using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using UnityEngine;
using UnityEngine.Events;
using UnityEngine.UI;
using UnityExplorer;
using UnityExplorer.Core;
using UnityExplorer.UI;
using UnityExplorer.UI.Models;

namespace UnityExplorer.UI.Utility
{
    // Basically just to fix an issue with Scrollbars, instead we use a Slider as the scrollbar.
    public class SliderScrollbar : UIBehaviourModel
    {
        public bool IsActive { get; private set; }

        public override GameObject UIRoot
        {
            get
            {
                if (m_slider)
                    return m_slider.gameObject;
                return null;
            }
        }

        public event Action<float> OnValueChanged;

        internal readonly Scrollbar m_scrollbar;
        internal readonly Slider m_slider;
        internal readonly RectTransform m_scrollRect;

        internal InputFieldScroller m_parentInputScroller;

        public SliderScrollbar(Scrollbar scrollbar, Slider slider)
        {
            //Instances.Add(this);

            this.m_scrollbar = scrollbar;
            this.m_slider = slider;
            this.m_scrollRect = scrollbar.transform.parent.GetComponent<RectTransform>();

            this.m_scrollbar.onValueChanged.AddListener(this.OnScrollbarValueChanged);
            this.m_slider.onValueChanged.AddListener(this.OnSliderValueChanged);

            this.RefreshVisibility();
            this.m_slider.Set(1f, false);
        }

        //internal bool CheckDestroyed()
        //{
        //    if (!m_slider || !m_scrollbar)
        //    {
        //        Instances.Remove(this);
        //        return true;
        //    }

        //    return false;
        //}

        public override void Update()
        {
            this.RefreshVisibility();
        }

        internal void RefreshVisibility()
        {
            if (!m_slider.gameObject.activeInHierarchy)
            {
                IsActive = false;
                return;
            }

            bool shouldShow = !Mathf.Approximately(this.m_scrollbar.size, 1);
            var obj = this.m_slider.handleRect.gameObject;

            if (IsActive != shouldShow)
            {
                IsActive = shouldShow;
                obj.SetActive(IsActive);

                if (IsActive)
                    this.m_slider.Set(this.m_scrollbar.value, false);
                else
                    m_slider.Set(1f, false);
            }
        }

        public void OnScrollbarValueChanged(float _value)
        {
            if (this.m_slider.value != _value)
                this.m_slider.Set(_value, false);
            OnValueChanged?.Invoke(_value);
        }

        public void OnSliderValueChanged(float _value)
        {
            this.m_scrollbar.value = _value;
            OnValueChanged?.Invoke(_value);
        }

        #region UI CONSTRUCTION

        public static GameObject CreateSliderScrollbar(GameObject parent, out Slider slider)
        {
            GameObject sliderObj = UIFactory.CreateUIObject("SliderScrollbar", parent, UIFactory._smallElementSize);

            GameObject bgObj = UIFactory.CreateUIObject("Background", sliderObj);
            //GameObject fillAreaObj = UIFactory.CreateUIObject("Fill Area", sliderObj);
            //GameObject fillObj = UIFactory.CreateUIObject("Fill", fillAreaObj);
            GameObject handleSlideAreaObj = UIFactory.CreateUIObject("Handle Slide Area", sliderObj);
            GameObject handleObj = UIFactory.CreateUIObject("Handle", handleSlideAreaObj);

            Image bgImage = bgObj.AddComponent<Image>();
            bgImage.type = Image.Type.Sliced;
            bgImage.color = new Color(0.05f, 0.05f, 0.05f, 1.0f);

            RectTransform bgRect = bgObj.GetComponent<RectTransform>();
            bgRect.anchorMin = Vector2.zero;
            bgRect.anchorMax = Vector2.one;
            bgRect.sizeDelta = Vector2.zero;
            bgRect.offsetMax = new Vector2(0f, 0f);

            RectTransform handleSlideRect = handleSlideAreaObj.GetComponent<RectTransform>();
            handleSlideRect.anchorMin = new Vector2(0f, 0f);
            handleSlideRect.anchorMax = new Vector2(1f, 1f);
            handleSlideRect.pivot = new Vector2(0.5f, 0.5f);
            handleSlideRect.offsetMin = new Vector2(27f, 30f);
            handleSlideRect.offsetMax = new Vector2(-15f, 0f);
            handleSlideRect.sizeDelta = new Vector2(-20f, -30f);

            Image handleImage = handleObj.AddComponent<Image>();
            handleImage.color = new Color(0.5f, 0.5f, 0.5f, 1.0f);

            var handleRect = handleObj.GetComponent<RectTransform>();
            handleRect.sizeDelta = new Vector2(15f, 30f);
            handleRect.offsetMin = new Vector2(-13f, -28f);
            handleRect.offsetMax = new Vector2(2f, -2f);

            var sliderBarLayout = sliderObj.AddComponent<LayoutElement>();
            sliderBarLayout.minWidth = 25;
            sliderBarLayout.flexibleWidth = 0;
            sliderBarLayout.minHeight = 30;
            sliderBarLayout.flexibleHeight = 5000;

            slider = sliderObj.AddComponent<Slider>();
            //slider.fillRect = fillObj.GetComponent<RectTransform>();
            slider.handleRect = handleObj.GetComponent<RectTransform>();
            slider.targetGraphic = handleImage;
            slider.direction = Slider.Direction.BottomToTop;

            RuntimeProvider.Instance.SetColorBlock(slider, 
                new Color(0.25f, 0.25f, 0.25f), 
                new Color(0.3f, 0.3f, 0.3f), 
                new Color(0.2f, 0.2f, 0.2f));

            return sliderObj;
        }

        public override void ConstructUI(GameObject parent)
        {
            throw new NotImplementedException();
        }

        #endregion
    }
}