# Source code for fontTools.ufoLib.filenames

    """
    User name to file name conversion.
    This was taken from the UFO 3 spec.
    """

    # Restrictions are taken mostly from
    # https://docs.microsoft.com/en-gb/windows/win32/fileio/naming-a-file#naming-conventions.
    #
    # 1. Integer value zero, sometimes referred to as the ASCII NUL character.
    # 2. Characters whose integer representations are in the range 1 to 31,
    #    inclusive.
    # 3. Various characters that (mostly) Windows and POSIX-y filesystems don't
    #    allow, plus "(" and ")", as per the specification.
    illegalCharacters = {
        "\x00",
        "\x01",
        "\x02",
        "\x03",
        "\x04",
        "\x05",
        "\x06",
        "\x07",
        "\x08",
        "\t",
        "\n",
        "\x0b",
        "\x0c",
        "\r",
        "\x0e",
        "\x0f",
        "\x10",
        "\x11",
        "\x12",
        "\x13",
        "\x14",
        "\x15",
        "\x16",
        "\x17",
        "\x18",
        "\x19",
        "\x1a",
        "\x1b",
        "\x1c",
        "\x1d",
        "\x1e",
        "\x1f",
        '"',
        "*",
        "+",
        "/",
        ":",
        "<",
        ">",
        "?",
        "[",
        "\\",
        "]",
        "(",
        ")",
        "|",
        "\x7f",
    }
    reservedFileNames = {
        "aux",
        "clock$",
        "com1",
        "com2",
        "com3",
        "com4",
        "com5",
        "com6",
        "com7",
        "com8",
        "com9",
        "con",
        "lpt1",
        "lpt2",
        "lpt3",
        "lpt4",
        "lpt5",
        "lpt6",
        "lpt7",
        "lpt8",
        "lpt9",
        "nul",
        "prn",
    }
    maxFileNameLength = 255

    class NameTranslationError(Exception):
    	pass

    def userNameToFileName(userName: str, existing=(), prefix="", suffix=""):
    	"""
    	`existing` should be a set-like object.

    	>>> userNameToFileName("a") == "a"
    	True
    	>>> userNameToFileName("A") == "A_"
    	True
    	>>> userNameToFileName("AE") == "A_E_"
    	True
    	>>> userNameToFileName("Ae") == "A_e"
    	True
    	>>> userNameToFileName("ae") == "ae"
    	True
    	>>> userNameToFileName("aE") == "aE_"
    	True
    	>>> userNameToFileName("a.alt") == "a.alt"
    	True
    	>>> userNameToFileName("A.alt") == "A_.alt"
    	True
    	>>> userNameToFileName("A.Alt") == "A_.A_lt"
    	True
    	>>> userNameToFileName("A.aLt") == "A_.aL_t"
    	True
    	>>> userNameToFileName(u"A.alT") == "A_.alT_"
    	True
    	>>> userNameToFileName("T_H") == "T__H_"
    	True
    	>>> userNameToFileName("T_h") == "T__h"
    	True
    	>>> userNameToFileName("t_h") == "t_h"
    	True
    	>>> userNameToFileName("F_F_I") == "F__F__I_"
    	True
    	>>> userNameToFileName("f_f_i") == "f_f_i"
    	True
    	>>> userNameToFileName("Aacute_V.swash") == "A_acute_V_.swash"
    	True
    	>>> userNameToFileName(".notdef") == "_notdef"
    	True
    	>>> userNameToFileName("con") == "_con"
    	True
    	>>> userNameToFileName("CON") == "C_O_N_"
    	True
    	>>> userNameToFileName("con.alt") == "_con.alt"
    	True
    	>>> userNameToFileName("alt.con") == "alt._con"
    	True
    	"""
    	# the incoming name must be a string
    	if not isinstance(userName, str):
    		raise ValueError("The value for userName must be a string.")
    	# establish the prefix and suffix lengths
    	prefixLength = len(prefix)
    	suffixLength = len(suffix)
    	# replace an initial period with an _
    	# if no prefix is to be added
    	if not prefix and userName[0] == ".":
    		userName = "_" + userName[1:]
    	# filter the user name
    	filteredUserName = []
    	for character in userName:
    		# replace illegal characters with _
    		if character in illegalCharacters:
    			character = "_"
    		# add _ to all non-lower characters
    		elif character != character.lower():
    			character += "_"
    		filteredUserName.append(character)
    	userName = "".join(filteredUserName)
    	# clip to 255
    	sliceLength = maxFileNameLength - prefixLength - suffixLength
    	userName = userName[:sliceLength]
    	# test for illegal files names
    	parts = []
    	for part in userName.split("."):
    		if part.lower() in reservedFileNames:
    			part = "_" + part
    		parts.append(part)
    	userName = ".".join(parts)
    	# test for clash
    	fullName = prefix + userName + suffix
    	if fullName.lower() in existing:
    		fullName = handleClash1(userName, existing, prefix, suffix)
    	# finished
    	return fullName

