# SPDX-FileCopyrightText: 2020 The Magma Authors.
# SPDX-FileCopyrightText: 2022 Open Networking Foundation <support@opennetworking.org>
#
# SPDX-License-Identifier: BSD-3-Clause

from logger import EnodebdLogger as logger
from state_machines.enb_acs_manager import StateMachineManager
from spyne.decorator import rpc
from spyne.model.complex import ComplexModelBase
from spyne.server.wsgi import WsgiMethodContext
from spyne.service import ServiceBase

from . import models

# Allow methods without 'self' as first input. Required by spyne
# pylint: disable=no-self-argument

# RPC methods supported by ACS
RPC_METHODS = ['Inform', 'GetRPCMethods', 'TransferComplete']
RPC_RESPONSES = [method + 'Response' for method in RPC_METHODS]
# RPC methods supported by CPE
CPE_RPC_METHODS = [
    'SetParameterValues',
    'GetParameterValues',
    'GetParameterNames',
    'SetParameterAttributes',
    'GetParameterAttributes',
    'AddObject',
    'DeleteObject',
    'Download',
    'Reboot',
]
CPE_RPC_RESPONSES = [method + 'Response' for method in CPE_RPC_METHODS]
# ACS RPC methods that are not explicitly described by the spec (hence shouldn't
# be advertised by GetRPCMethods). Note: No responses for these
PSEUDO_RPC_METHODS = ['Fault']
# Top-level CWMP header elements. Namespaces should be preserved on these (since
# they are not within other CWMP elements)
TOP_LEVEL_HEADER_ELEMENTS = ['ID', 'HoldRequests']


def fill_response_header(ctx):
    """ Echo message ID from input header to output header, when responding to
        CPE->ACS RPC calls """
    ctx.out_header = models.ID(mustUnderstand='1')
    ctx.out_header.Data = ctx.in_header.Data


class AutoConfigServer(ServiceBase):
    """ TR-069 ACS implementation. The TR-069/CWMP RPC messages are defined, as
        per cwmp-1-0.xsd schema definition, in the RPC decorators below. These
        RPC methods are intended to be called by TR-069-compliant customer
        premesis equipment (CPE), over the SOAP/HTTP interface defined by
        TR-069.

        Per spyne documentation, this class is never instantiated, so all RPC
        functions are implicitly staticmethods. Hence use static class variables
        to hold state.
        This also means that only a single thread can be used (since there are
        no locks).
        Note that staticmethod decorator can't be used in conjunction with rpc
        decorator.
    """
    __out_header__ = models.ID
    __in_header__ = models.ID
    _acs_to_cpe_queue = None
    _cpe_to_acs_queue = None

    """ Set maxEnvelopes to 1, as per TR-069 spec """
    _max_envelopes = 1

    @classmethod
    def set_state_machine_manager(
        cls,
        state_machine_manager: StateMachineManager,
    ) -> None:
        cls.state_machine_manager = state_machine_manager

    @classmethod
    def _handle_tr069_message(
        cls,
        ctx: WsgiMethodContext,
        message: ComplexModelBase,
    ) -> ComplexModelBase:
        # Log incoming msg
        if hasattr(message, 'as_dict'):
            logger.debug('Handling TR069 message: %s', str(type(message)))
        else:
            logger.debug('Handling TR069 message.')

        req = cls._get_tr069_response_from_sm(ctx, message)

        # Log outgoing msg
        if hasattr(req, 'as_dict'):
            logger.debug('Sending TR069 message: %s', str(req.as_dict()))
        else:
            logger.debug('Sending TR069 message.')

        # Set header
        ctx.out_header = models.ID(mustUnderstand='1')
        ctx.out_header.Data = 'null'

        # Set return message name
        if isinstance(req, models.DummyInput):
            # Generate 'empty' request to CPE using empty message name
            ctx.descriptor.out_message.Attributes.sub_name = 'EmptyHttp'
            return models.AcsToCpeRequests()
        ctx.descriptor.out_message.Attributes.sub_name = req.__class__.__name__
        return cls._generate_acs_to_cpe_request_copy(req)

    @classmethod
    def _get_tr069_response_from_sm(
            cls,
            ctx: WsgiMethodContext,
            message: ComplexModelBase,
    ) -> ComplexModelBase:
        # We want to blanket-catch all exceptions because a problem with one
        # tr-069 session shouldn't tank the service for all other enodeB's
        # being managed
        try:
            return cls.state_machine_manager.handle_tr069_message(ctx, message)
        except Exception:   # pylint: disable=broad-except
            logger.exception(
                'Unexpected exception from state machine manager, returning '
                'empty request',
            )
            return models.DummyInput()

