import os
import random
from datasets import ClassLabel, Dataset, DatasetDict, load_dataset
from datasets.features import Audio
import pandas as pd
import numpy as np
from tqdm import tqdm
from IPython.display import display, HTML

# Function to load your custom dataset
def load_custom_dataset(data_dir):
    data = {
        "audio": [],
        "text": []
    }

    wav_dir = os.path.join(data_dir, 'wav')
    txt_dir = os.path.join(data_dir, 'transcription')

        # Assuming filenames in 'wav' and 'txt' match
    for wav_file in os.listdir(wav_dir):
            if wav_file.endswith('.wav'):
                txt_file = wav_file.replace('.wav', '.txt')
                wav_path = os.path.join(wav_dir, wav_file)
                txt_path = os.path.join(txt_dir, txt_file)

                # Read the transcription text
                with open(txt_path, 'r', encoding='utf-8') as f:
                    transcription = f.read().strip()

                # Append to the dataset
                data["audio"].append(wav_path)
                data["text"].append(transcription)

    # Create a pandas dataframe
    df = pd.DataFrame(data)

    # Convert to a Hugging Face dataset
    dataset = Dataset.from_pandas(df)

    # Define the audio feature (for .wav files)
    dataset = dataset.cast_column("audio", Audio(sampling_rate=16_000))  # Adjust the sampling rate if needed

    return dataset

custom_train_dataset = load_custom_dataset("./")

# Combine them into a DatasetDict
dataset_dict = DatasetDict({
    "train": custom_train_dataset,
})

# Select 975 random samples from train and add them to test
train_size = len(dataset_dict["train"])
sample_indices = random.sample(range(train_size), 975)

# Select the samples
test_samples = dataset_dict["train"].select(sample_indices)

# Filter out the selected samples from the train dataset
remaining_train_samples = dataset_dict["train"].filter(lambda example, idx: idx not in sample_indices, with_indices=True)

# Add the selected samples to the test dataset
dataset_dict["test"] = test_samples
dataset_dict["train"] = remaining_train_samples

print(dataset_dict)

def show_random_elements(dataset, num_examples=10):
    assert num_examples <= len(dataset), "Can't pick more elements than there are in the dataset."
    picks = []
    for _ in range(num_examples):
        pick = random.randint(0, len(dataset)-1)
        while pick in picks:
            pick = random.randint(0, len(dataset)-1)
        picks.append(pick)

    df = pd.DataFrame(dataset[picks])

show_random_elements(dataset_dict["train"])

import re
chars_to_ignore_regex = '[\,\?\.\!\-\;\:\"]'

def remove_special_characters(batch):
    batch["text"] = re.sub(chars_to_ignore_regex, '', batch["text"]).lower()
    return batch

dataset_dict = dataset_dict.map(remove_special_characters)

show_random_elements(dataset_dict["train"])

def extract_all_chars(batch):
  all_text = " ".join(batch["text"])
  vocab = list(set(all_text))
  return {"vocab": [vocab], "all_text": [all_text]}

vocabs = dataset_dict.map(extract_all_chars, batched=True, batch_size=-1, keep_in_memory=True, remove_columns=dataset_dict.column_names["train"])

vocab_list = list(set(vocabs["train"]["vocab"][0]))

vocab_dict = {v: k for k, v in enumerate(vocab_list)}
print(vocab_dict)

vocab_dict["[UNK]"] = len(vocab_dict)
vocab_dict["[PAD]"] = len(vocab_dict)
print(len(vocab_dict))

import json
with open('vocab.json', 'w') as vocab_file:
    json.dump(vocab_dict, vocab_file)

from transformers import Wav2Vec2CTCTokenizer

tokenizer = Wav2Vec2CTCTokenizer("./vocab.json", unk_token="[UNK]", pad_token="[PAD]", word_delimiter_token="|", vocab_size=len(vocab_dict))

from transformers import Wav2Vec2FeatureExtractor

feature_extractor = Wav2Vec2FeatureExtractor(feature_size=1, sampling_rate=16000, padding_value=0.0, do_normalize=True, return_attention_mask=False)

from transformers import Wav2Vec2Processor

processor = Wav2Vec2Processor(feature_extractor=feature_extractor, tokenizer=tokenizer)

rand_int = random.randint(0, len(dataset_dict["train"]))

print("Target text:", dataset_dict["train"][rand_int]["text"])
print("Input array shape:", np.asarray(dataset_dict["train"][rand_int]["audio"]["array"]).shape)
print("Sampling rate:", dataset_dict["train"][rand_int]["audio"]["sampling_rate"])

def prepare_dataset(batch):
    audio = batch["audio"]

