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

from .models import Invitation


User = get_user_model()


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

    class Meta:
        model = User
        fields = [
            'id',
            'username',
            'first_name',
            'last_name',
            'email',
            'is_active',
            'is_staff',
            'is_superuser',
            'is_admin',
            'date_joined',
            'color',
        ]
        read_only_fields = ['id', 'date_joined', 'is_admin']

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


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

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

    def validate(self, attrs):
        if attrs['password'] != attrs['password_confirm']:
            raise serializers.ValidationError({
                'password_confirm': (
                    'Les mots de passe ne correspondent pas.'
                )
            })

        return attrs

    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 expiré ou déjà utilisé.'
            )

        return value

    def create(self, validated_data):
        invitation_token = validated_data.pop('invite')
        validated_data.pop('password_confirm')

        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 expiré ou déjà utilisé.'
                    )
                })

            user = User.objects.create_user(**validated_data)

            invitation.used_at = timezone.now()
            invitation.save(update_fields=['used_at'])

        return user