import numpy as np

def read_obj_vertices(obj_file_path):
    """读取OBJ文件中的顶点数据"""
    vertices = []
    with open(obj_file_path, 'r') as f:
        for line in f:
            line = line.strip()
            if line.startswith('v ') and not line.startswith('vt ') and not line.startswith('vn '):
                parts = line.split()
                if len(parts) >= 4:
                    # 提取顶点坐标，转换为浮点数
                    vertex = [float(parts[1]), float(parts[2]), float(parts[3])]
                    vertices.append(vertex)
    return np.array(vertices)

def find_vertex_mapping(original_vertices, modified_vertices, tolerance=1e-4):
    """
    找到修改后顶点在原始顶点中的索引映射
    使用严格的数值匹配，匹配失败或重复匹配都会报错
    """
    mapping = []
    used_indices = set()
    
    for i, mod_vertex in enumerate(modified_vertices):
        matches = []
        
        # 查找所有在容差范围内的匹配顶点
        for j, orig_vertex in enumerate(original_vertices):
            if np.allclose(mod_vertex, orig_vertex, atol=tolerance):
                matches.append(j)
        
        # 检查匹配结果
        if len(matches) == 0:
            # 没有找到匹配
            print(f"错误: 无法为修改后顶点 {i} ({mod_vertex}) 找到匹配的原始顶点")
            print(f"      最近的原始顶点:")
            # 找到最近的几个顶点供参考
            distances = []
            for j, orig_vertex in enumerate(original_vertices):
                dist = np.linalg.norm(mod_vertex - orig_vertex)
                distances.append((dist, j, orig_vertex))
            distances.sort()
            for dist, j, vertex in distances[:3]:  # 显示最近的3个
                print(f"      索引 {j}: {vertex}, 距离: {dist:.6f}")
            raise ValueError(f"顶点 {i} 匹配失败")
        
        elif len(matches) > 1:
            # 找到多个匹配
            print(f"错误: 为修改后顶点 {i} ({mod_vertex}) 找到多个匹配的原始顶点:")
            for match_idx in matches:
                print(f"      原始顶点索引 {match_idx}: {original_vertices[match_idx]}")
            raise ValueError(f"顶点 {i} 匹配到多个原始顶点")
        
        else:
            # 找到一个匹配
            match_idx = matches[0]
            if match_idx in used_indices:
                print(f"错误: 原始顶点 {match_idx} 已经被多个修改后顶点匹配")
                print(f"      当前修改后顶点 {i}: {mod_vertex}")
                # 找出哪个修改后顶点已经匹配了这个原始顶点
                for k, mapped_idx in enumerate(mapping):
                    if mapped_idx == match_idx:
                        print(f"      已经被修改后顶点 {k}: {modified_vertices[k]} 匹配")
                raise ValueError(f"原始顶点 {match_idx} 被重复匹配")
            
            mapping.append(match_idx)
            used_indices.add(match_idx)
    
    return mapping

def validate_mapping_completeness(mapping, original_vertices, modified_vertices):
    """验证映射的完整性"""
    print("\n验证映射完整性...")
    
    # 检查是否有未匹配的原始顶点
    all_original_indices = set(range(len(original_vertices)))
    used_original_indices = set(mapping)
    unused_original_indices = all_original_indices - used_original_indices
    
    if unused_original_indices:
        print(f"警告: 有 {len(unused_original_indices)} 个原始顶点未被使用:")
        for idx in list(unused_original_indices)[:5]:  # 只显示前5个
            print(f"      原始顶点 {idx}: {original_vertices[idx]}")
        if len(unused_original_indices) > 5:
            print(f"      ... 还有 {len(unused_original_indices) - 5} 个")
    
    # 检查顶点数量是否一致
    if len(modified_vertices) != len(original_vertices):
        print(f"警告: 顶点数量不一致 - 原始: {len(original_vertices)}, 修改后: {len(modified_vertices)}")
    
    return len(unused_original_indices) == 0

def generate_header_file(mapping, output_file="map.h"):
    """生成C++头文件"""
    with open(output_file, 'w') as f:
        f.write("#ifndef VERTEX_MAP_H\n")
        f.write("#define VERTEX_MAP_H\n\n")
        f.write("// 顶点索引映射表\n")
        f.write("// 用于将face_picture_3dmax.obj的顶点索引映射到face_picture.obj的顶点索引\n")
        f.write("// 生成说明: modified_vertex_index -> original_vertex_index\n")
        f.write("// 注意: 这个映射是严格的一对一匹配，匹配容差为1e-4\n")
        f.write(f"const int indexMap[{len(mapping)}] = {{\n")
        
        # 每行输出10个元素
        for i in range(0, len(mapping), 10):
            line_indices = mapping[i:i+10]
            line = "    " + ", ".join(f"{idx:3d}" for idx in line_indices)
            if i + 10 < len(mapping):
                line += ","
            f.write(line + "\n")
        
        f.write("};\n\n")
        f.write("#endif // VERTEX_MAP_H\n")

def main():
    # 文件路径
    original_obj = "../assets/face_picture.obj"
    modified_obj = "../assets/face_picture_3dmax.obj"
    output_header = "map.h"
    
    # 匹配容差 - 根据你的数据精度调整这个值
    tolerance = 1e-4
    
    print("正在读取OBJ文件...")
    
    try:
        # 读取顶点数据
        original_vertices = read_obj_vertices(original_obj)
        modified_vertices = read_obj_vertices(modified_obj)
        
        print(f"原始文件顶点数: {len(original_vertices)}")
        print(f"修改文件顶点数: {len(modified_vertices)}")
        print(f"匹配容差: {tolerance}")
        
        # 找到顶点映射
        print("正在严格匹配顶点...")
        mapping = find_vertex_mapping(original_vertices, modified_vertices, tolerance)
        
        # 验证完整性
        is_complete = validate_mapping_completeness(mapping, original_vertices, modified_vertices)
        
        if is_complete:
            print("✓ 所有原始顶点都被正确使用")
        else:
            print("⚠ 部分原始顶点未被使用")
        
        print(f"✓ 成功匹配所有 {len(mapping)} 个顶点")
        
        # 生成头文件
        print(f"生成头文件: {output_header}")
        generate_header_file(mapping, output_header)
        
        print("\n完成！映射文件已生成。")
        
    except Exception as e:
        print(f"\n❌ 错误: {e}")
        print("映射生成失败，请检查数据或调整匹配容差")

if __name__ == "__main__":
    main()