"""Regression scenarios for host exhaustion hidden by a roomy WSL filesystem."""

import importlib.util
from pathlib import Path
import shutil
import unittest
from unittest.mock import patch

SPEC = importlib.util.spec_from_file_location(
    "workstation_disk_guard", Path(__file__).parents[1] / "scripts/workstation_disk_guard.py")
guard = importlib.util.module_from_spec(SPEC)
SPEC.loader.exec_module(guard)


class DiskGuardTests(unittest.TestCase):
    def report(self, host_free, guest_free=783, reserve=0):
        usage_type = type(shutil.disk_usage("/"))
        def usage(path):
            free = (host_free if path == "/mnt/c" else guest_free) * guard.GIB
            return usage_type(1024 * guard.GIB, 1024 * guard.GIB - free, free)
        with patch.object(guard.Path, "is_mount", return_value=True), \
                patch.object(guard.shutil, "disk_usage", side_effect=usage):
            return guard.collect(reserve * guard.GIB)

    def test_crash_capacity_is_critical_despite_roomy_guest(self):
        report = self.report(1)
        self.assertEqual(report["status"], "critical")
        self.assertEqual(report["volumes"][1]["status"], "ok")

    def test_reclaimed_capacity_warns_and_projected_build_can_refuse(self):
        self.assertEqual(self.report(53)["status"], "warning")
        self.assertEqual(self.report(53, reserve=25)["status"], "critical")

    def test_guest_exhaustion_is_also_critical(self):
        self.assertEqual(self.report(100, guest_free=5)["status"], "critical")

    def test_thresholds_and_healthy_capacity(self):
        self.assertEqual(self.report(30)["status"], "warning")
        self.assertEqual(self.report(60)["status"], "ok")

    def test_unmounted_host_cannot_silently_use_guest_capacity(self):
        with patch.object(guard.Path, "is_mount", return_value=False):
            self.assertEqual(guard.collect()["status"], "unknown")

    def test_unreadable_capacity_is_unknown(self):
        with patch.object(guard.Path, "is_mount", return_value=True), \
                patch.object(guard.shutil, "disk_usage", side_effect=OSError):
            self.assertEqual(guard.collect()["status"], "unknown")

    def test_bad_reserve_inputs_are_rejected(self):
        for value in ("nan", "inf", "-1"):
            with self.subTest(value=value), self.assertRaises(guard.argparse.ArgumentTypeError):
                guard.nonnegative_gib(value)


if __name__ == "__main__":
    unittest.main()