# Copyright      2021  Piotr Żelasko
#                2022  Xiaomi Corp.        (authors: Fangjun Kuang)
#
# See ../../../../LICENSE for clarification regarding multiple authors
#
# 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.

import argparse
import logging
from pathlib import Path
from typing import Optional

from lhotse import CutSet, Fbank, FbankConfig
from lhotse.dataset import (
    CutMix,
    DynamicBucketingSampler,
    K2SpeechRecognitionDataset,
    SpecAugment,
)
from lhotse.dataset.input_strategies import (
    OnTheFlyFeatures,
    PrecomputedFeatures,
)
from torch.utils.data import DataLoader

from icefall.utils import str2bool


class AsrDataModule:
    def __init__(self, args: argparse.Namespace):
        self.args = args

    @classmethod
    def add_arguments(cls, parser: argparse.ArgumentParser):
        group = parser.add_argument_group(
            title="ASR data related options",
            description="These options are used for the preparation of "
            "PyTorch DataLoaders from Lhotse CutSet's -- they control the "
            "effective batch sizes, sampling strategies, applied data "
            "augmentations, etc.",
        )

        group.add_argument(
            "--max-duration",
            type=int,
            default=200.0,
            help="Maximum pooled recordings duration (seconds) in a "
            "single batch. You can reduce it if it causes CUDA OOM.",
        )

        group.add_argument(
            "--bucketing-sampler",
            type=str2bool,
            default=True,
            help="When enabled, the batches will come from buckets of "
            "similar duration (saves padding frames).",
        )

        group.add_argument(
            "--num-buckets",
            type=int,
            default=30,
            help="The number of buckets for the DynamicBucketingSampler. "
            "(you might want to increase it for larger datasets).",
        )

        group.add_argument(
            "--shuffle",
            type=str2bool,
            default=True,
            help="When enabled (=default), the examples will be "
            "shuffled for each epoch.",
        )

        group.add_argument(
            "--return-cuts",
            type=str2bool,
            default=True,
            help="When enabled, each batch will have the "
            "field: batch['supervisions']['cut'] with the cuts that "
            "were used to construct it.",
        )

        group.add_argument(
            "--num-workers",
            type=int,
            default=2,
            help="The number of training dataloader workers that "
            "collect the batches.",
        )

        group.add_argument(
            "--on-the-fly-num-workers",
            type=int,
            default=0,
            help="The number of workers for on-the-fly feature extraction",
        )

        group.add_argument(
            "--enable-spec-aug",
            type=str2bool,
            default=True,
            help="When enabled, use SpecAugment for training dataset.",
        )

        group.add_argument(
            "--spec-aug-time-warp-factor",
            type=int,
            default=80,
            help="Used only when --enable-spec-aug is True. "
            "It specifies the factor for time warping in SpecAugment. "
            "Larger values mean more warping. "
            "A value less than 1 means to disable time warp.",
        )

        group.add_argument(
            "--enable-musan",
            type=str2bool,
            default=True,
            help="When enabled, select noise from MUSAN and mix it"
            "with training dataset. ",
        )

        group.add_argument(
            "--manifest-dir",
            type=Path,
            default=Path("data/fbank"),
            help="Path to directory with train/valid/test cuts.",
        )

        group.add_argument(
            "--on-the-fly-feats",
            type=str2bool,
            default=False,
            help="When enabled, use on-the-fly cut mixing and feature "
            "extraction. Will drop existing precomputed feature manifests "
            "if available. Used only in dev/test CutSet",
        )

    def train_dataloaders(
        self,
        cuts_train: CutSet,
        on_the_fly_feats: bool,
        cuts_musan: Optional[CutSet] = None,
    ) -> DataLoader:
        """
        Args:
          cuts_train:
            Cuts for training.
          cuts_musan:
            If not None, it is the cuts for mixing.
          on_the_fly_feats:
            True to use OnTheFlyFeatures;
            False to use PrecomputedFeatures.
        """
        transforms = []
        if cuts_musan is not None:
            logging.info("Enable MUSAN")
            transforms.append(
                CutMix(
                    cuts=cuts_musan, prob=0.5, snr=(10, 20), preserve_id=True
                )
            )
        else:
            logging.info("Disable MUSAN")

