"""Guards against plugin settings outliving the plugin they configure.

The `http` plugin was folded into the unified Monitor entity, but its
`plugin.http` DEFAULTS entry survived — so the operator saw a plugin that no
longer exists reported as enabled, with no way to clear it (deleting the row
did nothing; the default reasserted it). These tests make that class of drift a
CI failure instead of a support question.
"""
from pathlib import Path

from steward.core.settings import DEFAULTS, find_orphaned_plugin_names
from steward.settings.routes import CAPABILITY_PLUGINS

BUNDLED_PLUGINS_DIR = Path(__file__).resolve().parents[2] / "plugins"


def _bundled_plugin_names() -> set[str]:
    """Plugin dirs shipped inside the image, identified by their plugin.yaml."""
    return {
        entry.name
        for entry in BUNDLED_PLUGINS_DIR.iterdir()
        if entry.is_dir() and (entry / "plugin.yaml").exists()
    }


def _default_plugin_names() -> set[str]:
    prefix = "plugin."
    return {k[len(prefix):] for k in DEFAULTS if k.startswith(prefix)}


def test_bundled_plugins_dir_is_discoverable():
    # Guards the test itself: a wrong path would make everything below vacuous.
    assert _bundled_plugin_names(), f"no bundled plugins found under {BUNDLED_PLUGINS_DIR}"


def test_every_default_plugin_key_has_a_real_bundled_plugin():
    """A plugin.* default naming a non-existent plugin is always a bug.

    Bundled plugins ship in the image and version atomically with core, so
    unlike external plugins they cannot be transiently missing — there is no
    benign reason for this to fail.
    """
    missing = _default_plugin_names() - _bundled_plugin_names()
    assert not missing, (
        f"DEFAULTS declares plugin(s) with no bundled directory: {sorted(missing)}. "
        f"If the plugin was removed, delete its plugin.<name> key from DEFAULTS "
        f"and add a migration dropping the stored row."
    )


def test_http_plugin_default_is_gone():
    # Explicit regression: this exact key is what the operator hit.
    assert "plugin.http" not in DEFAULTS


def test_capability_plugins_all_exist():
    """CAPABILITY_PLUGINS classifies discovered plugins; stale names are dead weight."""
    missing = CAPABILITY_PLUGINS - _bundled_plugin_names()
    assert not missing, f"CAPABILITY_PLUGINS names non-existent plugin(s): {sorted(missing)}"


# ── orphan detection ─────────────────────────────────────────────────────────


def test_orphans_are_stored_names_with_no_installed_plugin():
    assert find_orphaned_plugin_names(
        ["docker", "traefik", "ancient"], ["docker", "traefik"]
    ) == ["ancient"]


def test_no_orphans_when_everything_is_installed():
    assert find_orphaned_plugin_names(["docker", "snmp"], ["docker", "snmp"]) == []


def test_installed_plugin_without_stored_settings_is_not_an_orphan():
    # Never configured is not the same as left behind.
    assert find_orphaned_plugin_names([], ["docker"]) == []


def test_orphans_are_sorted_and_deduped_of_empties():
    assert find_orphaned_plugin_names(["zeta", "", "alpha"], []) == ["alpha", "zeta"]


def test_accepts_arbitrary_iterables():
    # Callers pass a generator of discovered dirs, not a list.
    assert find_orphaned_plugin_names(
        (n for n in ["gone"]), (n for n in ["here"])
    ) == ["gone"]