#!/usr/bin/python

from charmhelpers.core import hookenv
from charms.reactive import Endpoint
from charms.reactive import toggle_flag, is_flag_set, clear_flag, set_flag


class CNIPluginProvider(Endpoint):
    def manage_flags(self):
        toggle_flag(self.expand_name('{endpoint_name}.connected'),
                    self.is_joined)
        toggle_flag(self.expand_name('{endpoint_name}.available'),
                    self.config_available())
        if is_flag_set(self.expand_name('endpoint.{endpoint_name}.changed')):
            clear_flag(self.expand_name('{endpoint_name}.configured'))
            clear_flag(self.expand_name('endpoint.{endpoint_name}.changed'))

    def set_config(self, is_master, kubeconfig_path):
        ''' Relays a dict of kubernetes configuration information. '''
        for relation in self.relations:
            relation.to_publish_raw.update({
                'is_master': is_master,
                'kubeconfig_path': kubeconfig_path
            })
        set_flag(self.expand_name('{endpoint_name}.configured'))

    def config_available(self):
        ''' Ensures all config from the CNI plugin is available. '''
        goal_state = hookenv.goal_state()
        related_apps = [
            app for app in goal_state.get('relations', {}).get(self.endpoint_name, '')
            if '/' not in app
        ]
        if not related_apps:
            return False
        configs = self.get_configs()
        return all(
            'cidr' in config and 'cni-conf-file' in config
            for config in [
                configs.get(related_app, {}) for related_app in related_apps
            ]
        )

    def get_config(self, default=None):
        ''' Get CNI config for one related application.

        If default is specified, and there is a related application with a
        matching name, then that application is chosen. Otherwise, the
        application is chosen alphabetically.

        Whichever application is chosen, that application's CNI config is
        returned.
        '''
        configs = self.get_configs()
        if not configs:
            return {}
        elif default and default not in configs:
            msg = 'relation not found for default CNI %s, ignoring' % default
            hookenv.log(msg, level='WARN')
            return self.get_config()
        elif default:
            return configs.get(default, {})
        else:
            return configs.get(sorted(configs)[0], {})

    def get_configs(self):
        ''' Get CNI configs for all related applications.

        This returns a mapping of application names to CNI configs. Here's an
        example return value:
        {
            'flannel': {
                'cidr': '10.1.0.0/16',
                'cni-conf-file': '10-flannel.conflist'
            },
            'calico': {
                'cidr': '192.168.0.0/16',
                'cni-conf-file': '10-calico.conflist'
            }
        }
        '''
        return {
            relation.application_name: relation.joined_units.received_raw
            for relation in self.relations if relation.application_name
        }