#!/usr/bin/env python

import importlib
import srt
import srt_tools.utils
import logging

log = logging.getLogger(__name__)


def strip_to_matching_lines_only(subtitles, imports, func_str, invert, per_sub):
    for import_name in imports:
        real_import = importlib.import_module(import_name)
        globals()[import_name] = real_import

    raw_func = eval(func_str)  # pylint: disable-msg=eval-used

    if invert:
        func = lambda line: not raw_func(line)
    else:
        func = raw_func

    for subtitle in subtitles:
        if per_sub:
            if not func(subtitle.content):
                subtitle.content = ''
        else:
            subtitle.content = '\n'.join(
                line for line in subtitle.content.splitlines()
                if func(line)
            )

        yield subtitle


def parse_args():
    parser = srt_tools.utils.basic_parser()
    parser.add_argument(
        '-f', '--func',
        help='a function to use to match lines',
        required=True,
    )
    parser.add_argument(
        '-m', '--module',
        help='modules to import in the function context',
        action='append', default=[],
    )
    parser.add_argument(
        '-s', '--per-subtitle',
        help='match the content of each subtitle, not each line',
        action='store_true',
    )
    parser.add_argument(
        '-v', '--invert',
        help='invert matching -- only match lines returning False',
        action='store_true',
    )
    return parser.parse_args()


def main():
    args = parse_args()
    logging.basicConfig(level=args.log_level)
    srt_tools.utils.set_basic_args(args)
    matching_subtitles_only = strip_to_matching_lines_only(
        args.input, args.module, args.func, args.invert, args.per_subtitle,
    )
    output = srt_tools.utils.compose_suggest_on_fail(
        matching_subtitles_only, strict=args.strict,
    )

    try:
        args.output.write(output)
    except (UnicodeEncodeError, TypeError):  # Python 2 fallback
        args.output.write(output.encode(args.encoding))


if __name__ == '__main__':
    main()
