import os

# Check for case-sensitive match.  full_path is the full path to a file
# (or directory), which must exist, albeit perhaps case-insensitively.
# On a case-insensitive filesystem, we want to ensure that the basename
# matches case-sensitively.  Two cases:
#
# 1. We want a case-sensitive match to the entire basename, like a
#    directory name.  Then pass False for loose_extension_match.
#       case_ok('/a/b/c/ZODB', False)
#    This returns True iff directory /a/b/c/ contains a file or
#    directory with name exactly 'ZODB'.
#
# 2. We're trying to check a Python file.  This is more complicated,
#    because while Python does case-sensitive imports even on case-
#    insensitive filesystems, the case-sensitiviy applies only to the
#    name being imported, not to the extension on the file.  For example,
#    gorp.pyo and gorp.PyO both work on Windows if you want to import gorp.
#    In this case, pass  True for loose_extension_match.  For example,
#        case_ok('/a/b/c/ZODB/__init__.py', True)
#    This returns True iff directory /a/b/c/ZODB/ contains a file (not
#    a directory!) with root name exactly '__init__' and an extension
#    that is a case-insensitive match to .py.

def case_ok(full_path, loose_extension_match):
    assert os.path.exists(full_path)
    parentdir, basename = os.path.split(full_path)
    all_files = os.listdir(parentdir)
    if not loose_extension_match:
        return basename in all_files

    basename_name, basename_ext = os.path.splitext(basename)
    name_len = len(basename_name)
    basename_ext = basename_ext.lower()
    for fname in all_files:
        if fname[:name_len] != basename_name:
            continue
        # We have a case-sensitive match to basename_name on a prefix
        # of fname.
        root, ext = os.path.splitext(fname)
        if (len(root) == name_len and
              ext.lower() == basename_ext and
              os.path.isfile(os.path.join(parentdir, fname))):
            return True

    return False