using DG.Tweening;
using UniRx;
using UniRx.Triggers;
using UnityEngine;
using UnityEngine.UI;

public class BtnScrollViewPanel : MonoBehaviour
{
    protected CompositeDisposable disposables = new CompositeDisposable();
    public ScrollRect scrollRect;
    public GameObject bg_mask;
    public Image img_mask;
    public Button btn_arrow_top;
    public Button btn_arrow_bottom;
    public float height = 164f;
    public int ShowCount = 7;
    public int TopPX = 50;
    public int BottomPX = 50;
    public float duration = 0.3f;
    int currentShowCount = 0;
    private void Start()
    {
        scrollRect.onValueChanged.AddListener(OnScrollValueChanged);
        btn_arrow_top.onClick.AddListener(() =>
        {
            scrollRect.DOVerticalNormalizedPos(1, duration);
        });
        btn_arrow_bottom.onClick.AddListener(() =>
        {
            scrollRect.DOVerticalNormalizedPos(0, duration);
        });
        //所有子物体 添加监听 激活状态改变时 检测ScrollRect是否可用
        foreach (Transform child in scrollRect.content)
        {
            child.OnEnableAsObservable()
                 .Subscribe(_ => CheckScrollRectEnabled()).AddTo(disposables);
            child.OnDisableAsObservable()
                 .Subscribe(_ => CheckScrollRectEnabled()).AddTo(disposables);
        }
        CheckScrollRectEnabled();
        ShowCount = Mathf.RoundToInt((scrollRect.viewport.rect.height + 16) / height);
    }
    private void OnScrollValueChanged(Vector2 value)
    {
        SetBtnArrow(currentShowCount > ShowCount);
    }
    async void CheckScrollRectEnabled()
    {
        currentShowCount = 0;
        foreach (Transform child in scrollRect.content)
        {
            if (child.gameObject.activeSelf)
            {
                currentShowCount++;
            }
        }
        await Awaiters.NextFrame;
        SetScrollRectEnabled(currentShowCount > ShowCount);
    }
    void SetScrollRectEnabled(bool enabled)
    {
        if (this == null)
        {
            return;
        }
        img_mask.enabled = enabled;
        scrollRect.enabled = enabled;
        bg_mask.SetActive(enabled);
        SetBtnArrow(enabled);
        Vector2 offsetMax = scrollRect.viewport.offsetMax;
        Vector2 offsetMin = scrollRect.viewport.offsetMin;
        if (enabled)
        {
            offsetMax = new Vector2(offsetMax.x, -TopPX);
            offsetMin = new Vector2(offsetMin.x, BottomPX);
        }
        else
        {
            offsetMax = new Vector2(offsetMax.x, 0);
            offsetMin = new Vector2(offsetMin.x, 0);
            scrollRect.content.anchoredPosition = Vector2.zero;
        }
        if ((int)scrollRect.viewport.offsetMax.y != (int)offsetMax.y)
        {
            scrollRect.viewport.offsetMax = offsetMax;
        }
        if ((int)scrollRect.viewport.offsetMin.y != (int)offsetMin.y)
        {
            scrollRect.viewport.offsetMin = offsetMin;
        }
    }
    void SetBtnArrow(bool enabled)
    {
        if (!enabled)
        {
            btn_arrow_top.gameObject.SetActive(false);
            btn_arrow_bottom.gameObject.SetActive(false);
            return;
        }

        if (scrollRect.content.anchoredPosition.y > 10)
        {
            btn_arrow_top.gameObject.SetActive(true);
        }
        else
        {
            btn_arrow_top.gameObject.SetActive(false);
        }

        if (scrollRect.content.anchoredPosition.y + scrollRect.viewport.rect.height < scrollRect.content.rect.height - 10)
        {
            btn_arrow_bottom.gameObject.SetActive(true);
        }
        else
        {
            btn_arrow_bottom.gameObject.SetActive(false);
        }
    }
    void OnDisable()
    {
        disposables?.Dispose();
        disposables = null;
    }
}