from charms.reactive import Endpoint
from charmhelpers.core import hookenv
from charms.reactive.flags import toggle_flag


'''
This interface is desiged to be compatible with a previous
implementation based on RelationBase.

Specifically
- the `{endpoint_name}.available` flags
- the use of `to_publish_raw` to avoid double quoting of the values
  as the old interface used plain values here
'''


class PrometheusProvides(Endpoint):
    def manage_flags(self):
        """
        Managing the available flag.
        """
        toggle_flag(self.expand_name('endpoint.{endpoint_name}.available'),
                    self.is_joined)
        # compatibility
        toggle_flag(self.expand_name('{endpoint_name}.available'),
                    self.is_joined)

    def configure(self, port, path='/metrics',
                  scrape_interval=None, scrape_timeout=None, labels={},
                  hostname=None):
        """
        Interface method to set information provided to remote units
        """

        # Use our unit name if the label isn't provided
        if labels.get('host') is None:
            unit_name = hookenv.local_unit()
            labels['host'] = unit_name.replace("/", "-")

        for relation in self.relations:
            relation.to_publish_raw['hostname'] = hookenv.ingress_address(
                relation.relation_id, hookenv.local_unit()
            ) if hostname is None else hostname

            relation.to_publish_raw['port'] = port
            relation.to_publish_raw['metrics_path'] = path
            relation.to_publish['labels'] = labels
            if scrape_interval is not None:
                relation.to_publish_raw['scrape_interval'] = scrape_interval
            if scrape_timeout is not None:
                relation.to_publish_raw['scrape_timeout'] = scrape_timeout