from flask_wtf import FlaskForm
from werkzeug.security import generate_password_hash
from wtforms import BooleanField, EmailField, PasswordField, validators

from ereuse_devicehub.resources.user.models import User


class LoginForm(FlaskForm):
    email = EmailField('Email Address', [validators.Length(min=6, max=35)])
    password = PasswordField('Password', [validators.DataRequired()])
    remember = BooleanField('Remember me')

    error_messages = {
        'invalid_login': (
            "Please enter a correct email and password. Note that both "
            "fields may be case-sensitive."
        ),
        'inactive': "This account is inactive.",
    }

    def validate(self, extra_validators=None):
        is_valid = super().validate(extra_validators)

        if not is_valid:
            return False

        email = self.email.data
        password = self.password.data
        self.user_cache = self.authenticate(email, password)

        if self.user_cache is None:
            self.form_errors.append(self.error_messages['invalid_login'])
            return False

        return self.confirm_login_allowed(self.user_cache)

    def authenticate(self, email, password):
        if email is None or password is None:
            return
        user = User.query.filter_by(email=email).first()
        if user is None:
            # Run the default password hasher once to reduce the timing
            # difference between an existing and a nonexistent user (#20760).
            generate_password_hash(password)
        else:
            if user.check_password(password):
                return user

    def confirm_login_allowed(self, user):
        """
        Controls whether the given User may log in. This is a policy setting,
        independent of end-user authentication. This default behavior is to
        allow login by active users, and reject login by inactive users.
        If the given user cannot log in, this method should raise a
        ``ValidationError``.
        If the given user may log in, this method should return None.
        """
        if not user.is_active:
            self.form_errors.append(self.error_messages['inactive'])

        return user.is_active
