backend/main.py

import os
import tempfile
import shutil
from typing import List, Dict, Any
from fastapi import FastAPI, UploadFile, File, Form, HTTPException
from fastapi.middleware.cors import CORSMiddleware
from fastapi.staticfiles import StaticFiles  # Add this import
from pydantic import BaseModel
from aimakerspace.text_utils import CharacterTextSplitter, TextFileLoader, PDFLoader
from aimakerspace.openai_utils.prompts import (
    UserRolePrompt,
    SystemRolePrompt,
    AssistantRolePrompt,
)
from aimakerspace.openai_utils.embedding import EmbeddingModel
from aimakerspace.vectordatabase import VectorDatabase
from aimakerspace.openai_utils.chatmodel import ChatOpenAI

app = FastAPI()

# Add CORS middleware
app.add_middleware(
    CORSMiddleware,
    allow_origins=["*"],  # In production, replace with your frontend URL
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)

# Initialize components
text_splitter = CharacterTextSplitter()
vector_db = None
chat_openai = ChatOpenAI(model_name="gpt-3.5-turbo")

system_template = """\
Use the following context to answer a users question. If you cannot find the answer in the context, say you don't know the answer."""
system_role_prompt = SystemRolePrompt(system_template)

user_prompt_template = """\
Context:
{context}

Question:
{question}
"""
user_role_prompt = UserRolePrompt(user_prompt_template)

class QuestionRequest(BaseModel):
    question: str

class QuestionResponse(BaseModel):
    response: str
    context: List[tuple]

def process_file(file_path: str, file_name: str):
    print(f"Processing file: {file_name}")
    
    # Create appropriate loader
    if file_name.lower().endswith('.pdf'):
        loader = PDFLoader(file_path)
    else:
        loader = TextFileLoader(file_path)
        
    # Load and process the documents
    documents = loader.load_documents()
    texts = text_splitter.split_texts(documents)
    return texts

class RetrievalAugmentedQAPipeline:
    def __init__(self, llm: ChatOpenAI, vector_db_retriever: VectorDatabase) -> None:
        self.llm = llm
        self.vector_db_retriever = vector_db_retriever

    async def run_pipeline(self, user_query: str):
        context_list = self.vector_db_retriever.search_by_text(user_query, k=4)

        context_prompt = ""
        for context in context_list:
            context_prompt += context[0] + "\n"

        formatted_system_prompt = system_role_prompt.create_message()
        formatted_user_prompt = user_role_prompt.create_message(question=user_query, context=context_prompt)

        # Remove await since run is not an async method
        response = await self.llm.run([formatted_system_prompt, formatted_user_prompt])
        
        return {"response": response, "context": context_list}

@app.post("/upload")
async def upload_file(file: UploadFile = File(...)):
    global vector_db
    
    # Validate file type
    if not file.filename.lower().endswith(('.txt', '.pdf')):
        raise HTTPException(status_code=400, detail="Only .txt and .pdf files are allowed")
    
    # Create a temporary file
    suffix = f".{file.filename.split('.')[-1]}"
    with tempfile.NamedTemporaryFile(delete=False, suffix=suffix) as temp_file:
        # Copy the uploaded file content to the temporary file
        content = await file.read()
        print(f"File read complete. Size: {len(content)} bytes")
        with open(temp_file.name, "wb") as f:
            f.write(content)
        
        try:
            # Process the file
            texts = process_file(temp_file.name, file.filename)
            print(f"Processing {len(texts)} text chunks")
            
            # Create a vector store
            vector_db = VectorDatabase()
            vector_db = await vector_db.abuild_from_list(texts)
            print("Document processing complete")
            
            return {"message": f"File {file.filename} processed successfully", "chunks": len(texts)}
        finally:
            # Clean up the temporary file
            try:
                os.unlink(temp_file.name)
            except Exception as e:
                print(f"Error cleaning up temporary file: {e}")

@app.post("/ask", response_model=QuestionResponse)
async def ask_question(request: QuestionRequest):
    global vector_db
    
    if vector_db is None:
        raise HTTPException(status_code=400, detail="Please upload a file first")
    
    # Create a chain
    retrieval_augmented_qa_pipeline = RetrievalAugmentedQAPipeline(
        vector_db_retriever=vector_db,
        llm=chat_openai
    )
    
    # Run the pipeline
    result = await retrieval_augmented_qa_pipeline.run_pipeline(request.question)
    
    return QuestionResponse(
        response=result["response"],
        context=result["context"]
    )

@app.get("/health")
async def health_check():
    return {"status": "healthy"}

# app.mount("/", StaticFiles(directory="../frontend/build", html=True), name="frontend")