import sys
import unittest


class CacheTestMixin:

    Cache = None

    def test_defaults(self):
        cache = self.Cache(maxsize=1)
        self.assertEqual(0, len(cache))
        self.assertEqual(1, cache.maxsize)
        self.assertEqual(0, cache.currsize)
        self.assertEqual(1, cache.getsizeof(None))
        self.assertEqual(1, cache.getsizeof(""))
        self.assertEqual(1, cache.getsizeof(0))
        self.assertTrue(repr(cache).startswith(cache.__class__.__name__))

    def test_insert(self):
        cache = self.Cache(maxsize=2)

        cache.update({1: 1, 2: 2})
        self.assertEqual(2, len(cache))
        self.assertEqual(1, cache[1])
        self.assertEqual(2, cache[2])

        cache[3] = 3
        self.assertEqual(2, len(cache))
        self.assertEqual(3, cache[3])
        self.assertTrue(1 in cache or 2 in cache)

        cache[4] = 4
        self.assertEqual(2, len(cache))
        self.assertEqual(4, cache[4])
        self.assertTrue(1 in cache or 2 in cache or 3 in cache)

    def test_update(self):
        cache = self.Cache(maxsize=2)

        cache.update({1: 1, 2: 2})
        self.assertEqual(2, len(cache))
        self.assertEqual(1, cache[1])
        self.assertEqual(2, cache[2])

        cache.update({1: 1, 2: 2})
        self.assertEqual(2, len(cache))
        self.assertEqual(1, cache[1])
        self.assertEqual(2, cache[2])

        cache.update({1: "a", 2: "b"})
        self.assertEqual(2, len(cache))
        self.assertEqual("a", cache[1])
        self.assertEqual("b", cache[2])

    def test_delete(self):
        cache = self.Cache(maxsize=2)

        cache.update({1: 1, 2: 2})
        self.assertEqual(2, len(cache))
        self.assertEqual(1, cache[1])
        self.assertEqual(2, cache[2])

        del cache[2]
        self.assertEqual(1, len(cache))
        self.assertEqual(1, cache[1])
        self.assertNotIn(2, cache)

        del cache[1]
        self.assertEqual(0, len(cache))
        self.assertNotIn(1, cache)
        self.assertNotIn(2, cache)

        with self.assertRaises(KeyError):
            del cache[1]
        self.assertEqual(0, len(cache))
        self.assertNotIn(1, cache)
        self.assertNotIn(2, cache)

    def test_pop(self):
        cache = self.Cache(maxsize=2)

        cache.update({1: 1, 2: 2})
        self.assertEqual(2, cache.pop(2))
        self.assertEqual(1, len(cache))
        self.assertEqual(1, cache.pop(1))
        self.assertEqual(0, len(cache))

        with self.assertRaises(KeyError):
            cache.pop(2)
        with self.assertRaises(KeyError):
            cache.pop(1)
        with self.assertRaises(KeyError):
            cache.pop(0)

        self.assertEqual(None, cache.pop(2, None))
        self.assertEqual(None, cache.pop(1, None))
        self.assertEqual(None, cache.pop(0, None))

    def test_popitem(self):
        cache = self.Cache(maxsize=2)

        cache.update({1: 1, 2: 2})
        self.assertIn(cache.pop(1), {1: 1, 2: 2})
        self.assertEqual(1, len(cache))
        self.assertIn(cache.pop(2), {1: 1, 2: 2})
        self.assertEqual(0, len(cache))

        with self.assertRaises(KeyError):
            cache.popitem()

    @unittest.skipUnless(sys.version_info >= (3, 7), "requires Python 3.7")
    def test_popitem_exception_context(self):
        # since Python 3.7, MutableMapping.popitem() suppresses
        # exception context as implementation detail
        exception = None
        try:
            self.Cache(maxsize=2).popitem()
        except Exception as e:
            exception = e
        self.assertIsNone(exception.__cause__)
        self.assertTrue(exception.__suppress_context__)

    def test_missing(self):
        class DefaultCache(self.Cache):
            def __missing__(self, key):
                self[key] = key
                return key

        cache = DefaultCache(maxsize=2)

        self.assertEqual(0, cache.currsize)
        self.assertEqual(2, cache.maxsize)
        self.assertEqual(0, len(cache))
        self.assertEqual(1, cache[1])
        self.assertEqual(2, cache[2])
        self.assertEqual(2, len(cache))
        self.assertTrue(1 in cache and 2 in cache)

        self.assertEqual(3, cache[3])
        self.assertEqual(2, len(cache))
        self.assertTrue(3 in cache)
        self.assertTrue(1 in cache or 2 in cache)
        self.assertTrue(1 not in cache or 2 not in cache)

        self.assertEqual(4, cache[4])
        self.assertEqual(2, len(cache))
        self.assertTrue(4 in cache)
        self.assertTrue(1 in cache or 2 in cache or 3 in cache)

