from __future__ import annotations
from datetime import datetime
from sqlalchemy import DateTime, Float, Integer, SmallInteger, String
from sqlalchemy.orm import Mapped, mapped_column
from .base import Base


class MetricNorm(Base):
    """What one metric usually does in one time slot (#5739), learned from
    its own history by steward.core.norms.rebuild_norms.

    `kind` says what a slot is: "day" (0–23, the UTC hour of day) or "week"
    (0–167, Monday 00:00 UTC first). A key has slots of one kind at a time.
    The whole table is rebuilt each pass, so a row is never edited."""
    __tablename__ = "metric_norms"

    source_module: Mapped[str] = mapped_column(String(64), primary_key=True)
    resource_name: Mapped[str] = mapped_column(String(255), primary_key=True)
    metric_name: Mapped[str] = mapped_column(String(128), primary_key=True)
    slot: Mapped[int] = mapped_column(SmallInteger, primary_key=True)
    kind: Mapped[str] = mapped_column(String(8), nullable=False)
    # The level the slot's hours usually held, and how high they usually
    # peaked: the 90th percentile, across past days, of each hour's p95 and max.
    usual_hold: Mapped[float] = mapped_column(Float, nullable=False)
    usual_peak: Mapped[float] = mapped_column(Float, nullable=False)
    days_seen: Mapped[int] = mapped_column(Integer, nullable=False)
    updated_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), nullable=False)