import time
from collections import deque

from app.sample import Sample


class HistoryStore:
    def __init__(self, maxlen: int) -> None:
        self._buf: deque[Sample] = deque(maxlen=maxlen)

    def record(self, sample: Sample) -> None:
        sample.ts = time.time()
        self._buf.append(sample)

    def snapshot(self) -> list[Sample]:
        return list(self._buf)

    def latest(self) -> Sample | None:
        return self._buf[-1] if self._buf else None

    def __len__(self) -> int:
        return len(self._buf)