import dataclasses

import pytest

from domain.postcode import Postcode


def test_postcode_uppercases() -> None:
    # act / assert
    assert Postcode("sw1a1aa").value == "SW1A1AA"


def test_postcode_strips_internal_spaces() -> None:
    # act / assert
    assert Postcode("sw1a 1aa").value == "SW1A1AA"


def test_postcode_strips_leading_and_trailing_whitespace() -> None:
    # act / assert
    assert Postcode("  sw1a 1aa  ").value == "SW1A1AA"


def test_postcode_strips_tabs_and_newlines() -> None:
    # CSV ingestion occasionally introduces stray whitespace characters; the
    # canonical form must absorb them just like literal spaces.
    # act / assert
    assert Postcode("sw1a\t1aa\n").value == "SW1A1AA"


def test_postcode_construction_is_idempotent() -> None:
    # arrange
    once = Postcode("sw1a 1aa")
    # act / assert
    assert Postcode(once.value).value == "SW1A1AA"


def test_postcode_empty_string() -> None:
    # act / assert
    assert Postcode("").value == ""


def test_postcode_str_returns_canonical_value() -> None:
    # act / assert
    assert str(Postcode("sw1a 1aa")) == "SW1A1AA"


def test_postcode_equality_ignores_surface_form() -> None:
    # Differing case / whitespace sanitise to the same canonical value, so
    # the value objects compare equal.
    # act / assert
    assert Postcode("sw1a 1aa") == Postcode("SW1A1AA")


def test_postcode_is_frozen() -> None:
    # arrange
    postcode = Postcode("SW1A1AA")
    # act / assert
    with pytest.raises(dataclasses.FrozenInstanceError):
        postcode.value = "OTHER"  # type: ignore[misc]


@pytest.mark.parametrize(
    "raw",
    ["sw1a 1aa", "M1 1AA", "b33 8th", "cr2 6xh", "dn55 1pt", "ec1a 1bb", "w1a 0ax"],
)
def test_valid_uk_postcode_formats_are_valid(raw: str) -> None:
    # act / assert — a pure format check on the canonical value, no network.
    assert Postcode(raw).is_valid() is True


@pytest.mark.parametrize("raw", ["", "   ", "NONSENSE", "12345", "SW1A 1A", "ZZ"])
def test_malformed_or_empty_postcodes_are_invalid(raw: str) -> None:
    # act / assert
    assert Postcode(raw).is_valid() is False