import os
from unittest import mock
from datetime import datetime

from curateipsum import backup as bk


class TestBackupCleanup:
    """Tests for backup cleanup and retention policies."""

    def test_no_backups(self, backup_dir, run_cleanup):
        """Test behaviour with no available backups"""
        backup_dir.mkdir()
        bk.cleanup_old_backups(str(backup_dir))
        assert not os.listdir(str(backup_dir))

    @mock.patch(f"{bk.__name__}.datetime", wraps=datetime)
    def test_only_one_backup(self, mock_datetime, add_backup, run_cleanup,
                             check_backups):
        """Test the only backup will not be removed in any case"""
        mock_datetime.now.return_value = datetime(2021, 10, 20)
        # very old backup
        only_backup = add_backup("20010101_0000")
        run_cleanup(keep_all=1)
        check_backups([only_backup])

    @mock.patch(f"{bk.__name__}.datetime", wraps=datetime)
    def test_at_least_one_should_be_left(self, mock_datetime, add_backup,
                                          run_cleanup, check_backups):
        """Test at least one backup should be left"""
        mock_datetime.now.return_value = datetime(2021, 10, 20)
        backups = [
            add_backup("20211103_0300"),  # latest, should be kept
            add_backup("20201216_0100"),  # rest should be removed
            add_backup("20200716_0100"),
            add_backup("20181116_0100"),
        ]
        expected_backups = [backups[0]]
        run_cleanup()
        check_backups(expected_backups)

    @mock.patch(f"{bk.__name__}.datetime", wraps=datetime)
    def test_keep_all_threshold_only(self, mock_datetime, add_backup,
                                      run_cleanup, check_backups):
        """Test threshold for keeping all backups"""
        mock_datetime.now.return_value = datetime(2021, 10, 20)
        backups = [
            add_backup("20211019_0300"),  # keep
            add_backup("20211017_0100"),  # keep
            add_backup("20211016_2300"),  # remove, older than 3 days
        ]
        expected_backups = backups[:2]
        run_cleanup(keep_all=3)
        check_backups(expected_backups)

    @mock.patch(f"{bk.__name__}.datetime", wraps=datetime)
    def test_keep_daily_threshold_only(self, mock_datetime, add_backup,
                                        run_cleanup, check_backups):
        """Test threshold for keeping daily backups"""
        mock_datetime.now.return_value = datetime(2021, 10, 20)
        backups = [
            add_backup("20211019_0300"),  # keep, first daily at 2021-10-19
            add_backup("20211017_2100"),  # remove, not first daily
            add_backup("20211017_0100"),  # remove, not first daily
            add_backup("20211017_0030"),  # keep, first daily at 2021-10-17
            add_backup("20211016_2300"),  # remove, older than 3 days
            add_backup("20211016_0100"),  # remove, older than 3 days
        ]
        expected_backups = [backups[0], backups[3]]
        run_cleanup(keep_daily=3)
        check_backups(expected_backups)

    @mock.patch(f"{bk.__name__}.datetime", wraps=datetime)
    def test_keep_all_and_daily_thresholds(self, mock_datetime, add_backup,
                                            run_cleanup, check_backups):
        """Test threshold for keeping all and daily backups"""
        mock_datetime.now.return_value = datetime(2021, 10, 20)
        backups = [
            add_backup("20211019_0300"),  # keep, newer than 3 days
            add_backup("20211017_0200"),  # keep, newer than 3 days
            add_backup("20211017_0100"),  # keep, newer than 3 days
            add_backup("20211016_2300"),  # remove, not first daily
            add_backup("20211016_2200"),  # keep, first daily at 2021-10-16
            add_backup("20211015_2200"),  # remove, not first daily
            add_backup("20211015_1500"),  # remove, not first daily
            add_backup("20211015_0200"),  # keep, first daily at 2021-10-15
            add_backup("20211014_2200"),  # remove, older than 5 days
            add_backup("20211014_2000"),  # remove, older than 5 days
            add_backup("20211014_1232"),  # remove, older than 5 days
        ]
        expected_backups = backups[0:3] + [backups[4]] + [backups[7]]
        run_cleanup(keep_all=3, keep_daily=5)
        check_backups(expected_backups)

