from django.contrib.auth.models import Group
from rest_framework import serializers, exceptions
from dj_rest_auth.serializers import LoginSerializer
from dj_rest_auth.registration.serializers import RegisterSerializer
from .models import CustomUser


class UserAuthSerializer(serializers.ModelSerializer):

    def to_representation(self, instance):
        result = super().to_representation(instance)

        result['is_finished_onboarding'] = True
        if instance.groups.exists():
            result['role'] = instance.groups.first().name
            if result['role'] == 'client':
                if hasattr(instance, 'diet_questionnaire'):
                    result['is_finished_onboarding'] = \
                        (len(instance.diet_questionnaire.finished_steps) == 6)
                else:
                    result['is_finished_onboarding'] = False

        if instance.is_staff:
            result['role'] = 'admin'

        if instance.cart.exists():
            result['transaction_status'] = instance.cart.last().transaction_status
            result['cart_id'] = instance.cart.last().id
        else:
            result['transaction_status'] = None
            result['cart_id'] = None

        return result

    class Meta:
        model = CustomUser
        fields = ('id', 'name', 'email',)
        read_only_fields = ('id', 'email',)


class CustomUserDetailsSerializer(serializers.ModelSerializer):

    def to_representation(self, instance):
        result = super().to_representation(instance)
        if instance.groups.exists():
            result['role'] = instance.groups.first().name
        if instance.is_staff:
            result['role'] = 'admin'
        return result

    class Meta:
        model = CustomUser
        fields = ('id', 'name', 'email',)
        read_only_fields = ('id', 'email',)


class CustomLoginSerializer(LoginSerializer):

    def validate_auth_user_status(self, user):
        request = self.context.get('request')
        if not request.data.get('role'):
            msg = 'Role is missing from the payload.'
            raise exceptions.ValidationError(msg)
        if not user.groups.filter(name=request.data.get('role')).exists():
            msg = 'Invalid role for the user.'
            raise exceptions.ValidationError(msg)

    def create(self, validated_data):
        pass    # Empty because the function is not needed
                # but Pylint demanded to implement it anyway

    def update(self, instance, validated_data):
        pass    # Empty because the function is not needed
                # but Pylint demanded to implement it anyway


class CustomRegisterSerializer(RegisterSerializer):
    name = serializers.CharField()

    def get_cleaned_data(self):
        super().get_cleaned_data()
        return {
            'email': self.validated_data.get('email', ''),
            'password1': self.validated_data.get('password1', ''),
            'name': self.validated_data.get('name', '')
        }

    def create(self, validated_data):
        pass    # Empty because the function is not needed
                # but Pylint demanded to implement it anyway

    def update(self, instance, validated_data):
        pass    # Empty because the function is not needed
                # but Pylint demanded to implement it anyway

    def save(self, request):
        user = super().save(request)
        user.name = self.get_cleaned_data().get('name')
        user.save()
        client_role, _created = Group.objects.get_or_create(name='client')
        user.groups.add(client_role)
        return user