#!/usr/bin/env python3
"""
A custom user model.
"""
import string

from django.db import models
from django.contrib.auth.models import AbstractUser
from django.core.validators import MinLengthValidator, MaxLengthValidator

from .validators import CharValidator

class User(AbstractUser):
	"""
	A custom user model.
	"""
	username_char = CharValidator(
		string.ascii_letters + string.digits,
		"Username must only contain alphanumeric characters."
	)
	username_min = MinLengthValidator(
		3,
		"Username must contain more than 3 characters."
	)
	username_max = MaxLengthValidator(
		20,
		"Username must contain less than 20 characters."
	)
	username = models.CharField(
		'username',
		max_length=20,
		unique=True,
		help_text="Must be between 3 and 20 characters. " \
			+ "Letters and digits only.",
		validators=[username_char, username_min, username_max],
		error_messages={
			'unique': "A user with that username already exists.",
		},
	)
	first_name = None
	last_name = None
	email = models.EmailField('email address')

	def get_full_name(self):
		return None
	def get_short_name(self):
		return None