# -*- coding: utf-8 -*-
"""
gltf_exporter.py - glTF 格式导出器

将 Model3D 导出为 glTF 2.0 格式，用于 Web 显示（Three.js）
"""

from typing import List
import numpy as np
import math

try:
    from pygltflib import GLTF2, Scene, Node, Mesh, Primitive, Buffer, BufferView, Accessor
    from pygltflib import Material, PbrMetallicRoughness
    PYGLTFLIB_AVAILABLE = True
except ImportError:
    PYGLTFLIB_AVAILABLE = False
    print("警告: pygltflib 未安装，无法导出 glTF 文件")
    print("安装命令: pip install pygltflib")

from ..geometry.element_geometry import Model3D, FrameElement3D, CableElement3D
from ..geometry.section_profile import create_profile_from_sap_section


class GLTFExporter:
    """glTF 导出器"""
    
    def __init__(self):
        if not PYGLTFLIB_AVAILABLE:
            raise ImportError("需要安装 pygltflib: pip install pygltflib")
    
    def export(self, model_3d: Model3D, output_path: str, num_segments: int = 16):
        """
        导出为 glTF 文件
        
        Args:
            model_3d: Model3D 对象
            output_path: 输出文件路径（.gltf 或 .glb）
            num_segments: 圆形截面分段数
            
        Example:
            exporter = GLTFExporter()
            exporter.export(model_3d, "model.gltf")
        """
        print(f"导出 glTF 文件: {output_path}")
        print(f"单元数量: {len(model_3d.elements)}")
        
        # TODO: 实现完整的 glTF 导出逻辑
        # 这里提供简化版本，完整实现需要：
        # 1. 为每个单元生成网格（拉伸截面轮廓）
        # 2. 合并顶点和索引
        # 3. 创建 Buffer、BufferView、Accessor
        # 4. 设置材质和场景
        
        print("⚠️  完整的 glTF 导出功能正在开发中")
        print("建议先使用 OBJ 格式或 JSON 格式")
        
        # 简化版：导出为线框模型
        self._export_wireframe(model_3d, output_path)
    
    def _export_wireframe(self, model_3d: Model3D, output_path: str):
        """导出为线框模型（简化版）"""
        vertices = []
        indices = []
        
        vertex_index = 0
        for elem in model_3d.elements:
            # 添加起点和终点
            vertices.extend([elem.point_i.x, elem.point_i.y, elem.point_i.z])
            vertices.extend([elem.point_j.x, elem.point_j.y, elem.point_j.z])
            
            # 添加线段索引
            indices.extend([vertex_index, vertex_index + 1])
            vertex_index += 2
        
        # 转换为 numpy 数组
        vertices_array = np.array(vertices, dtype=np.float32)
        indices_array = np.array(indices, dtype=np.uint16)
        
        print(f"顶点数: {len(vertices) // 3}")
        print(f"线段数: {len(indices) // 2}")
        
        # 保存为简单的文本格式（临时方案）
        with open(output_path + ".txt", 'w') as f:
            f.write(f"# SAP2000 Model Wireframe\n")
            f.write(f"# Vertices: {len(vertices) // 3}\n")
            f.write(f"# Lines: {len(indices) // 2}\n\n")
            
            f.write("# Vertices (x, y, z)\n")
            for i in range(0, len(vertices), 3):
                f.write(f"v {vertices[i]:.6f} {vertices[i+1]:.6f} {vertices[i+2]:.6f}\n")
            
            f.write("\n# Lines (i, j)\n")
            for i in range(0, len(indices), 2):
                f.write(f"l {indices[i]+1} {indices[i+1]+1}\n")
        
        print(f"✓ 已导出线框模型: {output_path}.txt")
        print("  （完整的 glTF 实体模型功能开发中）")
