#!/usr/bin/env python3
#
#       This program is free software; you can redistribute it and/or modify
#       it under the terms of the GNU General Public License as published by
#       the Free Software Foundation; either version 3 of the License, or
#       (at your option) any later version.
#
#       This program is distributed in the hope that it will be useful,
#       but WITHOUT ANY WARRANTY; without even the implied warranty of
#       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#       GNU General Public License for more details.
#
#       You should have received a copy of the GNU General Public License
#       along with this program; if not, write to the Free Software
#       Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
#       MA 02110-1301, USA.

import sys, os, random
import CodeLIB

def main():
    length, filename = usr_args()
    if not length:
        length = CodeLIB.get_int("Length", min=1, max=6144, default=20)
    if not filename:
        filename = file_choose()
    list = file_open(filename)
    list = " ".join(list.split())
    index = random.randint(length, len(list))
    print(list[(index - length):index])

def usr_args():
    try:
        CodeLIB.help("[length file]", arg=True)
        length = int(sys.argv[1])
        filename = sys.argv[2]
    except IndexError:
        return None, None
    except ValueError as err:
        print("Error:", err)
        CodeLIB.help("[length file]")
    return length, filename

def file_open(filename):
    lines = ""
    fh = None
    try:
        fh = open(filename)
        for line in fh:
            if line.strip():
                lines += line
    except (IOError, OSError) as err:
        print(err)
        return ""
    finally:
        if fh is not None:
            fh.close()
    return lines

def file_choose():
    files = [x for x in os.listdir(".") if os.path.isfile(x)]
    for x in range(len(files)):
        print((x + 1), ": ", files[x], sep="")
    open_index = CodeLIB.get_int("Open file number", min=1, max=len(files)) - 1
    print("Opening file", files[open_index])
    return files[open_index]

if __name__ == "__main__":
    main()