#!/usr/bin/env python3
import argparse
import logging
import sys


def make_parser():
    parser = argparse.ArgumentParser(
        description='Select column(s) of CSV file by name assuming the first '
                    'row of the CSV lists the column names. Currently the '
                    'script does not support quoting.')
    parser.add_argument('-d', '--delimiter', default=',',
                        help='field delimiter, default to comma')
    parser.add_argument('-F', '--no-print-field', action='store_false',
                        dest='print_field',
                        help='to print the selected title')
    parser.add_argument('-S', '--strict', action='store_true',
                        help='raise error if one of FIELDs does not exist')
    parser.add_argument('fields', nargs='*', metavar='FIELD',
                        help='FIELD to select')
    return parser


def _main():
    args = make_parser().parse_args()
    logging.basicConfig(format='%(filename)s: %(levelname)s: %(message)s',
                        level=logging.DEBUG)
    try:
        infile = sys.stdin
        titles = next(infile).rstrip('\n').split(args.delimiter)
        indices = []
        for i, x in enumerate(args.fields):
            try:
                j = titles.index(x)
            except ValueError:
                if args.strict:
                    logging.error('Field "%s" does not exist; aborted',
                                  args.fields[i])
                    return 4
                logging.warning('Field %s does not exist', args.fields[i])
            else:
                indices.append(j)
        if args.print_field:
            print(args.delimiter.join(titles[j] for j in indices))
        if args.fields:
            for line in infile:
                tokens = line.rstrip('\n').split(args.delimiter)
                try:
                    filtered_line = [tokens[j] for j in indices]
                except IndexError:
                    filtered_line = []
                    for jj in indices:
                        try:
                            filtered_lin.append(tokens[jj])
                        except IndexError:
                            pass
                if filtered_line:
                    print(args.delimiter.join(filtered_line))
    except KeyboardInterrupt:
        return 130
    except BrokenPipeError:
        sys.stderr.close()
    else:
        return 0


if __name__ == '__main__':
    sys.exit(_main())