from __future__ import annotations
from datetime import datetime, timezone
from sqlalchemy import DateTime, Float, Index, Integer, String, UniqueConstraint
from sqlalchemy.orm import Mapped, mapped_column
from .base import Base
from steward.core.ids import time_ordered_id


class PluginMetric(Base):
    __tablename__ = "plugin_metrics"

    id: Mapped[str] = mapped_column(String(36), primary_key=True, default=time_ordered_id)
    source_module: Mapped[str] = mapped_column(String(64), nullable=False)
    resource_name: Mapped[str] = mapped_column(String(255), nullable=False)
    metric_name: Mapped[str] = mapped_column(String(128), nullable=False)
    value: Mapped[float] = mapped_column(Float, nullable=False)
    recorded_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True), nullable=False, default=lambda: datetime.now(timezone.utc)
    )

    # This time-series table grows by (sources × resources × sample cadence); every
    # host-detail / full-metrics / dashboard-widget read filters by
    # (source_module, resource_name) over a recorded_at range. Without these it's a
    # full sequential scan on every load.
    __table_args__ = (
        Index("ix_plugin_metrics_module_resource_recorded",
              "source_module", "resource_name", "recorded_at"),
        # One series over a time range, read from the index alone: `value` is
        # carried in it. Built after boot by core/metric_index.py, not by a
        # migration, since a build over the live table takes minutes (#5490).
        Index("ix_plugin_metrics_series_value",
              "source_module", "resource_name", "metric_name", "recorded_at",
              postgresql_include=["value"]),
    )


class PluginMetricLatest(Base):
    """The newest sample of each (source, resource, metric), kept beside
    plugin_metrics by record_metrics so "what is it now" never scans history.

    Postgres has no skip scan, so a newest-per-key query over plugin_metrics
    reads every raw sample in the window: on a seven-day window that took a
    dashboard widget a minute (#5208). This table is one row per key. Retention
    drops a row once its sample has aged out of the raw window, so a resource
    that stopped reporting disappears when its raw history does.
    """
    __tablename__ = "plugin_metric_latest"

    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)
    value: Mapped[float] = mapped_column(Float, nullable=False)
    recorded_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), nullable=False)


class PluginMetricHourly(Base):
    """Hourly rollup of plugin_metrics — the coarse series that retention rolls
    raw samples into before pruning them, so multi-day/week history stays cheap.

    One row per (source_module, resource_name, metric_name, hour bucket); the
    unique constraint is the conflict target for the idempotent rollup upsert.
    Charts read this for the part of a range older than the raw-retention window.
    """
    __tablename__ = "plugin_metrics_hourly"

    id: Mapped[str] = mapped_column(String(36), primary_key=True, default=time_ordered_id)
    source_module: Mapped[str] = mapped_column(String(64), nullable=False)
    resource_name: Mapped[str] = mapped_column(String(255), nullable=False)
    metric_name: Mapped[str] = mapped_column(String(128), nullable=False)
    bucket: Mapped[datetime] = mapped_column(DateTime(timezone=True), nullable=False)
    value_avg: Mapped[float] = mapped_column(Float, nullable=False, default=0.0)
    value_max: Mapped[float] = mapped_column(Float, nullable=False, default=0.0)
    # The level the hour held for all but its briefest 5% (#5738): a spike of
    # a minute or two raises value_max and leaves this low. NULL on hours
    # rolled up before it was kept; read those as value_avg.
    value_p95: Mapped[float | None] = mapped_column(Float, nullable=True)
    sample_count: Mapped[int] = mapped_column(Integer, nullable=False, default=0)

    __table_args__ = (
        UniqueConstraint("source_module", "resource_name", "metric_name", "bucket",
                         name="uq_plugin_metrics_hourly_bucket"),
        Index("ix_plugin_metrics_hourly_lookup",
              "source_module", "resource_name", "metric_name", "bucket"),
    )