"""
Transform points to voxels using sparse conv library
"""
import sys

import numpy as np
import torch
from cumm import tensorview as tv
from spconv.utils import Point2VoxelCPU3d

from hmvit.data_utils.pre_processor.base_preprocessor import \
    BasePreprocessor


class SpVoxelPreprocessor(BasePreprocessor):
    def __init__(self, preprocess_params, train):
        super(SpVoxelPreprocessor, self).__init__(preprocess_params,
                                                  train)

        self.lidar_range = self.params['cav_lidar_range']
        self.voxel_size = self.params['args']['voxel_size']
        self.max_points_per_voxel = self.params['args']['max_points_per_voxel']

        if train:
            self.max_voxels = self.params['args']['max_voxel_train']
        else:
            self.max_voxels = self.params['args']['max_voxel_test']

        grid_size = (np.array(self.lidar_range[3:6]) -
                     np.array(self.lidar_range[0:3])) / np.array(self.voxel_size)
        self.grid_size = np.round(grid_size).astype(np.int64)

        # use sparse conv library to generate voxel
        self.voxel_generator = Point2VoxelCPU3d(
            vsize_xyz=self.voxel_size,
            coors_range_xyz=self.lidar_range,
            max_num_points_per_voxel=self.max_points_per_voxel,
            num_point_features=4,
            max_num_voxels=self.max_voxels
        )

    def preprocess(self, pcd_np):
        data_dict = {}
        pcd_tv = tv.from_numpy(pcd_np)
        voxel_output = self.voxel_generator.point_to_voxel(pcd_tv)
        if isinstance(voxel_output, dict):
            voxels, coordinates, num_points = \
                voxel_output['voxels'], voxel_output['coordinates'], \
                voxel_output['num_points_per_voxel']
        else:
            voxels, coordinates, num_points = voxel_output

        data_dict['voxel_features'] = voxels.numpy()
        data_dict['voxel_coords'] = coordinates.numpy()
        data_dict['voxel_num_points'] = num_points.numpy()

        return data_dict

    def collate_batch(self, batch):
        """
        Customized pytorch data loader collate function.

        Parameters
        ----------
        batch : list or dict
            List or dictionary.

        Returns
        -------
        processed_batch : dict
            Updated lidar batch.
        """

        if isinstance(batch, list):
            return self.collate_batch_list(batch)
        elif isinstance(batch, dict):
            return self.collate_batch_dict(batch)
        else:
            sys.exit('Batch has too be a list or a dictionarn')

    @staticmethod
    def collate_batch_list(batch):
        """
        Customized pytorch data loader collate function.

        Parameters
        ----------
        batch : list
            List of dictionary. Each dictionary represent a single frame.

        Returns
        -------
        processed_batch : dict
            Updated lidar batch.
        """
        voxel_features = []
        voxel_num_points = []
        voxel_coords = []

        for i in range(len(batch)):
            voxel_features.append(batch[i]['voxel_features'])
            voxel_num_points.append(batch[i]['voxel_num_points'])
            coords = batch[i]['voxel_coords']
            voxel_coords.append(
                np.pad(coords, ((0, 0), (1, 0)),
                       mode='constant', constant_values=i))

        voxel_num_points = torch.from_numpy(np.concatenate(voxel_num_points))
        voxel_features = torch.from_numpy(np.concatenate(voxel_features))
        voxel_coords = torch.from_numpy(np.concatenate(voxel_coords))

        return {'voxel_features': voxel_features,
                'voxel_coords': voxel_coords,
                'voxel_num_points': voxel_num_points}

    @staticmethod
    def collate_batch_dict(batch: dict):
        """
        Collate batch if the batch is a dictionary,
        eg: {'voxel_features': [feature1, feature2...., feature n]}

        Parameters
        ----------
        batch : dict

        Returns
        -------
        processed_batch : dict
            Updated lidar batch.
        """
        voxel_features = \
            torch.from_numpy(np.concatenate(batch['voxel_features']))
        voxel_num_points = \
            torch.from_numpy(np.concatenate(batch['voxel_num_points']))
        coords = batch['voxel_coords']
        voxel_coords = []

        for i in range(len(coords)):
            voxel_coords.append(
                np.pad(coords[i], ((0, 0), (1, 0)),
                       mode='constant', constant_values=i))
        voxel_coords = torch.from_numpy(np.concatenate(voxel_coords))

        return {'voxel_features': voxel_features,
                'voxel_coords': voxel_coords,
                'voxel_num_points': voxel_num_points}
