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

namespace NGS.MeshFusionPro;

public class MeshCutterSimpleSTD : IMeshCutter
{
	private static List<Vector3> _vertices;

	private static List<Vector3> _normals;

	private static List<Vector4> _tangents;

	private static List<int> _triangles;

	private static List<Vector2>[] _uvs;

	private static int _maxUVsCount;

	static MeshCutterSimpleSTD()
	{
		_maxUVsCount = 4;
		_vertices = new List<Vector3>();
		_normals = new List<Vector3>();
		_tangents = new List<Vector4>();
		_triangles = new List<int>();
		_uvs = new List<Vector2>[_maxUVsCount];
		for (int i = 0; i < _maxUVsCount; i++)
		{
			_uvs[i] = new List<Vector2>();
		}
	}

	public void Cut(Mesh mesh, MeshCuttingInfo info)
	{
		Cut(mesh, new MeshCuttingInfo[1] { info });
	}

	public void Cut(Mesh mesh, IList<MeshCuttingInfo> infos)
	{
		ValidateMeshOrThrowException(mesh);
		CollectData(mesh);
		foreach (MeshCuttingInfo item in infos.OrderByDescending((MeshCuttingInfo i) => i.triangleStart))
		{
			RemoveData(item);
			OffsetTriangles(item);
		}
		ApplyDataToMesh(mesh);
		ClearData();
	}

	private void ValidateMeshOrThrowException(Mesh mesh)
	{
		if (mesh == null)
		{
			throw new ArgumentNullException("mesh is null");
		}
		if (mesh.subMeshCount > 1)
		{
			throw new ArgumentException("SimpleMeshCutter::'mesh' should has only 1 submesh");
		}
	}

	private void CollectData(Mesh mesh)
	{
		mesh.GetVertices(_vertices);
		mesh.GetNormals(_normals);
		mesh.GetTangents(_tangents);
		mesh.GetTriangles(_triangles, 0);
		for (int i = 0; i < _maxUVsCount; i++)
		{
			mesh.GetUVs(i, _uvs[i]);
		}
	}

	private void RemoveData(MeshCuttingInfo cuttingInfo)
	{
		int vertexStart = cuttingInfo.vertexStart;
		int vertexCount = cuttingInfo.vertexCount;
		_vertices.RemoveRange(vertexStart, vertexCount);
		if (_normals.Count > 0)
		{
			_normals.RemoveRange(vertexStart, vertexCount);
		}
		if (_tangents.Count > 0)
		{
			_tangents.RemoveRange(vertexStart, vertexCount);
		}
		_triangles.RemoveRange(cuttingInfo.triangleStart, cuttingInfo.triangleCount);
		for (int i = 0; i < _uvs.Length; i++)
		{
			if (_uvs[i].Count > 0)
			{
				_uvs[i].RemoveRange(vertexStart, vertexCount);
			}
		}
	}

	private void OffsetTriangles(MeshCuttingInfo info)
	{
		int vertexCount = info.vertexCount;
		int triangleStart = info.triangleStart;
		int count = _triangles.Count;
		for (int i = triangleStart; i < count; i++)
		{
			_triangles[i] -= vertexCount;
		}
	}

	private void ApplyDataToMesh(Mesh mesh)
	{
		mesh.SetTriangles(_triangles, 0);
		mesh.SetVertices(_vertices);
		mesh.SetNormals(_normals);
		mesh.SetTangents(_tangents);
		for (int i = 0; i < _maxUVsCount; i++)
		{
			if (_uvs[i].Count > 0)
			{
				mesh.SetUVs(i, _uvs[i]);
			}
		}
	}

	private void ClearData()
	{
		_vertices.Clear();
		_normals.Clear();
		_tangents.Clear();
		_triangles.Clear();
		for (int i = 0; i < _maxUVsCount; i++)
		{
			_uvs[i].Clear();
		}
	}
}