try:
    from unittest import mock
except ImportError:
    import mock  # noqa: F401

import pytest

from xarray.backends.lru_cache import LRUCache


def test_simple():
    cache = LRUCache(maxsize=2)
    cache['x'] = 1
    cache['y'] = 2

    assert cache['x'] == 1
    assert cache['y'] == 2
    assert len(cache) == 2
    assert dict(cache) == {'x': 1, 'y': 2}
    assert list(cache.keys()) == ['x', 'y']
    assert list(cache.items()) == [('x', 1), ('y', 2)]

    cache['z'] = 3
    assert len(cache) == 2
    assert list(cache.items()) == [('y', 2), ('z', 3)]


def test_trivial():
    cache = LRUCache(maxsize=0)
    cache['x'] = 1
    assert len(cache) == 0


def test_invalid():
    with pytest.raises(TypeError):
        LRUCache(maxsize=None)
    with pytest.raises(ValueError):
        LRUCache(maxsize=-1)


def test_update_priority():
    cache = LRUCache(maxsize=2)
    cache['x'] = 1
    cache['y'] = 2
    assert list(cache) == ['x', 'y']
    assert 'x' in cache  # contains
    assert list(cache) == ['y', 'x']
    assert cache['y'] == 2  # getitem
    assert list(cache) == ['x', 'y']
    cache['x'] = 3  # setitem
    assert list(cache.items()) == [('y', 2), ('x', 3)]


def test_del():
    cache = LRUCache(maxsize=2)
    cache['x'] = 1
    cache['y'] = 2
    del cache['x']
    assert dict(cache) == {'y': 2}


def test_on_evict():
    on_evict = mock.Mock()
    cache = LRUCache(maxsize=1, on_evict=on_evict)
    cache['x'] = 1
    cache['y'] = 2
    on_evict.assert_called_once_with('x', 1)


def test_on_evict_trivial():
    on_evict = mock.Mock()
    cache = LRUCache(maxsize=0, on_evict=on_evict)
    cache['x'] = 1
    on_evict.assert_called_once_with('x', 1)


def test_resize():
    cache = LRUCache(maxsize=2)
    assert cache.maxsize == 2
    cache['w'] = 0
    cache['x'] = 1
    cache['y'] = 2
    assert list(cache.items()) == [('x', 1), ('y', 2)]
    cache.maxsize = 10
    cache['z'] = 3
    assert list(cache.items()) == [('x', 1), ('y', 2), ('z', 3)]
    cache.maxsize = 1
    assert list(cache.items()) == [('z', 3)]

    with pytest.raises(ValueError):
        cache.maxsize = -1