# 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.

"""
Data loader.
"""

import random
from typing import Dict, List, Tuple, Union
from omegaconf import ListConfig

from torchtyping import TensorType

from pyrad.cameras.cameras import get_camera
from pyrad.cameras.rays import RayBundle
from pyrad.data.image_dataset import ImageDataset
from pyrad.data.image_sampler import ImageSampler
from pyrad.data.pixel_sampler import PixelSampler
from pyrad.data.structs import DatasetInputs
from pyrad.data.utils import get_dataset_inputs_from_dataset_config
from pyrad.utils import profiler
from pyrad.utils.config import DataConfig
from pyrad.utils.misc import get_dict_to_torch, instantiate_from_dict_config


@profiler.time_function
def setup_dataset_train(config: DataConfig, device: str) -> Tuple[DatasetInputs, "TrainDataloader"]:
    """Helper method to load train dataset
    Args:
        config (DataConfig): Configuration of training dataset.
        device (str): device to load the dataset to

    Returns:
        Tuple[DatasetInputs, "TrainDataloader"]: returns both the dataset input information and associated dataloader
    """
    dataset_inputs_train = get_dataset_inputs_from_dataset_config(**config.dataset_inputs_train, split="train")
    # ImageDataset
    image_dataset_train = instantiate_from_dict_config(config.image_dataset_train, **dataset_inputs_train.as_dict())
    # ImageSampler
    image_sampler_train = instantiate_from_dict_config(
        config.dataloader_train.image_sampler, dataset=image_dataset_train, device=device
    )
    # PixelSampler
    pixel_sampler_train = instantiate_from_dict_config(config.dataloader_train.pixel_sampler)
    # Dataloader
    dataloader_train = TrainDataloader(image_sampler_train, pixel_sampler_train)
    return dataset_inputs_train, dataloader_train


@profiler.time_function
def setup_dataset_eval(config: DataConfig, test_mode: bool, device: str) -> Tuple[DatasetInputs, "EvalDataloader"]:
    """Helper method to load test or val dataset based on test/train mode
    Args:
        config (DataConfig): Configuration of training dataset.
        test_mode (bool): specifies whether you are training/testing mode, to load validation/test data
        device (str): device to load the dataset to

    Returns:
        Tuple[DatasetInputs, "TrainDataloader"]: returns both the dataset input information and associated dataloader
    """
    eval_split = "test" if test_mode else "val"
    dataset_inputs_eval = get_dataset_inputs_from_dataset_config(**config.dataset_inputs_eval, split=eval_split)
    image_dataset_eval = instantiate_from_dict_config(config.image_dataset_eval, **dataset_inputs_eval.as_dict())
    dataloader_eval = instantiate_from_dict_config(
        config.dataloader_eval,
        image_dataset=image_dataset_eval,
        device=device,
        **dataset_inputs_eval.as_dict(),
    )
    return dataset_inputs_eval, dataloader_eval


class TrainDataloader:
    """Training dataloader base class."""

    def __init__(self, image_sampler: ImageSampler, pixel_sampler: PixelSampler):
        self.image_sampler = image_sampler
        self.pixel_sampler = pixel_sampler
        self.iter_image_sampler = iter(self.image_sampler)
        self.count = 0

    def __iter__(self):
        self.count = 0
        return self

    def __next__(self) -> Tuple[TensorType["num_rays", 3], Dict]:
        self.count += 1
        image_batch = next(self.iter_image_sampler)
        batch = self.pixel_sampler.sample(image_batch)
        ray_indices = batch["indices"]
        return ray_indices, batch


class EvalDataloader:  # pylint: disable=too-few-public-methods
    """Evaluation dataloader base class"""

    def __init__(
        self, image_dataset: ImageDataset, intrinsics, camera_to_world, num_rays_per_chunk: int, device="cpu", **kwargs
    ):
        super().__init__()
        self.image_dataset = image_dataset
        self.intrinsics = intrinsics
        self.camera_to_world = camera_to_world
        self.num_rays_per_chunk = num_rays_per_chunk
        self.device = device
        self.kwargs = kwargs

    def get_data_from_image_idx(self, image_idx) -> Tuple[RayBundle, Dict]:
        """Returns the data for a specific image index."""
        intrinsics = self.intrinsics[image_idx].to(self.device)
        camera_to_world = self.camera_to_world[image_idx].to(self.device)
        camera = get_camera(intrinsics, camera_to_world, camera_index=image_idx)
        ray_bundle = camera.get_camera_ray_bundle(device=self.device)
        ray_bundle.num_rays_per_chunk = self.num_rays_per_chunk
        batch = self.image_dataset[image_idx]
        batch = get_dict_to_torch(batch, device=self.device)
        return ray_bundle, batch


class FixedIndicesEvalDataloader(EvalDataloader):
    """Dataloader that returns a fixed set of indices."""

    def __init__(
        self,
        image_dataset: ImageDataset,
        intrinsics,
        camera_to_world,
        num_rays_per_chunk: int,
        image_indices: Union[List[int], ListConfig],
        device="cpu",
        **kwargs,
    ):
        super().__init__(image_dataset, intrinsics, camera_to_world, num_rays_per_chunk, device, **kwargs)
        self.image_indices = image_indices
        self.num_rays_per_chunk = num_rays_per_chunk
        self.count = 0

    def __iter__(self):
        self.count = 0
        return self

    def __next__(self):
        if self.count < len(self.image_indices):
            image_idx = self.image_indices[self.count]
            ray_bundle, batch = self.get_data_from_image_idx(image_idx)
            ray_bundle.num_rays_per_chunk = self.num_rays_per_chunk
            self.count += 1
            return ray_bundle, batch
        raise StopIteration


class RandIndicesEvalDataloader(EvalDataloader):
    """Dataloader that returns random images."""

    def __init__(
        self, image_dataset: ImageDataset, intrinsics, camera_to_world, num_rays_per_chunk: int, device="cpu", **kwargs
    ):
        super().__init__(image_dataset, intrinsics, camera_to_world, num_rays_per_chunk, device, **kwargs)
        self.count = 0

    def __iter__(self):
        self.count = 0
        return self

    def __next__(self):
        if self.count < 1:
            image_indices = range(len(self.camera_to_world))
            image_idx = random.choice(image_indices)
            ray_bundle, batch = self.get_data_from_image_idx(image_idx)
            self.count += 1
            return ray_bundle, batch
        raise StopIteration