'''

field serializing and deserializing metacategorization protocols

'''

import json

import logging

from rest_framework import serializers

from notes import constants, settings

from protocols.models import Protocol, ProtocolRevision

from protocols.serializers import ProtocolRevisionSerializer

logger = logging.getLogger(__name__)

class ProtocolField(serializers.Field):

    default_error_messages = {

        'incorrect_format_str': 'Incorrect format. Expected `'+constants.PROTOCOL_URN_PREFIX+'<ext_id>.<version>`.',

        'protocol_unknown': 'Incorrect protocol, protocol {ext_id}, version {version} does not exists.',

        'incorrect_format': 'Incorrect format. Expected `'+constants.PROTOCOL_URN_PREFIX+'<ext_id>.<version>` or dict.'

    }

    def __init__(self, *args, **kwargs):

        logger.debug("ProtocolField.__init__ %r || %r", args, kwargs)

        super().__init__(*args, **kwargs)

    # def get_attribute(self, *args, **kwargs):

    #     logger.debug("ProtocolField.get_attribute %r || %r", args, kwargs)

    #     logger.debug("ProtocolField.get_attribute source %r", self.source)

    #     # We pass the object instance onto `to_representation`,

    #     # not just the field attribute.

    #     return kwargs.get('obj')

    def to_representation(self, value):

        if isinstance(value, str) and value.startswith(constants.PROTOCOL_URN_PREFIX) :

            protocol_id, protocol_version = value[len(constants.PROTOCOL_URN_PREFIX):].split('.')

            # TODO: treat error case, i.e. protocol is not found

            protocol_revision = ProtocolRevision.objects.get(protocol__ext_id=protocol_id, version=protocol_version)

            serializer = ProtocolRevisionSerializer(protocol_revision)

            return serializer.data

        elif isinstance(value, str):

            logger.debug("ProtocolField.to_representation value %r" % value)

            return json.loads(value)

        else:

            return value

    def to_internal_value(self, data):

        if isinstance(data, str) and data.startswith(constants.PROTOCOL_URN_PREFIX):

            try:

                ext_id, version = data[len(constants.PROTOCOL_URN_PREFIX):].split('.')

            except ValueError:

                self.fail('incorrect_format_str')

            if not ProtocolRevision.objects.filter(protocol__ext_id=ext_id, version=version).exists():

                self.fail('protocol_unknown', ext_id=ext_id, version=version)

            else:

                return data

        elif isinstance(data, dict):

            return data

        else:

            self.fail('incorrect_format')