from Levenshtein import *
from warnings import warn

class StringMatcher:
    """A SequenceMatcher-like class built on the top of Levenshtein"""

    def _reset_cache(self):
        self._ratio = self._distance = None
        self._opcodes = self._editops = self._matching_blocks = None

    def __init__(self, isjunk=None, seq1='', seq2=''):
        if isjunk:
            warn("isjunk not NOT implemented, it will be ignored")
        self._str1, self._str2 = seq1, seq2
        self._reset_cache()

    def set_seqs(self, seq1, seq2):
        self._str1, self._str2 = seq1, seq2
        self._reset_cache()

    def set_seq1(self, seq1):
        self._str1 = seq1
        self._reset_cache()

    def set_seq2(self, seq2):
        self._str2 = seq2
        self._reset_cache()

    def get_opcodes(self):
        if not self._opcodes:
            if self._editops:
                self._opcodes = opcodes(self._editops, self._str1, self._str2)
            else:
                self._opcodes = opcodes(self._str1, self._str2)
        return self._opcodes

    def get_editops(self):
        if not self._editops:
            if self._opcodes:
                self._editops = editops(self._opcodes, self._str1, self._str2)
            else:
                self._editops = editops(self._str1, self._str2)
        return self._editops

    def get_matching_blocks(self):
        if not self._matching_blocks:
            self._matching_blocks = matching_blocks(self.get_opcodes(),
                                                    self._str1, self._str2)
        return self._matching_blocks

    def ratio(self):
        if not self._ratio:
            self._ratio = ratio(self._str1, self._str2)
        return self._ratio

    def quick_ratio(self):
        # This is usually quick enough :o)
        if not self._ratio:
            self._ratio = ratio(self._str1, self._str2)
        return self._ratio

    def real_quick_ratio(self):
        len1, len2 = len(self._str1), len(self._str2)
        return 2.0 * min(len1, len2) / (len1 + len2)

    def distance(self):
        if not self._distance:
            self._distance = distance(self._str1, self._str2)
        return self._distance