Add tab-completion for paths

[ulken]

Supported commands: all commands accepting a path argument (ls, rm, mv, edit, show).

Caveats
Completions must match exact structure of paths. As a result, it doesn't:

• support db-prefixes
• support case-insensitivty
• support regexes

Additional changes

• Add login command (for explicit caching, when zenity is missing)
• Remove extra '' around form label in zenity
• Remove period from error message
• Fix incorrect name being passed to default section prompt
• Handle more cases in decompose_path + return tuple
• Fix info_parser comment

Closes #44

[ulken]

@Evidlo I've yet to update the documentation with how to set it up, but please have a look/try it out. I'll update the docs when we've settled on something.

[ulken]

In the meantime, if you're not familiar with argcomplete, have a look at the docs how to set things up: argcomplete - Bash tab completion for argparse

[Evidlo]

I did some experimentation with prompting for the password during the completion to eliminate the need for login().

ph_complete

#!/bin/env python3

from getpass import getpass
import argcomplete, argparse

def path_completer(prefix, parsed_args, **kwargs):
    password = getpass('\nInput Password:')

    if password == 'password':
        return ['helloworld', 'foobar']

parser = argparse.ArgumentParser()

patharg = parser.add_argument('path', metavar='PATH', type=str, help='item path')
patharg.completer = path_completer

argcomplete.autocomplete(parser)
args = parser.parse_args()
print(f'selected item: {args.path}')

And for testing:

chmod +x ph_complete
eval "$(register-python-argcomplete ./ph_complete)"

It's not fully working, as you have to hit enter twice for some reason after entering a password and the prompt line isn't redrawn when the completion is finished. Also, argcomplete hijacks stdout so I had to abuse argcomplete.warn() for the password prompt. We could probably do some digging around and make a patched version of the argcomplete class that doesn't do this.

Ideally, tab completion when entering a password would look something like this:

$ ./ph_complete hello[TAB]
Input password:
$ ./ph_complete helloworld