# -*- coding: utf-8 -*-
'''
State module for Cisco NSO Proxy minions

.. versionadded: 2016.11.0

For documentation on setting up the cisconso proxy minion look in the documentation
for :mod:`salt.proxy.cisconso <salt.proxy.cisconso>`.
'''

# Import Python libs
from __future__ import absolute_import, print_function, unicode_literals

# Import Salt libs
import salt.utils.compat


def __virtual__():
    return 'cisconso.set_data_value' in __salt__


def value_present(name, datastore, path, config):
    '''
    Ensure a specific value exists at a given path

    :param name: The name for this rule
    :type  name: ``str``

    :param datastore: The datastore, e.g. running, operational.
        One of the NETCONF store IETF types
    :type  datastore: :class:`DatastoreType` (``str`` enum).

    :param path: The device path to set the value at,
        a list of element names in order, / separated
    :type  path: ``list``, ``str`` OR ``tuple``

    :param config: The new value at the given path
    :type  config: ``dict``

    Examples:

    .. code-block:: yaml

        enable pap auth:
          cisconso.config_present:
            - name: enable_pap_auth
            - datastore: running
            - path: devices/device/ex0/config/sys/interfaces/serial/ppp0/authentication
            - config:
                authentication:
                    method: pap
                    "list-name": foobar

    '''
    ret = {'name': name,
           'result': False,
           'changes': {},
           'comment': ''}

    existing = __salt__['cisconso.get_data'](datastore, path)

    if salt.utils.compat.cmp(existing, config):
        ret['result'] = True
        ret['comment'] = 'Config is already set'

    elif __opts__['test'] is True:
        ret['result'] = None
        ret['comment'] = 'Config will be added'
        diff = _DictDiffer(existing, config)
        ret['changes']['new'] = diff.added()
        ret['changes']['removed'] = diff.removed()
        ret['changes']['changed'] = diff.changed()

    else:
        __salt__['cisconso.set_data_value'](datastore, path, config)
        ret['result'] = True
        ret['comment'] = 'Successfully added config'
        diff = _DictDiffer(existing, config)
        ret['changes']['new'] = diff.added()
        ret['changes']['removed'] = diff.removed()
        ret['changes']['changed'] = diff.changed()

    return ret


class _DictDiffer(object):
    '''
    Calculate the difference between two dictionaries as:
    (1) items added
    (2) items removed
    (3) keys same in both but changed values
    (4) keys same in both and unchanged values
    '''
    def __init__(self, current_dict, past_dict):
        self.current_dict, self.past_dict = current_dict, past_dict
        self.set_current, self.set_past = set(current_dict.keys()), set(past_dict.keys())
        self.intersect = self.set_current.intersection(self.set_past)

    def added(self):
        return self.set_current - self.intersect

    def removed(self):
        return self.set_past - self.intersect

    def changed(self):
        return set(o for o in self.intersect if self.past_dict[o] != self.current_dict[o])

    def unchanged(self):
        return set(o for o in self.intersect if self.past_dict[o] == self.current_dict[o])
