# Copyright (c) OpenMMLab. All rights reserved.
from enum import IntEnum, unique

import numpy as np
import torch

from mmdet3d.structures.points import (BasePoints, CameraPoints, DepthPoints,
                                       LiDARPoints)
from .base_box3d import BaseInstance3DBoxes
from .box_3d_mode import Box3DMode


@unique
class Coord3DMode(IntEnum):
    r"""Enum of different ways to represent a box
        and point cloud.

    Coordinates in LiDAR:

    .. code-block:: none

                    up z
                       ^   x front
                       |  /
                       | /
        left y <------ 0

    The relative coordinate of bottom center in a LiDAR box is (0.5, 0.5, 0),
    and the yaw is around the z axis, thus the rotation axis=2.

    Coordinates in camera:

    .. code-block:: none

                z front
               /
              /
             0 ------> x right
             |
             |
             v
        down y

    The relative coordinate of bottom center in a CAM box is [0.5, 1.0, 0.5],
    and the yaw is around the y axis, thus the rotation axis=1.

    Coordinates in Depth mode:

    .. code-block:: none

        up z
           ^   y front
           |  /
           | /
           0 ------> x right

    The relative coordinate of bottom center in a DEPTH box is (0.5, 0.5, 0),
    and the yaw is around the z axis, thus the rotation axis=2.
    """

    LIDAR = 0
    CAM = 1
    DEPTH = 2

    @staticmethod
    def convert(input, src, dst, rt_mat=None, with_yaw=True, is_point=True):
        """Convert boxes or points from `src` mode to `dst` mode.

        Args:
            input (tuple | list | np.ndarray | torch.Tensor |
                :obj:`BaseInstance3DBoxes` | :obj:`BasePoints`):
                Can be a k-tuple, k-list or an Nxk array/tensor, where k = 7.
            src (:obj:`Box3DMode` | :obj:`Coord3DMode`): The source mode.
            dst (:obj:`Box3DMode` | :obj:`Coord3DMode`): The target mode.
            rt_mat (np.ndarray | torch.Tensor, optional): The rotation and
                translation matrix between different coordinates.
                Defaults to None.
                The conversion from `src` coordinates to `dst` coordinates
                usually comes along the change of sensors, e.g., from camera
                to LiDAR. This requires a transformation matrix.
            with_yaw (bool): If `box` is an instance of
                :obj:`BaseInstance3DBoxes`, whether or not it has a yaw angle.
                Defaults to True.
            is_point (bool): If `input` is neither an instance of
                :obj:`BaseInstance3DBoxes` nor an instance of
                :obj:`BasePoints`, whether or not it is point data.
                Defaults to True.

        Returns:
            (tuple | list | np.ndarray | torch.Tensor |
                :obj:`BaseInstance3DBoxes` | :obj:`BasePoints`):
                The converted box of the same type.
        """
        if isinstance(input, BaseInstance3DBoxes):
            return Coord3DMode.convert_box(
                input, src, dst, rt_mat=rt_mat, with_yaw=with_yaw)
        elif isinstance(input, BasePoints):
            return Coord3DMode.convert_point(input, src, dst, rt_mat=rt_mat)
        elif isinstance(input, (tuple, list, np.ndarray, torch.Tensor)):
            if is_point:
                return Coord3DMode.convert_point(
                    input, src, dst, rt_mat=rt_mat)
            else:
                return Coord3DMode.convert_box(
                    input, src, dst, rt_mat=rt_mat, with_yaw=with_yaw)
        else:
            raise NotImplementedError

    @staticmethod
    def convert_box(box, src, dst, rt_mat=None, with_yaw=True):
        """Convert boxes from `src` mode to `dst` mode.

        Args:
            box (tuple | list | np.ndarray |
                torch.Tensor | :obj:`BaseInstance3DBoxes`):
                Can be a k-tuple, k-list or an Nxk array/tensor, where k = 7.
            src (:obj:`Box3DMode`): The src Box mode.
            dst (:obj:`Box3DMode`): The target Box mode.
            rt_mat (np.ndarray | torch.Tensor, optional): The rotation and
                translation matrix between different coordinates.
                Defaults to None.
                The conversion from `src` coordinates to `dst` coordinates
                usually comes along the change of sensors, e.g., from camera
                to LiDAR. This requires a transformation matrix.
            with_yaw (bool): If `box` is an instance of
                :obj:`BaseInstance3DBoxes`, whether or not it has a yaw angle.
                Defaults to True.

