import os
import toml
from typing import Dict

def load_stsecrets(config_path: str = '.streamlit/secrets.toml') -> Dict:
    """
    Load configuration from Streamlit secrets TOML file and replace placeholders with environment variables.
    
    :param config_path: Path to the Streamlit secrets TOML file
    :return: Dictionary containing the credentials
    """
    # Read the TOML file
    with open(config_path, 'r') as f:
        config = toml.load(f)
    
    # Replace placeholders with environment variables
    credentials = config.get('credentials', {})
    for key, value in credentials.items():
        if isinstance(value, str) and value.startswith('${') and value.endswith('}'):
            env_var = value[2:-1]  # Remove ${ and }
            credentials[key] = os.environ.get(env_var)
            if credentials[key] is None:
                raise ValueError(f"Environment variable {env_var} is not set")
    
    return credentials