"""
Shared OAuth 2.0 Service for NordaBiz
=====================================

Supports:
- Google OAuth 2.0 (GBP Business Profile API, Search Console API)
- Meta OAuth 2.0 (Facebook Graph API, Instagram Graph API)

Config via environment variables:
- GOOGLE_OAUTH_CLIENT_ID, GOOGLE_OAUTH_CLIENT_SECRET
- META_APP_ID, META_APP_SECRET
- OAUTH_REDIRECT_BASE_URL (e.g., https://nordabiznes.pl)
"""

import os
import logging
from datetime import datetime, timedelta
from typing import Optional, Dict, Tuple

import requests

logger = logging.getLogger(__name__)


# OAuth Provider Configurations
OAUTH_PROVIDERS = {
    'google': {
        'auth_url': 'https://accounts.google.com/o/oauth2/v2/auth',
        'token_url': 'https://oauth2.googleapis.com/token',
        'scopes': {
            'gbp': 'https://www.googleapis.com/auth/business.manage',
            'search_console': 'https://www.googleapis.com/auth/webmasters',
        },
    },
    'meta': {
        'auth_url': 'https://www.facebook.com/v21.0/dialog/oauth',
        'token_url': 'https://graph.facebook.com/v21.0/oauth/access_token',
        'scopes': {
            'facebook': 'pages_show_list,pages_read_engagement,pages_manage_posts,read_insights',
            'instagram': 'instagram_basic,instagram_manage_insights,pages_show_list',
        },
    },
}


class OAuthService:
    """Shared OAuth 2.0 service for external API integrations."""

    def __init__(self):
        self.google_client_id = os.getenv('GOOGLE_OAUTH_CLIENT_ID')
        self.google_client_secret = os.getenv('GOOGLE_OAUTH_CLIENT_SECRET')
        self.meta_app_id = os.getenv('META_APP_ID')
        self.meta_app_secret = os.getenv('META_APP_SECRET')
        self.redirect_base = os.getenv('OAUTH_REDIRECT_BASE_URL', 'https://nordabiznes.pl')

    def get_authorization_url(self, provider: str, service: str, state: str) -> Optional[str]:
        """Generate OAuth authorization URL for a provider/service.

        Args:
            provider: 'google' or 'meta'
            service: 'gbp', 'search_console', 'facebook', 'instagram'
            state: CSRF state token (include company_id and user_id encoded)

        Returns:
            Authorization URL or None if provider not configured
        """
        config = OAUTH_PROVIDERS.get(provider)
        if not config:
            logger.error(f"Unknown OAuth provider: {provider}")
            return None

        scopes = config['scopes'].get(service, '')
        redirect_uri = f"{self.redirect_base}/api/oauth/callback/{provider}"

        if provider == 'google':
            if not self.google_client_id:
                logger.warning("Google OAuth not configured (GOOGLE_OAUTH_CLIENT_ID)")
                return None
            params = {
                'client_id': self.google_client_id,
                'redirect_uri': redirect_uri,
                'response_type': 'code',
                'scope': scopes,
                'state': state,
                'access_type': 'offline',
                'prompt': 'consent',
            }
        elif provider == 'meta':
            if not self.meta_app_id:
                logger.warning("Meta OAuth not configured (META_APP_ID)")
                return None
            params = {
                'client_id': self.meta_app_id,
                'redirect_uri': redirect_uri,
                'response_type': 'code',
                'scope': scopes,
                'state': state,
            }
        else:
            return None

        query = '&'.join(f'{k}={requests.utils.quote(str(v))}' for k, v in params.items())
        return f"{config['auth_url']}?{query}"

    def exchange_code(self, provider: str, code: str) -> Optional[Dict]:
        """Exchange authorization code for access token.

        Args:
            provider: 'google' or 'meta'
            code: Authorization code from callback

        Returns:
            Dict with access_token, refresh_token, expires_in or None on error
        """
        config = OAUTH_PROVIDERS.get(provider)
        if not config:
            return None

        redirect_uri = f"{self.redirect_base}/api/oauth/callback/{provider}"

        if provider == 'google':
            data = {
                'code': code,
                'client_id': self.google_client_id,
                'client_secret': self.google_client_secret,
                'redirect_uri': redirect_uri,
                'grant_type': 'authorization_code',
            }
        elif provider == 'meta':
            data = {
                'code': code,
                'client_id': self.meta_app_id,
                'client_secret': self.meta_app_secret,
                'redirect_uri': redirect_uri,
            }
        else:
            return None

        try:
            response = requests.post(config['token_url'], data=data, timeout=15)
            if response.status_code != 200:
                logger.error(f"OAuth token exchange failed for {provider}: {response.status_code} - {response.text}")
                return None
            return response.json()
        except Exception as e:
            logger.error(f"OAuth token exchange error for {provider}: {e}")
            return None

    def refresh_access_token(self, provider: str, refresh_token: str) -> Optional[Dict]:
        """Refresh an expired access token.

