import pandas as pd
import pytest
from src.transform.clean import drop_nulls, deduplicate, cast_types


def test_drop_nulls_removes_rows():
    df = pd.DataFrame({"id": [1, 2, None], "val": ["a", "b", "c"]})
    result = drop_nulls(df, ["id"])
    assert len(result) == 2
    assert 3 not in result["id"].values


def test_deduplicate_keeps_last():
    df = pd.DataFrame({"id": [1, 1, 2], "val": ["old", "new", "only"]})
    result = deduplicate(df, ["id"])
    assert len(result) == 2
    assert result[result["id"] == 1]["val"].values[0] == "new"


def test_cast_types():
    df = pd.DataFrame({"count": ["1", "2", "3"]})
    result = cast_types(df, {"count": int})
    assert result["count"].dtype == int


def test_strip_pii_hashes_values():
    import hashlib
    df = pd.DataFrame({"email": ["alice@example.com"]})
    from src.transform.clean import strip_pii
    result = strip_pii(df, ["email"])
    expected = hashlib.sha256(b"alice@example.com").hexdigest()
    assert result["email"].values[0] == expected