import os, sys, unittest
sys.path.insert(0, os.path.dirname(__file__))
from lcp_array import build_suffix_array, build_lcp, lcp_of


class TestLCP(unittest.TestCase):
    def _check(self, text):
        sa = build_suffix_array(text)
        lcp = build_lcp(text, sa)
        if not text:
            self.assertEqual(lcp, [])
            return
        self.assertEqual(lcp[0], 0)
        for i in range(1, len(text)):
            a, b = sa[i-1], sa[i]
            self.assertEqual(lcp[i], lcp_of(text, a, b),
                             "mismatch at %d for %r" % (i, text))

    def test_banana(self):
        self._check("banana")

    def test_empty(self):
        self.assertEqual(build_lcp("", []), [])

    def test_single(self):
        self._check("a")

    def test_repeated(self):
        self._check("aaaa")

    def test_random(self):
        import random
        for _ in range(200):
            n = random.randint(0, 12)
            alphabet = "ab"
            t = "".join(random.choice(alphabet) for _ in range(n))
            self._check(t)

    def test_invalid_sa_length(self):
        with self.assertRaises(ValueError):
            build_lcp("abc", [0, 1])

    def test_invalid_sa_permutation(self):
        with self.assertRaises(ValueError):
            build_lcp("abc", [0, 0, 2])


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