#!/usr/local/sbin/charm-env python3
import os
from yaml import safe_load as load
from charmhelpers.core.hookenv import (
    action_get,
    action_set,
    action_fail,
    action_name
)
from charmhelpers.core.templating import render
from subprocess import check_output


os.environ['PATH'] += os.pathsep + os.path.join(os.sep, 'snap', 'bin')


def kubectl(args):
    cmd = ['kubectl'] + args
    return check_output(cmd)


def namespace_list():
    y = load(kubectl(['get', 'namespaces', '-o', 'yaml']))
    ns = [i['metadata']['name'] for i in y['items']]
    action_set({'namespaces': ', '.join(ns)+'.'})
    return ns


def namespace_create():
    name = action_get('name')
    if name in namespace_list():
        action_fail('Namespace "{}" already exists.'.format(name))
        return

    render('create-namespace.yaml.j2', '/etc/kubernetes/addons/create-namespace.yaml',
           context={'name': name})
    kubectl(['create', '-f', '/etc/kubernetes/addons/create-namespace.yaml'])
    action_set({'msg': 'Namespace "{}" created.'.format(name)})


def namespace_delete():
    name = action_get('name')
    if name in ['default', 'kube-system']:
        action_fail('Not allowed to delete "{}".'.format(name))
        return
    if name not in namespace_list():
        action_fail('Namespace "{}" does not exist.'.format(name))
        return
    kubectl(['delete', 'ns/'+name])
    action_set({'msg': 'Namespace "{}" deleted.'.format(name)})


action = action_name().replace('namespace-', '')
if action == 'create':
    namespace_create()
elif action == 'list':
    namespace_list()
elif action == 'delete':
    namespace_delete()