    @mock.patch(f"{bk.__name__}.datetime", wraps=datetime)
    def test_keep_weekly_threshold_only(self, mock_datetime, add_backup,
                                         run_cleanup, check_backups):
        """Test threshold for keeping weekly backups"""
        mock_datetime.now.return_value = datetime(2021, 11, 11)
        backups = [
            add_backup("20211111_0300"),  # remove, not first weekly (Thu)
            add_backup("20211110_0300"),  # remove, not first weekly (Wed)
            add_backup("20211108_0100"),  # keep, first weekly 2021-11-08 (Mon)
            add_backup("20211107_2300"),  # remove, not first weekly (Sun)
            add_backup("20211107_0100"),  # keep, first weekly 2021-11-07 (Sun)
            add_backup("20211031_0100"),  # remove, not first weekly (Sun)
            add_backup("20211025_0100"),  # keep, first weekly 2021-10-25 (Mon)
            add_backup("20211024_0100"),  # remove, not first weekly (Sun)
            add_backup("20211023_0100"),  # remove, not first weekly (Sat)
            add_backup("20211022_0100"),  # keep, first weekly 2021-10-22 (Fri)
            add_backup("20211008_0100"),  # remove, not first weekly (Fri)
            add_backup("20211007_0100"),  # remove, not first weekly (Thu)
            add_backup("20211004_0100"),  # keep, first weekly 2021-10-04 (Mon)
            add_backup("20211003_0100"),  # remove, older than 5 weeks
            add_backup("20211002_0100"),  # remove, older than 5 weeks

        ]
        expected_backups = [backups[2], backups[4], backups[6],
                            backups[9], backups[12]]
        run_cleanup(keep_weekly=5)
        check_backups(expected_backups)

    @mock.patch(f"{bk.__name__}.datetime", wraps=datetime)
    def test_keep_weekly_threshold_inclusive(self, mock_datetime, add_backup,
                                              run_cleanup, check_backups):
        """Test threshold for keeping weekly backups"""
        mock_datetime.now.return_value = datetime(2021, 11, 11)
        backups = [
            add_backup("20211111_0300"),  # remove, not first weekly (Thu)
            add_backup("20211110_0300"),  # keep, first weekly (Wed)
            add_backup("20211107_0100"),  # remove, not first weekly (Sun)
            add_backup("20211102_0100"),  # keep, first weekly (Tue)
        ]
        expected_backups = [backups[1], backups[3]]
        run_cleanup(keep_weekly=5)
        check_backups(expected_backups)

    @mock.patch(f"{bk.__name__}.datetime", wraps=datetime)
    def test_keep_monthly_threshold_only(self, mock_datetime, add_backup,
                                          run_cleanup, check_backups):
        """Test threshold for keeping monthly backups"""
        mock_datetime.now.return_value = datetime(2021, 11, 11)
        backups = [
            add_backup("20211103_0300"),  # keep, first monthly at 2021-11
            add_backup("20211019_0300"),  # remove, not first monthly
            add_backup("20211017_2100"),  # remove, not first monthly
            add_backup("20211017_0100"),  # keep, first monthly at 2021-10
            add_backup("20210916_2300"),  # remove, not first monthly
            add_backup("20210916_0100"),  # keep, first monthly at 2021-09
            add_backup("20210816_0100"),  # remove, not first monthly
            add_backup("20210810_0000"),  # keep, first monthly at 2021-08
            add_backup("20210716_0100"),  # remove, older than 3 months
            add_backup("20210715_0100"),  # remove, older than 3 months
        ]
        expected_backups = [backups[0], backups[3], backups[5], backups[7]]
        run_cleanup(keep_monthly=3)
        check_backups(expected_backups)

    @mock.patch(f"{bk.__name__}.datetime", wraps=datetime)
    def test_keep_yearly_threshold_only(self, mock_datetime, add_backup,
                                         run_cleanup, check_backups):
        """Test threshold for keeping yearly backups"""
        mock_datetime.now.return_value = datetime(2021, 11, 11)
        backups = [
            add_backup("20211103_0300"),  # remove, not first yearly in 2021
            add_backup("20210810_0000"),  # remove, not first yearly in 2021
            add_backup("20210716_0100"),  # keep, first yearly in 2021
            add_backup("20201216_0100"),  # remove, not first yearly in 2020
            add_backup("20200716_0100"),  # keep, first yearly in 2020
            add_backup("20191216_0100"),  # remove, not first yearly in 2019
            add_backup("20190316_0100"),  # keep, first yearly in 2019
            add_backup("20181216_0100"),  # remove, not first yearly in 2018
            add_backup("20181116_0100"),  # keep, first yearly in 2018
            add_backup("20171116_0100"),  # remove, older than 3 years
            add_backup("20171115_0100"),  # remove, older than 3 years
        ]
        expected_backups = [backups[2], backups[4], backups[6], backups[8]]
        run_cleanup(keep_yearly=3)
        check_backups(expected_backups)

