"""Pricing a known handful of product variants ranks only their own observations.

The home page's featured savings priced their eight cards through
`list_product_variants(only_ids=...)`, whose latest-observation subquery ranked every price
observation in the catalogue: about 450 of the request's 600 ms on staging (11 Sep),
six seconds for some airport sets, and growing with every collection. Scoped to the
product variants' listings, 130 to 220 ms with identical results. This pins the scoping.
"""

from sqlalchemy import select
from sqlalchemy.dialects import postgresql

from app.services import catalog_queries


def _sql(clause) -> str:
    return str(clause.compile(dialect=postgresql.dialect(), compile_kwargs={"literal_binds": True}))


def test_a_known_handful_ranks_only_its_own_listings():
    sql = _sql(select(catalog_queries._latest_observation_subquery([52, 820])))
    assert "row_number() OVER (PARTITION BY price_observations.listing_id" in sql
    assert "price_observations.listing_id IN (SELECT listings.id" in sql
    assert "listings.variant_id IN (52, 820)" in sql


def test_a_browse_still_ranks_the_catalogue():
    sql = _sql(select(catalog_queries._latest_observation_subquery()))
    assert "listings.variant_id IN" not in sql


def test_list_products_passes_its_ids_to_the_ranking():
    base = catalog_queries._summary_base(None, None, variant_ids=[7])
    assert "listings.variant_id IN (7)" in _sql(base)
    assert "listings.variant_id IN" not in _sql(catalog_queries._summary_base(None, None))


def test_a_route_ranks_only_its_products_at_its_shops():
    """The savings page (services/trip.py): a two-airport route took 0.7 to 2.3 s on
    staging (11 Sep) ranking the catalogue, and the planner re-ran the route's
    candidate query once per price row; now candidates are fetched once and the
    ranking covers only them at the route's shops, 1 to 80 ms, identical output."""
    sql = _sql(select(catalog_queries._latest_observation_subquery(variant_ids=[5, 6], shop_ids=[8, 13])))
    assert "listings.variant_id IN (5, 6)" in sql
    assert "listings.shop_id IN (8, 13)" in sql