"""# Summary

SSEInMemoryBus — in-memory event bus for SSE progress events.

---

Buffer published progress events so they can be replayed (and streamed) per
correlation key, such as a job, upload, or fetch-request id.
"""
from typing import Generic, TypeVar

T = TypeVar("T")


class SSEInMemoryBus(Generic[T]):
    """Buffer SSE progress events in memory, keyed by an event attribute.

    Attributes:
        _events (List[T]): Events published since the last clear.
        _key_attr (str): Event attribute used to correlate a stream.
    """

    def __init__(self, key_attr: str = "id"):
        """Initialize an empty event buffer.

        Args:
            key_attr (str): Attribute name on each event holding the stream
                correlation key (for example ``"job_id"``).
        """
        self._events: list[T] = []
        self._key_attr = key_attr

    async def publish(self, event: T) -> None:
        """Append an event to the buffer.

        Args:
            event (T): Event to append.
        """
        self._events.append(event)

    def get_events(self, key: str) -> list[T]:
        """Return buffered events for a correlation key.

        Args:
            key (str): Value matched against the configured ``key_attr``.

        Returns:
            List[T]: Events whose ``key_attr`` equals ``key``.
        """
        return [e for e in self._events if getattr(e, self._key_attr, None) == key]

    def clear(self) -> None:
        """Remove all buffered events."""
        self._events.clear()