#!/usr/bin/env python3
import logging
import sys
from dataclasses import dataclass, field
from typing import Any, Dict, List, Optional, Union

import torch
from datasets import DatasetDict, load_dataset
from packaging import version
from torch import nn

import librosa
from transformers import (
    HfArgumentParser,
    Trainer,
    TrainingArguments,
    Wav2Vec2Config,
    Wav2Vec2FeatureExtractor,
    Wav2Vec2ForPreTraining,
    is_apex_available,
    trainer_utils,
)
from transformers.models.wav2vec2.modeling_wav2vec2 import _compute_mask_indices


if is_apex_available():
    from apex import amp

if version.parse(torch.__version__) >= version.parse("1.6"):
    _is_native_amp_available = True
    from torch.cuda.amp import autocast


logger = logging.getLogger(__name__)


@dataclass
class ModelArguments:
    """
    Arguments pertaining to which model/config/tokenizer we are going to fine-tune from.
    """

    model_name_or_path: str = field(
        metadata={"help": "Path to pretrained model or model identifier from huggingface.co/models"}
    )
    cache_dir: Optional[str] = field(
        default=None,
        metadata={"help": "Where do you want to store the pretrained models downloaded from huggingface.co"},
    )
    freeze_feature_extractor: Optional[bool] = field(
        default=True, metadata={"help": "Whether to freeze the feature extractor layers of the model."}
    )
    verbose_logging: Optional[bool] = field(
        default=False,
        metadata={"help": "Whether to log verbose messages or not."},
    )
    max_gumbel_temperature: Optional[float] = field(
        default=2.0, metadata={"help": "Maximum temperature for gumbel softmax."}
    )
    min_gumbel_temperature: Optional[float] = field(
        default=0.5, metadata={"help": "Minimum temperature for gumbel softmax."}
    )
    gumbel_temperature_decay: Optional[float] = field(
        default=0.999995, metadata={"help": "Decay of gumbel temperature during training."}
    )


def configure_logger(model_args: ModelArguments, training_args: TrainingArguments):
    logging.basicConfig(
        format="%(asctime)s - %(levelname)s - %(name)s - %(message)s",
        datefmt="%m/%d/%Y %H:%M:%S",
        handlers=[logging.StreamHandler(sys.stdout)],
    )
    logging_level = logging.WARNING
    if model_args.verbose_logging:
        logging_level = logging.DEBUG
    elif trainer_utils.is_main_process(training_args.local_rank):
        logging_level = logging.INFO
    logger.setLevel(logging_level)


@dataclass
class DataTrainingArguments:
    """
    Arguments pertaining to what data we are going to input our model for training and eval.

    Using `HfArgumentParser` we can turn this class
    into argparse arguments to be able to specify them on
    the command line.
    """

    dataset_name: str = field(
        default=None, metadata={"help": "The name of the dataset to use (via the datasets library)."}
    )
    dataset_config_name: Optional[str] = field(
        default=None, metadata={"help": "The configuration name of the dataset to use (via the datasets library)."}
    )
    train_split_name: Optional[str] = field(
        default="train",
        metadata={
            "help": "The name of the training data set split to use (via the datasets library). Defaults to 'train'"
        },
    )
    validation_split_name: Optional[str] = field(
        default="validation",
        metadata={
            "help": (
                "The name of the validation data set split to use (via the datasets library). Defaults to 'validation'"
            )
        },
    )
    speech_file_column: Optional[str] = field(
        default="file",
        metadata={"help": "Column in the dataset that contains speech file path. Defaults to 'file'"},
    )
    overwrite_cache: bool = field(
        default=False, metadata={"help": "Overwrite the cached preprocessed datasets or not."}
    )
    validation_split_percentage: Optional[int] = field(
        default=1,
        metadata={
            "help": "The percentage of the train set used as validation set in case there's no validation split"
        },
    )
    preprocessing_num_workers: Optional[int] = field(
        default=None,
        metadata={"help": "The number of processes to use for the preprocessing."},
    )
    max_duration_in_seconds: Optional[float] = field(
        default=20.0, metadata={"help": "Filter audio files that are longer than `max_duration_in_seconds` seconds"}
    )


@dataclass
class DataCollatorForWav2Vec2Pretraining:
    """
    Data collator that will dynamically pad the inputs received and prepare masked indices
    for self-supervised pretraining.

