# Copyright (c) 2020, NVIDIA CORPORATION.  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.

"""
# Preparing the Tokenizer for the dataset
Use the `process_asr_text_tokenizer.py` script under <NEMO_ROOT>/scripts/tokenizers/ in order to prepare the tokenizer.

```sh
python <NEMO_ROOT>/scripts/tokenizers/process_asr_text_tokenizer.py \
        --manifest=<path to train manifest files, seperated by commas>
        OR
        --data_file=<path to text data, seperated by commas> \
        --data_root="<output directory>" \
        --vocab_size=<number of tokens in vocabulary> \
        --tokenizer=<"spe" or "wpe"> \
        --no_lower_case \
        --spe_type=<"unigram", "bpe", "char" or "word"> \
        --spe_character_coverage=1.0 \
        --log
```

# Training the model
```sh
python speech_to_text_ctc_bpe.py \
    # (Optional: --config-path=<path to dir of configs> --config-name=<name of config without .yaml>) \
    model.train_ds.manifest_filepath=<path to train manifest> \
    model.validation_ds.manifest_filepath=<path to val/test manifest> \
    model.tokenizer.dir=<path to directory of tokenizer (not full path to the vocab file!)> \
    model.tokenizer.type=<either bpe or wpe> \
    trainer.devices=-1 \
    trainer.accelerator="gpu" \
    trainer.strategy="ddp" \
    trainer.max_epochs=100 \
    model.optim.name="adamw" \
    model.optim.lr=0.001 \
    model.optim.betas=[0.9,0.999] \
    model.optim.weight_decay=0.0001 \
    model.optim.sched.warmup_steps=2000
    exp_manager.create_wandb_logger=True \
    exp_manager.wandb_logger_kwargs.name="<Name of experiment>" \
    exp_manager.wandb_logger_kwargs.project="<Name of project>"
```

# Fine-tune a model

For documentation on fine-tuning this model, please visit -
https://docs.nvidia.com/deeplearning/nemo/user-guide/docs/en/main/asr/configs.html#fine-tuning-configurations

# Pretrained Models

For documentation on existing pretrained models, please visit -
https://docs.nvidia.com/deeplearning/nemo/user-guide/docs/en/main/asr/results.html

"""

import pytorch_lightning as pl
from omegaconf import OmegaConf

from nemo.collections.asr.models.ctc_bpe_models import EncDecCTCModelBPE
from nemo.core.config import hydra_runner
from nemo.utils import logging
from nemo.utils.exp_manager import exp_manager


@hydra_runner(config_path="../conf/citrinet/", config_name="config_bpe")
def main(cfg):
    logging.info(f'Hydra config: {OmegaConf.to_yaml(cfg)}')

    trainer = pl.Trainer(**cfg.trainer)
    exp_manager(trainer, cfg.get("exp_manager", None))
    asr_model = EncDecCTCModelBPE(cfg=cfg.model, trainer=trainer)

    # Initialize the weights of the model from another model, if provided via config
    asr_model.maybe_init_from_pretrained_checkpoint(cfg)

    trainer.fit(asr_model)

    if hasattr(cfg.model, 'test_ds') and cfg.model.test_ds.manifest_filepath is not None:
        if asr_model.prepare_test(trainer):
            trainer.test(asr_model)


if __name__ == '__main__':
    main()
