"""Generic slash-command confirmation primitive (gateway-side).

Slash commands with an expensive side effect worth surfacing (currently only
``/reload-mcp``, which invalidates the provider prompt cache) route through
here. Adapters with button UIs render Approve Once / Always Approve / Cancel
and call ``resolve()`` from the callback; text-only adapters get a prompt and
the gateway intercepts ``/approve``, ``/always``, ``/cancel`` replies.

State is module-level (like ``tools.approval``) so adapters can resolve
callbacks without a ``GatewayRunner`` backreference. The CLI has its own
synchronous variant (``_prompt_slash_confirm`` in ``cli.py``).
"""

from __future__ import annotations

import logging
import threading
import time
from typing import Any, Awaitable, Callable, Dict, Optional

logger = logging.getLogger(__name__)

# session_key -> {"confirm_id", "command", "handler", "created_at"}
_pending: Dict[str, Dict[str, Any]] = {}
_lock = threading.RLock()

# A pending confirm older than this is discarded when the next message
# arrives for the same session (buttons live as long as the adapter keeps
# the callback_data).
DEFAULT_TIMEOUT_SECONDS = 300


def register(
    session_key: str,
    confirm_id: str,
    command: str,
    handler: Callable[[str], Awaitable[Optional[str]]],
) -> None:
    """Register a pending confirm, superseding any prior one for the session."""
    with _lock:
        _pending[session_key] = {
            "confirm_id": confirm_id,
            "command": command,
            "handler": handler,
            "created_at": time.time(),
        }


def get_pending(session_key: str) -> Optional[Dict[str, Any]]:
    """Return a copy of the pending confirm dict for a session, or None."""
    with _lock:
        entry = _pending.get(session_key)
        return dict(entry) if entry else None


def clear(session_key: str) -> None:
    """Drop the pending confirm for ``session_key`` without running it."""
    with _lock:
        _pending.pop(session_key, None)


def _is_stale(entry: Dict[str, Any], timeout: float) -> bool:
    return time.time() - float(entry.get("created_at", 0) or 0) > timeout


def clear_if_stale(session_key: str, timeout: float = DEFAULT_TIMEOUT_SECONDS) -> bool:
    """Drop the pending confirm if older than ``timeout`` seconds; True if dropped."""
    with _lock:
        entry = _pending.get(session_key)
        if entry and _is_stale(entry, timeout):
            _pending.pop(session_key, None)
            return True
        return False


async def resolve(
    session_key: str,
    confirm_id: str,
    choice: str,
    timeout: float = DEFAULT_TIMEOUT_SECONDS,
) -> Optional[str]:
    """Run the pending handler with ``choice`` ("once" / "always" / "cancel").

    Returns the handler's output string, or None if the confirm was stale,
    already resolved, or the confirm_id doesn't match (superseded prompt).
    Safe from an asyncio button callback or the gateway's message intercept.
    """
    with _lock:
        entry = _pending.get(session_key)
        if not entry or entry.get("confirm_id") != confirm_id:
            return None
        # Pop before running so duplicate callbacks (button double-click)
        # cannot run the handler twice.
        _pending.pop(session_key, None)
        if _is_stale(entry, timeout):
            return None
        handler = entry.get("handler")
        command = entry.get("command", "?")

    if not handler:
        return None
    try:
        result = await handler(choice)
    except Exception as exc:
        logger.error(
            "Slash-confirm handler for /%s raised: %s",
            command, exc, exc_info=True,
        )
        return f"❌ Error handling confirmation: {exc}"
    return result if isinstance(result, str) else None