"""Unit tests for ``resolve_group_ambiguity`` (ADR-0057).

Each address is matched independently, so one UPRN can be the best match for
two *different* addresses (a coarse EPC record absorbing several real
addresses). Withholding that UPRN is a pure function of a postcode group's
``(uprn, normalised_address)`` pairs — no S3, EPC API, or scoring needed — so
it is unit-tested directly here.
"""

from __future__ import annotations

from backend.address2UPRN.scoring import resolve_group_ambiguity


def test_distinct_addresses_sharing_one_uprn_are_withheld() -> None:
    # Flat 1 and Flat 2 both matched the same coarse EPC UPRN — distinct
    # addresses, so both are withheld rather than silently merged.
    result = resolve_group_ambiguity(
        [
            ("100", "flat 1 42 moreton road"),
            ("100", "flat 2 42 moreton road"),
        ]
    )
    assert result == [(None, "ambiguous_duplicate"), (None, "ambiguous_duplicate")]


def test_same_address_listed_twice_keeps_the_uprn() -> None:
    # A genuine re-listing of one property (identical normalised address) is a
    # real duplicate, not an ambiguous match — the UPRN is kept on both.
    result = resolve_group_ambiguity(
        [
            ("100", "42 moreton road"),
            ("100", "42 moreton road"),
        ]
    )
    assert result == [("100", "matched"), ("100", "matched")]


def test_distinct_uprns_are_each_matched() -> None:
    result = resolve_group_ambiguity(
        [
            ("100", "42 moreton road"),
            ("101", "44 moreton road"),
        ]
    )
    assert result == [("100", "matched"), ("101", "matched")]


def test_none_uprn_is_unmatched() -> None:
    result = resolve_group_ambiguity([(None, "99 nowhere lane")])
    assert result == [(None, "unmatched")]


def test_order_is_preserved_across_mixed_group() -> None:
    # A withheld pair, an unmatched row, and a clean match — all in one group;
    # the output aligns positionally with the input.
    result = resolve_group_ambiguity(
        [
            ("100", "flat 1 42 moreton road"),  # ambiguous (with row 3)
            (None, "no epc candidate"),  # unmatched
            ("100", "flat 2 42 moreton road"),  # ambiguous (with row 0)
            ("200", "sole match road"),  # matched
        ]
    )
    assert result == [
        (None, "ambiguous_duplicate"),
        (None, "unmatched"),
        (None, "ambiguous_duplicate"),
        ("200", "matched"),
    ]