# Copyright 2022 Canonical Ltd.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
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"""Base classes for defining OVN relation handlers."""

import ipaddress
import itertools
import logging

from typing import Callable, Dict, Iterator, List

import ops.charm
import ops.framework

from .. import relation_handlers as sunbeam_rhandlers

logger = logging.getLogger(__name__)


class OVNRelationUtils():
    """Common utilities for processing OVN relations."""

    DB_NB_PORT = 6641
    DB_SB_PORT = 6642
    DB_SB_ADMIN_PORT = 16642
    DB_NB_CLUSTER_PORT = 6643
    DB_SB_CLUSTER_PORT = 6644

    def _format_addr(self, addr: str) -> str:
        """Validate and format IP address.

        :param addr: IPv6 or IPv4 address
        :type addr: str
        :returns: Address string, optionally encapsulated in brackets ([])
        :rtype: str
        :raises: ValueError
        """
        ipaddr = ipaddress.ip_address(addr)
        if isinstance(ipaddr, ipaddress.IPv6Address):
            fmt = '[{}]'
        else:
            fmt = '{}'
        return fmt.format(ipaddr)

    def _remote_addrs(self, key: str) -> Iterator[str]:
        """Retrieve addresses published by remote units.

        :param key: Relation data key to retrieve value from.
        :type key: str
        :returns: IPv4 or IPv6 addresses published by remote units.
        :rtype: Iterator[str]
        """
        for addr in self.interface.get_all_unit_values(key):
            try:
                addr = self._format_addr(addr)
                yield addr
            except ValueError:
                continue

    @property
    def cluster_remote_addrs(self) -> Iterator[str]:
        """Retrieve remote addresses bound to remote endpoint.

        :returns: IPv4 or IPv6 addresses bound to remote endpoints.
        :rtype: Iterator[str]
        """
        return self._remote_addrs('bound-address')

    def db_connection_strs(
            self,
            addrs: List[ipaddress.IPv4Address],
            port: int,
            proto: str = 'ssl') -> Iterator[str]:
        """Provide connection strings.

        :param addrs: List of addresses to include in conn strs
        :type addrs: List[ipaddress.IPv4Address]
        :param port: Port number
        :type port: int
        :param proto: Protocol
        :type proto: str
        :returns: connection strings
        :rtype: Iterator[str]
        """
        for addr in addrs:
            yield ':'.join((proto, str(addr), str(port)))

    @property
    def db_nb_port(self) -> int:
        """Provide port number for OVN Northbound OVSDB.

        :returns: port number for OVN Northbound OVSDB.
        :rtype: int
        """
        return self.DB_NB_PORT

    @property
    def db_sb_port(self) -> int:
        """Provide port number for OVN Southbound OVSDB.

        :returns: port number for OVN Southbound OVSDB.
        :rtype: int
        """
        return self.DB_SB_PORT

    @property
    def db_sb_admin_port(self) -> int:
        """Provide admin port number for OVN Southbound OVSDB.

        This is a special listener to allow ``ovn-northd`` to connect to an
        endpoint without RBAC enabled as there is currently no RBAC profile
        allowing ``ovn-northd`` to perform its work.

        :returns: admin port number for OVN Southbound OVSDB.
        :rtype: int
        """
        return self.DB_SB_ADMIN_PORT

    @property
    def db_nb_cluster_port(self) -> int:
        """Provide port number for OVN Northbound OVSDB.

        :returns port number for OVN Northbound OVSDB.
        :rtype: int
        """
        return self.DB_NB_CLUSTER_PORT

    @property
    def db_sb_cluster_port(self) -> int:
        """Provide port number for OVN Southbound OVSDB.

        :returns: port number for OVN Southbound OVSDB.
        :rtype: int
        """
        return self.DB_SB_CLUSTER_PORT

    @property
    def db_nb_connection_strs(self) -> Iterator[str]:
        """Provide OVN Northbound OVSDB connection strings.

        :returns: OVN Northbound OVSDB connection strings.
        :rtpye: Iterator[str]
        """
        return self.db_connection_strs(self.cluster_remote_addrs,
                                       self.db_nb_port)

    @property
    def db_sb_connection_strs(self) -> Iterator[str]:
        """Provide OVN Southbound OVSDB connection strings.

