#!/usr/bin/env python2
# Copyright 2015  Lars Wirzenius
#
# 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, see <http://www.gnu.org/licenses/>.
#
# =*= License: GPL-3+ =*=


'''Add things to a YAML file.

Read an object from a YAML file. The object must be a dictionary. Add
a new value to the dictionary, or a sub-dictionary. Save the object
back to its original file.

Example:

    echo '{}' > foo.ick
    yaml-add foo.ick key1 key2 value

This would result in:

    key1:
        key2: value

If there is already a value, the value is made into a list and the new
value appended to the list. If the value is already a list, the value
is appended to the list.

'''


import sys

import yaml


if len(sys.argv) < 4:
    sys.stderr.write('too few args\n')
    sys.exit(1)


with open(sys.argv[1]) as f:
    obj = yaml.safe_load(f)


keys = sys.argv[2:-1]
value = sys.argv[-1]
print keys
print value

thing = obj
for key in keys[:-1]:
    if key not in thing:
        thing[key] = {}
    thing = thing[key]

key = keys[-1]
old_value = thing.get(key)
if old_value is None:
    thing[key] = value
elif type(old_value) is list:
    old_value.append(value)
else:
    thing[key] = [old_value, value]

with open(sys.argv[1], 'w') as f:
    yaml.safe_dump(obj, stream=f, default_flow_style=False, indent=4)