import torch
import torch.nn as nn
import torch.optim as optim
import numpy as np
import pickle
from torch.utils.data import Dataset, DataLoader
from safetensors.torch import save_file
import logging
import json

# Set up logging
logging.basicConfig(level=logging.INFO, format='%(asctime)s - %(levelname)s - %(message)s')

# Hyperparameters
sequence_length = 64
batch_size = 16
num_epochs = 1
learning_rate = 0.00001
embedding_dim = 256
hidden_dim = 800
num_layers = 4

# Read the text file
logging.info('Reading the text file...')
with open('fulltext.json', 'r') as file:
    text = file.read()
logging.info('Text file read successfully.')

# Preprocess the text
logging.info('Preprocessing the text...')
words = json.loads(text)
vocab = set(words)
vocab.add('<pad>')
vocab.add('<UNK>')
word2idx = {word: idx for idx, word in enumerate(vocab)}
idx2word = {idx: word for idx, word in enumerate(vocab)}
vocab_size = len(vocab)

logging.info(f'Vocabulary size: {vocab_size}')
#logging.info(f'Word to index mapping: {word2idx}')

# Create sequences
logging.info('Creating sequences...')
sequences = []
for i in range(len(words) - sequence_length):
    seq = words[i:i + sequence_length]
    label = words[i + sequence_length]
    sequences.append((seq, label))

logging.info(f'Number of sequences: {len(sequences)}')

# Dataset and DataLoader
class TextDataset(Dataset):
    def __init__(self, sequences, word2idx):
        self.sequences = sequences
        self.word2idx = word2idx

    def __len__(self):
        return len(self.sequences)

    def __getitem__(self, idx):
        seq, label = self.sequences[idx]
        seq_idx = [self.word2idx.get(word, self.word2idx['<UNK>']) for word in seq]
        label_idx = self.word2idx.get(label, self.word2idx['<UNK>'])
        return torch.tensor(seq_idx, dtype=torch.long), torch.tensor(label_idx, dtype=torch.long)

logging.info('Creating dataset and dataloader...')
dataset = TextDataset(sequences, word2idx)
dataloader = DataLoader(dataset, batch_size=batch_size, shuffle=True)

# LSTM Model
class LSTMModel(nn.Module):
    def __init__(self, vocab_size, embedding_dim, hidden_dim, num_layers):
        super(LSTMModel, self).__init__()
        self.embedding = nn.Embedding(vocab_size, embedding_dim)
        self.lstm = nn.LSTM(embedding_dim, hidden_dim, num_layers, batch_first=True)
        self.fc = nn.Linear(hidden_dim, vocab_size)

    def forward(self, x):
        embeds = self.embedding(x)
        lstm_out, _ = self.lstm(embeds)
        logits = self.fc(lstm_out[:, -1, :])
        return logits

logging.info('Initializing the LSTM model...')
model = LSTMModel(vocab_size, embedding_dim, hidden_dim, num_layers)
criterion = nn.CrossEntropyLoss()
optimizer = optim.Adam(model.parameters(), lr=learning_rate)

# Training loop
logging.info('Starting training...')
for epoch in range(num_epochs):
    for batch_idx, batch in enumerate(dataloader):
        inputs, targets = batch
        outputs = model(inputs)
        loss = criterion(outputs, targets)

        optimizer.zero_grad()
        loss.backward()
        optimizer.step()

        if batch_idx % 10 == 0:
            logging.info(f'Epoch [{epoch+1}/{num_epochs}], Batch [{batch_idx}/{len(dataloader)}], Loss: {loss.item():.4f}')

# Save the model
logging.info('Saving the model...')
save_file(model.state_dict(), 'lstm_model.safetensors')
with open('word2idx.pkl', 'wb') as f:
    pickle.dump(word2idx, f)
with open('idx2word.pkl', 'wb') as f:
    pickle.dump(idx2word, f)

logging.info('Model and vocabulary saved successfully.')