    Args:
        model (:class:`~transformers.Wav2Vec2ForPreTraining`):
            The Wav2Vec2 model used for pretraining. The data collator needs to have access
            to config and ``_get_feat_extract_output_lengths`` function for correct padding.
        feature_extractor (:class:`~transformers.Wav2Vec2FeatureExtractor`):
            The processor used for proccessing the data.
        padding (:obj:`bool`, :obj:`str` or :class:`~transformers.tokenization_utils_base.PaddingStrategy`, `optional`, defaults to :obj:`True`):
            Select a strategy to pad the returned sequences (according to the model's padding side and padding index)
            among:
            * :obj:`True` or :obj:`'longest'`: Pad to the longest sequence in the batch (or no padding if only a single
              sequence if provided).
            * :obj:`'max_length'`: Pad to a maximum length specified with the argument :obj:`max_length` or to the
              maximum acceptable input length for the model if that argument is not provided.
            * :obj:`False` or :obj:`'do_not_pad'` (default): No padding (i.e., can output a batch with sequences of
              different lengths).
        max_length (:obj:`int`, `optional`):
            Maximum length of the ``input_values`` of the returned list and optionally padding length (see above).
        pad_to_multiple_of (:obj:`int`, `optional`):
            If set will pad the sequence to a multiple of the provided value.
            This is especially useful to enable the use of Tensor Cores on NVIDIA hardware with compute capability >=
            7.5 (Volta).
    """

    model: Wav2Vec2ForPreTraining
    feature_extractor: Wav2Vec2FeatureExtractor
    padding: Union[bool, str] = "longest"
    pad_to_multiple_of: Optional[int] = None
    max_length: Optional[int] = None

    def __call__(self, features: List[Dict[str, Union[List[int], torch.Tensor]]]) -> Dict[str, torch.Tensor]:
        # reformat list to dict and set to pytorch format
        batch = self.feature_extractor.pad(
            features,
            max_length=self.max_length,
            padding=self.padding,
            pad_to_multiple_of=self.pad_to_multiple_of,
            return_tensors="pt",
        )
        mask_indices_seq_length = self.model._get_feat_extract_output_lengths(batch["input_values"].shape[-1])

        batch_size = batch["input_values"].shape[0]

        # make sure that no loss is computed on padded inputs
        if batch["attention_mask"] is not None:
            # compute real output lengths according to convolution formula
            output_lengths = self.model._get_feat_extract_output_lengths(batch["attention_mask"].sum(-1)).to(
                torch.long
            )

            attention_mask = torch.zeros(
                (batch_size, mask_indices_seq_length), dtype=torch.long, device=batch["input_values"].device
            )

            # these two operations makes sure that all values
            # before the output lengths indices are attended to
            attention_mask[
                (torch.arange(attention_mask.shape[0], device=batch["input_values"].device), output_lengths - 1)
            ] = 1
            attention_mask = attention_mask.flip([-1]).cumsum(-1).flip([-1]).bool()

        # sample randomly masked indices
        batch["mask_time_indices"] = _compute_mask_indices(
            (batch_size, mask_indices_seq_length),
            self.model.config.mask_time_prob,
            self.model.config.mask_time_length,
            attention_mask=attention_mask,
            min_masks=2,
        )

        return batch


class Wav2Vec2PreTrainer(Trainer):
    """
    Subclassed :class:`~transformers.Trainer` for Wav2Vec2-like pretraining. Trainer can decay gumbel softmax temperature during training.
    """

    def __init__(self, *args, max_gumbel_temp=1, min_gumbel_temp=0, gumbel_temp_decay=1.0, **kwargs):
        super().__init__(*args, **kwargs)
        self.num_update_step = 0
        self.max_gumbel_temp = max_gumbel_temp
        self.min_gumbel_temp = min_gumbel_temp
        self.gumbel_temp_decay = gumbel_temp_decay

    def training_step(self, model: nn.Module, inputs: Dict[str, Union[torch.Tensor, Any]]) -> torch.Tensor:
        """
        Perform a training step on a batch of inputs.

        Subclass and override to inject custom behavior.

        Args:
            model (:obj:`nn.Module`):
                The model to train.
            inputs (:obj:`Dict[str, Union[torch.Tensor, Any]]`):
                The inputs and targets of the model.

                The dictionary will be unpacked before being fed to the model. Most models expect the targets under the
                argument :obj:`labels`. Check your model's documentation for all accepted arguments.

        Return:
            :obj:`torch.Tensor`: The tensor with training loss on this batch.
        """

        model.train()
        inputs = self._prepare_inputs(inputs)

        if self.use_amp:
            with autocast():
                loss = self.compute_loss(model, inputs)
        else:
            loss = self.compute_loss(model, inputs)

        if self.args.n_gpu > 1 or self.deepspeed:
            if model.module.config.ctc_loss_reduction == "mean":
                loss = loss.mean()
            elif model.module.config.ctc_loss_reduction == "sum":
                loss = loss.sum() / (inputs["mask_time_indices"]).sum()
            else:
                raise ValueError(f"{model.config.ctc_loss_reduction} is not valid. Choose one of ['mean', 'sum']")

        if self.args.gradient_accumulation_steps > 1:
            loss = loss / self.args.gradient_accumulation_steps

        if self.use_amp:
            self.scaler.scale(loss).backward()
        elif self.use_apex:
            with amp.scale_loss(loss, self.optimizer) as scaled_loss:
                scaled_loss.backward()
        elif self.deepspeed:
            self.deepspeed.backward(loss)
        else:
            loss.backward()

