import random

import pytest

from patterns import (LRUCache, edit_distance, longest_unique_substring, lower_bound, merge_intervals,
                      shortest_path, top_k_frequent, topo_order, two_sum)


def test_two_sum():
    assert two_sum([3, 3], 6) == (0, 1)
    assert two_sum([1, 2], 10) is None


@pytest.mark.parametrize("s,n", [("", 0), ("bbbb", 1), ("pwwkew", 3), ("abba", 2), ("你好你们好", 3)])
def test_longest_unique(s, n):
    assert longest_unique_substring(s) == n


def test_lower_bound_matches_bisect():
    import bisect
    rng = random.Random(0)
    for _ in range(200):                     # 与标准库对拍
        arr = sorted(rng.randint(0, 20) for _ in range(rng.randint(0, 15)))
        t = rng.randint(-1, 21)
        assert lower_bound(arr, t) == bisect.bisect_left(arr, t)


def test_top_k():
    assert top_k_frequent([], 3) == []
    assert top_k_frequent(list("aaabbc"), 1) == ["a"]


def test_shortest_path_blocked():
    assert shortest_path([[0, 1], [1, 0]], (0, 0), (1, 1)) == -1
    assert shortest_path([[0]], (0, 0), (0, 0)) == 0


def test_topo_cycle_and_order():
    assert topo_order({"a": ["b"], "b": ["a"]}) is None
    order = topo_order({"app": ["db", "cache"], "cache": ["net"], "db": ["net"]})
    assert order is not None
    pos = {n: i for i, n in enumerate(order)}
    assert pos["net"] < pos["db"] < pos["app"] and pos["net"] < pos["cache"] < pos["app"]


def test_edit_distance():
    assert edit_distance("", "abc") == 3
    assert edit_distance("退货申请", "退款申请") == 1


def test_lru():
    c = LRUCache(2)
    c.put("a", 1)
    c.put("b", 2)
    assert c.get("a") == 1                   # a 变成最近使用
    c.put("c", 3)                            # 淘汰 b
    assert c.get("b") is None and c.get("a") == 1 and c.get("c") == 3


def test_merge_intervals():
    assert merge_intervals([]) == []
    assert merge_intervals([(1, 4), (4, 5)]) == [(1, 5)]
    assert merge_intervals([(5, 6), (1, 2)]) == [(1, 2), (5, 6)]