'''
to make a backend named <backend> you need to...
1. define a function <backend>_authenticate(request, library)
    returns true if can request.user can be authenticated to the library, and attaches a credential property to the library object
    returns fals if otherwise.
2. define a class <backend>_authenticator
    with a process((self, authenticator, success_url, deny_url) method which is expected to return a response
3. make a libraryauth/<backend>_join.html template (authenticator will be in its context) to insert a link or form for a user to join the library
4. if you need to show the user a form, define a model form class <backend>_form with init method  __init__(self, request, library, *args, **kwargs)
    and model LibraryUser
5. add new auth choice to Library.backend choices and the admin as desired

'''
import logging
from django.db.models import Q
from django import forms
from django.http import HttpResponseRedirect
from django.shortcuts import render

from .models import Block, IP, LibraryUser, CardPattern, EmailPattern
                    

logger = logging.getLogger(__name__)

def ip_authenticate(request, library):
    try:
        ip = IP(request.META['REMOTE_ADDR'])
        blocks = Block.objects.filter(Q(lower=ip) | Q(lower__lte=ip, upper__gte=ip))
        for block in blocks:
            if block.library==library:
                logger.info('%s authenticated for %s from %s'%(request.user, library, ip))
                library.credential=ip
                return True
        return False
    except KeyError:
        return False
     
class ip_authenticator():
    def process(authenticator, success_url, deny_url):
        return HttpResponseRedirect(deny_url)

class ip_admin_form(forms.ModelForm):
    class Meta:
        model = Block
        exclude = "library"
    
def cardnum_authenticate(request, library):
    return False

class cardnum_authenticator():
    def process(self, authenticator, success_url, deny_url):
        if authenticator.form and authenticator.request.method=='POST' and authenticator.form.is_valid():
            library = authenticator.form.cleaned_data['library']
            library.credential = authenticator.form.cleaned_data['credential']
            logger.info('%s authenticated for %s from %s'%(authenticator.request.user, authenticator.library, authenticator.form.cleaned_data.get('number')))
            library.add_user(authenticator.form.cleaned_data['user'])
            return HttpResponseRedirect(success_url)
        else:
            return render(authenticator.request, 'libraryauth/library.html', {
                    'library':authenticator.library,
                    'authenticator':authenticator,
                    })

class cardnum_admin_form(forms.ModelForm):
    class Meta:
        model = CardPattern
        exclude = "library"
    
class cardnum_form(forms.ModelForm):
    credential = forms.RegexField(
            label="Enter Your Library Card Number", 
            max_length=20, 
            regex=r'^\d+$',
            required = True,
            help_text = "(digits only)",
            error_messages = {'invalid': "digits only!",}
        )
    def __init__(self, request, library, *args, **kwargs):
        if request.method=="POST":
            data=request.POST
            super(cardnum_form, self).__init__(data=data)
        else:
            initial={'user':request.user, 'library':library}
            super(cardnum_form, self).__init__(initial=initial)
    
    def clean(self):
        library = self.cleaned_data.get('library', None)
        credential = self.cleaned_data.get('credential', '')
        for card_pattern in library.cardnum_auths.all():
            if card_pattern.is_valid(credential):
                return self.cleaned_data
        raise forms.ValidationError("the library card number must be VALID.")
        
    class Meta:
        model = LibraryUser
        widgets = { 'library': forms.HiddenInput, 'user': forms.HiddenInput }
        
def email_authenticate(request, library):
    if request.user.is_anonymous():
        return False
    email = request.user.email
    for email_pattern in library.email_auths.all():
        if email_pattern.is_valid(email):
            logger.info('%s authenticated for %s from %s'%(request.user, library, email))
            library.credential=email
            return True
    return False
     
class email_authenticator():
    def process(authenticator, success_url, deny_url):
        return HttpResponseRedirect(deny_url)

class email_admin_form(forms.ModelForm):
    class Meta:
        model = EmailPattern
        exclude = "library"