import sys
import threading
import types
from unittest.mock import MagicMock

import commands
from libs.db_migration_lock import LockNotOwnedError, RedisError

HEARTBEAT_WAIT_TIMEOUT_SECONDS = 5.0


def _install_fake_flask_migrate(monkeypatch, upgrade_impl) -> None:
    module = types.ModuleType("flask_migrate")
    module.upgrade = upgrade_impl
    monkeypatch.setitem(sys.modules, "flask_migrate", module)


def _invoke_upgrade_db() -> int:
    try:
        commands.upgrade_db.callback()
    except SystemExit as e:
        return int(e.code or 0)
    return 0


def test_upgrade_db_skips_when_lock_not_acquired(monkeypatch, capsys):
    monkeypatch.setattr(commands, "DB_UPGRADE_LOCK_TTL_SECONDS", 1234)

    lock = MagicMock()
    lock.acquire.return_value = False
    commands.redis_client.lock.return_value = lock

    exit_code = _invoke_upgrade_db()
    captured = capsys.readouterr()

    assert exit_code == 0
    assert "Database migration skipped" in captured.out

    commands.redis_client.lock.assert_called_once_with(name="db_upgrade_lock", timeout=1234, thread_local=False)
    lock.acquire.assert_called_once_with(blocking=False)
    lock.release.assert_not_called()


def test_upgrade_db_failure_not_masked_by_lock_release(monkeypatch, capsys):
    monkeypatch.setattr(commands, "DB_UPGRADE_LOCK_TTL_SECONDS", 321)

    lock = MagicMock()
    lock.acquire.return_value = True
    lock.release.side_effect = LockNotOwnedError("simulated")
    commands.redis_client.lock.return_value = lock

    def _upgrade():
        raise RuntimeError("boom")

    _install_fake_flask_migrate(monkeypatch, _upgrade)

    exit_code = _invoke_upgrade_db()
    captured = capsys.readouterr()

    assert exit_code == 1
    assert "Database migration failed: boom" in captured.out

    commands.redis_client.lock.assert_called_once_with(name="db_upgrade_lock", timeout=321, thread_local=False)
    lock.acquire.assert_called_once_with(blocking=False)
    lock.release.assert_called_once()


def test_upgrade_db_success_ignores_lock_not_owned_on_release(monkeypatch, capsys):
    monkeypatch.setattr(commands, "DB_UPGRADE_LOCK_TTL_SECONDS", 999)

    lock = MagicMock()
    lock.acquire.return_value = True
    lock.release.side_effect = LockNotOwnedError("simulated")
    commands.redis_client.lock.return_value = lock

    _install_fake_flask_migrate(monkeypatch, lambda: None)

    exit_code = _invoke_upgrade_db()
    captured = capsys.readouterr()

    assert exit_code == 0
    assert "Database migration successful!" in captured.out

    commands.redis_client.lock.assert_called_once_with(name="db_upgrade_lock", timeout=999, thread_local=False)
    lock.acquire.assert_called_once_with(blocking=False)
    lock.release.assert_called_once()


def test_upgrade_db_renews_lock_during_migration(monkeypatch, capsys):
    """
    Ensure the lock is renewed while migrations are running, so the base TTL can stay short.
    """

    # Use a small TTL so the heartbeat interval triggers quickly.
    monkeypatch.setattr(commands, "DB_UPGRADE_LOCK_TTL_SECONDS", 0.3)

    lock = MagicMock()
    lock.acquire.return_value = True
    commands.redis_client.lock.return_value = lock

    renewed = threading.Event()

    def _reacquire():
        renewed.set()
        return True

    lock.reacquire.side_effect = _reacquire

    def _upgrade():
        assert renewed.wait(HEARTBEAT_WAIT_TIMEOUT_SECONDS)

    _install_fake_flask_migrate(monkeypatch, _upgrade)

    exit_code = _invoke_upgrade_db()
    _ = capsys.readouterr()

    assert exit_code == 0
    assert lock.reacquire.call_count >= 1


def test_upgrade_db_ignores_reacquire_errors(monkeypatch, capsys):
    # Use a small TTL so heartbeat runs during the upgrade call.
    monkeypatch.setattr(commands, "DB_UPGRADE_LOCK_TTL_SECONDS", 0.3)

    lock = MagicMock()
    lock.acquire.return_value = True
    commands.redis_client.lock.return_value = lock

    attempted = threading.Event()

    def _reacquire():
        attempted.set()
        raise RedisError("simulated")

    lock.reacquire.side_effect = _reacquire

    def _upgrade():
        assert attempted.wait(HEARTBEAT_WAIT_TIMEOUT_SECONDS)

    _install_fake_flask_migrate(monkeypatch, _upgrade)

    exit_code = _invoke_upgrade_db()
    _ = capsys.readouterr()

    assert exit_code == 0
    assert lock.reacquire.call_count >= 1