"""Spotify OAuth token management with automatic refresh"""
import base64
import requests


class SpotifyAuth:
    """Manages Spotify OAuth tokens with automatic refresh"""

    def __init__(self, refresh_token: str, client_id: str, client_secret: str, access_token: str = ''):
        self._access_token = access_token
        self._refresh_token = refresh_token
        self._client_id = client_id
        self._client_secret = client_secret

    def get_access_token(self) -> str:
        """Get current access token"""
        return self._access_token

    def has_access_token(self) -> bool:
        """Check if access token exists"""
        return bool(self._access_token)

    def refresh_access_token(self) -> str:
        """
        Refresh access token using refresh token

        Raises:
            Exception: If token refresh fails
        """
        if not self._refresh_token:
            raise Exception('No refresh token available')

        # Create Basic auth header (client_id:client_secret encoded in base64)
        auth_string = f'{self._client_id}:{self._client_secret}'
        auth_bytes = auth_string.encode('ascii')
        auth_b64 = base64.b64encode(auth_bytes).decode('ascii')

        try:
            response = requests.post(
                'https://accounts.spotify.com/api/token',
                data={
                    'grant_type': 'refresh_token',
                    'refresh_token': self._refresh_token,
                },
                headers={
                    'Authorization': f'Basic {auth_b64}',
                    'Content-Type': 'application/x-www-form-urlencoded',
                },
                timeout=10
            )
            response.raise_for_status()

            token_data = response.json()
            self._access_token = token_data['access_token']

            # Update refresh token if provided
            if token_data.get('refresh_token'):
                self._refresh_token = token_data['refresh_token']

            return self._access_token

        except requests.RequestException as e:
            error_msg = str(e)
            if hasattr(e, 'response') and e.response is not None:
                try:
                    error_data = e.response.json()
                    error_msg = error_data.get('error_description', error_msg)
                except ValueError:
                    # If response is not JSON, we ignore this exception and use the original error message above
                    pass
            raise Exception(f'Failed to refresh token: {error_msg}')

    def get_client_credentials_token(self) -> str:
        """
        Get access token using client credentials flow (no user refresh token)
        Used for looking up public artist/track metadata

        Returns:
            str: Access token

        Raises:
            Exception: If token request fails
        """
        # Create Basic auth header (client_id:client_secret encoded in base64)
        auth_string = f'{self._client_id}:{self._client_secret}'
        auth_bytes = auth_string.encode('ascii')
        auth_b64 = base64.b64encode(auth_bytes).decode('ascii')

        try:
            response = requests.post(
                'https://accounts.spotify.com/api/token',
                data={
                    'grant_type': 'client_credentials',
                },
                headers={
                    'Authorization': f'Basic {auth_b64}',
                    'Content-Type': 'application/x-www-form-urlencoded',
                },
                timeout=10
            )
            response.raise_for_status()

            token_data = response.json()
            self._access_token = token_data['access_token']

            return self._access_token

        except requests.RequestException as e:
            error_msg = str(e)
            if hasattr(e, 'response') and e.response is not None:
                try:
                    error_data = e.response.json()
                    error_msg = error_data.get('error_description', error_msg)
                except ValueError:
                    # If response is not JSON, we ignore this exception and use the original error message above
                    pass
            raise Exception(f'Failed to get client credentials token: {error_msg}')

    def ensure_valid_token(self) -> None:
        """Ensure token is valid, refresh if needed or missing"""
        if not self.has_access_token():
            self.refresh_access_token()