        input_transforms = []

        if self.args.enable_spec_aug:
            logging.info("Enable SpecAugment")
            logging.info(
                f"Time warp factor: {self.args.spec_aug_time_warp_factor}"
            )
            input_transforms.append(
                SpecAugment(
                    time_warp_factor=self.args.spec_aug_time_warp_factor,
                    num_frame_masks=2,
                    features_mask_size=27,
                    num_feature_masks=2,
                    frames_mask_size=100,
                )
            )
        else:
            logging.info("Disable SpecAugment")

        logging.info("About to create train dataset")
        train = K2SpeechRecognitionDataset(
            cut_transforms=transforms,
            input_transforms=input_transforms,
            return_cuts=self.args.return_cuts,
        )

        # NOTE: the PerturbSpeed transform should be added only if we
        # remove it from data prep stage.
        # Add on-the-fly speed perturbation; since originally it would
        # have increased epoch size by 3, we will apply prob 2/3 and use
        # 3x more epochs.
        # Speed perturbation probably should come first before
        # concatenation, but in principle the transforms order doesn't have
        # to be strict (e.g. could be randomized)
        # transforms = [PerturbSpeed(factors=[0.9, 1.1], p=2/3)] + transforms   # noqa
        # Drop feats to be on the safe side.
        train = K2SpeechRecognitionDataset(
            cut_transforms=transforms,
            input_strategy=(
                OnTheFlyFeatures(
                    extractor=Fbank(FbankConfig(num_mel_bins=80)),
                    num_workers=self.args.on_the_fly_num_workers,
                )
                if on_the_fly_feats
                else PrecomputedFeatures()
            ),
            input_transforms=input_transforms,
            return_cuts=self.args.return_cuts,
        )

        logging.info("Using DynamicBucketingSampler.")
        train_sampler = DynamicBucketingSampler(
            cuts_train,
            max_duration=self.args.max_duration,
            shuffle=self.args.shuffle,
            num_buckets=self.args.num_buckets,
            drop_last=True,
        )

        logging.info("About to create train dataloader")
        train_dl = DataLoader(
            train,
            sampler=train_sampler,
            batch_size=None,
            num_workers=self.args.num_workers,
            persistent_workers=False,
        )
        return train_dl

    def valid_dataloaders(self, cuts_valid: CutSet) -> DataLoader:
        transforms = []

        logging.info("About to create dev dataset")
        if self.args.on_the_fly_feats:
            validate = K2SpeechRecognitionDataset(
                cut_transforms=transforms,
                input_strategy=OnTheFlyFeatures(
                    Fbank(FbankConfig(num_mel_bins=80))
                ),
                return_cuts=self.args.return_cuts,
            )
        else:
            validate = K2SpeechRecognitionDataset(
                cut_transforms=transforms,
                return_cuts=self.args.return_cuts,
            )
        valid_sampler = DynamicBucketingSampler(
            cuts_valid,
            max_duration=self.args.max_duration,
            shuffle=False,
            num_buckets=self.args.num_buckets,
            drop_last=False,
        )
        logging.info("About to create dev dataloader")
        valid_dl = DataLoader(
            validate,
            sampler=valid_sampler,
            batch_size=None,
            num_workers=2,
            persistent_workers=False,
        )

        return valid_dl

    def test_dataloaders(self, cuts: CutSet) -> DataLoader:
        logging.debug("About to create test dataset")
        test = K2SpeechRecognitionDataset(
            input_strategy=OnTheFlyFeatures(Fbank(FbankConfig(num_mel_bins=80)))
            if self.args.on_the_fly_feats
            else PrecomputedFeatures(),
            return_cuts=self.args.return_cuts,
        )
        sampler = DynamicBucketingSampler(
            cuts,
            max_duration=self.args.max_duration,
            shuffle=False,
            num_buckets=self.args.num_buckets,
            drop_last=True,
        )
        logging.debug("About to create test dataloader")
        test_dl = DataLoader(
            test,
            batch_size=None,
            sampler=sampler,
            num_workers=self.args.num_workers,
        )
        return test_dl
