# Copyright 2022 The Plenoptix Team. All rights reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

"""
Code for camera paths.
"""

from typing import Optional, Tuple

import torch

import nerfactory.cameras.utils as camera_utils
from nerfactory.cameras.cameras import Cameras
from nerfactory.cameras.utils import get_interpolated_poses_many


def get_interpolated_camera_path(cameras: Cameras, steps: int) -> Cameras:
    """Generate a camera path between two cameras.

    Args:
        camera_a: The first camera.
        camera_b: The second camera.
        steps: The number of steps to interpolate between the two cameras.

    Returns:
        A new set of cameras along a path.
    """
    Ks = cameras.get_intrinsics_matrices().cpu().numpy()
    poses = cameras.camera_to_worlds().cpu().numpy()
    poses, Ks = get_interpolated_poses_many(poses, Ks, steps_per_transition=steps)

    cameras = Cameras(fx=Ks[:, 0, 0], fy=Ks[:, 1, 1], cx=Ks[0, 0, 2], cy=Ks[0, 1, 2], camera_to_worlds=poses)
    return cameras


def get_spiral_path(
    camera: Cameras,
    steps: int = 30,
    radius: Optional[float] = None,
    radiuses: Optional[Tuple[float]] = None,
    rots: int = 2,
    zrate: float = 0.5,
) -> Cameras:
    """
    Returns a list of camera in a sprial trajectory.

    Args:
        camera: The camera to start the spiral from.
        steps: The number of cameras in the generated path.
        radius: The radius of the spiral for all xyz directions.
        radiuses: The list of radii for the spiral in xyz directions.
        rots: The number of rotations to apply to the camera.
        zrate: How much to change the z position of the camera.

    Returns:
        A spiral camera path.
    """

    assert radius is not None or radiuses is not None, "Either radius or radiuses must be specified."
    if radius is not None and radiuses is None:
        rad = torch.tensor([radius] * 3, device=camera.device)
    elif radiuses is not None and radius is None:
        rad = torch.tensor(radiuses, device=camera.device)
    else:
        raise ValueError("Only one of radius or radiuses must be specified.")

    # TODO: don't hardcode this. pass this in
    up = camera.camera_to_worlds[0, :3, 2]  # scene is z up
    # up = camera.camera_to_world[:3, 1] # this will rotate 90 degrees
    focal = torch.min(camera.fx[0], camera.fy[0])
    target = torch.tensor([0, 0, -focal], device=camera.device)  # camera looking in -z direction

    c2w = camera.camera_to_worlds[0]
    ones = torch.tensor([0, 0, 0, 1], device=c2w.device)[None]
    c2wh_global = torch.cat([c2w, ones], dim=0)

    local_c2whs = []
    for theta in torch.linspace(0.0, 2.0 * torch.pi * rots, steps + 1)[:-1]:
        center = (
            torch.tensor([torch.cos(theta), -torch.sin(theta), -torch.sin(theta * zrate)], device=camera.device) * rad
        )
        lookat = center - target
        c2w = camera_utils.viewmatrix(lookat, up, center)
        ones = torch.tensor([0, 0, 0, 1], device=c2w.device)[None]
        c2wh = torch.cat([c2w, ones], dim=0)
        local_c2whs.append(c2wh)

    new_c2ws = []
    for local_c2wh in local_c2whs:
        c2wh = torch.matmul(c2wh_global, local_c2wh)
        new_c2ws.append(c2wh[:3, :4])

    return Cameras(fx=camera.fx[0], fy=camera.fy[0], cx=camera.cx, cy=camera.cy, camera_to_worlds=new_c2ws)