from cache.FastCache import FastCache


def test_i_can_put_an_retrieve_values():
    cache = FastCache()
    cache.put("key", "value")

    assert cache.get("key") == "value"
    assert cache.cache == {"key": "value"}
    assert cache.lru == ["key"]


def test_i_can_put_and_retrieve_multiple_items():
    cache = FastCache()
    cache.put("key1", "value1")
    cache.put("key2", "value2")
    cache.put("key3", "value3")

    assert cache.cache == {"key1": "value1", "key2": "value2", "key3": "value3"}
    assert cache.lru == ["key1", "key2", "key3"]


def test_i_the_least_used_is_remove_first():
    cache = FastCache(3)
    cache.put("key1", "value1")
    cache.put("key2", "value2")
    cache.put("key3", "value3")

    cache.put("key4", "value4")
    assert cache.cache == {"key4": "value4", "key2": "value2", "key3": "value3"}
    assert cache.lru == ["key2", "key3", "key4"]

    cache.put("key5", "value5")
    assert cache.cache == {"key4": "value4", "key5": "value5", "key3": "value3"}
    assert cache.lru == ["key3", "key4", "key5"]


def test_i_can_put_the_same_key_several_times():
    cache = FastCache()
    cache.put("key1", "value1")
    cache.put("key2", "value2")
    cache.put("key1", "value3")

    assert cache.cache == {"key1": "value3", "key2": "value2"}
    assert cache.lru == ["key2", "key1"]


def test_none_is_returned_when_not_found():
    cache = FastCache()
    assert cache.get("foo") is None


def test_i_can_evict_by_key():
    cache = FastCache()
    cache.put("key1", "value1")
    cache.put("to_keep1", "to_keep_value1")
    cache.put("key2", "value2")
    cache.put("to_keep2", "to_keep_value2")
    cache.put("key3", "value3")
    cache.put("to_keep3", "to_keep_value3")

    cache.evict_by_key(lambda k: k.startswith("key"))
    assert cache.cache == {"to_keep1": "to_keep_value1",
                           "to_keep2": "to_keep_value2",
                           "to_keep3": "to_keep_value3"}

    assert cache.lru == ["to_keep1", "to_keep2", "to_keep3"]