app.py

from transformers import AutoModelForSequenceClassification, AutoTokenizer
from fastapi import FastAPI, HTTPException
from pydantic import BaseModel
import torch
from transformers import AutoModelForSequenceClassification, AutoTokenizer


roberta_model = AutoModelForSequenceClassification.from_pretrained("roberta-base")
roberta_tokenizer = AutoTokenizer.from_pretrained("roberta-base")

# Load BERT model and tokenizer
bert_model = AutoModelForSequenceClassification.from_pretrained("bert-base-uncased")
bert_tokenizer = AutoTokenizer.from_pretrained("bert-base-uncased")

app = FastAPI()

class TextData(BaseModel):
    text: str

# Helper function to make predictions and convert to 0 (human) or 100 (AI)
def predict_text(model, tokenizer, text):
    # Preprocess the text
    inputs = tokenizer(text, truncation=True, padding='max_length', max_length=128, return_tensors='pt')

    # Move to the correct device (GPU/CPU)
    device = torch.device("cuda") if torch.cuda.is_available() else torch.device("cpu")
    model.to(device)
    inputs = {k: v.to(device) for k, v in inputs.items()}

    # Get model predictions
    with torch.no_grad():
        outputs = model(**inputs)
    
    # Convert logits to probabilities
    logits = outputs.logits
    probabilities = torch.softmax(logits, dim=-1)
    predicted_class = torch.argmax(probabilities, dim=-1).item()
    #ai_prob = probabilities[0][1].item() * 100
    #print(ai_prob)
    # Return 0 for human, 100 for AI
    return 100 if predicted_class == 1 else 0

# Endpoint to predict with RoBERTa
@app.post("/predict_copyleaks_V1")
def predict_roberta(data: TextData):
    predicted_value = predict_text(roberta_model, roberta_tokenizer, data.text)
    return {"text": data.text, "Score": predicted_value}

# Endpoint to predict with BERT
@app.post("/predict_copyleaks_V2")
def predict_bert(data: TextData):
    predicted_value = predict_text(bert_model, bert_tokenizer, data.text)
    return {"text": data.text, "Score": predicted_value}