"""Smart-corners IPC subscriber.

Listens to fenster's `:smart_corners` event and emits a per-output signal
when the WM's smart-corners state flips. Caches the latest state per output
so widgets created after the event can ask for the current value.
"""
from fabric.core.service import Service, Signal
from loguru import logger

from sims.services.fenster import get_i3_connection


_service: "SmartCornersService | None" = None


class SmartCornersService(Service):
    @Signal
    def state_changed(self, output: str, active: bool) -> None:
        """Emitted when a fenster output flips smart-corners state."""

    def __init__(self, **kwargs):
        super().__init__(**kwargs)
        self._state: dict[str, bool] = {}
        i3 = get_i3_connection()
        i3.connect("event::smart_corners", self._on_event)

    def get(self, output: str) -> bool:
        """Latest known state for an output, or False if unseen."""
        return self._state.get(output, False)

    def _on_event(self, _i3, event):
        change = event.data.get("change")
        output = event.data.get("output")
        if not isinstance(output, str) or change not in ("active", "inactive"):
            logger.warning(f"[SmartCorners] unexpected event payload: {event.data!r}")
            return
        active = change == "active"
        if self._state.get(output) == active:
            return
        self._state[output] = active
        self.state_changed(output, active)


def get_smart_corners_service() -> SmartCornersService:
    global _service
    if _service is None:
        _service = SmartCornersService()
    return _service