"""
SAML/SSO authentication provider
"""

import uuid
import logging
from typing import Dict, Any, List
from datetime import datetime, timedelta

from .base import AuthenticationProvider
from ..types import AuthenticationResult, AuthenticationType, CredentialInfo
from abap_accelerator.utils.security import sanitize_for_logging

logger = logging.getLogger(__name__)


class SAMLSSOAuthProvider(AuthenticationProvider):
    """SAML/SSO authentication provider"""
    
    def __init__(self, sso_config: Dict[str, Any] = None):
        self.name = "SAML/SSO Authentication"
        self.description = "Enterprise Single Sign-On authentication"
        self.sso_config = sso_config or {}
        self.pending_requests = {}  # request_id -> request_info
    
    async def authenticate(self, credentials: Dict[str, Any]) -> AuthenticationResult:
        """
        Complete SAML/SSO authentication
        
        Expected credentials:
        - request_id: SSO request ID from initiate_sso_flow
        - saml_response: SAML response from SSO provider
        """
        try:
            request_id = credentials.get('request_id')
            saml_response = credentials.get('saml_response')
            
            if not request_id or not saml_response:
                return AuthenticationResult(
                    success=False,
                    error_message="Both 'request_id' and 'saml_response' are required for SAML authentication",
                    auth_type=self.get_auth_type()
                )
            
            # Validate request ID
            if request_id not in self.pending_requests:
                return AuthenticationResult(
                    success=False,
                    error_message="Invalid or expired SSO request ID",
                    auth_type=self.get_auth_type()
                )
            
            request_info = self.pending_requests[request_id]
            
            # Validate SAML response
            user_info = await self._validate_saml_response(saml_response, request_info)
            if not user_info:
                return AuthenticationResult(
                    success=False,
                    error_message="Invalid SAML response or authentication failed",
                    auth_type=self.get_auth_type()
                )
            
            # Create SAP session using SSO
            sap_client = await self._create_sap_sso_session(user_info, saml_response, request_info)
            if not sap_client:
                return AuthenticationResult(
                    success=False,
                    error_message="Failed to create SAP session with SSO credentials",
                    auth_type=self.get_auth_type()
                )
            
            # Generate session token
            session_token = str(uuid.uuid4())
            
            # Add SAP client to user info
            user_info['sap_client_instance'] = sap_client
            user_info['auth_type'] = self.get_auth_type().value
            user_info['authenticated_at'] = datetime.now().isoformat()
            
            # Clean up pending request
            del self.pending_requests[request_id]
            
            logger.info(f"Successfully authenticated {user_info.get('username', 'user')} via SAML/SSO")
            
            return AuthenticationResult(
                success=True,
                session_token=session_token,
                user_info=user_info,
                auth_type=self.get_auth_type()
            )
            
        except Exception as e:
            # Use warning level when re-raising - caller handles the error
            logger.warning(f"SAML/SSO authentication error: {sanitize_for_logging(str(e))}")
            return AuthenticationResult(
                success=False,
                error_message=f"SAML authentication failed: {str(e)}",
                auth_type=self.get_auth_type()
            )
    
    async def initiate_sso_flow(self, sap_host: str, session_id: str) -> Dict[str, str]:
        """
        Initiate SAML/SSO authentication flow
        
        Args:
            sap_host: SAP system hostname
            session_id: MCP session ID
            
        Returns:
            Dictionary with SSO URL and request ID
        """
        try:
            request_id = str(uuid.uuid4())
            
            # Store request info
            self.pending_requests[request_id] = {
                'sap_host': sap_host,
                'session_id': session_id,
                'initiated_at': datetime.now(),
                'status': 'pending',
                'expires_at': datetime.now() + timedelta(minutes=15)  # 15-minute timeout
            }
            
            # Build SSO URL
            sso_url = self._build_sso_url(sap_host, request_id)
            
            logger.info(f"Initiated SSO flow for {sap_host}, request_id: {request_id}")
            
            return {
                'sso_url': sso_url,
                'request_id': request_id,
                'expires_in_minutes': 15,
                'instructions': 'Complete authentication in your browser, then call authenticate with the SAML response'
            }
            
        except Exception as e:
            # Use warning level when re-raising - caller handles the error
            logger.warning(f"Failed to initiate SSO flow: {sanitize_for_logging(str(e))}")
            raise Exception(f"SSO initiation failed: {str(e)}")
    
    def _build_sso_url(self, sap_host: str, request_id: str) -> str:
        """Build SSO URL for authentication"""
        # This would be configured based on your SSO provider
        # Examples for different providers:
        
        base_sso_url = self.sso_config.get('sso_base_url', 'https://your-sso-provider.com')
        