        self.num_update_step += 1
        # make sure gumbel softmax temperature is decayed
        if self.args.n_gpu > 1 or self.deepspeed:
            model.module.set_gumbel_temperature(
                max(self.max_gumbel_temp * self.gumbel_temp_decay**self.num_update_step, self.min_gumbel_temp)
            )
        else:
            model.set_gumbel_temperature(
                max(self.max_gumbel_temp * self.gumbel_temp_decay**self.num_update_step, self.min_gumbel_temp)
            )

        return loss.detach()


def main():
    # See all possible arguments in src/transformers/training_args.py
    # or by passing the --help flag to this script.
    # We now keep distinct sets of args, for a cleaner separation of concerns.

    parser = HfArgumentParser((ModelArguments, DataTrainingArguments, TrainingArguments))

    model_args, data_args, training_args = parser.parse_args_into_dataclasses()
    configure_logger(model_args, training_args)

    # Downloading and loading a dataset from the hub.
    datasets = load_dataset(data_args.dataset_name, data_args.dataset_config_name, cache_dir=model_args.cache_dir)

    if "validation" not in datasets.keys():
        # make sure only "validation" and "train" keys remain"
        datasets = DatasetDict()
        datasets["validation"] = load_dataset(
            data_args.dataset_name,
            data_args.dataset_config_name,
            split=f"{data_args.train_split_name}[:{data_args.validation_split_percentage}%]",
            cache_dir=model_args.cache_dir,
        )
        datasets["train"] = load_dataset(
            data_args.dataset_name,
            data_args.dataset_config_name,
            split=f"{data_args.train_split_name}[{data_args.validation_split_percentage}%:]",
            cache_dir=model_args.cache_dir,
        )
    else:
        # make sure only "validation" and "train" keys remain"
        datasets = DatasetDict()
        datasets["validation"] = load_dataset(
            data_args.dataset_name,
            data_args.dataset_config_name,
            split="validation",
            cache_dir=model_args.cache_dir,
        )
        datasets["train"] = load_dataset(
            data_args.dataset_name,
            data_args.dataset_config_name,
            split=f"{data_args.train_split_name}",
            cache_dir=model_args.cache_dir,
        )

    # only normalized-inputs-training is supported
    feature_extractor = Wav2Vec2FeatureExtractor.from_pretrained(
        model_args.model_name_or_path, cache_dir=model_args.cache_dir, do_normalize=True
    )

    def prepare_dataset(batch):
        # check that all files have the correct sampling rate
        batch["speech"], _ = librosa.load(batch[data_args.speech_file_column], sr=feature_extractor.sampling_rate)
        return batch

    # load audio files into numpy arrays
    vectorized_datasets = datasets.map(
        prepare_dataset, num_proc=data_args.preprocessing_num_workers, remove_columns=datasets["train"].column_names
    )

    # filter audio files that are too long
    vectorized_datasets = vectorized_datasets.filter(
        lambda data: len(data["speech"]) < int(data_args.max_duration_in_seconds * feature_extractor.sampling_rate)
    )

    def normalize(batch):
        return feature_extractor(batch["speech"], sampling_rate=feature_extractor.sampling_rate)

    # normalize and transform to `BatchFeatures`
    vectorized_datasets = vectorized_datasets.map(
        normalize,
        batched=True,
        num_proc=data_args.preprocessing_num_workers,
        load_from_cache_file=not data_args.overwrite_cache,
        remove_columns=vectorized_datasets["train"].column_names,
    )

    # pretraining is only supported for "newer" stable layer norm architecture
    # apply_spec_augment has to be True, mask_feature_prob has to be 0.0
    config = Wav2Vec2Config.from_pretrained(
        model_args.model_name_or_path,
        cache_dir=model_args.cache_dir,
        gradient_checkpointing=training_args.gradient_checkpointing,
    )

    if not config.do_stable_layer_norm or config.feat_extract_norm != "layer":
        raise ValueError(
            "PreTraining is only supported for ``config.do_stable_layer_norm=True`` and"
            " ``config.feat_extract_norm='layer'"
        )

    model = Wav2Vec2ForPreTraining(config)

    data_collator = DataCollatorForWav2Vec2Pretraining(model=model, feature_extractor=feature_extractor)

    trainer = Wav2Vec2PreTrainer(
        model=model,
        data_collator=data_collator,
        args=training_args,
        train_dataset=vectorized_datasets["train"],
        eval_dataset=vectorized_datasets["validation"],
        tokenizer=feature_extractor,
        max_gumbel_temp=model_args.max_gumbel_temperature,
        min_gumbel_temp=model_args.min_gumbel_temperature,
        gumbel_temp_decay=model_args.gumbel_temperature_decay,
    )
    trainer.train()


if __name__ == "__main__":
    main()