        :returns: OVN Southbound OVSDB connection strings.
        :rtpye: Iterator[str]
        """
        return self.db_connection_strs(self.cluster_remote_addrs,
                                       self.db_sb_port)

    @property
    def cluster_local_addr(self) -> ipaddress.IPv4Address:
        """Retrieve local address bound to endpoint.

        :returns: IPv4 or IPv6 address bound to endpoint
        :rtype: str
        """
        return self._endpoint_local_bound_addr()

    def _endpoint_local_bound_addr(self) -> ipaddress.IPv4Address:
        """Retrieve local address bound to endpoint.

        :returns: IPv4 or IPv6 address bound to endpoint
        :rtype: str
        """
        addr = None
        for relation in self.charm.model.relations.get(self.relation_name, []):
            binding = self.charm.model.get_binding(relation)
            addr = binding.network.bind_address
            break
        return addr


class OVNDBClusterPeerHandler(sunbeam_rhandlers.BasePeerHandler,
                              OVNRelationUtils):
    """Handle OVN peer relation."""

    def publish_cluster_local_addr(
            self,
            addr: ipaddress.IPv4Address = None) -> Dict:
        """Announce address on relation.

        This will be used by our peers and clients to build a connection
        string to the remote cluster.

        :param addr: Override address to announce.
        :type addr: Optional[str]
        """
        _addr = addr or self.cluster_local_addr
        if _addr:
            self.interface.set_unit_data({'bound-address': str(_addr)})

    def expected_peers_available(self) -> bool:
        """Whether expected peers have joined and published data on peer rel.

        NOTE: This does not work for the normal inter-charm relations, please
              refer separate method for that in the shared interface library.

        :returns: True if expected peers have joined and published data,
                  False otherwise.
        :rtype: bool
        """
        joined_units = self.interface.all_joined_units()
        # Remove this unit from expected_peer_units count
        expected_remote_units = self.interface.expected_peer_units() - 1
        if len(joined_units) < expected_remote_units:
            logging.debug(
                f"Expected {expected_remote_units} but only {joined_units} "
                "have joined so far")
            return False
        addresses = self.interface.get_all_unit_values('bound-address')
        if all(addresses) < expected_remote_units:
            logging.debug(
                "Not all units have published a bound-address. Current "
                f"address list: {addresses}")
            return False
        else:
            logging.debug(
                f"All expected peers are present. Addresses: {addresses}")
            return True

    @property
    def db_nb_connection_strs(self) -> Iterator[str]:
        """Provide Northbound DB connection strings.

        We override the parent property because for the peer relation
        ``cluster_remote_addrs`` does not contain self.

        :returns: Northbound DB connection strings
        :rtype: Iterator[str]
        """
        return itertools.chain(
            self.db_connection_strs((self.cluster_local_addr,),
                                    self.db_nb_port),
            self.db_connection_strs(self.cluster_remote_addrs,
                                    self.db_nb_port))

    @property
    def db_nb_cluster_connection_strs(self) -> Iterator[str]:
        """Provide Northbound DB Cluster connection strings.

        We override the parent property because for the peer relation
        ``cluster_remote_addrs`` does not contain self.

        :returns: Northbound DB connection strings
        :rtype: Iterator[str]
        """
        return itertools.chain(
            self.db_connection_strs((self.cluster_local_addr,),
                                    self.db_nb_cluster_port),
            self.db_connection_strs(self.cluster_remote_addrs,
                                    self.db_nb_cluster_port))

    @property
    def db_sb_cluster_connection_strs(self) -> Iterator[str]:
        """Provide Southbound DB Cluster connection strings.

        We override the parent property because for the peer relation
        ``cluster_remote_addrs`` does not contain self.

        :returns: Southbound DB connection strings
        :rtype: Iterator[str]
        """
        return itertools.chain(
            self.db_connection_strs((self.cluster_local_addr,),
                                    self.db_sb_cluster_port),
            self.db_connection_strs(self.cluster_remote_addrs,
                                    self.db_sb_cluster_port))

    @property
    def db_sb_connection_strs(self) -> Iterator[str]:
        """Provide Southbound DB connection strings.

        We override the parent property because for the peer relation
        ``cluster_remote_addrs`` does not contain self.  We use a different
        port for connecting to the SB DB as there is currently no RBAC profile
        that provide the privileges ``ovn-northd`` requires to operate.

