app.py

from fastapi import FastAPI, HTTPException
from fastapi.middleware.cors import CORSMiddleware
from contextlib import asynccontextmanager
import base64
import os

# Create the FastAPI app
@asynccontextmanager
async def lifespan(app: FastAPI):
    # Load LoRA weights during app startup
    lora_path = "./lora_file.pth"
    if os.path.exists(lora_path):
        with open(lora_path, "rb") as f:
            # Base64 encode the LoRA weights for easy JSON transmission
            app.state.lora_weights = base64.b64encode(f.read()).decode("utf-8")
            print("LoRA weights loaded and preprocessed successfully.")
    else:
        print("LoRA file not found during startup.")
        raise RuntimeError("LoRA file not found.")

    # Yield control to the application
    yield

    # Perform any cleanup (if needed) here
    print("Application shutting down.")

app = FastAPI(lifespan=lifespan)

# Middleware to handle CORS (optional, but useful for cross-origin requests)
app.add_middleware(
    CORSMiddleware,
    allow_origins=["*"],  # Adjust for security
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)

@app.post("/modify-prompt")
async def modify_prompt(prompt: str):
    lora_weights = getattr(app.state, "lora_weights", None)
    if lora_weights is None:
        raise HTTPException(status_code=500, detail="LoRA weights not loaded.")
    
    # Combine prompt with preprocessed LoRA data
    extended_prompt = {
        "prompt": prompt,
        "lora": lora_weights
    }
    return extended_prompt