"""Tests for deploy/prune_releases.py -- PEP 440-aware release pruning.

See MuseHub staging issue #128: `sort -V` doesn't understand PEP 440 channel
precedence (dev < a < b < rc < final), so it deleted the newest nightly from
S3 immediately after upload. `stale_releases()` replaces `sort -V` with
`packaging.version.Version`, which sorts by actual PEP 440 precedence.

Test IDs (pinned in issue #128's plan):
  PRUNE_01  exact incident reproduction (dev1 survives, rc14 pruned)
  PRUNE_02  mixed channels, full precedence coverage
  PRUNE_03  keep >= len(filenames) prunes nothing
  PRUNE_04  unparseable filename raises, never silently mis-sorts
  PRUNE_05  stable releases sort after all pre-release channels
"""
from __future__ import annotations

import pytest

from deploy.prune_releases import stale_releases


class TestStaleReleases:
    def test_PRUNE_01_same_base_version_dev_is_lowest_precedence_not_newest(self) -> None:
        """Correct PEP 440 precedence for the exact incident's four filenames.

        dev1 and rc14-16 all share the base version "0.2.0" -- PEP 440 defines
        dev-releases as the *lowest*-precedence pre-release stage for a given
        version (dev < a < b < rc < final), so 0.2.0.dev1 correctly sorts
        BEFORE 0.2.0rc16 despite being built later in wall-clock time. This is
        not the bug: sort -V's bug was comparing "dev1" against "rc14" as
        plain text and getting 'd' < 'r' right by accident-adjacent means but
        wrong reasoning for the general case. The actual root cause of the
        incident is that the channel-pivot reused "0.2.0" for the new nightly
        instead of bumping the base version (see docs/versioning.md) -- once
        that discipline is followed, this exact ambiguity can't recur, because
        a same-day pivot bumps to e.g. 0.2.1.dev1, which correctly outranks
        every 0.2.0 build regardless of pre-release tag.
        """
        filenames = [
            "muse-0.2.0rc14.tar.gz",
            "muse-0.2.0rc15.tar.gz",
            "muse-0.2.0rc16.tar.gz",
            "muse-0.2.0.dev1.tar.gz",
        ]
        assert stale_releases(filenames, keep=3) == ["muse-0.2.0.dev1.tar.gz"]

    def test_PRUNE_01b_pivot_with_bumped_version_keeps_new_nightly(self) -> None:
        """The correct fix for the incident: bump the base version on a pivot.

        Once the next nightly is labeled against a NEW base version (0.2.1,
        not 0.2.0), PEP 440 precedence unambiguously ranks it above every
        0.2.0 build, pre-release or not -- this is the behavior
        docs/versioning.md's new "channel pivot" rule exists to guarantee.
        """
        filenames = [
            "muse-0.2.0rc14.tar.gz",
            "muse-0.2.0rc15.tar.gz",
            "muse-0.2.0rc16.tar.gz",
            "muse-0.2.1.dev1.tar.gz",
        ]
        assert stale_releases(filenames, keep=3) == ["muse-0.2.0rc14.tar.gz"]

    def test_PRUNE_02_mixed_channels_full_precedence_coverage(self) -> None:
        """dev < a < b < rc precedence across all four pre-release channels."""
        filenames = [
            "muse-0.2.0.dev1.tar.gz",
            "muse-0.2.0a1.tar.gz",
            "muse-0.2.0b1.tar.gz",
            "muse-0.2.0rc1.tar.gz",
            "muse-0.2.0rc2.tar.gz",
        ]
        stale = stale_releases(filenames, keep=2)
        assert sorted(stale) == sorted([
            "muse-0.2.0.dev1.tar.gz",
            "muse-0.2.0a1.tar.gz",
            "muse-0.2.0b1.tar.gz",
        ])

    def test_PRUNE_03_keep_greater_than_len_prunes_nothing(self) -> None:
        filenames = ["muse-0.2.0rc1.tar.gz", "muse-0.2.0rc2.tar.gz"]
        assert stale_releases(filenames, keep=5) == []

    def test_PRUNE_03b_keep_equal_to_len_prunes_nothing(self) -> None:
        filenames = ["muse-0.2.0rc1.tar.gz", "muse-0.2.0rc2.tar.gz"]
        assert stale_releases(filenames, keep=2) == []

    def test_PRUNE_04_unparseable_filename_raises(self) -> None:
        filenames = ["muse-0.2.0rc1.tar.gz", "muse-not-a-version.tar.gz"]
        with pytest.raises(ValueError):
            stale_releases(filenames, keep=1)

    def test_PRUNE_05_stable_sorts_after_all_prerelease_channels(self) -> None:
        """A stable release must never be pruned ahead of any pre-release build."""
        filenames = [
            "muse-0.2.0.dev1.tar.gz",
            "muse-0.2.0rc1.tar.gz",
            "muse-0.2.0.tar.gz",
        ]
        stale = stale_releases(filenames, keep=1)
        assert stale == ["muse-0.2.0.dev1.tar.gz", "muse-0.2.0rc1.tar.gz"]

    def test_PRUNE_08_empty_filename_list_returns_empty(self) -> None:
        assert stale_releases([], keep=3) == []

    def test_PRUNE_09_returns_oldest_first_stable_ordering(self) -> None:
        """Stale list should be ordered oldest-first, for readable log output."""
        filenames = [
            "muse-0.2.0rc3.tar.gz",
            "muse-0.2.0rc1.tar.gz",
            "muse-0.2.0rc2.tar.gz",
        ]
        assert stale_releases(filenames, keep=1) == [
            "muse-0.2.0rc1.tar.gz",
            "muse-0.2.0rc2.tar.gz",
        ]