    # batched output is "un-batched" to ensure mapping is correct
    batch["input_values"] = processor(audio["array"], sampling_rate=audio["sampling_rate"]).input_values[0]

    with processor.as_target_processor():
        batch["labels"] = processor(batch["text"]).input_ids
    return batch

dataset_dict = dataset_dict.map(prepare_dataset, remove_columns=dataset_dict.column_names["train"], num_proc=None)

import torch

from dataclasses import dataclass, field
from typing import Any, Dict, List, Optional, Union

@dataclass
class DataCollatorCTCWithPadding:
    """
    Data collator that will dynamically pad the inputs received.
    Args:
        processor (:class:`~transformers.Wav2Vec2Processor`)
            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).
        max_length_labels (:obj:`int`, `optional`):
            Maximum length of the ``labels`` 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).
    """

    processor: Wav2Vec2Processor
    padding: Union[bool, str] = True
    max_length: Optional[int] = None
    max_length_labels: Optional[int] = None
    pad_to_multiple_of: Optional[int] = None
    pad_to_multiple_of_labels: Optional[int] = None

    def __call__(self, features: List[Dict[str, Union[List[int], torch.Tensor]]]) -> Dict[str, torch.Tensor]:
        # split inputs and labels since they have to be of different lengths and need
        # different padding methods
        input_features = [{"input_values": feature["input_values"]} for feature in features]
        label_features = [{"input_ids": feature["labels"]} for feature in features]

        batch = self.processor.pad(
            input_features,
            padding=self.padding,
            max_length=self.max_length,
            pad_to_multiple_of=self.pad_to_multiple_of,
            return_tensors="pt",
        )
        with self.processor.as_target_processor():
            labels_batch = self.processor.pad(
                label_features,
                padding=self.padding,
                max_length=self.max_length_labels,
                pad_to_multiple_of=self.pad_to_multiple_of_labels,
                return_tensors="pt",
            )

        # replace padding with -100 to ignore loss correctly
        labels = labels_batch["input_ids"].masked_fill(labels_batch.attention_mask.ne(1), -100)

        batch["labels"] = labels

        return batch

data_collator = DataCollatorCTCWithPadding(processor=processor, padding=True)

import evaluate

wer_metric = evaluate.load("wer")

def compute_metrics(pred):
    pred_logits = pred.predictions
    pred_ids = np.argmax(pred_logits, axis=-1)

    pred.label_ids[pred.label_ids == -100] = processor.tokenizer.pad_token_id

    pred_str = processor.batch_decode(pred_ids)
    # we do not want to group tokens when computing the metrics
    label_str = processor.batch_decode(pred.label_ids, group_tokens=False)

    wer = wer_metric.compute(predictions=pred_str, references=label_str)

    return {"wer": wer}

from transformers import Wav2Vec2ForCTC

model = Wav2Vec2ForCTC.from_pretrained(
    "facebook/wav2vec2-large",
    ctc_loss_reduction="mean",
    pad_token_id=processor.tokenizer.pad_token_id,
    vocab_size=len(vocab_dict),
)

model.freeze_feature_encoder()

model.gradient_checkpointing_enable()

from transformers import TrainingArguments

training_args = TrainingArguments(
  output_dir='wav2vec2-large-mal',
  group_by_length=True,
  per_device_train_batch_size=36,
  eval_strategy="steps",
  num_train_epochs=30,
  fp16=True,
  gradient_checkpointing=True,
  save_steps=500,
  eval_steps=500,
  logging_steps=500,
  learning_rate=1e-4,
  weight_decay=0.005,
  warmup_steps=1000,
  save_total_limit=2,
)

from transformers import Trainer

trainer = Trainer(
    model=model,
    data_collator=data_collator,
    args=training_args,
    compute_metrics=compute_metrics,
    train_dataset=dataset_dict["train"],
    eval_dataset=dataset_dict["test"],
    processing_class=processor.feature_extractor,
)

trainer.train()

def map_to_result(batch):
  with torch.no_grad():
    input_values = torch.tensor(batch["input_values"], device="cuda").unsqueeze(0)
    logits = model(input_values).logits

  pred_ids = torch.argmax(logits, dim=-1)
  batch["pred_str"] = processor.batch_decode(pred_ids)[0]
  batch["text"] = processor.decode(batch["labels"], group_tokens=False)

  return batch

results = dataset_dict["test"].map(map_to_result, remove_columns=dataset_dict["test"].column_names)

print("Test WER: {:.3f}".format(wer_metric.compute(predictions=results["pred_str"], references=results["text"])))