# Copyright (c) Meta Platforms, Inc. and affiliates.
# All rights reserved.
#
# This source code is licensed under the BSD-style license found in the
# LICENSE file in the root directory of this source tree.

from typing import cast, Optional, Tuple

import torch
from pytorch3d.implicitron.tools.point_cloud_utils import get_rgbd_point_cloud
from pytorch3d.structures import Pointclouds

from .implicitron_dataset import FrameData, ImplicitronDataset


def get_implicitron_sequence_pointcloud(
    dataset: ImplicitronDataset,
    sequence_name: Optional[str] = None,
    mask_points: bool = True,
    max_frames: int = -1,
    num_workers: int = 0,
    load_dataset_point_cloud: bool = False,
) -> Tuple[Pointclouds, FrameData]:
    """
    Make a point cloud by sampling random points from each frame the dataset.
    """

    if len(dataset) == 0:
        raise ValueError("The dataset is empty.")

    if not dataset.load_depths:
        raise ValueError("The dataset has to load depths (dataset.load_depths=True).")

    if mask_points and not dataset.load_masks:
        raise ValueError(
            "For mask_points=True, the dataset has to load masks"
            + " (dataset.load_masks=True)."
        )

    # setup the indices of frames loaded from the dataset db
    sequence_entries = list(range(len(dataset)))
    if sequence_name is not None:
        sequence_entries = [
            ei
            for ei in sequence_entries
            if dataset.frame_annots[ei]["frame_annotation"].sequence_name
            == sequence_name
        ]
        if len(sequence_entries) == 0:
            raise ValueError(
                f'There are no dataset entries for sequence name "{sequence_name}".'
            )

    # subsample loaded frames if needed
    if (max_frames > 0) and (len(sequence_entries) > max_frames):
        sequence_entries = [
            sequence_entries[i]
            for i in torch.randperm(len(sequence_entries))[:max_frames].sort().values
        ]

    # take only the part of the dataset corresponding to the sequence entries
    sequence_dataset = torch.utils.data.Subset(dataset, sequence_entries)

    # load the required part of the dataset
    loader = torch.utils.data.DataLoader(
        sequence_dataset,
        batch_size=len(sequence_dataset),
        shuffle=False,
        num_workers=num_workers,
        collate_fn=FrameData.collate,
    )

    frame_data = next(iter(loader))  # there's only one batch

    # scene point cloud
    if load_dataset_point_cloud:
        if not dataset.load_point_clouds:
            raise ValueError(
                "For load_dataset_point_cloud=True, the dataset has to"
                + " load point clouds (dataset.load_point_clouds=True)."
            )
        point_cloud = frame_data.sequence_point_cloud

    else:
        point_cloud = get_rgbd_point_cloud(
            frame_data.camera,
            frame_data.image_rgb,
            frame_data.depth_map,
            (cast(torch.Tensor, frame_data.fg_probability) > 0.5).float()
            if frame_data.fg_probability is not None
            else None,
            mask_points=mask_points,
        )

    return point_cloud, frame_data
