"""Filename matching with shell patterns.

fnmatch(FILENAME, PATTERN) matches according to the local convention.
fnmatchcase(FILENAME, PATTERN) always takes case in account.

The functions operate by translating the pattern into a regular
expression.  They cache the compiled regular expressions for speed.

The function translate(PATTERN) returns a regular expression
corresponding to PATTERN.  (It does not compile it.)
"""

import re

__all__ = ["fnmatch", "fnmatchcase", "translate"]

_cache = {}
_MAXCACHE = 100


def _purge():
    """Clear the pattern cache"""
    _cache.clear()


def fnmatch(name, pat):
    """Test whether FILENAME matches PATTERN.

    Patterns are Unix shell style:

    *       matches everything
    ?       matches any single character
    [seq]   matches any character in seq
    [!seq]  matches any char not in seq

    An initial period in FILENAME is not special.
    Both FILENAME and PATTERN are first case-normalized
    if the operating system requires it.
    If you don't want this, use fnmatchcase(FILENAME, PATTERN).
    """

    import os
    name = os.path.normcase(name)
    pat = os.path.normcase(pat)
    return fnmatchcase(name, pat)


def fnmatchcase(name, pat):
    """Test whether FILENAME matches PATTERN, including case.

    This is a version of fnmatch() which doesn't case-normalize
    its arguments.
    """

    try:
        re_pat = _cache[pat]
    except KeyError:
        res = translate(pat)
        if len(_cache) >= _MAXCACHE:
            _cache.clear()
        _cache[pat] = re_pat = re.compile(res)
    return re_pat.match(name) is not None


def translate(pat):
    """Translate a shell PATTERN to a regular expression.

    There is no way to quote meta-characters.
    """

    recursive_mode = False
    i, n = 0, len(pat)
    res = ''
    while i < n:
        c = pat[i]
        i = i + 1
        if c == '*':
            if i < n and pat[i] == '*':
                recursive_mode = True
                i = i + 1
            res = res + '.*'
        elif c == '?':
            res = res + '.'
        elif c == '[':
            j = i
            if j < n and pat[j] == '!':
                j = j + 1
            if j < n and pat[j] == ']':
                j = j + 1
            while j < n and pat[j] != ']':
                j = j + 1
            if j >= n:
                res = res + '\\['
            else:
                stuff = pat[i:j].replace('\\', '\\\\')
                i = j + 1
                if stuff[0] == '!':
                    stuff = '^' + stuff[1:]
                elif stuff[0] == '^':
                    stuff = '\\' + stuff
                res = '%s[%s]' % (res, stuff)
        elif recursive_mode and c == '/':
            res = res + '/?'
        else:
            res = res + re.escape(c)
    return res + '\Z(?ms)'
