import torch

from ..common.quaternion import qinv, qrot


# Recover global angle and positions for rotation dataset
# root_rot_velocity (B, seq_len, 1)
# root_linear_velocity (B, seq_len, 2)
# root_y (B, seq_len, 1)
# ric_data (B, seq_len, (joint_num - 1)*3)
# rot_data (B, seq_len, (joint_num - 1)*6)
# local_velocity (B, seq_len, joint_num*3)
# foot contact (B, seq_len, 4)
def recover_root_rot_pos(data: torch.Tensor) -> tuple[torch.Tensor, torch.Tensor]:
    rot_vel = data[..., 0]
    r_rot_ang = torch.zeros_like(rot_vel).to(data.device)
    '''Get Y-axis rotation from rotation velocity'''
    r_rot_ang[..., 1:] = rot_vel[..., :-1]
    r_rot_ang = torch.cumsum(r_rot_ang, dim=-1)

    r_rot_quat = torch.zeros(data.shape[:-1] + (4,)).to(data.device)
    r_rot_quat[..., 0] = torch.cos(r_rot_ang)
    r_rot_quat[..., 2] = torch.sin(r_rot_ang)

    r_pos = torch.zeros(data.shape[:-1] + (3,)).to(data.device)
    r_pos[..., 1:, [0, 2]] = data[..., :-1, 1:3]
    '''Add Y-axis rotation to root position'''
    r_pos = qrot(qinv(r_rot_quat), r_pos)

    r_pos = torch.cumsum(r_pos, dim=-2)

    r_pos[..., 1] = data[..., 3]
    return r_rot_quat, r_pos


def recover_from_ric(data: torch.Tensor, joints_num: int) -> torch.Tensor:
    r_rot_quat, r_pos = recover_root_rot_pos(data)
    positions = data[..., 4:(joints_num - 1) * 3 + 4]
    positions = positions.view(positions.shape[:-1] + (-1, 3))

    '''Add Y-axis rotation to local joints'''
    positions = qrot(qinv(r_rot_quat[..., None, :]).expand(positions.shape[:-1] + (4,)), positions)

    '''Add root XZ to joints'''
    positions[..., 0] += r_pos[..., 0:1]
    positions[..., 2] += r_pos[..., 2:3]

    '''Concat root and joints'''
    positions = torch.cat([r_pos.unsqueeze(-2), positions], dim=-2)

    return positions