from datetime import UTC, datetime

from opengoods.etl.merge import Candidate, merge_records, resolve_field


def _ts(y, m, d):
    return datetime(y, m, d, tzinfo=UTC)


def test_resolve_field_prefers_trust_then_recency():
    cands = [
        Candidate(value="A", source="off", trust=0.7, fetched_at=_ts(2024, 1, 1)),
        Candidate(value="B", source="gs1", trust=0.9, fetched_at=_ts(2023, 1, 1)),
    ]
    res = resolve_field(cands)
    assert res is not None
    assert res.value == "B"
    assert res.source == "gs1"


def test_resolve_field_recency_tiebreak_on_equal_trust():
    cands = [
        Candidate(value="old", source="a", trust=0.7, fetched_at=_ts(2023, 1, 1)),
        Candidate(value="new", source="b", trust=0.7, fetched_at=_ts(2024, 6, 1)),
    ]
    assert resolve_field(cands).value == "new"


def test_resolve_field_skips_empty():
    cands = [
        Candidate(value="", source="a", trust=0.99),
        Candidate(value=None, source="b", trust=0.99),
        Candidate(value="kept", source="c", trust=0.1),
    ]
    assert resolve_field(cands).value == "kept"
    assert resolve_field([Candidate(value="", source="a")]) is None


def test_merge_records_provenance():
    records = [
        {
            "name": Candidate("Water", "off", 0.7, _ts(2024, 1, 1)),
            "brand": Candidate("", "off", 0.7),
        },
        {
            "brand": Candidate("Acme", "gs1", 0.9, _ts(2024, 2, 1)),
            "gtin": Candidate("123", "gs1", 0.9),
        },
    ]
    merged = merge_records(records)
    assert merged.values["name"] == "Water"
    assert merged.values["brand"] == "Acme"
    assert merged.values["gtin"] == "123"
    assert merged.provenance["brand"] == "gs1"
    assert merged.provenance["name"] == "off"


def test_merge_records_accepts_bare_values():
    merged = merge_records([{"x": 1}, {"x": 2}])
    # both bare -> trust tie, no timestamps -> first max() wins deterministically
    assert merged.values["x"] in (1, 2)
    assert merged.provenance["x"] == "unknown"