'''
bitwise_or
==========

Merge two or more files by performing bitwise or on their bits.

> bitwise_or file1 file2 --output file3
'''
import argparse
import os
import sys

from voussoirkit import betterhelp
from voussoirkit import interactive
from voussoirkit import operatornotify
from voussoirkit import pathclass
from voussoirkit import pipeable
from voussoirkit import vlogging
from voussoirkit import winglob

log = vlogging.getLogger(__name__, 'bitwise_or')

CHUNK_SIZE = 2**20

def bitwise_or_argparse(args):
    patterns = pipeable.input_many(args.files, skip_blank=True, strip=True)
    files = [file for pattern in patterns for file in winglob.glob(pattern)]
    files = [pathclass.Path(file) for file in files]

    if len(files) < 2:
        log.fatal('Need at least two input files.')
        return 1

    output = pathclass.Path(args.output)
    if output.is_dir:
        log.fatal('Output path "%s" is a directory.', args.output)
        return 1

    if any(output == file for file in files):
        log.fatal('Output cannot be one of the inputs.')
        return 1

    if not output.exists:
        pass
    elif args.overwrite:
        pass
    elif not interactive.getpermission(f'Overwrite "{output.absolute_path}"?'):
        return 1

    handles = [file.open('rb') for file in files]
    output_handle = output.open('wb')
    while True:
        chunk = 0
        length = 1
        for handle in handles[:]:
            read = handle.read(CHUNK_SIZE)
            length = max(length, len(read))
            if not read:
                handles.remove(handle)
            chunk |= int.from_bytes(read, 'big')
        if not handles:
            break
        output_handle.write(chunk.to_bytes(length, 'big'))
    pipeable.stdout(output.absolute_path)

def main(argv):
    argv = vlogging.main_level_by_argv(argv)

    parser = argparse.ArgumentParser(description=__doc__)

    parser.add_argument('files', nargs='+')
    parser.add_argument('--output', required=True)
    parser.add_argument('--overwrite', action='store_true')
    parser.set_defaults(func=bitwise_or_argparse)

    return betterhelp.single_main(argv, parser, __doc__)

if __name__ == '__main__':
    raise SystemExit(main(sys.argv[1:]))