#!/usr/bin/python3

# pylint: disable=import-error

'''drscut - cut with consistent semantics and no escaping'''

import os
import sys

sys.path.insert(0, os.path.expanduser('/usr/local/lib'))
sys.path.insert(0, os.path.expanduser('~/lib'))

import readline0


def usage(retval):
    '''Output a usage message and exit'''
    sys.stderr.write(('Usage: %s [-i inputFieldDelimiter] [-o outputFieldDelimiter] ' % (sys.argv[0], )) + \
        '[-r outputRecordDelimiter] [-f fieldno] [-0] [-l] [-L] [-h]\n')
    sys.stderr.write('The default "inputFieldDelimiter" is 1 or more occurences of any whitespace\n')
    sys.stderr.write('-f may be repeated as many times as you like, in any order you like\n')
    sys.stderr.write('-n says to ignore lines that do not have enough fields\n')
    sys.stderr.write('-0 says to read lines that are null terminated, not newline terminated\n')
    sys.stderr.write('-l says to leave out any missing fields\n')
    sys.stderr.write('-L says to leave out any line with one or more missing fields\n')
    sys.stderr.write('-D says to run in debug mode\n')
    sys.exit(retval)


class Options(object):
    # pylint: disable=too-many-instance-attributes,too-few-public-methods
    '''Just a container for command line option-related variables'''
    def __init__(self):
        self.input_delimiter_specified = False
        self.input_delimiter = ''
        self.output_field_delimiter = ' '
        self.output_record_delimiter = '\n'
        self.field_numbers = []
        self.use_readline0 = False
        self.leave_out_short_lines = False
        self.leave_missing_fields_empty = False
        self.debug = False

    def handle_argv(self, argv):
        '''Parse up sys.argv'''
        while argv[1:]:
            if argv[1] == '-i' and argv[2:]:
                self.input_delimiter = argv[2]
                self.input_delimiter_specified = 1
                del argv[1]
            elif argv[1] == '-o' and argv[2:]:
                self.output_field_delimiter = argv[2]
                del argv[1]
            elif argv[1] == '-r' and argv[2:]:
                self.output_record_delimiter = argv[2]
                del argv[1]
            elif argv[1] == '-f' and argv[2:]:
                self.field_numbers.append(int(argv[2]))
                del argv[1]
            elif argv[1] == '-D':
                self.debug = True
            elif argv[1] == '-l':
                self.leave_missing_fields_empty = True
            elif argv[1] == '-L':
                self.leave_out_short_lines = True
            elif argv[1] == '-f' and argv[2:]:
                self.field_numbers.append(int(argv[2]))
                del argv[1]
            elif argv[1] == '-h':
                usage(0)
            elif argv[1] == '-0':
                self.use_readline0 = True
            else:
                usage(1)
            del argv[1]


def main():
    # pylint: disable=too-many-branches
    '''Main function'''

    options = Options()
    options.handle_argv(sys.argv)

    def my_readline(file_):
        '''Readline that either delimits using nulls or newlines'''
        if options.use_readline0:
            for line in readline0.readline0(file_):
                yield line
        else:
            for line in file_:
                yield line.rstrip('\n')

    line_number = 0
    for line in my_readline(sys.stdin):
        if options.debug:
            sys.stderr.write('Got line %s\n' % line)
        if options.input_delimiter_specified:
            fields = line.split(options.input_delimiter)
        else:
            fields = line.split()
        output_list = []
        skip = False
        for fieldno in options.field_numbers:
            #sys.stderr.write("%d\n" % fieldno)
            if fields[fieldno:]:
                output_list.append(fields[fieldno])
            else:
                if options.leave_out_short_lines:
                    skip = True
                    break
                elif options.leave_missing_fields_empty:
                    output_list.append('')
                else:
                    sys.stderr.write('Sorry, line number %d (prefix %s) does not have all ' \
                        'requested fields - consider using -l or -L\n' % (line_number, line[:20]))
                    usage(1)
        if not skip:
            sys.stdout.write(options.output_field_delimiter.join(output_list) + options.output_record_delimiter)
        skip = False
        line_number += 1

main()