lolita subtitle font changer

lolisubify.py

#!/usr/bin/env python
"""
lolita subtitle font changer
"""

from argparse import ArgumentParser, Namespace
from typing import List
from typing import NoReturn
from os.path import exists
from sys import exit as die
from platform import system


if system() == 'Windows':
    EX_OK = 0
    EX_DATAERR = 65
    EX_NOINPUT = 66
else:
    from os import EX_OK
    from os import EX_DATAERR
    from os import EX_NOINPUT


def _loli_ify(content: str, target: str) -> str:
	buff = []
	flag = False
	font_idx = -1
	cnt = 0
	for lineno, line in enumerate(content.split('\n')):
		stripped_line = line.strip()
		if stripped_line and not stripped_line.startswith(';'):
			if stripped_line.startswith('[') and stripped_line.endswith(']'):
				tag_name = stripped_line[1:-1].strip()
				if tag_name:
					flag = tag_name == 'V4+ Styles'
					font_fmt = -1
			elif flag:
				if stripped_line.count(':') < 1:
					print('syntax error at line %d' % lineno)
					die(EX_DATAERR)
				else:
					idx = stripped_line.index(':')
					field_name = stripped_line[:idx].strip()
					value = stripped_line[idx + 1:].strip()
					if field_name == 'Format':
						if font_idx == -1:
							if value:
								fmt_list = value.split(',')
								for fmt_idx, fmt in enumerate(fmt_list):
									stripped_fmt = fmt.strip()
									if stripped_fmt == 'Fontname':
										font_idx = fmt_idx
										break
								else:
									print('no \'Fontname\' in \'Format field\' at line %d', lineno)
									die(EX_DATAERR)
							else:
								print('empty value in \'Format\' field at line %d' % lineno)
								die(EX_DATAERR)
						else:
							print('duplicated \'Format\' field in \'V4+ Styles\' tag at line %d' % lineno)
							die(EX_DATAERR)
					elif field_name == 'Style':
						prop_list = value.split(',')
						if font_idx == -1:
							print('don\'t know where is the font property at line %d' % lineno)
							die(EX_DATAERR)
						if prop_list[font_idx] != target:
							prop_list[font_idx] = target
							new_value = ','.join(prop_list)
							buff.append(f'{field_name}: {new_value}')
							cnt += 1
							continue
		buff.append(line)
	if cnt > 0:
		print('replaced %d style(s) to loli' % cnt)
	return '\n'.join(buff)


def loli_ify(sub_files: List[str], dry_run: bool, target: str):
	for sub_file in sub_files:
		stripped_subfile = sub_file.strip()
		if stripped_subfile and exists(stripped_subfile):
			print('handle file \'%s\'' % stripped_subfile)
			in_fd = open(sub_file, 'r', encoding='utf-8')
			content = in_fd.read()
			in_fd.close()
			new_content = _loli_ify(content, target)
			if content != new_content:
				if not dry_run:
					with open(sub_file, 'w', encoding='utf-8') as out_fd:
						out_fd.write(new_content)
		else:
			print('\'%s\' does not exist' % sub_file)
			die(EX_NOINPUT)


def main(args: Namespace) -> NoReturn:
	sub_files = args.sub_file
	dry_run = args.dry_run
	if dry_run:
		print('dry run enabled')
	target = args.target
	print('start')
	loli_ify(sub_files, dry_run, target)
	print('Done!')
	die(EX_OK)


if __name__ == '__main__':
	parser = ArgumentParser(description='shitty tool for changing all fonts in SSA sub to lolita', epilog='powered by Python')
	parser.add_argument('-d', '--dry-run', action='store_true', help='dry run')
	parser.add_argument('-t', '--target', type=str, help='target font (defaults to \'Heiti SC\')', default='Heiti SC')
	parser.add_argument('sub_file', nargs='+', type=str, help='SSA subtitle file')
	args = parser.parse_args()
	main(args)