"""Terminal session manager for WebSocket connections."""

import asyncio
import logging
import uuid
from typing import Any

from fastapi import WebSocket

from src.services.terminal_session import TerminalSession

logger = logging.getLogger(__name__)


class TerminalManager:
    """Manages active terminal sessions with persistence support."""

    def __init__(self) -> None:
        # Track sessions by instance_id for persistence
        self._sessions: dict[str, TerminalSession] = {}
        self._idle_check_task: asyncio.Task | None = None
        self._start_idle_check()

    def _start_idle_check(self) -> None:
        """Start the idle timeout background task."""
        if self._idle_check_task is None or self._idle_check_task.done():
            self._idle_check_task = asyncio.create_task(self._idle_check_loop())

    async def _idle_check_loop(self) -> None:
        """Periodically check for idle sessions and clean them up."""
        while True:
            try:
                await asyncio.sleep(60)  # Check every minute
                await self._cleanup_idle_sessions()
            except Exception as exc:
                logger.error("Error in idle check loop: %s", exc)

    async def _cleanup_idle_sessions(self) -> None:
        """Clean up sessions that have been idle for too long."""
        idle_sessions = []
        for instance_id, session in list(self._sessions.items()):
            if session.is_idle():
                idle_sessions.append(instance_id)
        
        for instance_id in idle_sessions:
            logger.info("Cleaning up idle terminal session for instance %s", instance_id)
            session = self._sessions.pop(instance_id, None)
            if session:
                await session.close()

    async def get_or_create_session(
        self,
        instance_id: uuid.UUID,
        container_id: str,
    ) -> TerminalSession:
        """Get existing session or create a new one."""
        instance_id_str = str(instance_id)
        
        # Check for existing session
        if instance_id_str in self._sessions:
            session = self._sessions[instance_id_str]
            
            # Check if session is still alive
            if session.is_alive():
                logger.info("Reattaching to existing terminal session for instance %s", instance_id)
                return session
            else:
                # Session died, clean it up
                logger.info("Existing session for instance %s is dead, cleaning up", instance_id)
                await session.close()
                del self._sessions[instance_id_str]
        
        # Create new session
        logger.info("Creating new terminal session for instance %s", instance_id)
        session_id = str(uuid.uuid4())
        session = TerminalSession(session_id, instance_id, container_id)
        await session.start()
        self._sessions[instance_id_str] = session
        
        return session

    async def attach_websocket(
        self,
        session: TerminalSession,
        websocket: WebSocket,
    ) -> None:
        """Attach a WebSocket to an existing session."""
        # Handle concurrent connections - close existing ones
        if session.has_websockets():
            logger.info("Closing existing WebSocket connections for instance %s", session.instance_id)
            for ws in list(session._websockets):
                try:
                    await ws.close(code=4000, reason="New connection established")
                except Exception:
                    pass
            session._websockets.clear()
        
        # Attach new WebSocket
        session.attach_websocket(websocket)
        
        # Replay buffer
        buffer = session.get_buffer()
        if buffer:
            try:
                await websocket.send_bytes(buffer)
            except Exception:
                pass

    async def detach_websocket(
        self,
        session: TerminalSession,
        websocket: WebSocket,
    ) -> None:
        """Detach a WebSocket from a session."""
        session.detach_websocket(websocket)

    async def reset_session(
        self,
        instance_id: uuid.UUID,
        container_id: str,
    ) -> TerminalSession:
        """Reset a session by killing it and creating a new one."""
        instance_id_str = str(instance_id)
        
        # Close existing session if any
        if instance_id_str in self._sessions:
            logger.info("Resetting terminal session for instance %s", instance_id)
            old_session = self._sessions.pop(instance_id_str)
            await old_session.close()
        
        # Create new session
        session_id = str(uuid.uuid4())
        session = TerminalSession(session_id, instance_id, container_id)
        await session.start()
        self._sessions[instance_id_str] = session
        
        return session

    async def close_all(self) -> None:
        """Close all active sessions."""
        sessions = list(self._sessions.values())
        self._sessions.clear()
        for session in sessions:
            await session.close()
        
        if self._idle_check_task and not self._idle_check_task.done():
            self._idle_check_task.cancel()


# Global terminal manager instance
terminal_manager = TerminalManager()