"""get_supplementary_data_batch fetches one query per table for all URNs
(not ~5 per school) and returns the same per-URN block shape as the
single-URN function, picking the latest row per URN where relevant."""

import types

from backend import data_loader
from backend.data_loader import get_supplementary_data_batch


def _sort_key(criterion):
    """(column name, descending) for a SQLAlchemy order_by argument.

    A bare column (Model.year) arrives as an InstrumentedAttribute carrying
    .key; Model.year.desc() wraps it in a UnaryExpression whose column sits on
    .element.
    """
    name = getattr(criterion, "key", None)
    if name is not None:
        return name, False
    element = getattr(criterion, "element", None)
    name = getattr(element, "key", None)
    return name, "DESC" in str(criterion).upper()


class _FakeQuery:
    """Records that a query ran and serves canned rows filtered by an in-list.

    order_by is honoured rather than ignored. The batch loader picks a row per
    URN by position — first for "latest Ofsted", last for "latest cut-off
    distance" — which is only correct because the database returned them
    sorted. A double that drops the ORDER BY makes those picks depend on
    fixture insertion order instead, so the test would pass with the sort
    reversed or removed and prove nothing about the query.
    """

    def __init__(self, recorder, model_name, rows):
        self._rec = recorder
        self._model = model_name
        self._rows = rows

    def filter(self, *args, **kwargs):
        return self

    def order_by(self, *criteria):
        for crit in reversed(criteria):  # reversed = stable multi-key sort
            name, descending = _sort_key(crit)
            if not name:
                continue
            values = [getattr(r, name, None) for r in self._rows]
            # Only sort on plainly comparable values. Some fixtures stand dates
            # up as namespace objects, which raise on <; leaving those in their
            # given order matches what the real query would produce for them.
            if not all(isinstance(v, (int, float, str)) for v in values):
                continue
            self._rows = sorted(
                self._rows, key=lambda r: getattr(r, name), reverse=descending
            )
        return self

    def all(self):
        self._rec.append(self._model)
        return self._rows

    def first(self):
        self._rec.append(self._model)
        return self._rows[0] if self._rows else None


class _FakeSession:
    def __init__(self, rows_by_model):
        self.rows_by_model = rows_by_model
        self.queries: list[str] = []

    def query(self, model):
        name = model.__name__
        return _FakeQuery(self.queries, name, self.rows_by_model.get(name, []))

    def rollback(self):
        pass


def _ofsted_row(urn, date, oe):
    base = {f: None for f in (
        "framework", "inspection_type", "quality_of_education", "behaviour_attitudes",
        "personal_development", "leadership_management", "early_years_provision",
        "sixth_form_provision", "ungraded_outcome", "ungraded_grade",
        "rc_safeguarding_met", "rc_inclusion", "rc_curriculum_teaching", "rc_achievement",
        "rc_attendance_behaviour", "rc_personal_development", "rc_leadership_governance",
        "rc_early_years", "rc_sixth_form", "report_url",
    )}
    base.update(urn=urn, inspection_date=types.SimpleNamespace(isoformat=lambda: date),
                overall_effectiveness=oe, grade_source=None)
    return types.SimpleNamespace(**base)


def _adm_row(urn, year):
    return types.SimpleNamespace(
        urn=urn, year=year, school_phase="Primary", places_offered=100,
        total_applications=200, first_preference_applications=150,
        first_preference_offers=140, first_preference_offer_pct=93.3,
        oversubscription_ratio=1.5, oversubscribed=True,
        total_offers=100, second_preference_offers=5, third_preference_offers=2,
        cross_la_applications=10, cross_la_offers=3,
    )


def _dist_row(urn, year, distance_m, route_count=1):
    return types.SimpleNamespace(
        urn=urn, year=year, distance_m=distance_m, route_count=route_count,
        la_name="Camden", distance_unit_raw="miles", source_file="camden/guide.pdf",
    )


def test_one_query_per_table_and_latest_row_per_urn():
    rows = {
        # URN 1 has two Ofsted rows; the batch must keep the most recent (2023).
        "FactOfstedInspection": [
            _ofsted_row(1, "2023-01-01", 2),
            _ofsted_row(1, "2019-01-01", 3),
            _ofsted_row(2, "2021-06-01", 1),
        ],
        "FactAdmissions": [_adm_row(1, 202526), _adm_row(1, 202627), _adm_row(2, 202627)],
        # URN 1 has three years of cut-offs; only the most recent is served.
        # Deliberately not in year order — the ordering is the query's job.
        "FactAdmissionDistance": [
            _dist_row(1, 2026, 529.47),
            _dist_row(1, 2024, 772.49),
            _dist_row(1, 2025, 1421.05),
            _dist_row(2, 2023, 2029.38, route_count=4),
        ],
        "FactPupilCharacteristics": [],
        "FactDeprivation": [],
        "FactFinance": [],
    }
    session = _FakeSession(rows)
    out = get_supplementary_data_batch(session, [1, 2])

    # Exactly one query per table — six total, regardless of two URNs.
    assert sorted(session.queries) == [
        "FactAdmissionDistance", "FactAdmissions", "FactDeprivation",
        "FactFinance", "FactOfstedInspection", "FactPupilCharacteristics",
    ]

    # Latest Ofsted kept per URN
    assert out[1]["ofsted"]["overall_effectiveness"] == 2
    assert out[2]["ofsted"]["overall_effectiveness"] == 1

    # Admissions history grouped per URN, latest exposed as `admissions`
    assert [r["year"] for r in out[1]["admissions_history"]] == [202526, 202627]
    assert out[1]["admissions"]["year"] == 202627
    assert out[2]["admissions_history"] == [{**out[2]["admissions_history"][0]}]

    # Cut-off distance: full history oldest-first, with the newest year also
    # exposed on its own. The fixture rows are deliberately out of order, so
    # this only passes if the query's ORDER BY is doing the work.
    assert [r["year"] for r in out[1]["admission_distance_history"]] == [2024, 2025, 2026]
    assert out[1]["admission_distance"]["year"] == 2026
    assert out[1]["admission_distance"]["distance_m"] == 529.47
    # route_count travels with the figure — the page needs it to say the
    # distance is the furthest of several bands rather than the only one.
    assert out[2]["admission_distance"]["route_count"] == 4

    # Empty tables degrade to the null block, not a crash
    assert out[1]["census"] is None and out[1]["deprivation"] is None


def test_single_wrapper_matches_batch(monkeypatch):
    session = _FakeSession({"FactOfstedInspection": [_ofsted_row(5, "2022-01-01", 2)]})
    single = data_loader.get_supplementary_data(session, 5)
    assert single["ofsted"]["overall_effectiveness"] == 2
    assert single["admissions_history"] == []
    assert single["admission_distance"] is None
    assert single["admission_distance_history"] == []