using System.Collections.Generic;
using UnityEngine;
using UnityEngine.Serialization;
using UnityEngine.UI;

#if UNITY_EDITOR
using UnityEditor;
#endif

namespace XericLibrary.Runtime.UIGraph
{
    /// <summary>
    /// UI上线条绘制组件
    /// 支持设置线条厚度、居中显示，并为线段之间添加斜角边缘
    /// 继承自 MaskableGraphic，可与 UI 遮罩系统配合使用
    /// </summary>
    [AddComponentMenu("Xeric Library/UI/UILineRenderer", 15)]
    public class UILineRenderer : XericRendererComponent
    {
        // todo 根据优弧劣弧绘制线段，这么说可能不太准确，但我需要在90度以内绘制漂亮的转角，大于90度则用中心圆代替
        #region 字段属性
        
        /// <summary>
        /// 线条的顶点数组，至少需要 2 个点才能绘制线条
        /// 点的坐标基于本地空间，中心点由 center 属性控制
        /// </summary>
        public List<Vector2> points = new List<Vector2>();
        private Vector2[] _points;
        
        /// <summary>
        /// 线路宽度
        /// </summary>
        public float thickness = 10f;
        /// <summary>
        /// 居中对齐
        /// </summary>
        public bool center = true;
        /// <summary>
        /// 循环线路
        /// </summary>
        public bool cycleLoop = false;
        /// <summary>
        /// 启用额外绘制的矢量箭头
        /// </summary>
        public bool enableVectorArrow = false;
        /// <summary>
        /// 矢量箭头尺寸（宽长）
        /// </summary>
        public Vector2 vectorArrowSize = Vector2.one;

        public bool absVectorProgress = true;
        public float vectorProgress = 15f;
        public float vectorArrowProgress = 0.5f;
        public bool reverseVector = false;
        
        /// <summary>
        /// 是/否启用倒角功能
        /// </summary>
        public bool useChamfer = false;
        
        /// <summary>
        /// 倒角细分数量，控制圆弧的平滑度
        /// </summary>
        public int chamferSegments = 4;
        
        /// <summary>
        /// 内圆弧半径，当大于0时启用内圆弧
        /// </summary>
        public float innerRadius = 0f;

        #endregion
        
        
        /// <summary>
        /// 添加顶点
        /// </summary>
        /// <param name="point"></param>
        /// <param name="mergingRadius">合并弧度，指定一个弧度，在添加顶点时，自动合并之前的顶点为直线</param>
        public void AddPoint(Vector2 point, float mergingRadius = -1)
        {
            if (mergingRadius > 0 && points.Count >= 2) 
            {
                var a = points[^1];
                var b = Vector3.Dot((a - points[^2]).normalized, (a - point).normalized);

                if (b < mergingRadius)
                    points[^1] = point;
                return;
            }
            points.Add(point);
            Refresh();
        }

        public void RemovePoint(int index)
        {
            points.RemoveAt(index);
            Refresh();
        }
        
        public void CleanPoint(Vector2 point)
        {
            points.Clear();
            Refresh();
        }

        /// <summary>
        /// 生成线条网格
        /// </summary>
        /// <param name="vh">用于构建网格的 VertexHelper 对象</param>
        protected override void OnPopulateMesh(VertexHelper vh)
        {
            // 清空现有的网格数据
            vh.Clear();

            var offset = XericRendererUtils.SwitchCenterOffset(center, rectTransform.sizeDelta);
            _points = points.ToArray();
            
            // 切换线路绘制模式
            if (useChamfer)
            {
                vh.PopulateLineByPointsArray_CFAL(_points, thickness, cycleLoop, color, offset, chamferSegments, innerRadius);
            }
            else
            
            {
                vh.PopulateLineByPointsArray_DSL5(_points, thickness, cycleLoop, color, offset, 
                    enableVectorArrow,
                    color, vectorArrowSize, vectorProgress, vectorArrowProgress, absVectorProgress, reverseVector);
            }
            
            
            return;
            // 至少需要 2 个点才能绘制线条
            if (_points.Length < 2)
                return;

            // 计算线路总长度
            float totalLength = _points.CalculateTotalLength();
            float currentLength = 0f;

            // 遍历所有点，创建线段并添加到网格中
            for (int i = 0; i < _points.Length-1; i++)
            {
                // 使用静态工具方法创建当前点与下一个点之间的线段
                // 传递当前累积长度和总长度用于UV坐标计算
                vh.CreateLineSegment_CFAL(_points[i], _points[i+1],
                    i > 0 ? Mathf.Acos(Vector2.Dot((_points[i] - _points[i -1]).normalized, (_points[i + 1] - _points[i]).normalized)) * Mathf.Rad2Deg : 0,
                    i < _points.Length-2 ? Mathf.Acos(Vector2.Dot((_points[i] - _points[i + 1]).normalized, (_points[i + 1] - _points[i +2]).normalized)) * Mathf.Rad2Deg : 0,
                    thickness, center, rectTransform.sizeDelta, color, currentLength, totalLength);

                // 更新累积长度
                currentLength += Vector2.Distance(_points[i], _points[i+1]);

                // 计算当前线段的顶点索引（每个线段包含 5 个顶点）
                int index = i * 5;

                // 添加线段的两个三角形（构成矩形线段）
                vh.AddTriangle(index, index+1, index+3);
                vh.AddTriangle(index+3, index+2, index);

                // 为线段之间添加斜角边缘
                // 使用上一个线段的终点和当前线段的起点创建过渡三角形
                if (i != 0)
                {
                    vh.AddTriangle(index, index-1, index-3);
                    vh.AddTriangle(index+1, index-1, index-2);
                }
            }
        }

#if UNITY_EDITOR
        
        [MenuItem("GameObject/Xeric Library/UI/UILineRenderer", false, 10)]
        private static void CreateGameObject()
        {
            GameObject newObject = new GameObject(nameof(UILineRenderer), typeof(UILineRenderer));
        
            if (Selection.activeGameObject != null)
                newObject.transform.SetParent(Selection.activeGameObject.transform);

            Undo.RegisterCreatedObjectUndo(newObject, $"Create {nameof(UILineRenderer)}");
            Selection.activeObject = newObject;
        }
#endif
    }
}