using System;
using UnityEngine;
using UnityEngine.Events;
using UnityEngine.EventSystems;
using UnityEngine.UI;

[AddComponentMenu("UI/LongClickButton")]
public class LongClickButton : Button
{
    [Serializable]
    public class LongClickEvent : UnityEvent { }

    [SerializeField]
    private LongClickEvent m_onLongClick = null;
    public LongClickEvent onLongClick
    {
        get { return m_onLongClick; }
        set { m_onLongClick = value; }
    }

    private DateTime m_firstTime = default(DateTime);
    private DateTime m_secondTime = default(DateTime);

    private void Press()
    {
        if (null != onLongClick)
            onLongClick.Invoke();
        resetTime();
    }

    public override void OnPointerDown(PointerEventData eventData)
    {
        base.OnPointerDown(eventData);
        if (m_firstTime.Equals(default(DateTime)))
            m_firstTime = DateTime.Now;
    }

    public override void OnPointerUp(PointerEventData eventData)
    {
        base.OnPointerUp(eventData);
        if (!m_firstTime.Equals(default(DateTime)))
            m_secondTime = DateTime.Now;
        if (!m_firstTime.Equals(default(DateTime)) && !m_secondTime.Equals(default(DateTime)))
        {
            var intervalTime = m_secondTime - m_firstTime;
            int milliSeconds = intervalTime.Seconds * 1000 + intervalTime.Milliseconds;
            if (milliSeconds > 600) Press();
            else resetTime();
        }
    }

    public override void OnPointerExit(PointerEventData eventData)
    {
        base.OnPointerExit(eventData);
        resetTime();
    }

    private void resetTime()
    {
        m_firstTime = default(DateTime);
        m_secondTime = default(DateTime);
    }
}