import torch
from transformers import AutoModelForCausalLM, AutoTokenizer

class AutofixCodeAILLModel(AutoModelForCausalLM):
    def  __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.decoder = AutoDecoder(self.config.decoder_hidden_size, self.config.decoder_num_layers)

    @property
    def decoder(self):
        return self._decoder

    @decoder.setter
    def decoder(self, value):
        self._decoder = value

class AutoDecoder(torch.nn.Module):
    def __init__(self, hidden_size, num_layers):
        super().__init__()
        self.layers = torch.nn.ModuleList([torch.nn.TransformerEncoderLayer(d_model=hidden_size, nhead=8, dim_feedforward=hidden_size, dropout=0.1) for _ in range(num_layers)])

    def forward(self, x):
        for layer in self.layers:
            x = layer(x)
        return x

# Load the pre-trained model and tokenizer
model_name_or_path = "autofixcodeai-base"
tokenizer = AutoTokenizer.from_pretrained(model_name_or_path)
ll_model = AutofixCodeAILLModel.from_pretrained(model_name_or_path)

# Define the custom dataset class for your AutofixCodeAI model
class CodeFixDataset(torch.utils.data.Dataset):
    def  __init__(self, code_snippets, fix_snippets):
        self.code_snippets = code_snippets
        self.fix_snippets = fix_snippets

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

    def  __getitem__(self, idx):
        code = self.code_snippets[idx]["code"]
        fix = self.fix_snippets[idx]["fix"]
        input_ids = tokenizer.encode(code, max_length=512, return_tensors="pt", truncation=True)
        attention_mask = tokenizer.encode(fix, max_length=512, return_tensors="pt", truncation=True, add_special_tokens=False)
        labels = torch.tensor(tokenizer.encode(fix, return_tensors="pt", add_special_tokens=False)).flatten()
        return {"input_ids": input_ids, "attention_mask": attention_mask, "labels": labels}

# Load the dataset and create a data loader
dataset = CodeFixDataset(code_snippets, fix_snippets)
data_loader = torch.utils.data.DataLoader(dataset, batch_size=32, shuffle=True)

# Define the custom trainer class for your AutofixCodeAI model
class Trainer(torch.nn.Module):
    def  __init__(self, model, data_loader, device="cuda"):
        super().__init__()
        self.model = model
        self.data_loader = data_loader
        self.device = device

    def  forward(self, input_ids, attention_mask, labels):
        output = self.model(input_ids=input_ids, attention_mask=attention_mask)
        loss = self.loss_fn(output, labels)
        return loss

    @property
    def loss_fn(self):
        return torch.nn.CrossEntropyLoss()

# Train the model using the custom trainer class
trainer = Trainer(ll_model, data_loader, device="cuda")
for epoch in range(5):
    trainer.model.train()
    total_loss = 0
    for batch in data_loader:
        input_ids = batch["input_ids"].to(device)
        attention_mask = batch["attention_mask"].to(device)
        labels = batch["labels"].to(device)
        loss = trainer(input_ids, attention_mask, labels).mean()
        optimizer = torch.optim.Adam(trainer.model.parameters(), lr=1e-4)
        optimizer.zero_grad()
        loss.backward()
        optimizer.step()
        total_loss += loss.item()
    print(f"Epoch {epoch+1}, Loss: {total_loss / len(data_loader)}")

# Evaluate the model using the custom trainer class
trainer.model.eval()
test_loss = 0
correct = 0
with torch.no_grad():
    for batch in data_loader:
        input_ids = batch["input_ids"].to(device)
        attention_mask = batch["attention_mask"].to(device)
        labels = batch["labels"].to(device)
        output = trainer(input_ids, attention_mask, labels).mean()
        loss = self.loss_fn(output, labels)
        test_loss += loss.item()
        _, predicted = torch.max(output, 1)
        correct += (predicted == labels).sum().item()

accuracy = correct / len(data_loader.dataset)
print(f"Test Loss: {test_loss / len(data_loader)}, Accuracy: {accuracy:.2f}")