# deberta_multilabel_train.py

import torch
import torch.nn as nn
from torch.utils.data import Dataset, DataLoader
from transformers import DebertaTokenizer, DebertaModel
from sklearn.preprocessing import LabelEncoder
from sklearn.model_selection import train_test_split
import pandas as pd
import pickle
from tqdm import tqdm

# --- Config ---
DEVICE = torch.device("cuda" if torch.cuda.is_available() else "cpu")
TEXT_COLUMN = "Sanction_Context"
LABEL_COLUMNS = ['Red_Flag_Reason', 'Maker_Action', 'Escalation_Level',
                 'Risk_Category', 'Risk_Drivers', 'Investigation_Outcome']
MODEL_NAME = "microsoft/deberta-base"
BATCH_SIZE = 8
EPOCHS = 3
MAX_LEN = 256

# --- Load Data ---
df = pd.read_csv("/kaggle/input/deberta-model/synthetic_transactions_samples_5000.csv")  # Ensure TEXT_COLUMN and LABEL_COLUMNS are in this CSV
label_encoders = []

# Encode each label column
for col in LABEL_COLUMNS:
    le = LabelEncoder()
    df[col] = le.fit_transform(df[col])
    label_encoders.append(le)

# Save label encoders
with open("label_encoders.pkl", "wb") as f:
    pickle.dump(label_encoders, f)

# Train/val split
train_df, val_df = train_test_split(df, test_size=0.2, random_state=42)

# --- Tokenizer ---
tokenizer = DebertaTokenizer.from_pretrained(MODEL_NAME)

# --- Dataset ---
class TextDataset(Dataset):
    def _init_(self, dataframe, tokenizer):
        self.tokenizer = tokenizer
        self.texts = list(dataframe[TEXT_COLUMN])
        self.labels = dataframe[LABEL_COLUMNS].values

    def _len_(self):
        return len(self.texts)

    def _getitem_(self, idx):
        encodings = self.tokenizer(
            self.texts[idx],
            truncation=True,
            padding="max_length",
            max_length=MAX_LEN,
            return_tensors="pt"
        )
        item = {key: val.squeeze(0) for key, val in encodings.items()}
        item['labels'] = torch.tensor(self.labels[idx], dtype=torch.float)
        return item

train_dataset = TextDataset(train_df, tokenizer)
val_dataset = TextDataset(val_df, tokenizer)
train_loader = DataLoader(train_dataset, batch_size=BATCH_SIZE, shuffle=True)
val_loader = DataLoader(val_dataset, batch_size=BATCH_SIZE)

# --- Model ---
class DebertaMultiOutput(nn.Module):
    def _init_(self, num_labels):
        super(DebertaMultiOutput, self)._init_()
        self.deberta = DebertaModel.from_pretrained(MODEL_NAME)
        self.dropout = nn.Dropout(0.3)
        self.output = nn.Linear(self.deberta.config.hidden_size, num_labels)

    def forward(self, input_ids, attention_mask):
        outputs = self.deberta(input_ids=input_ids, attention_mask=attention_mask)
        pooled_output = outputs.last_hidden_state[:, 0]  # CLS token
        dropped = self.dropout(pooled_output)
        return self.output(dropped)

model = DebertaMultiOutput(num_labels=len(LABEL_COLUMNS)).to(DEVICE)
criterion = nn.BCEWithLogitsLoss()
optimizer = torch.optim.AdamW(model.parameters(), lr=2e-5)

# --- Training Loop ---
for epoch in range(EPOCHS):
    model.train()
    total_loss = 0
    for batch in tqdm(train_loader, desc=f"Epoch {epoch+1}"):
        input_ids = batch['input_ids'].to(DEVICE)
        attention_mask = batch['attention_mask'].to(DEVICE)
        labels = batch['labels'].to(DEVICE)

        optimizer.zero_grad()
        outputs = model(input_ids, attention_mask)
        loss = criterion(outputs, labels)
        loss.backward()
        optimizer.step()
        total_loss += loss.item()
    
    print(f"Epoch {epoch+1} Loss: {total_loss/len(train_loader):.4f}")

# --- Save Model & Tokenizer ---
torch.save(model.state_dict(), "deberta_model.pth")
tokenizer.save_pretrained("deberta_tokenizer")