
# Copyright 2017-present Open Networking Foundation
#
# 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,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.


from helpers import AttHelpers
from xossynchronizer.model_policies.policy import Policy

import os
import sys

sync_path = os.path.abspath(os.path.join(os.path.dirname(os.path.realpath(__file__)), ".."))
sys.path.append(sync_path)


class DeferredException(Exception):
    pass


class AttWorkflowDriverServiceInstancePolicy(Policy):
    model_name = "AttWorkflowDriverServiceInstance"

    def handle_create(self, si):
        self.logger.debug("MODEL_POLICY: handle_create for AttWorkflowDriverServiceInstance %s " % si.id)
        self.handle_update(si)

    def handle_update(self, si):
        self.logger.debug("MODEL_POLICY: handle_update for AttWorkflowDriverServiceInstance %s " %
                          (si.id), onu_state=si.admin_onu_state, authentication_state=si.authentication_state)

        # Changing ONU state can change auth state
        # Changing auth state can change DHCP state
        # So need to process in this order
        self.process_onu_state(si)
        self.process_auth_state(si)
        self.process_dhcp_state(si)

        self.validate_states(si)

        # handling the subscriber status
        # It's a combination of all the other states
        subscriber = self.get_subscriber(si.serial_number)
        if subscriber:
            self.update_subscriber(subscriber, si)

        si.save_changed_fields()

    # Check the whitelist to see if the ONU is valid.  If it is, make sure that it's enabled.
    def process_onu_state(self, si):
        [valid, message] = AttHelpers.validate_onu(self.model_accessor, self.logger, si)
        si.status_message = message
        if valid:
            si.admin_onu_state = "ENABLED"
            self.update_onu(si.serial_number, "ENABLED")
        else:
            si.admin_onu_state = "DISABLED"
            self.update_onu(si.serial_number, "DISABLED")

    # If the ONU has been disabled then we force re-authentication when it
    # is re-enabled.
    # Setting si.authentication_state = AWAITING:
    #   -> subscriber status = "awaiting_auth"
    #   -> service chain deleted
    #   -> need authentication to restore connectivity after ONU enabled
    def process_auth_state(self, si):
        auth_msgs = {
            "AWAITING": " - Awaiting Authentication",
            "REQUESTED": " - Authentication requested",
            "STARTED": " - Authentication started",
            "APPROVED": " - Authentication succeeded",
            "DENIED": " - Authentication denied"
        }
        if si.admin_onu_state == "DISABLED" or si.oper_onu_status == "DISABLED":
            si.authentication_state = "AWAITING"
        else:
            si.status_message += auth_msgs[si.authentication_state]

    # The DhcpL2Relay ONOS app generates events that update the fields below.
    # It only sends events when it processes DHCP packets.  It keeps no internal state.
    # We reset dhcp_state when:
    # si.authentication_state in ["AWAITING", "REQUESTED", "STARTED"]
    #   -> subscriber status = "awaiting_auth"
    #   -> service chain not present
    #   -> subscriber's OLT flow rules, xconnect not present
    #   -> DHCP packets won't go through
    # Note, however, that the DHCP state at the endpoints is not changed.
    # A previously issued DHCP lease may still be valid.
    def process_dhcp_state(self, si):
        if si.authentication_state in ["AWAITING", "REQUESTED", "STARTED"]:
            si.ip_address = ""
            si.mac_address = ""
            si.dhcp_state = "AWAITING"

    # Make sure the object is in a legitimate state
    # It should be after the above processing steps
    # However this might still fail if an event has fired in the meantime
    # Valid states:
    # ONU       | Auth     | DHCP
    # ===============================
    # AWAITING  | AWAITING | AWAITING
    # ENABLED   | *        | AWAITING
    # ENABLED   | APPROVED | *
    # DISABLED  | AWAITING | AWAITING
    def validate_states(self, si):
        if (si.admin_onu_state == "AWAITING" or si.admin_onu_state ==
                "DISABLED") and si.authentication_state == "AWAITING" and si.dhcp_state == "AWAITING":
            return
        if si.admin_onu_state == "ENABLED" and (si.authentication_state == "APPROVED" or si.dhcp_state == "AWAITING"):
            return
        self.logger.warning(
            "MODEL_POLICY (validate_states): invalid state combination",
            onu_state=si.admin_onu_state,
            auth_state=si.authentication_state,
            dhcp_state=si.dhcp_state)

