app.py

import torch
import json
from fastapi import FastAPI
from pydantic import BaseModel
from transformers import AutoTokenizer, AutoModelForSequenceClassification, pipeline
from typing import Optional
# --- 1. Load Model and Tokenizer ---

# Define the path to your trained model
MODEL_PATH = "./bertmodel"
# Define the path to your knowledge base
KNOWLEDGE_BASE_PATH = "womens_legal_rights_india_10000.json"

print("Loading tokenizer...")
tokenizer = AutoTokenizer.from_pretrained(MODEL_PATH)

print("Loading classification model...")
model = AutoModelForSequenceClassification.from_pretrained(MODEL_PATH)

# Set device to GPU (cuda:0) if available, otherwise CPU
device = 0 if torch.cuda.is_available() else -1

print(f"Creating classification pipeline on device: {'cuda' if device == 0 else 'cpu'}...")
# Create the text-classification pipeline
classifier = pipeline(
    "text-classification",
    model=model,
    tokenizer=tokenizer,
    device=device
)
print("Classification pipeline loaded successfully.")

# --- 2. Load Knowledge Base (Answers) ---


# We will now store a dictionary for each intent
intent_details_map = {}
print(f"Loading knowledge base from: {KNOWLEDGE_BASE_PATH}")
try:
    with open(KNOWLEDGE_BASE_PATH, 'r', encoding='utf-8') as f:
        knowledge_base_data = json.load(f)
    
    # Create a lookup map: Intent -> {answer, source}
    # We only need to add each intent once, since the answer/source is the same
    for item in knowledge_base_data:
        if item['intent'] not in intent_details_map:
            intent_details_map[item['intent']] = {
                "answer": item.get('answer', 'No answer found.'),
                "source": item.get('source', 'No source found.')
            }
            
    print(f"Knowledge base loaded with {len(intent_details_map)} intent-to-detail mappings.")

except FileNotFoundError:
    print(f"CRITICAL ERROR: Knowledge base file not found at {KNOWLEDGE_BASE_PATH}")
except Exception as e:
    print(f"Error loading knowledge base: {e}")



# --- 3. Initialize FastAPI App ---

app = FastAPI(
    title="Legal Intent & Answer API",
    description="API to predict the intent of a legal question and provide a suitable answer.",
    version="1.1.0"
)

# --- 4. Define Request and Response Models ---

# This is what the API will return

# This is what the user must send in their POST request
class Query(BaseModel):
    text: str

# This is what the API will return (now includes 'source')
class PredictionResponse(BaseModel):
    query: str
    predicted_intent: str
    confidence_score: float
    answer: str
    source: Optional[str] # Make source optional in case it's missing

 
# --- 5. Define API Endpoints ---

@app.get("/")
def read_root():
    """
    Root endpoint for health check.
    """
    return {"status": "API is running",
            "message": "Post to /predict with a 'text' field to get an intent and answer and source."}


@app.post("/predict", response_model=PredictionResponse)
def predict_intent(query: Query):
    """
    Predicts the intent of a given legal question and provides a suitable answer.
    """
    print(f"Received query: {query.text}")
    
    # 1. Get prediction from model
    model_result = classifier(query.text)[0]
    predicted_intent = model_result['label']
    confidence_score = model_result['score']
    
    # 2. Retrieve details (answer and source) from our knowledge base
    fallback_details = {
        "answer": "Could not find a specific answer for this intent. Please rephrase your question or contact a legal professional for advice.",
        "source": None
    }
    details = intent_details_map.get(predicted_intent, fallback_details)
    
    # 3. Return the combined response
    return {
        "query": query.text,
        "predicted_intent": predicted_intent,
        "confidence_score": confidence_score,
        "answer": details.get('answer'),
        "source": details.get('source')
    }