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

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

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

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

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 = pathclass.glob_many_files(patterns)

    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)

@vlogging.main_decorator
def main(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:]))