"""Tests for the CHANGELOG parser — the single source of truth for versioning."""

import pytest

from shared.changelog import (
    bump_kind,
    entry_for,
    is_valid_bump,
    latest_entry,
    parse_changelog,
    top_version,
    version_entries,
)

# A faithful slice of the real file: preamble prose, a plain version entry, a
# legacy combined entry, and date-only historical headers with no version.
SAMPLE = """# Changelog

What's changed in the **After-Hours Shift Manager**. Newest first.

Versions are `MAJOR.MINOR.PATCH`.

---

## v1.10.0 — June 11, 2026

**Release notes now announce themselves.** Big new feature line.

## v1.9.2 — June 1, 2026

**Setup-guide fix.** A patch.

## v1.9.0 / v1.9.1 — June 1, 2026

**Last-minute drops blocked.** Combined entry. *(v1.9.1 was a library update.)*

---

## May 2026 — Phone-system automation

- Live phone routing follows the schedule.

## April 3, 2026 — Launch 🎉

The first version.
"""


def test_preamble_is_not_an_entry():
    # The "# Changelog" h1 and prose before the first "##" must not parse as entries.
    entries = parse_changelog(SAMPLE)
    assert all("Changelog" not in e.title for e in entries)


def test_top_version_skips_preamble():
    assert top_version(SAMPLE) == "1.10.0"


def test_latest_entry_fields():
    entry = latest_entry(SAMPLE)
    assert entry.version == "1.10.0"
    assert entry.date_label == "June 11, 2026"
    assert "announce themselves" in entry.body


def test_combined_header_reports_higher_version():
    entry = entry_for(SAMPLE, "1.9.0")
    assert entry.versions == ("1.9.0", "1.9.1")
    assert entry.version == "1.9.1"  # the higher of the two


def test_combined_header_is_findable_by_either_version():
    assert entry_for(SAMPLE, "1.9.1") == entry_for(SAMPLE, "v1.9.0")


def test_body_excludes_thematic_break_rules():
    # The "---" rule separating eras must not bleed into the combined entry's notes.
    assert "---" not in entry_for(SAMPLE, "1.9.0").body


def test_date_only_headers_carry_no_version():
    titles = {e.title for e in parse_changelog(SAMPLE) if not e.versions}
    assert "May 2026 — Phone-system automation" in titles
    assert "April 3, 2026 — Launch 🎉" in titles


def test_version_entries_excludes_date_only():
    versions = [e.version for e in version_entries(SAMPLE)]
    assert versions == ["1.10.0", "1.9.2", "1.9.1"]


def test_entry_for_accepts_v_prefix():
    assert entry_for(SAMPLE, "v1.10.0").version == "1.10.0"


def test_entry_for_unknown_version_is_none():
    assert entry_for(SAMPLE, "2.0.0") is None


def test_empty_changelog_has_no_top_version():
    assert top_version("# Changelog\n\nNothing yet.\n") is None
    assert latest_entry("# Changelog\n") is None


@pytest.mark.parametrize(
    "new,prev,expected",
    [
        ("1.10.0", "1.9.2", "minor"),  # minor resets patch to 0
        ("2.0.0", "1.9.2", "major"),
        ("1.9.3", "1.9.2", "patch"),
        ("1.11.0", "1.9.2", None),  # skips a minor
        ("1.9.2", "1.9.2", None),  # no change
        ("1.9.1", "1.9.2", None),  # downgrade
        ("3.0.0", "1.9.2", None),  # skips a major
    ],
)
def test_bump_kind(new, prev, expected):
    assert bump_kind(new, prev) == expected
    assert is_valid_bump(new, prev) is (expected is not None)