight; } set { if (SetPropertyUtility.SetStruct(ref m_PreferredHeight, value)) SetDirty(); } }
        public virtual float flexibleWidth { get { return m_FlexibleWidth; } set { if (SetPropertyUtility.SetStruct(ref m_FlexibleWidth, value)) SetDirty(); } }
        public virtual float flexibleHeight { get { return m_FlexibleHeight; } set { if (SetPropertyUtility.SetStruct(ref m_FlexibleHeight, value)) SetDirty(); } }
        public virtual int layoutPriority { get { return m_LayoutPriority; } set { if (SetPropertyUtility.SetStruct(ref m_LayoutPriority, value)) SetDirty(); } }


        protected LayoutElement()
        {}

        protected override void OnEnable()
        {
            base.OnEnable();
            SetDirty();
        }

        protected override void OnTransformParentChanged()
        {
            SetDirty();
        }

        protected override void OnDisable()
        {
            SetDirty();
            base.OnDisable();
        }

        protected override void OnDidApplyAnimationProperties()
        {
            SetDirty();
        }

        protected override void OnBeforeTransformParentChanged()
        {
            SetDirty();
        }

        protected void SetDirty()
        {
            if (!IsActive())
                return;
            LayoutRebuilder.MarkLayoutForRebuild(transform as RectTransform);
        }

    #if UNITY_EDITOR
        protected override void OnValidate()
        {
            SetDirty();
        }

    #endif
    }
}