from __future__ import annotations

from collections import defaultdict
from collections.abc import Callable
from datetime import datetime
from typing import Any

from sqlalchemy import JSON, DateTime, Integer, String, func
from sqlalchemy.orm import Mapped, Session, mapped_column

from core.db import Base, SessionLocal

EventHandler = Callable[[str, dict[str, Any], Session], None]


class EventLog(Base):
    __tablename__ = "events"

    id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
    type: Mapped[str] = mapped_column(String(128), index=True)
    payload: Mapped[dict] = mapped_column(JSON, default=dict)
    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), server_default=func.now())


class EventBus:
    def __init__(self) -> None:
        self._handlers: dict[str, list[EventHandler]] = defaultdict(list)
        self._wildcards: list[tuple[str, EventHandler]] = []

    def subscribe(self, event_type: str, handler: EventHandler) -> None:
        """Subscribe to an event type. Supports 'namespace.*' wildcards."""
        if event_type.endswith(".*"):
            self._wildcards.append((event_type[:-2], handler))
        else:
            self._handlers[event_type].append(handler)

    def publish(self, event_type: str, payload: dict[str, Any], db: Session | None = None) -> None:
        """Publish event. Persists to events table and calls all handlers synchronously."""
        own_db = db is None
        if own_db:
            db = SessionLocal()
        try:
            db.add(EventLog(type=event_type, payload=payload))
            db.commit()

            for h in self._handlers.get(event_type, []):
                try:
                    h(event_type, payload, db)
                except Exception as e:  # noqa: BLE001
                    print(f"[event-handler-error] {event_type}: {e}")
            for prefix, h in self._wildcards:
                if event_type.startswith(prefix + ".") or event_type == prefix:
                    try:
                        h(event_type, payload, db)
                    except Exception as e:  # noqa: BLE001
                        print(f"[event-handler-error] {event_type}: {e}")
        finally:
            if own_db:
                db.close()


event_bus = EventBus()