''' Serializers for persistent data manipulation. '''
from typing import cast

from rest_framework import serializers

from apps.rsform.models import LibraryItem
from apps.rsform.serializers import LibraryItemDetailsSerializer
from shared import messages as msg

from ..models import Argument, Operation, OperationSchema


class OperationSerializer(serializers.ModelSerializer):
    ''' Serializer: Operation data. '''
    class Meta:
        ''' serializer metadata. '''
        model = Operation
        fields = '__all__'
        read_only_fields = ('id', 'oss')


class ArgumentSerializer(serializers.ModelSerializer):
    ''' Serializer: Operation data. '''
    class Meta:
        ''' serializer metadata. '''
        model = Argument
        fields = ('operation', 'argument')



class OperationPositionSerializer(serializers.ModelSerializer):
    ''' Serializer: Positions of a single operations in OSS. '''
    class Meta:
        ''' serializer metadata. '''
        model = Operation
        fields = 'id', 'position_x', 'position_y'

    def validate(self, attrs):
        oss = cast(LibraryItem, self.context['oss'])
        operation = cast(Operation, self.instance)
        if operation.oss != oss:
            raise serializers.ValidationError({
                'id': msg.operationNotOwned(oss.title)
            })
        return attrs


class OperationCreateSerializer(serializers.ModelSerializer):
    ''' Serializer: Constituenta creation. '''
    positions = serializers.ListField(
        child=OperationPositionSerializer(),
        default=[]
    )

    class Meta:
        ''' serializer metadata. '''
        model = Operation
        fields = \
            'alias', 'operation_type', 'title', \
            'comment', 'position_x', 'position_y'


class OperationSchemaSerializer(serializers.ModelSerializer):
    ''' Serializer: Detailed data for OSS. '''
    items = serializers.ListField(
        child=OperationSerializer()
    )
    graph = serializers.ListField(
        child=ArgumentSerializer()
    )

    class Meta:
        ''' serializer metadata. '''
        model = LibraryItem
        fields = '__all__'

    def to_representation(self, instance: LibraryItem):
        result = LibraryItemDetailsSerializer(instance).data
        oss = OperationSchema(instance)
        result['items'] = []
        for operation in oss.operations():
            result['items'].append(OperationSerializer(operation).data)
        result['graph'] = []
        for argument in oss.arguments():
            result['graph'].append(ArgumentSerializer(argument).data)
        result['substitutions'] = []
        for substitution in oss.substitutions().values(
            'original',
            'original__alias',
            'original__term_resolved',
            'substitution',
            'substitution__alias',
            'substitution__term_resolved',
            'transfer_term'
        ):
            result['substitutions'].append(substitution)
        return result