"""每个半小时刻度提前5分钟采集，返回值标记对应的半小时刻度。"""

import time

HALF_HOUR_SECONDS = 30 * 60
UPDATE_LEAD_SECONDS = 5 * 60


def half_hour_start(timestamp: float | None = None) -> int:
    if timestamp is None:
        timestamp = time.time()
    return int(timestamp) // HALF_HOUR_SECONDS * HALF_HOUR_SECONDS


def refresh_slot(timestamp: float | None = None) -> int:
    if timestamp is None:
        timestamp = time.time()
    return half_hour_start(timestamp + UPDATE_LEAD_SECONDS)