    @mock.patch(f"{bk.__name__}.datetime", wraps=datetime)
    def test_dry_run(self, mock_datetime, add_backup, run_cleanup,
                     check_backups):
        """Test dry run does not remove anything"""
        mock_datetime.now.return_value = datetime(2021, 11, 11)
        backups = [
            add_backup("20211103_0300"),
            add_backup("20210810_0000"),
            add_backup("20210716_0100"),
            add_backup("20200716_0100"),
            add_backup("20181116_0100"),
        ]
        run_cleanup(keep_all=2, dry_run=True)
        check_backups(backups)


class TestBackupLock:
    """Test suite for backup lock file functionality."""

    def test_lock_creation(self, backup_dir):
        """Test that lock file is created with current PID"""
        backup_dir.mkdir()
        result = bk.set_backups_lock(str(backup_dir))
        assert result

        lock_path = os.path.join(str(backup_dir), bk.LOCK_FILE)
        assert os.path.exists(lock_path)

        with open(lock_path, "r") as f:
            pid = int(f.read().strip())
        assert pid == os.getpid()

    def test_lock_prevents_concurrent_backup(self, backup_dir):
        """Test that second lock acquisition is blocked"""
        backup_dir.mkdir()
        # First lock should succeed
        result1 = bk.set_backups_lock(str(backup_dir))
        assert result1

        # The second lock should fail (same process trying to lock again)
        # Write a different PID to simulate another process
        lock_path = os.path.join(str(backup_dir), bk.LOCK_FILE)
        with open(lock_path, "w") as f:
            f.write(str(os.getpid()))

        result2 = bk.set_backups_lock(str(backup_dir), force=False)
        assert not result2

    def test_stale_lock_is_removed(self, backup_dir):
        """Test that lock from non-existent process is cleaned up"""
        backup_dir.mkdir()
        lock_path = os.path.join(str(backup_dir), bk.LOCK_FILE)

        # Create lock with non-existent PID
        with open(lock_path, "w") as f:
            f.write("999999")

        # Lock should succeed by removing stale lock
        result = bk.set_backups_lock(str(backup_dir))
        assert result

        # Verify new lock has current PID
        with open(lock_path, "r") as f:
            pid = int(f.read().strip())
        assert pid == os.getpid()

    def test_corrupted_lock_is_handled(self, backup_dir):
        """Test that corrupted lock file is handled gracefully"""
        backup_dir.mkdir()
        lock_path = os.path.join(str(backup_dir), bk.LOCK_FILE)

        # Create corrupted lock file (non-numeric content)
        with open(lock_path, "w") as f:
            f.write("not a number")

        # Lock should succeed by removing corrupted lock
        result = bk.set_backups_lock(str(backup_dir))
        assert result

        # Verify new lock has current PID
        with open(lock_path, "r") as f:
            pid = int(f.read().strip())
        assert pid == os.getpid()

    def test_empty_lock_is_handled(self, backup_dir):
        """Test that empty lock file is handled gracefully"""
        backup_dir.mkdir()
        lock_path = os.path.join(str(backup_dir), bk.LOCK_FILE)

        # Create the empty lock file
        open(lock_path, "w").close()

        # Lock should succeed by removing empty lock
        result = bk.set_backups_lock(str(backup_dir))
        assert result

        # Verify new lock has current PID
        with open(lock_path, "r") as f:
            pid = int(f.read().strip())
        assert pid == os.getpid()

    def test_lock_release(self, backup_dir):
        """Test that lock file is properly released"""
        backup_dir.mkdir()
        bk.set_backups_lock(str(backup_dir))
        lock_path = os.path.join(str(backup_dir), bk.LOCK_FILE)
        assert os.path.exists(lock_path)

        bk.release_backups_lock(str(backup_dir))
        assert not os.path.exists(lock_path)

    def test_release_nonexistent_lock(self, backup_dir):
        """Test that releasing non-existent lock doesn't raise error"""
        backup_dir.mkdir()
        # Should not raise any exception
        bk.release_backups_lock(str(backup_dir))

        lock_path = os.path.join(str(backup_dir), bk.LOCK_FILE)
        assert not os.path.exists(lock_path)


class TestBackupIteration:
    """Tests for internal backup iteration and validation functions."""

    def test_is_backup_valid_backup(self, add_backup):
        """Test _is_backup recognizes valid backup directory"""
        backup = add_backup("20210101_120000")
        assert bk._is_backup(backup)

    def test_is_backup_missing_marker(self, backup_dir, tmp_path):
        """Test _is_backup rejects directory without marker"""
        backup_dir.mkdir()
        backup_path = backup_dir / "20210101_120000"
        backup_path.mkdir()
        # Create content but no marker
        (backup_path / "file.txt").write_text("content")

        entry = os.scandir(str(backup_dir))
        backup = next(entry)
        entry.close()
        assert not bk._is_backup(backup)

