import unittest
from pathlib import Path
from subprocess import CalledProcessError
from unittest import mock

from swap_forge.cli import main


class TestMain(unittest.TestCase):
    def _run(self, argv, fs="ext4", old_size=0):
        with (
            mock.patch("swap_forge.cli.detect_root_fs", return_value=fs),
            mock.patch("swap_forge.cli.swap_path_for", return_value=Path("/swapfile")),
            mock.patch("swap_forge.cli.get_swap_size", return_value=old_size),
            mock.patch("swap_forge.cli.remove_swap") as remove,
            mock.patch("swap_forge.cli.create_swap") as create,
        ):
            exit_code = main(argv)
        return exit_code, remove, create

    def test_creates_a_missing_swapfile(self):
        exit_code, remove, create = self._run(["2048M"])

        remove.assert_not_called()
        create.assert_called_once_with(Path("/swapfile"), 2048, "ext4")
        self.assertEqual(exit_code, 0)

    def test_matching_size_is_left_alone(self):
        exit_code, remove, create = self._run(["2048M"], old_size=2048)

        remove.assert_not_called()
        create.assert_not_called()
        self.assertEqual(exit_code, 0)

    def test_wrong_size_is_recreated(self):
        exit_code, remove, create = self._run(["4G"], old_size=2048)

        remove.assert_called_once_with(Path("/swapfile"))
        create.assert_called_once_with(Path("/swapfile"), 4096, "ext4")
        self.assertEqual(exit_code, 0)

    def test_failing_command_reports_cleanly(self):
        with (
            mock.patch("swap_forge.cli.detect_root_fs", return_value="ext4"),
            mock.patch("swap_forge.cli.swap_path_for", return_value=Path("/swapfile")),
            mock.patch("swap_forge.cli.get_swap_size", return_value=0),
            mock.patch("swap_forge.cli.create_swap") as create,
        ):
            create.side_effect = CalledProcessError(255, ["swapon", "/swapfile"])
            exit_code = main(["2048M"])

        self.assertEqual(exit_code, 1)

    def test_invalid_size_exits_non_zero(self):
        with mock.patch("swap_forge.cli.detect_root_fs") as detect:
            exit_code = main(["64T"])

        detect.assert_not_called()
        self.assertEqual(exit_code, 1)


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