    @staticmethod
    def _generate_acs_to_cpe_request_copy(request):
        """ Create an AcsToCpeRequests instance with all the appropriate
            members set from the input request. AcsToCpeRequests is a union of
            all request messages, so field names match.
        """
        request_out = models.AcsToCpeRequests()
        for parameter in request.get_flat_type_info(request.__class__):
            try:
                setattr(request_out, parameter, getattr(request, parameter))
            except AttributeError:
                # Allow un-set parameters. If CPE can't handle this, it will
                # respond with an error message
                pass

        return request_out

    # CPE->ACS RPC calls

    @rpc(
        models.GetRPCMethods,
        _returns=models.GetRPCMethodsResponse,
        _body_style="bare",
        _operation_name="GetRPCMethods",
        _out_message_name="GetRPCMethodsResponse",
    )
    def get_rpc_methods(ctx, request):
        """ GetRPCMethods RPC call is terminated here. No need to pass to higher
            layer """
        fill_response_header(ctx)
        resp = AutoConfigServer._handle_tr069_message(ctx, request)
        return resp

    @rpc(
        models.Inform,
        _returns=models.InformResponse,
        _body_style="bare",
        _operation_name="Inform",
        _out_message_name="InformResponse",
    )
    def inform(ctx, request):
        """ Inform response generated locally """
        fill_response_header(ctx)
        resp = AutoConfigServer._handle_tr069_message(ctx, request)
        resp.MaxEnvelopes = AutoConfigServer._max_envelopes
        return resp

    @rpc(
        models.TransferComplete,
        _returns=models.TransferCompleteResponse,
        _body_style="bare",
        _operation_name="TransferComplete",
        _out_message_name="TransferCompleteResponse",
    )
    def transfer_complete(ctx, request):
        fill_response_header(ctx)
        resp = AutoConfigServer._handle_tr069_message(ctx, request)
        resp.MaxEnvelopes = AutoConfigServer._max_envelopes
        return resp

    # Spyne does not handle no input or SimpleModel input for 'bare' function
    # DummyInput is unused
    # pylint: disable=unused-argument
    @rpc(
        models.DummyInput,
        _returns=models.AcsToCpeRequests,
        _out_message_name="EmptyHttp",
        _body_style='bare',
        _operation_name="EmptyHttp",
    )
    def empty_http(ctx, dummy):
        # Function to handle empty HTTP request
        return AutoConfigServer._handle_tr069_message(ctx, dummy)

    # CPE->ACS responses to ACS->CPE RPC calls

    @rpc(
        models.SetParameterValuesResponse,
        _returns=models.AcsToCpeRequests,
        _out_message_name="MessageNameToBeReplaced",
        _body_style='bare',
        _operation_name="SetParameterValuesResponse",
    )
    def set_parameter_values_response(ctx, response):
        return AutoConfigServer._handle_tr069_message(ctx, response)

    @rpc(
        models.GetParameterValuesResponse,
        _returns=models.AcsToCpeRequests,
        _out_message_name="MessageNameToBeReplaced",
        _body_style='bare',
        _operation_name="GetParameterValuesResponse",
    )
    def get_parameter_values_response(ctx, response):
        return AutoConfigServer._handle_tr069_message(ctx, response)

    @rpc(
        models.GetParameterNamesResponse,
        _returns=models.AcsToCpeRequests,
        _out_message_name="MessageNameToBeReplaced",
        _body_style='bare',
        _operation_name="GetParameterNamesResponse",
    )
    def get_parameter_names_response(ctx, response):
        return AutoConfigServer._handle_tr069_message(ctx, response)

    @rpc(
        models.SetParameterAttributesResponse,
        _returns=models.AcsToCpeRequests,
        _out_message_name="MessageNameToBeReplaced",
        _body_style='bare',
        _operation_name="SetParameterAttributesResponse",
    )
    def set_parameter_attributes_response(ctx, response):
        return AutoConfigServer._handle_tr069_message(ctx, response)

    @rpc(
        models.GetParameterAttributesResponse,
        _returns=models.AcsToCpeRequests,
        _out_message_name="MessageNameToBeReplaced",
        _body_style='bare',
        _operation_name="GetParameterAttributesResponse",
    )
    def get_parameter_attributes_response(ctx, response):
        return AutoConfigServer._handle_tr069_message(ctx, response)

