"""Regression guard: list_persons must batch — a constant number of queries,
not one (or three) per person. A 2k-person tree took ~4s before this was fixed."""

import sqlalchemy as sa

from tests.conftest import auth, register


async def test_list_persons_does_not_n_plus_one(client, engine):
    owner = auth(await register(client, "perf-owner@ex.com"))
    tid = (await client.post("/api/v1/trees", json={"name": "Perf"}, headers=owner)).json()["id"]
    n = 25
    for i in range(n):
        await client.post(
            f"/api/v1/trees/{tid}/persons",
            json={"given": f"P{i}", "surname": "X"},
            headers=owner,
        )

    selects = 0

    def _count(conn, cursor, statement, params, context, executemany):
        nonlocal selects
        if statement.lstrip().upper().startswith("SELECT"):
            selects += 1

    sa.event.listen(engine.sync_engine, "before_cursor_execute", _count)
    try:
        resp = await client.get(f"/api/v1/trees/{tid}/persons", headers=owner)
    finally:
        sa.event.remove(engine.sync_engine, "before_cursor_execute", _count)

    assert resp.status_code == 200
    body = resp.json()
    assert len(body) == n
    assert all(p["primary_name"] for p in body)  # names still resolve correctly
    # Batched: a small constant (auth, role, persons, one names query, …) — NOT
    # proportional to n. The old per-person path was ~3·n SELECTs.
    assert 0 < selects < n, f"expected a constant query count, got {selects} for {n} people"