"""Integration: the covering series index on plugin_metrics (#5490), built
after boot against Postgres. It replaces the plain series index, a later boot
only checks, and a day of one series is then read from the index alone."""
from __future__ import annotations

import asyncio
import logging
import os

import pytest

pytestmark = pytest.mark.integration


@pytest.fixture
def app():
    if not os.environ.get("STEWARD_DATABASE_URL"):
        pytest.skip("needs Postgres")
    from steward.app import create_app
    return create_app(testing=False)


def test_the_series_index_is_built_once_and_replaces_the_plain_one(app):
    from sqlalchemy import text
    from steward.core.metric_index import REPLACES, SERIES_INDEX, ensure_series_index

    log = logging.getLogger("test")

    async def _indexes():
        async with app.db_sessionmaker() as s:
            return dict((await s.execute(text(
                "SELECT indexname, indexdef FROM pg_indexes WHERE tablename = 'plugin_metrics'"))).all())

    async def _go():
        first = await ensure_series_index(app._db_engine, log)
        got = await _indexes()
        assert SERIES_INDEX in got and REPLACES not in got
        assert "INCLUDE (value)" in got[SERIES_INDEX]
        assert await ensure_series_index(app._db_engine, log) == "present"
        assert first in ("built", "present")

        # One series over a day is answered from the index alone.
        async with app.db_sessionmaker() as s:
            await s.execute(text("SET enable_seqscan = off"))
            await s.execute(text("SET enable_bitmapscan = off"))
            plan = "\n".join(r[0] for r in (await s.execute(text(
                "EXPLAIN SELECT date_trunc('hour', recorded_at), avg(value) FROM plugin_metrics "
                "WHERE source_module = 'host_agent' AND resource_name = 'x' "
                "AND metric_name = 'cpu_pct' AND recorded_at >= now() - interval '1 day' "
                "GROUP BY 1"))).all())
        assert f"Index Only Scan using {SERIES_INDEX}" in plan, plan

    asyncio.run(_go())