import h5py
import numpy as np
import open3d
import os

class IO:
    @classmethod
    def get(cls, file_path):
        _, file_extension = os.path.splitext(file_path)

        if file_extension in ['.npy']:
            return cls._read_npy(file_path)
        elif file_extension in ['.pcd', '.ply']:
            return cls._read_pcd(file_path)
        elif file_extension in ['.h5']:
            return cls._read_h5(file_path)
        elif file_extension in ['.txt']:
            return cls._read_txt(file_path)
        else:
            raise Exception('Unsupported file extension: %s' % file_extension)

    # References: https://github.com/numpy/numpy/blob/master/numpy/lib/format.py
    @classmethod
    def _read_npy(cls, file_path):
        return np.load(file_path)
       
    # References: https://github.com/dimatura/pypcd/blob/master/pypcd/pypcd.py#L275
    # Support PCD files without compression ONLY!
    @classmethod
    def _read_pcd(cls, file_path):
        pc = open3d.io.read_point_cloud(file_path)
        ptcloud = np.array(pc.points)
        return ptcloud

    @classmethod
    def _read_txt(cls, file_path):
        return np.loadtxt(file_path)

    @classmethod
    def _read_h5(cls, file_path):
        f = h5py.File(file_path, 'r')
        return f['data'][()]