    def update_onu(self, serial_number, admin_state):
        onu = [onu for onu in self.model_accessor.ONUDevice.objects.all() if onu.serial_number.lower()
               == serial_number.lower()][0]
        if onu.admin_state == admin_state:
            self.logger.debug(
                "MODEL_POLICY: ONUDevice [%s] already has admin_state to %s" %
                (serial_number, admin_state))
        else:
            self.logger.debug("MODEL_POLICY: setting ONUDevice [%s] admin_state to %s" % (serial_number, admin_state))
            onu.admin_state = admin_state
            onu.save_changed_fields(always_update_timestamp=True)

    def get_subscriber(self, serial_number):
        try:
            return [s for s in self.model_accessor.RCORDSubscriber.objects.all() if s.onu_device.lower()
                    == serial_number.lower()][0]
        except IndexError:
            # If the subscriber doesn't exist we don't do anything
            self.logger.debug(
                "MODEL_POLICY: subscriber does not exists for this SI, doing nothing",
                onu_device=serial_number)
            return None

    def update_subscriber_ip(self, subscriber, ip):
        # TODO check if the subscriber has an IP and update it,
        # or create a new one
        try:
            ip = self.model_accessor.RCORDIpAddress.objects.filter(
                subscriber_id=subscriber.id,
                ip=ip
            )[0]
            self.logger.debug("MODEL_POLICY: found existing RCORDIpAddress for subscriber",
                              onu_device=subscriber.onu_device, subscriber_status=subscriber.status, ip=ip)
            ip.save_changed_fields()
        except IndexError:
            self.logger.debug(
                "MODEL_POLICY: Creating new RCORDIpAddress for subscriber",
                onu_device=subscriber.onu_device,
                subscriber_status=subscriber.status,
                ip=ip)
            ip = self.model_accessor.RCORDIpAddress(
                subscriber_id=subscriber.id,
                ip=ip,
                description="DHCP Assigned IP Address"
            )
            ip.save()

    def delete_subscriber_ip(self, subscriber, ip):
        try:
            ip = self.model_accessor.RCORDIpAddress.objects.filter(
                subscriber_id=subscriber.id,
                ip=ip
            )[0]
            self.logger.debug(
                "MODEL_POLICY: delete RCORDIpAddress for subscriber",
                onu_device=subscriber.onu_device,
                subscriber_status=subscriber.status,
                ip=ip)
            ip.delete()
        except BaseException:
            self.logger.warning("MODEL_POLICY: no RCORDIpAddress object found, cannot delete", ip=ip)

    def update_subscriber(self, subscriber, si):
        cur_status = subscriber.status
        # Don't change state if someone has disabled the subscriber
        if subscriber.status != "disabled":
            if si.authentication_state in ["AWAITING", "REQUESTED", "STARTED"]:
                subscriber.status = "awaiting-auth"
            elif si.authentication_state == "APPROVED":
                subscriber.status = "enabled"
            elif si.authentication_state == "DENIED":
                subscriber.status = "auth-failed"

        # NOTE we save the subscriber only if:
        # - the status has changed
        # - we get a DHCPACK event
        if cur_status != subscriber.status or si.dhcp_state == "DHCPACK":
            self.logger.debug(
                "MODEL_POLICY: updating subscriber",
                onu_device=subscriber.onu_device,
                authentication_state=si.authentication_state,
                subscriber_status=subscriber.status)
            if subscriber.status == "awaiting-auth":
                self.delete_subscriber_ip(subscriber, si.ip_address)
                subscriber.mac_address = ""
            elif si.ip_address and si.mac_address:
                self.update_subscriber_ip(subscriber, si.ip_address)
                subscriber.mac_address = si.mac_address
            subscriber.save_changed_fields(always_update_timestamp=True)
        else:
            self.logger.debug("MODEL_POLICY: subscriber status has not changed", onu_device=subscriber.onu_device,
                              authentication_state=si.authentication_state, subscriber_status=subscriber.status)

    def handle_delete(self, si):
        pass