        :returns: Southbound DB connection strings
        :rtype: Iterator[str]
        """
        return itertools.chain(
            self.db_connection_strs((self.cluster_local_addr,),
                                    self.db_sb_admin_port),
            self.db_connection_strs(self.cluster_remote_addrs,
                                    self.db_sb_admin_port))

    def _on_peers_relation_joined(
            self, event: ops.framework.EventBase) -> None:
        """Process peer joined event."""
        self.publish_cluster_local_addr()

    def context(self) -> dict:
        """Context from relation data."""
        ctxt = super().context()
        ctxt.update({
            'cluster_local_addr': self.cluster_local_addr,
            'cluster_remote_addrs': self.cluster_remote_addrs,
            'db_nb_cluster_connection_strs':
                self.db_nb_cluster_connection_strs,
            'db_sb_cluster_connection_strs':
                self.db_sb_cluster_connection_strs,
            'db_sb_cluster_port': self.db_sb_cluster_port,
            'db_nb_cluster_port': self.db_nb_cluster_port,
            'db_nb_connection_strs': list(self.db_nb_connection_strs),
            'db_sb_connection_strs': list(self.db_sb_connection_strs)})
        return ctxt


class OVSDBCMSProvidesHandler(sunbeam_rhandlers.RelationHandler,
                              OVNRelationUtils):
    """Handle provides side of ovsdb-cms."""

    def __init__(
        self,
        charm: ops.charm.CharmBase,
        relation_name: str,
        callback_f: Callable,
        mandatory: bool = False,
    ) -> None:
        """Run constructor."""
        super().__init__(charm, relation_name, callback_f, mandatory)

    def setup_event_handler(self) -> ops.charm.Object:
        """Configure event handlers for an Identity service relation."""
        # Lazy import to ensure this lib is only required if the charm
        # has this relation.
        logger.debug("Setting up ovs-cms provides event handler")
        import charms.sunbeam_ovn_central_operator.v0.ovsdb as ovsdb
        ovsdb_svc = ovsdb.OVSDBCMSProvides(
            self.charm,
            self.relation_name,
        )
        self.framework.observe(
            ovsdb_svc.on.ready,
            self._on_ovsdb_service_ready)
        return ovsdb_svc

    def _on_ovsdb_service_ready(self, event: ops.framework.EventBase) -> None:
        """Handle OVSDB CMS change events."""
        # Ready is only emitted when the interface considers
        # that the relation is complete (indicated by a password)
        # _addr = addr or self.cluster_local_addr
        self.interface.set_unit_data(
            {
                'bound-address': str(self.cluster_local_addr)})
        self.callback_f(event)

    @property
    def ready(self) -> bool:
        """Whether the interface is ready."""
        return True


class OVSDBCMSRequiresHandler(sunbeam_rhandlers.RelationHandler,
                              OVNRelationUtils):
    """Handle provides side of ovsdb-cms."""

    def __init__(
        self,
        charm: ops.charm.CharmBase,
        relation_name: str,
        callback_f: Callable,
        mandatory: bool = False,
    ) -> None:
        """Run constructor."""
        super().__init__(charm, relation_name, callback_f, mandatory)

    def setup_event_handler(self) -> ops.charm.Object:
        """Configure event handlers for an Identity service relation."""
        # Lazy import to ensure this lib is only required if the charm
        # has this relation.
        logger.debug("Setting up ovs-cms requires event handler")
        import charms.sunbeam_ovn_central_operator.v0.ovsdb as ovsdb
        ovsdb_svc = ovsdb.OVSDBCMSRequires(
            self.charm,
            self.relation_name,
        )
        self.framework.observe(
            ovsdb_svc.on.ready,
            self._on_ovsdb_service_ready)
        return ovsdb_svc

    def _on_ovsdb_service_ready(self, event: ops.framework.EventBase) -> None:
        """Handle OVSDB CMS change events."""
        self.callback_f(event)

    @property
    def ready(self) -> bool:
        """Whether the interface is ready."""
        return self.interface.remote_ready()

    def context(self) -> dict:
        """Context from relation data."""
        ctxt = super().context()
        ctxt.update({
            'local_address': self._endpoint_local_bound_addr(),
            'addresses': self.interface.bound_addresses(),
            'db_sb_connection_strs': ','.join(self.db_sb_connection_strs),
            'db_nb_connection_strs': ','.join(self.db_nb_connection_strs)})

        return ctxt