from sqlalchemy import create_engine, MetaData, Table, Column, String, Integer, Float, inspect

# Initialize database engine (Persistent SQLite)
engine = create_engine("sqlite:///database.db")
metadata_obj = MetaData()

# Function to check existing tables
def get_existing_tables():
    """
    Returns a list of existing tables in the database.

    Returns:
        list: List of table names.
    """
    inspector = inspect(engine)
    return inspector.get_table_names()

# Create a default table if no SQL file is uploaded
def create_placeholder_table():
    """
    Creates a default 'users' table with example data if no SQL file has been uploaded.
    """
    if "users" not in get_existing_tables():
        users_table = Table(
            "users", metadata_obj,
            Column("id", Integer, primary_key=True),
            Column("name", String(50)),
            Column("age", Integer),
            Column("balance", Float)
        )
        metadata_obj.create_all(engine)
        
        with engine.connect() as con:
            con.execute(users_table.insert(), [
                {"id": 1, "name": "Alice", "age": 30, "balance": 100.50},
                {"id": 2, "name": "Bob", "age": 24, "balance": 250.75},
                {"id": 3, "name": "Charlie", "age": 35, "balance": 80.00}
            ])
        print("✅ Created placeholder 'users' table with sample data.")

# Function to initialize database (Prevents crashes)
def initialize_database():
    """
    Ensures the database starts up with a placeholder table if no SQL file is uploaded.
    """
    tables = get_existing_tables()
    
    if not tables:
        print("No tables found. Creating a placeholder table...")
        create_placeholder_table()
    else:
        print(f"Database initialized with tables: {tables}")

initialize_database()