"""点云加载模块"""
import numpy as np
from pathlib import Path
import struct


class PointCloudLoader:
    """加载点云文件"""

    @staticmethod
    def load_ply(file_path: str) -> np.ndarray:
        """
        加载PLY格式点云

        Args:
            file_path: PLY文件路径

        Returns:
            np.ndarray: 点云数组 (N, 3)
        """
        path = Path(file_path)
        if not path.exists():
            raise FileNotFoundError(f"点云文件不存在: {file_path}")

        print(f"正在加载点云: {file_path}")

        with open(path, 'rb') as f:
            # 读取头部
            header_lines = []
            while True:
                line = f.readline().decode('ascii').strip()
                header_lines.append(line)
                if line == 'end_header':
                    break

            # 解析头部
            vertex_count = 0
            format_type = None
            properties = []

            for line in header_lines:
                if line.startswith('element vertex'):
                    vertex_count = int(line.split()[-1])
                elif line.startswith('format'):
                    format_type = line.split()[1]
                elif line.startswith('property'):
                    parts = line.split()
                    properties.append({
                        'type': parts[1],
                        'name': parts[2]
                    })

            if vertex_count == 0:
                raise ValueError("PLY文件中没有顶点数据")

            # 读取顶点数据
            if format_type == 'binary_little_endian':
                points = PointCloudLoader._read_binary_ply(f, vertex_count, properties)
            elif format_type == 'ascii':
                points = PointCloudLoader._read_ascii_ply(f, vertex_count)
            else:
                raise ValueError(f"不支持的PLY格式: {format_type}")

        print(f"  加载完成: {len(points)} 个点")
        return points

    @staticmethod
    def _read_binary_ply(f, vertex_count: int, properties: list) -> np.ndarray:
        """读取二进制PLY数据"""
        # 构建struct格式字符串
        type_map = {
            'float': 'f',
            'double': 'd',
            'uchar': 'B',
            'uint': 'I',
            'int': 'i'
        }

        fmt = '<'  # 小端序
        for prop in properties:
            fmt += type_map.get(prop['type'], 'f')

        struct_size = struct.calcsize(fmt)
        points = []

        for _ in range(vertex_count):
            data = struct.unpack(fmt, f.read(struct_size))
            # 只取前3个值作为xyz坐标
            points.append(data[:3])

        return np.array(points, dtype=np.float64)

    @staticmethod
    def _read_ascii_ply(f, vertex_count: int) -> np.ndarray:
        """读取ASCII PLY数据"""
        points = []
        for _ in range(vertex_count):
            line = f.readline().decode('ascii').strip()
            values = line.split()
            # 只取前3个值作为xyz坐标
            points.append([float(values[0]), float(values[1]), float(values[2])])

        return np.array(points, dtype=np.float64)