import os
import boto3
from sqlalchemy import create_engine
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker
from functools import lru_cache

@lru_cache(maxsize=1)
def get_db_credentials():
    """Fetch and cache DB credentials from SSM Parameter Store"""
    ssm = boto3.client('ssm')
    try:
        host = ssm.get_parameter(Name='/iptv-updater/DB_HOST', WithDecryption=True)['Parameter']['Value']
        user = ssm.get_parameter(Name='/iptv-updater/DB_USER', WithDecryption=True)['Parameter']['Value']
        password = ssm.get_parameter(Name='/iptv-updater/DB_PASSWORD', WithDecryption=True)['Parameter']['Value']
        dbname = ssm.get_parameter(Name='/iptv-updater/DB_NAME', WithDecryption=True)['Parameter']['Value']
        return f"postgresql://{user}:{password}@{host}/{dbname}"
    except Exception as e:
        raise RuntimeError(f"Failed to fetch DB credentials from SSM: {str(e)}")

engine = create_engine(get_db_credentials())

# Create all tables
from app.models import Base
Base.metadata.create_all(bind=engine)

SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)

def get_db():
    """Dependency for getting database session"""
    db = SessionLocal()
    try:
        yield db
    finally:
        db.close()