Refactor model path handling in main.py; define BASE_DIR and MODEL_DIR, ensure model directory exists, and set model download URL

main.py

@@ -4,7 +4,15 @@ from pathlib import Path
 import logging
 import sys
 from ctransformers import AutoModelForCausalLM
-from app.config import MODEL_PATH, MODEL_URL
+BASE_DIR = Path("/app")
+MODEL_DIR = BASE_DIR / "models"
+MODEL_NAME = "llama-2-7b-chat.q4_K_M.gguf"
+MODEL_PATH = MODEL_DIR / MODEL_NAME
+
+# Ensure model directory exists
+MODEL_DIR.mkdir(parents=True, exist_ok=True)
+# Model download URL
+MODEL_URL = "https://huggingface.co/TheBloke/Llama-2-7B-Chat-GGUF/resolve/main/llama-2-7b-chat.Q4_K_M.gguf"
 def download_model():
     """Download the model if it doesn't exist"""
     import requests