from django.contrib.auth.models import User

from django import forms

from django.contrib.auth import authenticate

class LoginForm(forms.ModelForm):

    """ a form to handle login.

    """

    class Meta:

        model = User

        fields = ['email', 'password']

    def clean_email(self):

        """ see if a user exists for this email.

        """

        email = self.cleaned_data['email']

        try:

            self.user = User.objects.get(email__iexact=email)

            return email

        except User.DoesNotExist:

            raise forms.ValidationError("Incorrect e-mail or password")

    def clean_password(self):

        """ now we know that the user exists.

        we see if he typed the password correctly.

        """

        password = self.cleaned_data['password']

        user = authenticate(self.user.username, password)

        if not user:

            raise forms.ValidationError("Incorrect e-mail or password")

        return password