"""The date-and-revision version scheme, and the forms packaging tools need."""
import re
import subprocess

import pytest

import bandsaunter


def test_displayed_version_is_date_and_padded_revision():
    assert re.fullmatch(r"\d{4}-\d{2}-\d{2}_\d{2,}", bandsaunter.__version__), \
        bandsaunter.__version__


def test_the_revision_is_padded_to_two_digits():
    assert bandsaunter.__version__.split("_")[1] == \
        f"{bandsaunter.VERSION_REVISION:02d}"
    assert len(bandsaunter.__version__.split("_")[1]) >= 2


def test_the_date_is_a_real_date():
    from datetime import date
    year, month, day = bandsaunter.VERSION_DATE.split("-")
    date(int(year), int(month), int(day))          # raises if not


def test_versions_sort_as_text_in_release_order():
    """Padding is the point: without it, revision 10 sorts before revision 2."""
    def displayed(d, r):
        return f"{d}_{r:02d}"
    ordered = [displayed("2026-08-21", 1), displayed("2026-08-21", 2),
               displayed("2026-08-21", 10), displayed("2026-09-01", 1),
               displayed("2026-12-31", 3), displayed("2027-01-01", 1)]
    assert sorted(ordered) == ordered


def test_the_pep440_form_is_valid_where_the_displayed_one_is_not():
    from packaging.version import InvalidVersion, Version
    with pytest.raises(InvalidVersion):
        Version(bandsaunter.__version__)       # dashes and underscore
    assert Version(bandsaunter.pep440_version())


def test_the_pep440_form_keeps_release_order():
    from packaging.version import Version
    assert Version("2026.8.21.1") < Version("2026.8.21.2")
    assert Version("2026.8.21.2") < Version("2026.8.21.10")
    assert Version("2026.8.21.10") < Version("2026.9.1.1")
    assert Version("2026.12.31.1") < Version("2027.1.1.1")


def test_the_debian_form_is_acceptable_to_dpkg():
    """Debian versions may not contain underscores."""
    debian = bandsaunter.debian_version()
    assert "_" not in debian
    assert re.fullmatch(r"[0-9][0-9.+~:-]*", debian), debian


@pytest.mark.skipif(not __import__("shutil").which("dpkg"),
                    reason="dpkg not available")
def test_dpkg_agrees_the_debian_versions_order_correctly():
    def older(a, b):
        return subprocess.run(["dpkg", "--compare-versions", a, "lt", b]
                              ).returncode == 0
    assert older("2026.08.21.01", "2026.08.21.02")
    assert older("2026.08.21.02", "2026.08.21.10")
    assert older("2026.08.21.10", "2026.09.01.01")
    assert older("2026.12.31.01", "2027.01.01.01")


def test_all_three_forms_describe_the_same_release():
    date_part = bandsaunter.VERSION_DATE
    rev = bandsaunter.VERSION_REVISION
    assert bandsaunter.__version__ == f"{date_part}_{rev:02d}"
    year, month, day = date_part.split("-")
    assert bandsaunter.pep440_version() == \
        f"{int(year)}.{int(month)}.{int(day)}.{rev}"
    assert bandsaunter.debian_version() == \
        f"{date_part.replace('-', '.')}.{rev:02d}"


def test_the_installed_package_reports_the_displayed_version():
    out = subprocess.run(["python3", "-m", "bandsaunter", "--version"],
                         capture_output=True, text=True, timeout=60)
    assert bandsaunter.__version__ in out.stdout