"""VPN Sync Service for synchronizing VPN connection state with database."""

from datetime import datetime
from sqlalchemy.orm import Session
from ..models.vpn_server import VPNServer
from ..models.vpn_profile import VPNProfile
from ..models.vpn_connection_log import VPNConnectionLog
from ..models.gateway import Gateway
from .vpn_server_service import VPNServerService


class VPNSyncService:
    """Service to sync VPN connections with gateway status and logs."""

    def __init__(self, db: Session):
        self.db = db
        self.vpn_service = VPNServerService(db)

    def sync_all_connections(self) -> dict:
        """
        Sync all VPN connections across all servers.
        Returns summary of changes.
        """
        result = {
            "servers_checked": 0,
            "clients_found": 0,
            "gateways_online": 0,
            "gateways_offline": 0,
            "new_connections": 0,
            "closed_connections": 0,
            "errors": []
        }

        # Get all active VPN servers
        servers = self.db.query(VPNServer).filter(VPNServer.is_active == True).all()

        # Collect all currently connected CNs
        connected_cns = set()

        for server in servers:
            result["servers_checked"] += 1
            try:
                clients = self.vpn_service.get_connected_clients(server)
                result["clients_found"] += len(clients)

                for client in clients:
                    cn = client.get("common_name")
                    if cn:
                        connected_cns.add(cn)
                        self._handle_connected_client(server, client, result)

            except Exception as e:
                result["errors"].append(f"Server {server.name}: {str(e)}")

        # Mark disconnected profiles/gateways
        self._handle_disconnected_profiles(connected_cns, result)

        self.db.commit()
        return result

    def _handle_connected_client(self, server: VPNServer, client: dict, result: dict):
        """Handle a connected VPN client - update profile, gateway, and log."""
        cn = client.get("common_name")
        real_address = client.get("real_address")
        bytes_rx = client.get("bytes_received", 0)
        bytes_tx = client.get("bytes_sent", 0)
        connected_since = client.get("connected_since")

        # Find profile by CN
        profile = self.db.query(VPNProfile).filter(
            VPNProfile.cert_cn == cn,
            VPNProfile.vpn_server_id == server.id
        ).first()

        if not profile:
            # Try finding by CN across all servers (in case of migration)
            profile = self.db.query(VPNProfile).filter(
                VPNProfile.cert_cn == cn
            ).first()

        if not profile:
            return  # Unknown client, skip

        gateway = profile.gateway

        # Update gateway status
        if not gateway.is_online:
            gateway.is_online = True
            gateway.last_seen = datetime.utcnow()
            result["gateways_online"] += 1

        # Update profile last connection
        profile.last_connection = datetime.utcnow()

        # Check for existing active connection log
        active_log = self.db.query(VPNConnectionLog).filter(
            VPNConnectionLog.vpn_profile_id == profile.id,
            VPNConnectionLog.disconnected_at.is_(None)
        ).first()

        if not active_log:
            # Create new connection log
            log = VPNConnectionLog(
                vpn_profile_id=profile.id,
                vpn_server_id=server.id,
                gateway_id=gateway.id,
                common_name=cn,
                real_address=real_address,
                connected_at=datetime.utcnow(),
                bytes_received=bytes_rx,
                bytes_sent=bytes_tx
            )
            self.db.add(log)
            result["new_connections"] += 1
        else:
            # Update traffic stats
            active_log.bytes_received = bytes_rx
            active_log.bytes_sent = bytes_tx
            active_log.real_address = real_address

    def _handle_disconnected_profiles(self, connected_cns: set, result: dict):
        """Mark profiles as disconnected if their CN is no longer connected."""
        # Find all active connection logs
        active_logs = self.db.query(VPNConnectionLog).filter(
            VPNConnectionLog.disconnected_at.is_(None)
        ).all()

        for log in active_logs:
            if log.common_name not in connected_cns:
                # Mark as disconnected
                log.disconnected_at = datetime.utcnow()
                result["closed_connections"] += 1

                # Update gateway status
                gateway = log.gateway

                # Check if gateway has any other active connections
                other_active = self.db.query(VPNConnectionLog).filter(
                    VPNConnectionLog.gateway_id == gateway.id,
                    VPNConnectionLog.id != log.id,
                    VPNConnectionLog.disconnected_at.is_(None)
                ).first()

                if not other_active:
                    gateway.is_online = False
                    result["gateways_offline"] += 1

    def get_profile_connection_logs(
        self,
        profile_id: int,
        limit: int = 50
    ) -> list[VPNConnectionLog]:
        """Get connection logs for a specific profile."""
        return self.db.query(VPNConnectionLog).filter(
            VPNConnectionLog.vpn_profile_id == profile_id
        ).order_by(VPNConnectionLog.connected_at.desc()).limit(limit).all()

    def get_gateway_connection_logs(
        self,
        gateway_id: int,
        limit: int = 50
    ) -> list[VPNConnectionLog]:
        """Get connection logs for a gateway (all profiles)."""
        return self.db.query(VPNConnectionLog).filter(
            VPNConnectionLog.gateway_id == gateway_id
        ).order_by(VPNConnectionLog.connected_at.desc()).limit(limit).all()

    def get_server_connection_logs(
        self,
        server_id: int,
        limit: int = 50
    ) -> list[VPNConnectionLog]:
        """Get connection logs for a VPN server."""
        return self.db.query(VPNConnectionLog).filter(
            VPNConnectionLog.vpn_server_id == server_id
        ).order_by(VPNConnectionLog.connected_at.desc()).limit(limit).all()

    def get_active_connections(self) -> list[VPNConnectionLog]:
        """Get all currently active VPN connections."""
        return self.db.query(VPNConnectionLog).filter(
            VPNConnectionLog.disconnected_at.is_(None)
        ).order_by(VPNConnectionLog.connected_at.desc()).all()