using UnityEngine;
using System.Collections.Generic;

[RequireComponent(typeof(MeshCollider))]
public class MeshColliderGizmo : MonoBehaviour
{
    [Tooltip("Gizmo显示颜色")]
    public Color lineColor = new Color(0, 1, 1, 0.8f);
    
    [Tooltip("线框宽度")]
    public float lineWidth = 1.0f;
    
    [Tooltip("是否在运行时显示")]
    public bool showInPlayMode = true;
    
    [Tooltip("是否只显示边缘")]
    public bool showEdgesOnly = true;
    
    private MeshCollider _meshCollider;
    private Mesh _mesh;
    private List<Vector3> _vertices = new List<Vector3>();
    private List<int> _triangles = new List<int>();
    private List<Vector3> _linePoints = new List<Vector3>();
    private Material _glMaterial;
    private Matrix4x4 _localToWorldMatrix;

    private void Awake()
    {
        _meshCollider = GetComponent<MeshCollider>();
        InitializeMeshData();
        InitializeGLMaterial();
    }

    private void InitializeMeshData()
    {
        // 尝试获取网格数据
        MeshFilter meshFilter = GetComponent<MeshFilter>();
        if (meshFilter != null && meshFilter.sharedMesh != null)
        {
            _mesh = meshFilter.sharedMesh;
        }
        else if (_meshCollider.sharedMesh != null)
        {
            _mesh = _meshCollider.sharedMesh;
        }
        
        if (_mesh != null)
        {
            _vertices.Clear();
            _triangles.Clear();
            _mesh.GetVertices(_vertices);
            _mesh.GetTriangles(_triangles, 0);
            GenerateLinePoints();
        }
        else
        {
            Debug.LogWarning("未找到有效的Mesh资源", this);
        }
    }

    private void InitializeGLMaterial()
    {
        // 创建用于GL绘制的材质
        _glMaterial = new Material(Shader.Find("Hidden/Internal-Colored"));
        _glMaterial.hideFlags = HideFlags.HideAndDontSave;
        _glMaterial.SetInt("ZWrite", 0);
        _glMaterial.SetInt("ZTest", (int)UnityEngine.Rendering.CompareFunction.Always);
    }

    private void GenerateLinePoints()
    {
        if (showEdgesOnly)
        {
            // 只显示边缘线（去重处理）
            HashSet<long> edgeSet = new HashSet<long>();
            _linePoints.Clear();

            for (int i = 0; i < _triangles.Count; i += 3)
            {
                AddEdge(_triangles[i], _triangles[i + 1], edgeSet);
                AddEdge(_triangles[i + 1], _triangles[i + 2], edgeSet);
                AddEdge(_triangles[i + 2], _triangles[i], edgeSet);
            }
        }
        else
        {
            // 显示所有三角形线
            _linePoints.Clear();
            for (int i = 0; i < _triangles.Count; i += 3)
            {
                _linePoints.Add(_vertices[_triangles[i]]);
                _linePoints.Add(_vertices[_triangles[i + 1]]);
                _linePoints.Add(_vertices[_triangles[i + 1]]);
                _linePoints.Add(_vertices[_triangles[i + 2]]);
                _linePoints.Add(_vertices[_triangles[i + 2]]);
                _linePoints.Add(_vertices[_triangles[i]]);
            }
        }
    }

    private void AddEdge(int v1, int v2, HashSet<long> edgeSet)
    {
        // 创建唯一的边ID，避免重复
        long edgeId = (long)Mathf.Min(v1, v2) << 32 | Mathf.Max(v1, v2);
        if (edgeSet.Contains(edgeId)) return;

        edgeSet.Add(edgeId);
        _linePoints.Add(_vertices[v1]);
        _linePoints.Add(_vertices[v2]);
    }

    private void Update()
    {
        _localToWorldMatrix = transform.localToWorldMatrix;
    }

    private void OnRenderObject()
    {
        if (!showInPlayMode || _mesh == null || _linePoints.Count == 0 || _glMaterial == null)
            return;

        // 设置材质和颜色
        _glMaterial.SetPass(0);
        GL.PushMatrix();
        GL.MultMatrix(_localToWorldMatrix);
        GL.Color(lineColor);

        // 设置线宽
        GL.Begin(GL.LINES);
        for (int i = 0; i < _linePoints.Count; i++)
        {
            GL.Vertex(_linePoints[i]);
        }
        GL.End();

        GL.PopMatrix();
    }

    // 编辑器下的Gizmo预览
#if UNITY_EDITOR
    private void OnDrawGizmos()
    {
        if (!Application.isPlaying && _mesh != null)
        {
            Gizmos.color = lineColor;
            Gizmos.matrix = transform.localToWorldMatrix;
            Gizmos.DrawWireMesh(_mesh);
        }
    }
#endif
}