        # Generic SAML URL structure
        sso_url = f"{base_sso_url}/saml/login"
        sso_url += f"?target={sap_host}"
        sso_url += f"&request_id={request_id}"
        sso_url += f"&return_url={self.sso_config.get('return_url', 'http://localhost:3000/callback')}"
        
        return sso_url
    
    async def _validate_saml_response(self, saml_response: str, request_info: Dict[str, Any]) -> Dict[str, Any]:
        """
        Validate SAML response and extract user information
        
        This is a placeholder implementation. In production, you would:
        1. Validate SAML signature
        2. Check assertion validity
        3. Extract user attributes
        4. Verify against request info
        """
        try:
            # TODO: Implement actual SAML validation
            # For now, this is a mock implementation
            
            # Check if request is expired
            if datetime.now() > request_info['expires_at']:
                logger.error("SAML request expired")
                return None
            
            # Mock SAML parsing (replace with actual SAML library)
            # In production, use libraries like python3-saml or pysaml2
            
            # Extract user info from SAML response
            # This would parse the actual SAML XML
            user_info = {
                'username': 'extracted_from_saml',  # Extract from SAML
                'email': 'user@company.com',        # Extract from SAML
                'display_name': 'User Name',        # Extract from SAML
                'sap_host': request_info['sap_host'],
                'sap_client': '100',  # This might come from SAML attributes
                'groups': [],         # Extract from SAML
                'session_id': request_info['session_id']
            }
            
            logger.info(f"Validated SAML response for user: {user_info['username']}")
            return user_info
            
        except Exception as e:
            logger.error(f"SAML validation failed: {sanitize_for_logging(str(e))}")
            return None
    
    async def _create_sap_sso_session(self, user_info: Dict[str, Any], 
                                    saml_response: str, request_info: Dict[str, Any]):
        """
        Create SAP session using SSO credentials
        
        This depends on your SAP system's SSO configuration.
        Options include:
        1. SAML assertion forwarding to SAP
        2. Trust relationship between SSO provider and SAP
        3. Service account with impersonation
        """
        try:
            # TODO: Implement SAP SSO session creation
            # This is highly dependent on your SAP and SSO setup
            
            # Option 1: Forward SAML assertion to SAP (if SAP supports it)
            # Option 2: Use service account with user context
            # Option 3: Convert SAML to SAP-compatible token
            
            # For now, return a mock SAP client
            # In production, this would create an actual SAPADTClient
            
            logger.info(f"Created SAP SSO session for {user_info['username']}")
            
            # This would return an actual SAPADTClient instance
            # configured for SSO authentication
            return None  # Placeholder
            
        except Exception as e:
            logger.error(f"Failed to create SAP SSO session: {sanitize_for_logging(str(e))}")
            return None
    
    async def validate_session(self, session_token: str) -> bool:
        """Validate SSO session token"""
        # SSO sessions might have different validation logic
        # Could involve checking with SSO provider
        return len(session_token) > 0
    
    async def refresh_session(self, session_token: str) -> str:
        """Refresh SSO session (if supported by SSO provider)"""
        # Some SSO providers support token refresh
        # This would depend on your SSO configuration
        return None
    
    def get_required_credentials(self) -> List[CredentialInfo]:
        """Get required credential fields for SAML/SSO authentication"""
        return [
            CredentialInfo(
                field_name="request_id",
                description="SSO request ID from initiate_sso_flow",
                required=True,
                example="550e8400-e29b-41d4-a716-446655440000"
            ),
            CredentialInfo(
                field_name="saml_response",
                description="SAML response from SSO provider (base64 encoded)",
                required=True,
                sensitive=True,
                example="PHNhbWxwOlJlc3BvbnNlIC4uLg=="
            )
        ]
    
    def get_auth_type(self) -> AuthenticationType:
        """Get authentication type"""
        return AuthenticationType.SAML_SSO
    
    def get_display_name(self) -> str:
        """Get display name"""
        return "SAML/SSO Authentication"
    
    def supports_refresh(self) -> bool:
        """SSO might support refresh depending on provider"""
        return self.sso_config.get('supports_refresh', False)
    
    def cleanup_expired_requests(self):
        """Clean up expired SSO requests"""
        now = datetime.now()
        expired_requests = [
            request_id for request_id, info in self.pending_requests.items()
            if now > info['expires_at']
        ]
        
        for request_id in expired_requests:
            del self.pending_requests[request_id]
            logger.info(f"Cleaned up expired SSO request: {request_id}")
        
        return len(expired_requests)