"""In-memory log ring buffer so the control UI can show recent agent logs
(detector loads, job errors, autoscaler decisions, outage back-offs) without
needing `docker logs`. A bounded deque holds the last N formatted lines; a
logging.Handler appends to it; the UI polls /logs."""
import logging
from collections import deque

LINES: deque[str] = deque(maxlen=600)


class RingHandler(logging.Handler):
    def emit(self, record: logging.LogRecord) -> None:
        try:
            LINES.append(self.format(record))
        except Exception:
            pass


_installed = False


def install(level: int = logging.INFO) -> None:
    """Attach the ring handler to the root logger once. fc_agent module loggers
    propagate to root, so their records land here."""
    global _installed
    if _installed:
        return
    _installed = True
    h = RingHandler()
    h.setFormatter(
        logging.Formatter("%(asctime)s %(levelname)s %(name)s: %(message)s", "%H:%M:%S")
    )
    root = logging.getLogger()
    root.addHandler(h)
    if root.level == logging.NOTSET or root.level > level:
        root.setLevel(level)
    # Keep the buffer signal-rich: drop the per-request access spam + ultralytics
    # banner noise to WARNING.
    logging.getLogger("uvicorn.access").setLevel(logging.WARNING)
    logging.getLogger("ultralytics").setLevel(logging.WARNING)