# my_pyramid_app/modules/signin/forms.py
from pyramid_webforms import Form
from my_pyramid_app.i18n import _
from . import validators


login_or_email = {
    'type': 'text',
    'title': _('Login or Email'),
    'tip': _('Please enter your login or email that was used during your registration.'),
    'size': 30,
    'maxlength': 50,
    'validator': validators.UserLoginOrEmail
}

password = {
    'type': 'password',
    'title': _('Password'),
    'tip': _('A password can contain any character of any alphabet (minimum is 1, maximum is 64 characters). '
             'For reliability we recommend using non-trivial and long passwords. Note that the case of '
             'the letters matters.'),
    'size': 30,
    'maxlength': 64,
    'validator': validators.UserPassword,
    'value': '',
}

remember_me = {
    'type': 'checkbox',
    'title': _('Remember me'),
    'tip': _('Set this checkbox if you want your current browser to keep '
             'your session for further visits.'),
    'selected': False,
    'validator': validators.RememberUserSession
}

class SignInForm(Form):
    # form attributes and metadata
    _id_ = 'signin-form'
    _submit_text_ = _('Sign in')
    _alternate_url_ = {'name': 'support.account_access'}
    _alternate_text_ = _("I cannot access my account")
    _fieldsets_ = [
        [['login_email', 'password', 'remember_me']]
    ]
    # form fields
    login_email = login_or_email
    password = password
    remember_me = remember_me

# my_pyramid_app/modules/signin/validators.py
import re
import formencode

# logins are 3-16 characters long
USERLOGINS = re.compile('[A-Za-z0-9][-A-Za-z0-9]{1,14}[A-Za-z0-9]', re.IGNORECASE)

RememberUserSession = formencode.validators.Bool

class UserLogin(formencode.validators.Regex):
    not_empty = True
    strip = True
    regex = USERLOGINS

class UserEmail(formencode.validators.Email):
    not_empty = True
    strip = True
    max = 50
    def _to_python(self, email, state):
        email = super(UserEmail, self)._to_python(email, state)
        return email.lower()

class UserLoginOrEmail(UserLogin):
    def _to_python(self, value, state):
        if '@' in value:
            validator = UserEmail
        else:
            validator = UserLogin
        value = validator.to_python(value, state)
        return value

    def validate_python(self, value, state):
        pass


class UserPassword(formencode.validators.UnicodeString):
    not_empty = True
    max = 64

# my_pyramid_app/modules/signin/views.py
from pyramid.view import view_config
from .forms import SignInForm


class SignInView(object):

    @view_config(route_name='session.signin', renderer='templates/signin.mako')
    def signin_form(self):
        request = self.request
        if request.POST:
            try:
                form = SignInForm.validate(request)
            except SignInForm.Invalid as error:
                # redirect or error handling
                pass
            else:
                # sign in user using form data
                pass

        return {'signin_form': forms.SignInForm()}