        Args:
            provider: 'google' or 'meta'
            refresh_token: The refresh token

        Returns:
            Dict with new access_token, expires_in or None
        """
        if provider == 'google':
            data = {
                'client_id': self.google_client_id,
                'client_secret': self.google_client_secret,
                'refresh_token': refresh_token,
                'grant_type': 'refresh_token',
            }
            token_url = OAUTH_PROVIDERS['google']['token_url']
        elif provider == 'meta':
            # Meta long-lived tokens: exchange short-lived for long-lived
            params = {
                'grant_type': 'fb_exchange_token',
                'client_id': self.meta_app_id,
                'client_secret': self.meta_app_secret,
                'fb_exchange_token': refresh_token,
            }
            try:
                response = requests.get(
                    OAUTH_PROVIDERS['meta']['token_url'],
                    params=params,
                    timeout=15
                )
                if response.status_code == 200:
                    return response.json()
                return None
            except Exception as e:
                logger.error(f"Meta token refresh error: {e}")
                return None
        else:
            return None

        try:
            response = requests.post(token_url, data=data, timeout=15)
            if response.status_code == 200:
                return response.json()
            logger.error(f"Token refresh failed for {provider}: {response.status_code}")
            return None
        except Exception as e:
            logger.error(f"Token refresh error for {provider}: {e}")
            return None

    def _try_refresh_token(self, db, token) -> bool:
        """Attempt to refresh an expired token in-place. Returns True on success."""
        if not token.refresh_token:
            return False
        try:
            new_data = self.refresh_access_token(token.provider, token.refresh_token)
            if new_data and new_data.get('access_token'):
                token.access_token = new_data['access_token']
                expires_in = new_data.get('expires_in')
                if expires_in:
                    token.expires_at = datetime.now() + timedelta(seconds=int(expires_in))
                token.updated_at = datetime.now()
                db.commit()
                logger.info(f"Auto-refreshed {token.provider}/{token.service} for company {token.company_id}")
                return True
            return False
        except Exception as e:
            logger.error(f"Token auto-refresh error {token.provider}/{token.service}: {e}")
            db.rollback()
            return False

    def save_token(self, db, company_id: int, user_id: int, provider: str,
                   service: str, token_data: Dict) -> bool:
        """Save or update OAuth token in database.

        Args:
            db: Database session
            company_id: Company ID
            user_id: User who authorized
            provider: 'google' or 'meta'
            service: 'gbp', 'search_console', 'facebook', 'instagram'
            token_data: Dict from exchange_code() or refresh_access_token()

        Returns:
            True if saved successfully
        """
        try:
            from database import OAuthToken

            # Find existing token or create new
            token = db.query(OAuthToken).filter(
                OAuthToken.company_id == company_id,
                OAuthToken.provider == provider,
                OAuthToken.service == service,
            ).first()

            if not token:
                token = OAuthToken(
                    company_id=company_id,
                    user_id=user_id,
                    provider=provider,
                    service=service,
                )
                db.add(token)

            token.access_token = token_data.get('access_token', '')
            token.refresh_token = token_data.get('refresh_token', token.refresh_token)
            token.token_type = token_data.get('token_type', 'Bearer')

            expires_in = token_data.get('expires_in')
            if expires_in:
                token.expires_at = datetime.now() + timedelta(seconds=int(expires_in))

            token.scopes = OAUTH_PROVIDERS.get(provider, {}).get('scopes', {}).get(service, '')
            token.is_active = True
            token.updated_at = datetime.now()

            db.commit()
            logger.info(f"OAuth token saved: {provider}/{service} for company {company_id}")
            return True

        except Exception as e:
            db.rollback()
            logger.error(f"Error saving OAuth token: {e}")
            return False

    def get_valid_token(self, db, company_id: int, provider: str, service: str) -> Optional[str]:
        """Get a valid access token, refreshing if needed.

        Args:
            db: Database session
            company_id: Company ID
            provider: 'google' or 'meta'
            service: Service name

        Returns:
            Valid access token string or None
        """
        try:
            from database import OAuthToken

            token = db.query(OAuthToken).filter(
                OAuthToken.company_id == company_id,
                OAuthToken.provider == provider,
                OAuthToken.service == service,
                OAuthToken.is_active == True,
            ).first()

            if not token:
                return None

            # Check if token is expired
            if token.is_expired:
                if token.refresh_token:
                    if not self._try_refresh_token(db, token):
                        token.is_active = False
                        db.commit()
                        return None
                else:
                    return None

            return token.access_token

        except Exception as e:
            logger.error(f"Error getting valid token: {e}")
            return None

    def get_connected_services(self, db, company_id: int) -> Dict[str, Dict]:
        """Get status of all connected OAuth services for a company.

        Returns:
            Dict like {'google/gbp': {'connected': True, 'account_name': '...', 'expires_at': ...}, ...}
        """
        try:
            from database import OAuthToken

            tokens = db.query(OAuthToken).filter(
                OAuthToken.company_id == company_id,
                OAuthToken.is_active == True,
            ).all()

            result = {}
            for token in tokens:
                key = f"{token.provider}/{token.service}"

                # Auto-refresh expired tokens
                refresh_failed = False
                if token.is_expired and token.refresh_token:
                    if not self._try_refresh_token(db, token):
                        refresh_failed = True

                result[key] = {
                    'connected': True,
                    'account_name': token.account_name,
                    'account_id': token.account_id,
                    'expires_at': token.expires_at.isoformat() if token.expires_at else None,
                    'is_expired': token.is_expired,
                    'refresh_failed': refresh_failed,
                    'updated_at': token.updated_at.isoformat() if token.updated_at else None,
                }
            return result

        except Exception as e:
            logger.error(f"Error getting connected services: {e}")
            return {}