    @rpc(
        models.AddObjectResponse,
        _returns=models.AcsToCpeRequests,
        _out_message_name="MessageNameToBeReplaced",
        _body_style='bare',
        _operation_name="AddObjectResponse",
    )
    def add_object_response(ctx, response):
        return AutoConfigServer._handle_tr069_message(ctx, response)

    @rpc(
        models.DeleteObjectResponse,
        _returns=models.AcsToCpeRequests,
        _out_message_name="MessageNameToBeReplaced",
        _body_style='bare',
        _operation_name="DeleteObjectResponse",
    )
    def delete_object_response(ctx, response):
        return AutoConfigServer._handle_tr069_message(ctx, response)

    @rpc(
        models.DownloadResponse,
        _returns=models.AcsToCpeRequests,
        _out_message_name="MessageNameToBeReplaced",
        _body_style='bare',
        _operation_name="DownloadResponse",
    )
    def download_response(ctx, response):
        return AutoConfigServer._handle_tr069_message(ctx, response)

    @rpc(
        models.RebootResponse,
        _returns=models.AcsToCpeRequests,
        _out_message_name="MessageNameToBeReplaced",
        _body_style='bare',
        _operation_name="RebootResponse",
    )
    def reboot_response(ctx, response):
        return AutoConfigServer._handle_tr069_message(ctx, response)

    @rpc(
        models.Fault,
        _returns=models.AcsToCpeRequests,
        _out_message_name="MessageNameToBeReplaced",
        _body_style='bare',
        _operation_name="Fault",
    )
    def fault(ctx, response):
        return AutoConfigServer._handle_tr069_message(ctx, response)


def on_method_return_string(ctx):
    """
    By default, spyne adds a namespace to every single XML element.
    There isn't a way to change this behavior, and the spyne-recommended way
    to fix this is by doing string manipulation. The TR-069 spec mandates that
    only the top-level CWMP elements contain namespaces. Hence this
    function is to remove namespaces from all elements except top-level CWMP
    elements (e.g. RPC request/response names, header elements).
    """
    # Format strings for XML tags, corresponding to:
    # 1) Normal start or end tag (without attribute)
    # 2) Open and close tag (when no attributes or sub-structures exist)
    # 3) Tag containing attributes
    # We don't just look for 'cwmp:%s' (with no character after %s) because this
    # would pick up all tags that start with the tag of interest (e.g
    # cwmp:SetParameterAttributes would also match
    # cwmp:SetParameterAttributesStruct)

    XML_FORMAT_STRS = [
        ["cwmp:%s>", "!!!TEMP_MOD!!!:%s>"],
        ["cwmp:%s/>", "!!!TEMP_MOD!!!:%s/>"],
        ["cwmp:%s ", "!!!TEMP_MOD!!!:%s "],
    ]
    fields_to_preserve_ns = list(RPC_METHODS) + list(RPC_RESPONSES) + \
        list(CPE_RPC_METHODS) + list(CPE_RPC_RESPONSES) + \
        list(PSEUDO_RPC_METHODS) + list(TOP_LEVEL_HEADER_ELEMENTS)
    for field in fields_to_preserve_ns:
        for formats in XML_FORMAT_STRS:
            orig_str = formats[0] % field
            temp_str = formats[1] % field
            ctx.out_string[0] = ctx.out_string[0].replace(
                orig_str.encode('ascii'), temp_str.encode('ascii'),
            )

    # Also preserve namespace inside strings, e.g. for arrayType="cwmp:..."
    orig_str = "=\"cwmp:"
    temp_str = "=\"!!!TEMP_MOD!!!:"
    ctx.out_string[0] = ctx.out_string[0].replace(
        orig_str.encode('ascii'), temp_str.encode('ascii'),
    )
    orig_str = "=\'cwmp:"
    temp_str = "=\'!!!TEMP_MOD!!!:"
    ctx.out_string[0] = ctx.out_string[0].replace(
        orig_str.encode('ascii'), temp_str.encode('ascii'),
    )

    ctx.out_string[0] = ctx.out_string[0].replace(b'cwmp:', b'')
    ctx.out_string[0] = ctx.out_string[0].replace(b'!!!TEMP_MOD!!!:', b'cwmp:')

    # Special-case handling so that 'EmptyHttp' RPC will be called using
    # completely empty HTTP request (not even containing a SOAP envelope), as
    # per TR-069 spec.
    if(ctx.descriptor.out_message.Attributes.sub_name == 'EmptyHttp'):
        ctx.out_string = [b'']

AutoConfigServer.event_manager.add_listener(
    'method_return_string',
    on_method_return_string,
)