"""Monitoring service contract (frozen, #34).

Split of responsibilities (ADR-007):
  * Lane B (#38) implements `MonitoringService`: builds a patient snapshot from the DB, runs the deterministic
    rules (`app.core.rules.evaluate`), persists `alert`/`crisis` actions and notifies the doctor itself.
  * It returns only the *dialog* actions (schedule_scale, med_info, reach_out, show_safety_plan, suggest_visit,
    crisis) so the engine (lane A, #10) can react in the conversation. The engine never creates alerts.
"""

from collections.abc import Callable
from importlib import import_module, util
from typing import Protocol

from app.core.rules import Action


class MonitoringService(Protocol):
    async def after_data_change(self, token: str) -> list[Action]: ...

    async def is_in_crisis(self, token: str) -> bool:
        """True while an `acute` alert is open (not acked by the doctor) — FSM stays in `crisis`."""
        ...


class NoopMonitoring:
    """Placeholder until #38 lands."""

    async def after_data_change(self, token: str) -> list[Action]:
        return []

    async def is_in_crisis(self, token: str) -> bool:
        return False


_factory: Callable[[], MonitoringService] = NoopMonitoring


def register_monitoring(factory: Callable[[], MonitoringService]) -> None:
    global _factory
    _factory = factory


def get_monitoring() -> MonitoringService:
    # find_spec instead of try/except ImportError: real import errors inside the module must surface.
    if util.find_spec("app.services.monitoring") is not None:
        import_module("app.services.monitoring")
    return _factory()