using System.Collections.Generic;
using System.Linq;
using UnityEngine;

namespace AibisDream
{
    public class CutLine : MonoBehaviour
    {
        private LineRenderer _lineRenderer;

        private Vector2[] _linePoints;
        private float[] _normalizedLinePoints;
        private Bounds _bounds;
        private List<Vector2> _recordedRanges = new();

        #region 初始化

        public void Init(List<Vector2> shapePoints, float clickRadius)
        {
            _lineRenderer = GetComponent<LineRenderer>();
            
            // 按照新点位重绘线条
            RedrawLine(shapePoints);
            // 生成归一化点
            NormalizePoints(shapePoints);
            // 生成基本的包围盒
            GeneBoundingBox(clickRadius);
            
            ClearRecordedRanges();
        }

        private void RedrawLine(List<Vector2> shapePoints)
        {
            var linePoints = shapePoints.Select(item => new Vector3(item.x, item.y, 0)).ToArray();
            _lineRenderer.SetPositions(linePoints);
        }

        private void NormalizePoints(List<Vector2> shapePoints)
        {
            // 先生成首尾相连的点，默认Loop
            shapePoints.Add(shapePoints[0]);
            _linePoints = shapePoints.ToArray();
            
            float totalLength = 0f;
            var segmentLengths = new List<float>();

            // 计算总长度和各段长度
            for (var i = 1; i < _linePoints.Length; i++)
            {
                var segmentLength = Vector2.Distance(_linePoints[i - 1], _linePoints[i]);
                segmentLengths.Add(segmentLength);
                totalLength += segmentLength;
            }

            // 计算每个点的归一化位置
            var normalizedLinePoints = new float[segmentLengths.Count + 1];
            normalizedLinePoints[0] = 0f;
            var accumulatedLength = 0f;
            
            for (var i = 0; i < segmentLengths.Count; i++)
            {
                accumulatedLength += segmentLengths[i];
                normalizedLinePoints[i + 1] = accumulatedLength / totalLength;
            }
        }
        
        private void GeneBoundingBox(float clickRadius)
        {
            _bounds = new Bounds();
            foreach (var point in _linePoints)
            {
                _bounds.Encapsulate(point);
            }
            
            _bounds.Expand(clickRadius * 2);
        }

        #endregion

        #region 切割检测
        
        public void DetectLineClick(Vector2 clickPosition, float clickRadius)
        {
            // 先进行包围盒检测，不在包围盒直接返回
            if (!_bounds.Contains(clickPosition))
            {
                return;
            }
            
            List<Vector2> newRanges = new List<Vector2>();

            // 检查每条线段
            for (int i = 1; i < _linePoints.Length; i++)
            {
                Vector2 start = _linePoints[i - 1];
                Vector2 end = _linePoints[i];

                // 计算点到线段的距离
                float distance = DistanceToSegment(clickPosition, start, end);

                if (distance <= clickRadius)
                {
                    // 计算点击影响的范围
                    float normalizedStart = _normalizedLinePoints[i - 1];
                    float normalizedEnd = _normalizedLinePoints[i];

                    // 计算实际影响的范围（考虑点击半径）
                    float segmentLength = Vector2.Distance(start, end);
                    float radiusRatio = clickRadius / segmentLength;

                    float rangeStart = Mathf.Clamp01(normalizedStart - radiusRatio);
                    float rangeEnd = Mathf.Clamp01(normalizedEnd + radiusRatio);

                    newRanges.Add(new Vector2(rangeStart, rangeEnd));
                }
            }

            // 合并新检测到的区间
            foreach (Vector2 range in newRanges)
            {
                _recordedRanges.Add(range);
            }

            // 合并所有重叠区间
            MergeRanges();

            // 打印当前所有区间（调试用）
            Debug.Log("Current recorded ranges:");
            foreach (Vector2 range in _recordedRanges)
            {
                Debug.Log($"Range: {range.x} - {range.y}");
            }
        }

        private float DistanceToSegment(Vector2 point, Vector2 segmentStart, Vector2 segmentEnd)
        {
            Vector2 segment = segmentEnd - segmentStart;
            Vector2 pointToStart = point - segmentStart;

            float dotProduct = Vector2.Dot(pointToStart, segment);

            // 检查点是否在线段的投影范围内
            if (dotProduct <= 0)
            {
                return Vector2.Distance(point, segmentStart);
            }

            float segmentLengthSquared = segment.sqrMagnitude;
            if (dotProduct >= segmentLengthSquared)
            {
                return Vector2.Distance(point, segmentEnd);
            }

            // 计算垂直距离
            return Mathf.Abs(segmentStart.y * segmentEnd.x - segmentStart.x * segmentEnd.y +
                             point.x * (segmentStart.y - segmentEnd.y) +
                             point.y * (segmentEnd.x - segmentStart.x)) /
                   Mathf.Sqrt(segmentLengthSquared);
        }

        private void MergeRanges()
        {
            if (_recordedRanges.Count <= 1) return;

            // 先按起始位置排序
            _recordedRanges.Sort((a, b) => a.x.CompareTo(b.x));

            List<Vector2> mergedRanges = new List<Vector2>();
            Vector2 currentRange = _recordedRanges[0];

            for (int i = 1; i < _recordedRanges.Count; i++)
            {
                Vector2 nextRange = _recordedRanges[i];

                // 检查是否有重叠或相邻
                if (nextRange.x <= currentRange.y)
                {
                    // 合并区间
                    currentRange.y = Mathf.Max(currentRange.y, nextRange.y);
                }
                else
                {
                    mergedRanges.Add(currentRange);
                    currentRange = nextRange;
                }
            }

            mergedRanges.Add(currentRange);
            _recordedRanges = mergedRanges;
        }
        
        #endregion

        // 获取当前所有记录的范围（0-1之间的值）
        public List<Vector2> GetRecordedRanges()
        {
            return new List<Vector2>(_recordedRanges);
        }

        // 清除所有记录的范围
        public void ClearRecordedRanges()
        {
            _recordedRanges.Clear();
        }
    }
}