    def handleClash1(userName, existing=[], prefix="", suffix=""):
    	"""
    	existing should be a case-insensitive list
    	of all existing file names.

    	>>> prefix = ("0" * 5) + "."
    	>>> suffix = "." + ("0" * 10)
    	>>> existing = ["a" * 5]

    	>>> e = list(existing)
    	>>> handleClash1(userName="A" * 5, existing=e,
    	...		prefix=prefix, suffix=suffix) == (
    	... 	'00000.AAAAA000000000000001.0000000000')
    	True

    	>>> e = list(existing)
    	>>> e.append(prefix + "aaaaa" + "1".zfill(15) + suffix)
    	>>> handleClash1(userName="A" * 5, existing=e,
    	...		prefix=prefix, suffix=suffix) == (
    	... 	'00000.AAAAA000000000000002.0000000000')
    	True

    	>>> e = list(existing)
    	>>> e.append(prefix + "AAAAA" + "2".zfill(15) + suffix)
    	>>> handleClash1(userName="A" * 5, existing=e,
    	...		prefix=prefix, suffix=suffix) == (
    	... 	'00000.AAAAA000000000000001.0000000000')
    	True
    	"""
    	# if the prefix length + user name length + suffix length + 15 is at
    	# or past the maximum length, silce 15 characters off of the user name
    	prefixLength = len(prefix)
    	suffixLength = len(suffix)
    	if prefixLength + len(userName) + suffixLength + 15 > maxFileNameLength:
    		l = (prefixLength + len(userName) + suffixLength + 15)
    		sliceLength = maxFileNameLength - l
    		userName = userName[:sliceLength]
    	finalName = None
    	# try to add numbers to create a unique name
    	counter = 1
    	while finalName is None:
    		name = userName + str(counter).zfill(15)
    		fullName = prefix + name + suffix
    		if fullName.lower() not in existing:
    			finalName = fullName
    			break
    		else:
    			counter += 1
    		if counter >= 999999999999999:
    			break
    	# if there is a clash, go to the next fallback
    	if finalName is None:
    		finalName = handleClash2(existing, prefix, suffix)
    	# finished
    	return finalName

    def handleClash2(existing=[], prefix="", suffix=""):
    	"""
    	existing should be a case-insensitive list
    	of all existing file names.

    	>>> prefix = ("0" * 5) + "."
    	>>> suffix = "." + ("0" * 10)
    	>>> existing = [prefix + str(i) + suffix for i in range(100)]

    	>>> e = list(existing)
    	>>> handleClash2(existing=e, prefix=prefix, suffix=suffix) == (
    	... 	'00000.100.0000000000')
    	True

    	>>> e = list(existing)
    	>>> e.remove(prefix + "1" + suffix)
    	>>> handleClash2(existing=e, prefix=prefix, suffix=suffix) == (
    	... 	'00000.1.0000000000')
    	True

    	>>> e = list(existing)
    	>>> e.remove(prefix + "2" + suffix)
    	>>> handleClash2(existing=e, prefix=prefix, suffix=suffix) == (
    	... 	'00000.2.0000000000')
    	True
    	"""
    	# calculate the longest possible string
    	maxLength = maxFileNameLength - len(prefix) - len(suffix)
    	maxValue = int("9" * maxLength)
    	# try to find a number
    	finalName = None
    	counter = 1
    	while finalName is None:
    		fullName = prefix + str(counter) + suffix
    		if fullName.lower() not in existing:
    			finalName = fullName
    			break
    		else:
    			counter += 1
    		if counter >= maxValue:
    			break
    	# raise an error if nothing has been found
    	if finalName is None:
    		raise NameTranslationError("No unique name could be found.")
    	# finished
    	return finalName

    if __name__ == "__main__":
    	import doctest
    	doctest.testmod()