"""K 线周期常量与每周期 bar 数 / 缓存 TTL。"""

CHART_INTERVALS: tuple[str, ...] = ("5m", "15m", "30m", "1h", "4h", "1d", "1w")

LONG_INTERVALS: frozenset[str] = frozenset({"1d", "1w"})

# 1d 及以上 500 根；以下 1000 根
INTERVAL_LIMITS: dict[str, int] = {
    "5m": 1000,
    "15m": 1000,
    "30m": 1000,
    "1h": 1000,
    "4h": 1000,
    "1d": 500,
    "1w": 500,
}

# 预取 / 本地 freshness（分钟）
INTERVAL_CACHE_MINUTES: dict[str, int] = {
    "5m": 5,
    "15m": 15,
    "30m": 15,
    "1h": 30,
    "4h": 30,
    "1d": 60,
    "1w": 60,
}


def validate_interval(interval: str) -> str:
    iv = interval.lower().strip()
    if iv not in CHART_INTERVALS:
        raise ValueError(f"unsupported interval: {interval}")
    return iv


def limit_for_interval(interval: str) -> int:
    iv = validate_interval(interval)
    return INTERVAL_LIMITS[iv]


def cache_minutes_for_interval(interval: str) -> int:
    iv = validate_interval(interval)
    return INTERVAL_CACHE_MINUTES[iv]