app.py

"""
FastAPI Application for Multimodal RAG System
US Army Medical Research Papers Q&A
"""

import os
import logging
from typing import List, Dict, Optional, Union
from contextlib import asynccontextmanager

from fastapi import FastAPI, HTTPException
from fastapi.middleware.cors import CORSMiddleware
from fastapi.responses import FileResponse
from fastapi.staticfiles import StaticFiles
from pydantic import BaseModel, Field

# Import from query_index (standalone)
from query_index import MultimodalRAGSystem

# Configure logging
logging.basicConfig(
    level=logging.INFO,
    format='%(asctime)s - %(name)s - %(levelname)s - %(message)s'
)
logger = logging.getLogger(__name__)

# Global variables
rag_system: Optional[MultimodalRAGSystem] = None

# Store last question-answer pair for simple follow-up
last_qa_context: Optional[str] = None

# Lifecycle management
@asynccontextmanager
async def lifespan(app: FastAPI):
    """Initialize and cleanup RAG system"""
    global rag_system
    
    logger.info("Starting RAG system initialization...")
    try:
        rag_system = MultimodalRAGSystem()
        logger.info("RAG system initialized successfully!")
    except Exception as e:
        logger.error(f"Error during initialization: {str(e)}")
        rag_system = None
    
    yield
    
    logger.info("Shutting down RAG system...")
    rag_system = None

# Create FastAPI app
app = FastAPI(
    title="Multimodal RAG API",
    description="Q&A system for US Army medical research papers (Text + Images)",
    version="2.0.0",
    lifespan=lifespan
)

# CORS middleware
app.add_middleware(
    CORSMiddleware,
    allow_origins=["*"],
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)

# Mount static files
app.mount("/static", StaticFiles(directory="static"), name="static")

# Mount extracted images
# This allows the frontend to load images via /extracted_images/filename.jpg
if os.path.exists("extracted_images"):
    app.mount("/extracted_images", StaticFiles(directory="extracted_images"), name="images")

# Mount PDF documents
if os.path.exists("WHEC_Documents"):
    app.mount("/documents", StaticFiles(directory="WHEC_Documents"), name="documents")

# Pydantic models
class QueryRequest(BaseModel):
    question: str = Field(..., min_length=1, max_length=1000, description="Question to ask")

class ImageSource(BaseModel):
    path: Optional[str]
    filename: Optional[str]
    score: Optional[float]
    page: Optional[Union[str, int]] # could be int or str depending on metadata
    file: Optional[str]
    link: Optional[str] = None

class TextSource(BaseModel):
    text: str
    score: float
    page: Optional[Union[str, int]]
    file: Optional[str]
    link: Optional[str] = None

class QueryResponse(BaseModel):
    answer: str
    images: List[ImageSource]
    texts: List[TextSource]
    question: str

class HealthResponse(BaseModel):
    status: str
    rag_initialized: bool

# API Endpoints

@app.get("/", tags=["Root"])
async def root():
    """Serve the frontend application"""
    return FileResponse('static/index.html')

@app.get("/health", response_model=HealthResponse, tags=["Health"])
async def health_check():
    """Health check endpoint"""
    return HealthResponse(
        status="healthy",
        rag_initialized=rag_system is not None
    )

@app.post("/query", response_model=QueryResponse, tags=["Query"])
async def query_rag(request: QueryRequest):
    """
    Query the RAG system
    """
    global last_qa_context
    
    if not rag_system:
        raise HTTPException(
            status_code=503,
            detail="RAG system not initialized. Check logs for errors."
        )
    
    try:
        # Build prompt using previous Q/A if available
        if last_qa_context:
            prompt = (
                f"Previous question and answer:\n"
                f"{last_qa_context}\n\n"
                f"Follow up question:\n"
                    f"{request.question}"
            )
        else:
            prompt = request.question

        # Query RAG system
        result = rag_system.ask(prompt)

        # Save current Q/A as context for next turn
        last_qa_context = (
            f"Question: {request.question}\n"
            f"Answer: {result['answer']}"
        )
        
        return QueryResponse(
            answer=result['answer'],
            images=result['images'],
            texts=result['texts'],
            question=request.question
        )
        
    except Exception as e:
        logger.error(f"Error processing query: {str(e)}")
        raise HTTPException(status_code=500, detail=f"Error processing query: {str(e)}")

if __name__ == "__main__":
    import uvicorn
    uvicorn.run(app, host="0.0.0.0", port=7860)