Securely Obtain OAuth2 Client Credentials Access Token

import requests
import os

# Configuration (ideally loaded from environment variables or a secure config store)
CLIENT_ID = os.environ.get('OAUTH_CLIENT_ID', 'your_client_id')
CLIENT_SECRET = os.environ.get('OAUTH_CLIENT_SECRET', 'your_client_secret')
TOKEN_URL = os.environ.get('OAUTH_TOKEN_URL', 'https://api.example.com/oauth/token')
SCOPE = os.environ.get('OAUTH_SCOPE', 'read write') # Optional, depends on API

def get_oauth_client_credentials_token():
    """
    Obtains an OAuth 2.0 access token using the Client Credentials Grant.
    This flow is suitable for server-to-server communication where there's
    no end-user involved.
    """
    if not all([CLIENT_ID, CLIENT_SECRET, TOKEN_URL]):
        raise ValueError("OAuth Client ID, Client Secret, or Token URL not configured.")

    headers = {
        'Content-Type': 'application/x-www-form-urlencoded'
    }
    payload = {
        'grant_type': 'client_credentials',
        'client_id': CLIENT_ID,
        'client_secret': CLIENT_SECRET
    }
    if SCOPE:
        payload['scope'] = SCOPE

    try:
        print(f"Requesting token from {TOKEN_URL}...")
        response = requests.post(TOKEN_URL, headers=headers, data=payload)
        response.raise_for_status() # Raise an exception for HTTP errors (4xx or 5xx)
        
        token_data = response.json()
        access_token = token_data.get('access_token')
        expires_in = token_data.get('expires_in')

        if not access_token:
            raise ValueError("Access token not found in response.")

        print(f"Successfully obtained access token. Expires in {expires_in} seconds.")
        return access_token
    except requests.exceptions.HTTPError as e:
        print(f"HTTP error during token request: {e}")
        print(f"Response content: {e.response.text}")
        raise
    except requests.exceptions.RequestException as e:
        print(f"Network or general request error: {e}")
        raise
    except ValueError as e:
        print(f"Data parsing error: {e}")
        raise

# Example usage:
# if __name__ == "__main__":
#     try:
#         token = get_oauth_client_credentials_token()
#         print(f"Access Token: {token}")
#         # Now use this token to make authenticated API calls:
#         # auth_headers = {'Authorization': f'Bearer {token}'}
#         # api_response = requests.get('https://api.example.com/protected-resource', headers=auth_headers)
#         # api_response.raise_for_status()
#         # print(api_response.json())
#     except Exception as e:
#         print(f"An error occurred: {e}")