# Copyright (c) 2012-2013, Eucalyptus Systems, Inc.
#
# Permission to use, copy, modify, and/or distribute this software for
# any purpose with or without fee is hereby granted, provided that the
# above copyright notice and this permission notice appear in all copies.
#
# THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
# ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
# OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

from . import Arg
from .command import BaseCommand

class TabifyingCommand(BaseCommand):
    '''
    A request mixin that provides the tabify() function along with its
    associated --show-empty-fields command line arg.
    '''

    ARGS = [Arg('--show-empty-fields', action='store_true', route_to=None,
                help='show empty values as "(nil)"')]

    def tabify(self, fields, include=None):
        '''
        Join a list of strings with tabs.  Nonzero items that Python considers
        false are printed as-is if they appear in the include list, replaced
        with '(nil)' if the user specifies --show-empty-fields at the command
        line, and omitted otherwise.
        '''
        def allowable(item):
            return bool(item) or item is 0 or item in (include or [])

        if self.args['show_empty_fields']:
            fstr = '(nil)'
        else:
            fstr = ''
        return '\t'.join([str(f) if allowable(f) else fstr for f in fields])