import random
import string
from collections.abc import MutableMapping

import pytest


def generate_random_strings(n, min_len, max_len):
    r = random.Random(42)
    out = []
    chars = string.ascii_lowercase + string.digits

    for i in range(n):
        nchars = r.randint(min_len, max_len)
        s = "".join(r.choice(chars) for _ in range(nchars))
        out.append(s)

    return out


def to_bytestring(s):
    if isinstance(s, bytes):
        return s
    else:
        return s.encode("latin1")


def check_items(z, expected_items):
    items = list(z.items())
    assert len(items) == len(expected_items)
    assert sorted(items) == sorted(expected_items)
    # All iterators should walk the mapping in the same order
    assert list(z.keys()) == [k for k, v in items]
    assert list(z.values()) == [v for k, v in items]
    assert list(z) == [k for k, v in items]


def stress_test_mapping_updates(z):
    # Certain mappings shuffle between several underlying stores
    # during updates.  This stress tests the internal mapping
    # consistency.
    r = random.Random(42)

    keys = list(string.ascii_lowercase)
    values = [to_bytestring(s) for s in generate_random_strings(len(keys), 1, 10)]

    z.clear()
    assert len(z) == 0

    for k, v in zip(keys, values):
        z[k] = v
    assert len(z) == len(keys)
    assert sorted(z) == sorted(keys)
    assert sorted(z.items()) == sorted(zip(keys, values))

    for i in range(3):
        r.shuffle(keys)
        r.shuffle(values)
        for k, v in zip(keys, values):
            z[k] = v
        check_items(z, list(zip(keys, values)))

        r.shuffle(keys)
        r.shuffle(values)
        z.update(zip(keys, values))
        check_items(z, list(zip(keys, values)))


def check_mapping(z):
    assert isinstance(z, MutableMapping)
    assert not z

    assert list(z) == list(z.keys()) == []
    assert list(z.values()) == []
    assert list(z.items()) == []
    assert len(z) == 0

    z["abc"] = b"456"
    z["xyz"] = b"12"
    assert len(z) == 2
    assert z["abc"] == b"456"

    check_items(z, [("abc", b"456"), ("xyz", b"12")])

    assert "abc" in z
    assert "xyz" in z
    assert "def" not in z

    with pytest.raises(KeyError):
        z["def"]

    z.update(xyz=b"707", uvw=b"000")
    check_items(z, [("abc", b"456"), ("xyz", b"707"), ("uvw", b"000")])
    z.update([("xyz", b"654"), ("uvw", b"999")])
    check_items(z, [("abc", b"456"), ("xyz", b"654"), ("uvw", b"999")])
    z.update({"xyz": b"321"})
    check_items(z, [("abc", b"456"), ("xyz", b"321"), ("uvw", b"999")])

    del z["abc"]
    with pytest.raises(KeyError):
        z["abc"]
    with pytest.raises(KeyError):
        del z["abc"]
    assert "abc" not in z
    assert set(z) == {"uvw", "xyz"}
    assert len(z) == 2

    z["def"] = b"\x00\xff"
    assert len(z) == 3
    assert z["def"] == b"\x00\xff"
    assert "def" in z

    stress_test_mapping_updates(z)


def check_closing(z):
    z.close()