import requests
import json
import time

class OAuthClient:
    def __init__(self, client_id, client_secret, token_url, initial_refresh_token=None):
        self.client_id = client_id
        self.client_secret = client_secret
        self.token_url = token_url
        self._access_token = None
        self._refresh_token = initial_refresh_token
        self._expires_at = 0 # Unix timestamp

    def _is_token_expired(self):
        return time.time() >= self._expires_at - 60 # Refresh 60 seconds before actual expiry

    def refresh_access_token(self):
        if not self._refresh_token:
            raise ValueError("No refresh token available to renew access token.")

        headers = {'Content-Type': 'application/x-www-form-urlencoded'}
        data = {
            'grant_type': 'refresh_token',
            'refresh_token': self._refresh_token,
            'client_id': self.client_id,
            'client_secret': self.client_secret
        }

        try:
            response = requests.post(self.token_url, headers=headers, data=data)
            response.raise_for_status() # Raise an exception for HTTP errors (4xx or 5xx)
            token_data = response.json()

            self._access_token = token_data.get('access_token')
            self._refresh_token = token_data.get('refresh_token', self._refresh_token) # Refresh token might be rotated
            expires_in = token_data.get('expires_in')
            if expires_in:
                self._expires_at = time.time() + expires_in
            else:
                self._expires_at = 0 # Indicate indefinite or unknown expiry

            print("Access token refreshed successfully.")
            return self._access_token
        except requests.exceptions.RequestException as e:
            print(f"Error refreshing access token: {e}")
            raise

    def get_access_token(self):
        if not self._access_token or self._is_token_expired():
            self.refresh_access_token()
        return self._access_token

    def make_authenticated_request(self, method, url, **kwargs):
        access_token = self.get_access_token()
        headers = kwargs.pop('headers', {})
        headers['Authorization'] = f'Bearer {access_token}'
        response = requests.request(method, url, headers=headers, **kwargs)
        response.raise_for_status()
        return response.json()

# Usage example:
# CLIENT_ID = 'your_client_id'
# CLIENT_SECRET = 'your_client_secret'
# TOKEN_URL = 'https://provider.com/oauth/token'
# INITIAL_REFRESH_TOKEN = 'your_long_lived_refresh_token'

# client = OAuthClient(CLIENT_ID, CLIENT_SECRET, TOKEN_URL, INITIAL_REFRESH_TOKEN)

# try:
#     # Make an API call using the client, it will refresh token if needed
#     user_profile = client.make_authenticated_request('GET', 'https://api.provider.com/user/profile')
#     print("User profile:", user_profile)

#     # Simulate token expiry and another request
#     # client._expires_at = time.time() - 100 # Force expiration
#     # more_data = client.make_authenticated_request('GET', 'https://api.provider.com/data')
#     # print("More data:", more_data)
# except Exception as e:
#     print(f"API request failed: {e}")