from django.contrib import admin
from django.contrib.auth.admin import UserAdmin
from django.contrib.auth.forms import UserChangeForm
from django.contrib.auth.models import User
from django import forms

import base64

from models import CommunityAuthSite

class CommunityAuthSiteAdminForm(forms.ModelForm):
	class Meta:
		model = CommunityAuthSite
		exclude = ()

	def clean_cryptkey(self):
		x = None
		try:
			x = base64.b64decode(self.cleaned_data['cryptkey'])
		except TypeError:
			raise forms.ValidationError("Crypto key must be base64 encoded")

		if (len(x) != 16 and len(x) != 24 and len(x) != 32):
			raise forms.ValidationError("Crypto key must be 16, 24 or 32 bytes before being base64-encoded")
		return self.cleaned_data['cryptkey']

class CommunityAuthSiteAdmin(admin.ModelAdmin):
	form = CommunityAuthSiteAdminForm

class PGUserChangeForm(UserChangeForm):
	"""just like UserChangeForm, butremoves "username" requirement"""
	def __init__(self, *args, **kwargs):
		super(PGUserChangeForm, self).__init__(*args, **kwargs)
		# because the auth.User model is set to "blank=False" and the Django
		# auth.UserChangeForm is setup as a ModelForm, it will always validate
		# the "username" even though it is not present.  Thus the best way to
		# avoid the validation is to remove the "username" field, if it exists
		if self.fields.get('username'):
			del self.fields['username']

class PGUserAdmin(UserAdmin):
	"""overrides default Django user admin"""
	form = PGUserChangeForm

	def get_readonly_fields(self, request, obj=None):
		"""this prevents users from changing a username once created"""
		if obj:
			return self.readonly_fields + ('username',)
		return self.readonly_fields

admin.site.register(CommunityAuthSite, CommunityAuthSiteAdmin)
admin.site.unregister(User) # have to unregister default User Admin...
admin.site.register(User, PGUserAdmin) # ...in order to add overrides