using UnityEngine;
using UnityEngine.UI;
using UnityEngine.Events;
namespace Kill.UI.Components
{
    [RequireComponent(typeof(ScrollRect))]
    public class VerticalScrollLoader : MonoBehaviour
    {
        [Header("触发设置")]
        [Range(0, 1)]
        [Tooltip("滚动到多少比例时触发加载 (0-1)")]
        public float triggerThreshold = 0.8f;

        [Header("事件")]
        public UnityEvent onLoadTriggered; // 触发加载事件 

        private ScrollRect scrollRect;
        private bool isLoading;
        private bool allDataLoaded; // 标记是否所有数据已加载完成 

        private void Awake()
        {
            scrollRect = GetComponent<ScrollRect>();
            scrollRect.onValueChanged.AddListener(OnScrollValueChanged);
            allDataLoaded = false;
        }

        private void OnScrollValueChanged(Vector2 normalizedPosition)
        {
            // 如果正在加载或所有数据已加载完成，则不再触发 
            if (isLoading || allDataLoaded) return;

            // 计算当前滚动位置比例（垂直滚动）
            float scrollPosition = 1 - normalizedPosition.y;

            // 如果滚动到阈值以下，触发加载 
            if (scrollPosition >= triggerThreshold)
            {
                isLoading = true;
                onLoadTriggered.Invoke();
            }
        }

        /// <summary>
        /// 加载完成后调用此方法 
        /// </summary>
        public void OnLoadComplete()
        {
            isLoading = false;
        }

        /// <summary>
        /// 当所有数据加载完成时调用此方法，停止触发加载 
        /// </summary>
        public void SetAllDataLoaded()
        {
            allDataLoaded = true;
        }

        /// <summary>
        /// 重置加载状态（当有新数据可加载时调用）
        /// </summary>
        public void ResetLoader()
        {
            allDataLoaded = false;
            isLoading = false;
        }
    }
}