from rest_framework import serializers
from django.contrib.auth import get_user_model
from rest_framework_simplejwt.tokens import RefreshToken

User = get_user_model()


class UserSerializer(serializers.ModelSerializer):
    class Meta:
        model = User
        fields = ('id', 'username', 'email', 'is_staff')


class RegisterSerializer(serializers.Serializer):
    username = serializers.CharField(min_length=3, max_length=20)
    email = serializers.EmailField()
    password = serializers.CharField(min_length=6, write_only=True)

    def validate_username(self, value):
        if User.objects.filter(username=value).exists():
            raise serializers.ValidationError('该用户名已被注册')
        return value

    def validate_email(self, value):
        if User.objects.filter(email=value).exists():
            raise serializers.ValidationError('该邮箱已被注册')
        return value

    def create(self, validated_data):
        user = User.objects.create_user(
            username=validated_data['username'],
            email=validated_data['email'],
            password=validated_data['password'],
        )
        return user


class LoginSerializer(serializers.Serializer):
    username = serializers.CharField()
    password = serializers.CharField(write_only=True)


class TokenResponseSerializer(serializers.Serializer):
    """Response serializer for auth endpoints."""
    user = UserSerializer()
    tokens = serializers.SerializerMethodField()

    def get_tokens(self, obj):
        refresh = RefreshToken.for_user(obj)
        return {
            'access': str(refresh.access_token),
            'refresh': str(refresh),
        }