    def test_is_backup_only_marker_no_content(self, backup_dir):
        """Test _is_backup rejects directory with only marker file"""
        backup_dir.mkdir()
        backup_path = backup_dir / "20210101_120000"
        backup_path.mkdir()
        # Create only marker, no content
        marker_name = f"{bk.BACKUP_MARKER}_20210101_120000"
        (backup_path / marker_name).touch()

        entry = os.scandir(str(backup_dir))
        backup = next(entry)
        entry.close()
        assert not bk._is_backup(backup)

    def test_is_backup_invalid_name_format(self, backup_dir):
        """Test _is_backup rejects invalid directory name"""
        backup_dir.mkdir()
        backup_path = backup_dir / "not-a-backup"
        backup_path.mkdir()
        # Create marker and content
        marker_name = f"{bk.BACKUP_MARKER}_not-a-backup"
        (backup_path / marker_name).touch()
        (backup_path / "file.txt").write_text("content")

        entry = os.scandir(str(backup_dir))
        backup = next(entry)
        entry.close()
        assert not bk._is_backup(backup)

    def test_iterate_backups_empty_directory(self, backup_dir):
        """Test _iterate_backups on empty directory"""
        backup_dir.mkdir()
        backups = list(bk._iterate_backups(str(backup_dir)))
        assert backups == []

    def test_iterate_backups_mixed_contents(self, backup_dir, add_backup):
        """Test _iterate_backups filters non-backup entries"""
        # Create valid backups
        backup1 = add_backup("20210101_120000")
        backup2 = add_backup("20210102_120000")

        # Create invalid entries
        (backup_dir / "random_file.txt").write_text("not a backup")
        (backup_dir / "invalid_dir").mkdir()
        (backup_dir / bk.LOCK_FILE).touch()

        backups = sorted(bk._iterate_backups(str(backup_dir)),
                        key=lambda e: e.name)
        assert len(backups) == 2
        assert backups[0].name == backup1.name
        assert backups[1].name == backup2.name

    def test_iterate_backups_incomplete_backup(self, backup_dir):
        """Test _iterate_backups skips backup without marker"""
        backup_dir.mkdir()
        # Create complete backup
        complete = backup_dir / "20210101_120000"
        complete.mkdir()
        (complete / "file.txt").write_text("content")
        marker_name = f"{bk.BACKUP_MARKER}_20210101_120000"
        (complete / marker_name).touch()

        # Create incomplete backup (no marker)
        incomplete = backup_dir / "20210102_120000"
        incomplete.mkdir()
        (incomplete / "file.txt").write_text("content")

        backups = list(bk._iterate_backups(str(backup_dir)))
        assert len(backups) == 1
        assert backups[0].name == "20210101_120000"

    def test_get_latest_backup_returns_most_recent(self, backup_dir,
                                                     add_backup):
        """Test _get_latest_backup returns most recent backup"""
        add_backup("20210101_120000")
        add_backup("20210102_120000")
        latest = add_backup("20210103_120000")

        result = bk._get_latest_backup(str(backup_dir))
        assert result is not None
        assert result.name == latest.name

    def test_get_latest_backup_empty_directory(self, backup_dir):
        """Test _get_latest_backup returns None for empty directory"""
        backup_dir.mkdir()
        result = bk._get_latest_backup(str(backup_dir))
        assert result is None

    def test_get_latest_backup_no_valid_backups(self, backup_dir):
        """Test _get_latest_backup returns None with no valid backups"""
        backup_dir.mkdir()
        # Create incomplete backup
        incomplete = backup_dir / "20210101_120000"
        incomplete.mkdir()
        (incomplete / "file.txt").write_text("content")
        # no marker

        result = bk._get_latest_backup(str(backup_dir))
        assert result is None

    def test_set_backup_marker_creates_marker(self, backup_dir):
        """Test set_backup_marker creates marker file"""
        backup_dir.mkdir()
        backup_path = backup_dir / "20210101_120000"
        backup_path.mkdir()

        backup_entry = bk.fs.PseudoDirEntry(str(backup_path))
        bk.set_backup_marker(backup_entry)

        marker_name = f"{bk.BACKUP_MARKER}_20210101_120000"
        marker_path = backup_path / marker_name
        assert marker_path.exists()

    def test_set_backup_marker_idempotent(self, backup_dir):
        """Test set_backup_marker is idempotent"""
        backup_dir.mkdir()
        backup_path = backup_dir / "20210101_120000"
        backup_path.mkdir()

        backup_entry = bk.fs.PseudoDirEntry(str(backup_path))
        bk.set_backup_marker(backup_entry)
        # Call again - should not fail
        bk.set_backup_marker(backup_entry)

        marker_name = f"{bk.BACKUP_MARKER}_20210101_120000"
        marker_path = backup_path / marker_name
        assert marker_path.exists()