        Returns:
            (tuple | list | np.ndarray | torch.Tensor |
                :obj:`BaseInstance3DBoxes`):
                The converted box of the same type.
        """
        return Box3DMode.convert(box, src, dst, rt_mat=rt_mat)

    @staticmethod
    def convert_point(point, src, dst, rt_mat=None):
        """Convert points from `src` mode to `dst` mode.

        Args:
            point (tuple | list | np.ndarray |
                torch.Tensor | :obj:`BasePoints`):
                Can be a k-tuple, k-list or an Nxk array/tensor.
            src (:obj:`CoordMode`): The src Point mode.
            dst (:obj:`CoordMode`): The target Point mode.
            rt_mat (np.ndarray | torch.Tensor, optional): The rotation and
                translation matrix between different coordinates.
                Defaults to None.
                The conversion from `src` coordinates to `dst` coordinates
                usually comes along the change of sensors, e.g., from camera
                to LiDAR. This requires a transformation matrix.

        Returns:
            (tuple | list | np.ndarray | torch.Tensor | :obj:`BasePoints`):
                The converted point of the same type.
        """
        if src == dst:
            return point

        is_numpy = isinstance(point, np.ndarray)
        is_InstancePoints = isinstance(point, BasePoints)
        single_point = isinstance(point, (list, tuple))
        if single_point:
            assert len(point) >= 3, (
                'CoordMode.convert takes either a k-tuple/list or '
                'an Nxk array/tensor, where k >= 3')
            arr = torch.tensor(point)[None, :]
        else:
            # avoid modifying the input point
            if is_numpy:
                arr = torch.from_numpy(np.asarray(point)).clone()
            elif is_InstancePoints:
                arr = point.tensor.clone()
            else:
                arr = point.clone()

        # convert point from `src` mode to `dst` mode.
        if src == Coord3DMode.LIDAR and dst == Coord3DMode.CAM:
            if rt_mat is None:
                rt_mat = arr.new_tensor([[0, -1, 0], [0, 0, -1], [1, 0, 0]])
        elif src == Coord3DMode.CAM and dst == Coord3DMode.LIDAR:
            if rt_mat is None:
                rt_mat = arr.new_tensor([[0, 0, 1], [-1, 0, 0], [0, -1, 0]])
        elif src == Coord3DMode.DEPTH and dst == Coord3DMode.CAM:
            if rt_mat is None:
                rt_mat = arr.new_tensor([[1, 0, 0], [0, 0, -1], [0, 1, 0]])
        elif src == Coord3DMode.CAM and dst == Coord3DMode.DEPTH:
            if rt_mat is None:
                rt_mat = arr.new_tensor([[1, 0, 0], [0, 0, 1], [0, -1, 0]])
        elif src == Coord3DMode.LIDAR and dst == Coord3DMode.DEPTH:
            if rt_mat is None:
                rt_mat = arr.new_tensor([[0, -1, 0], [1, 0, 0], [0, 0, 1]])
        elif src == Coord3DMode.DEPTH and dst == Coord3DMode.LIDAR:
            if rt_mat is None:
                rt_mat = arr.new_tensor([[0, 1, 0], [-1, 0, 0], [0, 0, 1]])
        else:
            raise NotImplementedError(
                f'Conversion from Coord3DMode {src} to {dst} '
                'is not supported yet')

        if not isinstance(rt_mat, torch.Tensor):
            rt_mat = arr.new_tensor(rt_mat)
        if rt_mat.size(1) == 4:
            extended_xyz = torch.cat(
                [arr[..., :3], arr.new_ones(arr.size(0), 1)], dim=-1)
            xyz = extended_xyz @ rt_mat.t()
        else:
            xyz = arr[..., :3] @ rt_mat.t()

        remains = arr[..., 3:]
        arr = torch.cat([xyz[..., :3], remains], dim=-1)

        # convert arr to the original type
        original_type = type(point)
        if single_point:
            return original_type(arr.flatten().tolist())
        if is_numpy:
            return arr.numpy()
        elif is_InstancePoints:
            if dst == Coord3DMode.CAM:
                target_type = CameraPoints
            elif dst == Coord3DMode.LIDAR:
                target_type = LiDARPoints
            elif dst == Coord3DMode.DEPTH:
                target_type = DepthPoints
            else:
                raise NotImplementedError(
                    f'Conversion to {dst} through {original_type}'
                    ' is not supported yet')
            return target_type(
                arr,
                points_dim=arr.size(-1),
                attribute_dims=point.attribute_dims)
        else:
            return arr
