#!/bin/python3
# -*- coding: utf-8 -*-

# ##### BEGIN LICENSE BLOCK #####
# Version: MPL 1.1/GPL 2.0/LGPL 2.1
#
# The contents of this file are subject to the Mozilla Public License Version
# 1.1 (the "License"); you may not use this file except in compliance with
# the License. You may obtain a copy of the License at
# http://www.mozilla.org/MPL/
#
# Software distributed under the License is distributed on an "AS IS" basis,
# WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
# for the specific language governing rights and limitations under the
# License.
#
# The Original Code is Mozilla Universal charset detector code.
#
# The Initial Developer of the Original Code is
# Netscape Communications Corporation.
# Portions created by the Initial Developer are Copyright (C) 2001
# the Initial Developer. All Rights Reserved.
#
# Contributor(s):
#          Jehan <jehan@girinstud.io>
#
# Alternatively, the contents of this file may be used under the terms of
# either the GNU General Public License Version 2 or later (the "GPL"), or
# the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
# in which case the provisions of the GPL or the LGPL are applicable instead
# of those above. If you wish to allow use of your version of this file only
# under the terms of either the GPL or the LGPL, and not to allow others to
# use your version of this file under the terms of the MPL, indicate your
# decision by deleting the provisions above and replace them with the notice
# and other provisions required by the GPL or the LGPL. If you do not delete
# the provisions above, a recipient may use your version of this file under
# the terms of any one of the MPL, the GPL or the LGPL.
#
# ##### END LICENSE BLOCK #####

import optparse
import os
import subprocess
import sys

script_path = os.path.relpath(__file__)

usage = 'Usage: {} <CHARSET-NAME>\n' \
        '\nEx: `{} ISO-8859-15`'.format(script_path, script_path)

description = "Internal tool to generate a charset table."
cmdline = optparse.OptionParser(usage, description = description)
(options, charset) = cmdline.parse_args()
if len(charset) != 1:
  sys.stderr.write("Please choose exactly one charset as argument.\n")
  exit(1)

charset = charset[0]

use_iconv = False
try:
  b' '.decode(charset)
except LookupError:
  use_iconv = True

def get_utf8_char(bchar, charset, iconv):
  if iconv:
    try:
      call = subprocess.Popen(['iconv', '-f', charset, '-t', 'UTF-8'],
                               stdin=subprocess.PIPE, stdout=subprocess.PIPE,
                               stderr=subprocess.DEVNULL)
      if call.poll() is not None:
        (_, error) = call.communicate(input='')
        sys.stderr.write('Error: `iconv` ended with error "{}".\n'.format(error))
        exit(1)
      (uchar, _) = call.communicate(input=bchar)
    except FileNotFoundError:
      sys.stderr.write('Error: `iconv` is not installed.\n')
      exit(1)
    if len(uchar) > 0:
      return uchar.decode('UTF-8')
    else:
      return None
  else:
    try:
      return bchar.decode(charset)
    except UnicodeDecodeError:
      # Typical error:
      # UnicodeDecodeError: 'charmap' codec can't decode byte 0x81 in position 0: character maps to <undefined>
      # It would mean an illegal character.
      return None

print('## Table generated by {} with {} ##'.format(script_path, 'iconv' if use_iconv else 'Python decode()'))

print('# X0  X1  X2  X3  X4  X5  X6  X7  X8  X9  XA  XB  XC  XD  XE  XF   #')
print('charmap = \\')
sys.stdout.write('[')
for l in range(0x10):
  sys.stdout.write('\n  ')
  has_printable = False
  for c in range(0x10):
    char = bytes([c + l * 0x10])
    char = get_utf8_char(char, charset, use_iconv)
    if char is None:
      sys.stdout.write('ILL,')
    elif char.isalpha():
      sys.stdout.write('LET,')
      has_printable = True
    elif char.isdigit():
      sys.stdout.write('NUM,')
      has_printable = True
    elif char == '\n' or char == '\r':
      sys.stdout.write('RET,')
    elif char.isprintable():
      sys.stdout.write('SYM,')
      has_printable = True
    else:
      sys.stdout.write('CTR,')

  sys.stdout.write(' # {}X'.format(hex(l)[-1:].upper()))

  if has_printable:
    sys.stdout.write('\n #')
    # The line has at least one printable character. Print in comment for
    # debugging.
    for c in range(0x10):
      char = bytes([c + l * 0x10])
      char = get_utf8_char(char, charset, use_iconv)
      if char is None:
        sys.stdout.write('ILL ')
      elif char == '\n' or char == '\r':
        sys.stdout.write('RET ')
      elif char.isalpha() or char.isdigit() or char.isprintable():
        sys.stdout.write("'{}' ".format(char))
      else:
        sys.stdout.write('CTR ')
sys.stdout.write('\n]')