"""The admin Configuration page reads every override in one query (E31 S4d).

`sysconfig.describe()` did a `db.get` per key to tell whether an override was set, and `get()` did one
more for its value: ~55 keys, and two round trips for a key with no row, since the session cannot cache
an absence. That was ~40 ms of the page's ~55 on prod. It now reads the table once. DB lane.
"""

from sqlalchemy import event

from app import sysconfig


def _statements(db, fn) -> int:
    seen: list[str] = []
    engine = db.get_bind()
    listener = lambda *a, **k: seen.append(a[2])  # noqa: E731 — (conn, cursor, statement, …)
    event.listen(engine, "before_cursor_execute", listener)
    try:
        fn()
    finally:
        event.remove(engine, "before_cursor_execute", listener)
    return len(seen)


def test_describe_reads_the_overrides_once(db):
    sysconfig.set_value(db, "quota_daily_budget", 5000)
    db.commit()
    assert _statements(db, lambda: sysconfig.describe(db)) == 1


def test_describe_shows_the_stored_value_and_the_default(db):
    sysconfig.set_value(db, "quota_daily_budget", 5000)
    db.commit()
    items = {i["key"]: i for g in sysconfig.describe(db)["groups"].values() for i in g}
    assert items["quota_daily_budget"]["is_set"] is True
    assert items["quota_daily_budget"]["value"] == 5000
    other = next(i for k, i in items.items() if k != "quota_daily_budget" and not i["secret"])
    assert other["is_set"] is False
    assert other["value"] == other["default"]