import unittest
from kmp import build_pi, search, search_count


class TestKMP(unittest.TestCase):
    def test_pi(self):
        self.assertEqual(build_pi("aabaaab"), [0,1,0,1,2,2,3])
        self.assertEqual(build_pi("aaaa"), [0,1,2,3])
        self.assertEqual(build_pi(""), [])
        self.assertEqual(build_pi("abc"), [0,0,0])

    def test_search_basic(self):
        self.assertEqual(search("ababcababa", "aba"), [0,5,7])
        self.assertEqual(search("aaaa", "aa"), [0,1,2])
        self.assertEqual(search("hello world", "xyz"), [])
        self.assertEqual(search("abc", "abcd"), [])

    def test_overlapping(self):
        self.assertEqual(search("aaaaa", "aaa"), [0,1,2])

    def test_single(self):
        self.assertEqual(search("abc", "a"), [0])
        self.assertEqual(search("abc", "c"), [2])

    def test_empty_pattern(self):
        self.assertEqual(search("abc", ""), [])
        self.assertEqual(search("", ""), [])

    def test_full_text(self):
        self.assertEqual(search("abc", "abc"), [0])

    def test_count(self):
        self.assertEqual(search_count("ababab", "ab"), 3)
        self.assertEqual(search_count("aaaa", "aa"), 3)

    def test_unicode(self):
        self.assertEqual(search("cafécafé", "café"), [0,4])

    def test_random_vs_naive(self):
        import random
        rng = random.Random(42)
        alpha = "ab"
        for _ in range(200):
            n = rng.randint(0, 60)
            m = rng.randint(1, 8)
            text = "".join(rng.choice(alpha) for _ in range(n))
            pat = "".join(rng.choice(alpha) for _ in range(m))
            naive = [i for i in range(len(text)-m+1) if text[i:i+m] == pat]
            self.assertEqual(search(text, pat), naive)


if __name__ == "__main__":
    unittest.main()