# Source code for certbot_dns_route53.dns_route53

    """Certbot Route53 authenticator plugin."""
    import collections
    import logging
    import time

    import boto3
    import zope.interface
    from botocore.exceptions import NoCredentialsError, ClientError

    from certbot import errors
    from certbot import interfaces
    from certbot.plugins import dns_common

    logger = logging.getLogger(__name__)

    INSTRUCTIONS = (
        "To use certbot-dns-route53, configure credentials as described at "
        "https://boto3.readthedocs.io/en/latest/guide/configuration.html#best-practices-for-configuring-credentials "  # pylint: disable=line-too-long
        "and add the necessary permissions for Route53 access.")

    @zope.interface.implementer(interfaces.IAuthenticator)
    @zope.interface.provider(interfaces.IPluginFactory)
    class Authenticator(dns_common.DNSAuthenticator):
        """Route53 Authenticator

        This authenticator solves a DNS01 challenge by uploading the answer to AWS
        Route53.
        """

        description = ("Obtain certificates using a DNS TXT record (if you are using AWS Route53 for "
                       "DNS).")
        ttl = 10

        def __init__(self, *args, **kwargs):
            super(Authenticator, self).__init__(*args, **kwargs)
            self.r53 = boto3.client("route53")
            self._resource_records = collections.defaultdict(list)

        def more_info(self):  # pylint: disable=missing-docstring,no-self-use
            return "Solve a DNS01 challenge using AWS Route53"

        def _setup_credentials(self):
            pass

        def _perform(self, domain, validation_domain_name, validation):
            try:
                change_id = self._change_txt_record("UPSERT", validation_domain_name, validation)

                self._wait_for_change(change_id)
            except (NoCredentialsError, ClientError) as e:
                logger.debug('Encountered error during perform: %s', e, exc_info=True)
                raise errors.PluginError("\n".join([str(e), INSTRUCTIONS]))

        def _cleanup(self, domain, validation_domain_name, validation):
            try:
                self._change_txt_record("DELETE", validation_domain_name, validation)
            except (NoCredentialsError, ClientError) as e:
                logger.debug('Encountered error during cleanup: %s', e, exc_info=True)

        def _find_zone_id_for_domain(self, domain):
            """Find the zone id responsible a given FQDN.

               That is, the id for the zone whose name is the longest parent of the
               domain.
            """
            paginator = self.r53.get_paginator("list_hosted_zones")
            zones = []
            target_labels = domain.rstrip(".").split(".")
            for page in paginator.paginate():
                for zone in page["HostedZones"]:
                    if zone["Config"]["PrivateZone"]:
                        continue

                    candidate_labels = zone["Name"].rstrip(".").split(".")
                    if candidate_labels == target_labels[-len(candidate_labels):]:
                        zones.append((zone["Name"], zone["Id"]))

            if not zones:
                raise errors.PluginError(
                    "Unable to find a Route53 hosted zone for {0}".format(domain)
                )

            # Order the zones that are suffixes for our desired to domain by
            # length, this puts them in an order like:
            # ["foo.bar.baz.com", "bar.baz.com", "baz.com", "com"]
            # And then we choose the first one, which will be the most specific.
            zones.sort(key=lambda z: len(z[0]), reverse=True)
            return zones[0][1]

        def _change_txt_record(self, action, validation_domain_name, validation):
            zone_id = self._find_zone_id_for_domain(validation_domain_name)

            rrecords = self._resource_records[validation_domain_name]
            challenge = {"Value": '"{0}"'.format(validation)}
            if action == "DELETE":
                # Remove the record being deleted from the list of tracked records
                rrecords.remove(challenge)
                if rrecords:
                    # Need to update instead, as we're not deleting the rrset
                    action = "UPSERT"
                else:
                    # Create a new list containing the record to use with DELETE
                    rrecords = [challenge]
            else:
                rrecords.append(challenge)

            response = self.r53.change_resource_record_sets(
                HostedZoneId=zone_id,
                ChangeBatch={
                    "Comment": "certbot-dns-route53 certificate validation " + action,
                    "Changes": [
                        {
                            "Action": action,
                            "ResourceRecordSet": {
                                "Name": validation_domain_name,
                                "Type": "TXT",
                                "TTL": self.ttl,
                                "ResourceRecords": rrecords,
                            }
                        }
                    ]
                }
            )
            return response["ChangeInfo"]["Id"]

        def _wait_for_change(self, change_id):
            """Wait for a change to be propagated to all Route53 DNS servers.
               https://docs.aws.amazon.com/Route53/latest/APIReference/API_GetChange.html
            """
            for unused_n in range(0, 120):
                response = self.r53.get_change(Id=change_id)
                if response["ChangeInfo"]["Status"] == "INSYNC":
                    return
                time.sleep(5)
            raise errors.PluginError(
                "Timed out waiting for Route53 change. Current status: %s" %
                response["ChangeInfo"]["Status"])