        # verify __missing__() is *not* called for any operations
        # besides __getitem__()

        self.assertEqual(4, cache.get(4))
        self.assertEqual(None, cache.get(5))
        self.assertEqual(5 * 5, cache.get(5, 5 * 5))
        self.assertEqual(2, len(cache))

        self.assertEqual(4, cache.pop(4))
        with self.assertRaises(KeyError):
            cache.pop(5)
        self.assertEqual(None, cache.pop(5, None))
        self.assertEqual(5 * 5, cache.pop(5, 5 * 5))
        self.assertEqual(1, len(cache))

        cache.clear()
        cache[1] = 1 + 1
        self.assertEqual(1 + 1, cache.setdefault(1))
        self.assertEqual(1 + 1, cache.setdefault(1, 1))
        self.assertEqual(1 + 1, cache[1])
        self.assertEqual(2 + 2, cache.setdefault(2, 2 + 2))
        self.assertEqual(2 + 2, cache.setdefault(2, None))
        self.assertEqual(2 + 2, cache.setdefault(2))
        self.assertEqual(2 + 2, cache[2])
        self.assertEqual(2, len(cache))
        self.assertTrue(1 in cache and 2 in cache)
        self.assertEqual(None, cache.setdefault(3))
        self.assertEqual(2, len(cache))
        self.assertTrue(3 in cache)
        self.assertTrue(1 in cache or 2 in cache)
        self.assertTrue(1 not in cache or 2 not in cache)

    def test_missing_getsizeof(self):
        class DefaultCache(self.Cache):
            def __missing__(self, key):
                try:
                    self[key] = key
                except ValueError:
                    pass  # not stored
                return key

        cache = DefaultCache(maxsize=2, getsizeof=lambda x: x)

        self.assertEqual(0, cache.currsize)
        self.assertEqual(2, cache.maxsize)

        self.assertEqual(1, cache[1])
        self.assertEqual(1, len(cache))
        self.assertEqual(1, cache.currsize)
        self.assertIn(1, cache)

        self.assertEqual(2, cache[2])
        self.assertEqual(1, len(cache))
        self.assertEqual(2, cache.currsize)
        self.assertNotIn(1, cache)
        self.assertIn(2, cache)

        self.assertEqual(3, cache[3])  # not stored
        self.assertEqual(1, len(cache))
        self.assertEqual(2, cache.currsize)
        self.assertEqual(1, cache[1])
        self.assertEqual(1, len(cache))
        self.assertEqual(1, cache.currsize)
        self.assertEqual((1, 1), cache.popitem())

    def _test_getsizeof(self, cache):
        self.assertEqual(0, cache.currsize)
        self.assertEqual(3, cache.maxsize)
        self.assertEqual(1, cache.getsizeof(1))
        self.assertEqual(2, cache.getsizeof(2))
        self.assertEqual(3, cache.getsizeof(3))

        cache.update({1: 1, 2: 2})
        self.assertEqual(2, len(cache))
        self.assertEqual(3, cache.currsize)
        self.assertEqual(1, cache[1])
        self.assertEqual(2, cache[2])

        cache[1] = 2
        self.assertEqual(1, len(cache))
        self.assertEqual(2, cache.currsize)
        self.assertEqual(2, cache[1])
        self.assertNotIn(2, cache)

        cache.update({1: 1, 2: 2})
        self.assertEqual(2, len(cache))
        self.assertEqual(3, cache.currsize)
        self.assertEqual(1, cache[1])
        self.assertEqual(2, cache[2])

        cache[3] = 3
        self.assertEqual(1, len(cache))
        self.assertEqual(3, cache.currsize)
        self.assertEqual(3, cache[3])
        self.assertNotIn(1, cache)
        self.assertNotIn(2, cache)

        with self.assertRaises(ValueError):
            cache[3] = 4
        self.assertEqual(1, len(cache))
        self.assertEqual(3, cache.currsize)
        self.assertEqual(3, cache[3])

        with self.assertRaises(ValueError):
            cache[4] = 4
        self.assertEqual(1, len(cache))
        self.assertEqual(3, cache.currsize)
        self.assertEqual(3, cache[3])

    def test_getsizeof_param(self):
        self._test_getsizeof(self.Cache(maxsize=3, getsizeof=lambda x: x))

    def test_getsizeof_subclass(self):
        class Cache(self.Cache):
            def getsizeof(self, value):
                return value

        self._test_getsizeof(Cache(maxsize=3))

    def test_pickle(self):
        import pickle

        source = self.Cache(maxsize=2)
        source.update({1: 1, 2: 2})

        cache = pickle.loads(pickle.dumps(source))
        self.assertEqual(source, cache)

        self.assertEqual(2, len(cache))
        self.assertEqual(1, cache[1])
        self.assertEqual(2, cache[2])

        cache[3] = 3
        self.assertEqual(2, len(cache))
        self.assertEqual(3, cache[3])
        self.assertTrue(1 in cache or 2 in cache)

        cache[4] = 4
        self.assertEqual(2, len(cache))
        self.assertEqual(4, cache[4])
        self.assertTrue(1 in cache or 2 in cache or 3 in cache)

        self.assertEqual(cache, pickle.loads(pickle.dumps(cache)))

    def test_pickle_maxsize(self):
        import pickle
        import sys

        # test empty cache, single element, large cache (recursion limit)
        for n in [0, 1, sys.getrecursionlimit() * 2]:
            source = self.Cache(maxsize=n)
            source.update((i, i) for i in range(n))
            cache = pickle.loads(pickle.dumps(source))
            self.assertEqual(n, len(cache))
            self.assertEqual(source, cache)