import argparse
'''
sub-commands and sub-sub-commands: example

mainScript.py  Command    Sub-commands       Arguments
-------------  ---------  -----------------  ----------------------------------
               mergePDF   
                          mergeFiles         f1, f2, ...
                          mergeInFolder      folderName
               editPDF  
                          deletePages        f, sPg, nPg...
                          rotatePages        f, sPg, nPg, q...
                          scalePages         f, sPg, nPg, s...
                          cropPages          f, sPg, nPg, wL, wT, wR, wB...
'''

if __name__ == '__main__':
  #Reference: /gist.github.com/jirihnidek
  
  # Create the top-level (main) parser
  parser = argparse.ArgumentParser(prog='PROG')
  parser.add_argument('--argX', action='store_true', help='Argument to main parser')

  # Create the sub-parser to top-level (main) parser
  sub_parsers = parser.add_subparsers(help='sub-command help')
  
  # ---------------------------------------------------------------------------
  # Create a parser for SUB-command "sub_cmd_1" 
  parser_sub_cmd_1 = sub_parsers.add_parser('sub_cmd_1', help='Sub-command 1')
  parser_sub_cmd_1.add_argument('--sub1', type=int, help='Argument: sub-cmd 1')
  
  # Create a sub-parser for SUB-command sub_cmd_1
  sc_1_sub_parsers = parser_sub_cmd_1.add_subparsers(help='Sub-sub-command help')
  
  # Create sub-commands to sub_cmd_1
  parser_sub_sub_c11 = sc_1_sub_parsers.add_parser('sub_sub_cmd_11', help='ssc 11')
  parser_sub_sub_c11.add_argument('-a11', action='store_const', const=True)
  
  parser_sub_sub_c12 = sc_1_sub_parsers.add_parser('sub_sub_cmd_12', help='ssc 12')
  parser_sub_sub_c12.add_argument('-a12', action='store_const', const=True)

  # ---------------------------------------------------------------------------
  # Create a parser for SUB-command "sub_cmd_2" 
  parser_sub_cmd_2 = sub_parsers.add_parser('sub_cmd_2', help='Sub-command 2')
  parser_sub_cmd_2.add_argument('--sub2', type=str, help='Argument: sub_cmd_2')

  # Create a sub-parser for SUB-command sub_cmd_2
  sc_2_sub_parsers = parser_sub_cmd_2.add_subparsers(help='Sub-sub-command help')
  
  # Create sub-commands to sub_cmd_2
  parser_sub_sub_c21 = sc_2_sub_parsers.add_parser('sub_sub_cmd_21', help='ssc 21')
  parser_sub_sub_c21.add_argument('-a21', action='store_const', const=True)
  
  parser_sub_sub_c22 = sc_2_sub_parsers.add_parser('sub_sub_cmd_22', help='ssc 22')
  parser_sub_sub_c22.add_argument('-a22', action='store_const', const=True)
  # ---------------------------------------------------------------------------
  
  args = parser.parse_args()
  
'''
python3 sub-parser.py -h
usage: PROG [-h] [--argX] {sub_cmd_1,sub_cmd_2} ...

positional arguments:
  {sub_cmd_1,sub_cmd_2}
                        sub-command help
    sub_cmd_1           Sub-command 1
    sub_cmd_2           Sub-command 2

optional arguments:
  -h, --help            show this help message and exit
  --argX                Argument to main parser

-------------------------------------------------------------------------------
python3 sub-parser.py sub_cmd_1 -h
usage: PROG sub_cmd_1 [-h] [--sub1 SUB1] {sub_sub_cmd_11,sub_sub_cmd_12} ...

positional arguments:
  {sub_sub_cmd_11,sub_sub_cmd_12}
                        Sub-sub-command help
    sub_sub_cmd_11      ssc 11
    sub_sub_cmd_12      ssc 12

optional arguments:
  -h, --help            show this help message and exit
  --sub1 SUB1           Argument: sub-cmd 1
------------------------------------------------------------------------------
python3 sub-parser.py sub_cmd_1 sub_sub_cmd_11 -h
usage: PROG sub_cmd_1 sub_sub_cmd_11 [-h] [-a11]

optional arguments:
  -h, --help  show this help message and exit
  -a11

'''