using System.Collections.Generic;
using SLSFramework.General;
using UI_Spline_Renderer;
using Unity.Mathematics;
using UnityEngine;
using UnityEngine.Splines;
using UnityEngine.UI;


namespace Continentis.MainGame.UI
{
    public class PointerArrow : MonoBehaviour
    {
        [Tooltip("箭头起点的Transform（例如：正在拖拽的卡牌）")]
        public RectTransform startPoint;

        [Tooltip("箭头线条")]
        public SplineContainer splineContainer;
        public UISplineRenderer arrowBody;

        [Tooltip("箭头头部的图片")]
        public Image endImage;
        
        [Header("曲线设置")]
        [Tooltip("曲线的弯曲程度，数值越大越弯曲")]
        public float curveOffset = 150f;

        [Tooltip("曲线的平滑度，点越多越平滑，性能开销也越大")]
        [Range(1, 100)]
        public int lineSegments = 50;

        public void SetArrow(Vector3 start, Vector3 end)
        {
            startPoint.position = start;

            Camera uiCamera = CombatUIManager.Instance.uiCamera;
            Camera worldCamera = CombatUIManager.Instance.combatCamera;
            RectTransform pageTransform = CombatUIManager.Instance.arrowsPage.rectTransform;
            
            Vector2 uiStart = SpaceConverter.WorldPointToUILocalPoint(pageTransform, start, uiCamera, worldCamera);
            Vector2 uiEnd = SpaceConverter.WorldPointToUILocalPoint(pageTransform, end, uiCamera, worldCamera);
            bool isEndOnLeftSide = uiEnd.x < uiStart.x;
            
            
            // 控制点在起点和终点的中点，并根据朝向进行偏移，使曲线更自然
            Vector2 midPoint = (uiStart + uiEnd) / 2f;
            Vector2 direction = (uiEnd - uiStart).normalized;
            Vector2 perpendicular = new Vector2(-direction.y, direction.x); // 计算垂直向量
            Vector2 controlPoint = midPoint + perpendicular * (isEndOnLeftSide ? -curveOffset : curveOffset);
            splineContainer.Spline.Clear();
            
            // 2. 计算贝塞尔曲线上所有的点
            List<BezierKnot> knots = new List<BezierKnot>();
            for (int i = 0; i < lineSegments; i++)
            {
                float t = (float)i / (lineSegments - 1);
                // 二次贝塞尔曲线公式: B(t) = (1-t)² * P₀ + 2(1-t)t * P₁ + t² * P₂
                float3 point = math.pow(1 - t, 2) * new float3(uiStart.x, uiStart.y, 0) +
                               2 * (1 - t) * t * new float3(controlPoint.x, controlPoint.y, 0) +
                               math.pow(t, 2) * new float3(uiEnd.x, uiEnd.y, 0);
                knots.Add(new BezierKnot(point));
            }
            splineContainer.Spline.Knots = knots;
            arrowBody.SetAllDirty(); // 通知UI系统重绘
        }

        public void SetColor(Color color)
        {
            endImage.color = color;
            arrowBody.color = color;
        }
    }
}