from django.contrib.auth.models import User
from django.db import transaction
from django.utils import timezone
from rest_framework import serializers

from .models import Invitation


class UserSerializer(serializers.ModelSerializer):
    is_admin = serializers.SerializerMethodField()

    class Meta:
        model = User
        fields = ['id', 'username', 'email', 'first_name', 'last_name', 'is_admin', 'date_joined']

    def get_is_admin(self, obj):
        return obj.is_superuser or obj.is_staff


class RegisterSerializer(serializers.ModelSerializer):
    password = serializers.CharField(write_only=True)
    invite = serializers.UUIDField(write_only=True)

    class Meta:
        model = User
        fields = ['username', 'password', 'email', 'first_name', 'last_name', 'invite']

    def validate_invite(self, value):
        try:
            invitation = Invitation.objects.get(token=value)
        except Invitation.DoesNotExist as error:
            raise serializers.ValidationError('Ce lien d’invitation est invalide.') from error
        if not invitation.is_valid:
            raise serializers.ValidationError('Ce lien d’invitation est expire ou deja utilise.')
        return value

    def create(self, validated_data):
        invitation_token = validated_data.pop('invite')
        with transaction.atomic():
            invitation = Invitation.objects.select_for_update().get(token=invitation_token)
            if not invitation.is_valid:
                raise serializers.ValidationError({'invite': 'Ce lien d’invitation est expire ou deja utilise.'})
            user = User.objects.create_user(**validated_data)
            invitation.used_at = timezone.now()
            invitation.save(update_fields=['used_at'])
        return user