"""
Session loop — the core driver for each active session.
One SessionLoop instance runs per session as an asyncio Task.
Never dispatches two LLM calls simultaneously.
Starts immediately for autonomous mode; waits for first talker message otherwise.
"""

import asyncio
import logging
from typing import TYPE_CHECKING

if TYPE_CHECKING:
    from fellowship.core.session import Session

logger = logging.getLogger(__name__)


class SessionLoop:
    def __init__(self, session: "Session") -> None:
        self.session = session
        self._task: asyncio.Task | None = None
        self._pause_event = asyncio.Event()
        self._pause_event.set()  # Not paused by default

    def start(self) -> None:
        """Start the loop as a background asyncio Task."""
        self._task = asyncio.create_task(self._run(), name=f"loop-{self.session.token[:8]}")

    def stop(self) -> None:
        """Cancel the loop task."""
        if self._task:
            self._task.cancel()

    def pause(self) -> None:
        """Pause the loop. Clears the internal event so the loop blocks."""
        self._pause_event.clear()

    def resume(self) -> None:
        """Resume a paused loop."""
        self._pause_event.set()

    async def _run(self) -> None:
        """
        Main loop body. Runs until the session ends or the task is cancelled.
        Each iteration:
          1. Wait if paused.
          2. Check for pending talker messages (all modes).
          3. Determine next bot speaker (round_robin or orchestrator).
          4. Execute bot turn.
          5. Check end conditions.
        """
        raise NotImplementedError

    async def _handle_talker_message(self) -> bool:
        """
        Drain one message from the talker queue into history.
        Returns True if a message was processed.
        """
        raise NotImplementedError

    async def _check_end_conditions(self) -> bool:
        """
        Check all configured end conditions (max_turns, max_time, max_context_tokens).
        Returns True if the session should end.
        """
        raise NotImplementedError