# Python
import re

# Django
from django.core.validators import RegexValidator
from django.db import models
from django.utils.timezone import now
from django.utils.translation import ugettext_lazy as _
from django.conf import settings

# Django OAuth Toolkit
from oauth2_provider.models import AbstractApplication, AbstractAccessToken
from oauth2_provider.generators import generate_client_secret
from oauthlib import oauth2

from awx.main.utils import get_external_account
from awx.main.fields import OAuth2ClientSecretField


DATA_URI_RE = re.compile(r'.*')  # FIXME

__all__ = ['OAuth2AccessToken', 'OAuth2Application']


class OAuth2Application(AbstractApplication):

    class Meta:
        app_label = 'main'
        verbose_name = _('application')
        unique_together = (("name", "organization"),)
    
    CLIENT_CONFIDENTIAL = "confidential"
    CLIENT_PUBLIC = "public"
    CLIENT_TYPES = (
        (CLIENT_CONFIDENTIAL, _("Confidential")),
        (CLIENT_PUBLIC, _("Public")),
    )

    GRANT_AUTHORIZATION_CODE = "authorization-code"
    GRANT_IMPLICIT = "implicit"
    GRANT_PASSWORD = "password"
    GRANT_TYPES = (
        (GRANT_AUTHORIZATION_CODE, _("Authorization code")),
        (GRANT_IMPLICIT, _("Implicit")),
        (GRANT_PASSWORD, _("Resource owner password-based")),
    )

    description = models.TextField(
        default='',
        blank=True,
    )
    logo_data = models.TextField(
        default='',
        editable=False,
        validators=[RegexValidator(DATA_URI_RE)],
    )
    organization = models.ForeignKey(
        'Organization',
        related_name='applications',
        help_text=_('Organization containing this application.'),
        on_delete=models.CASCADE,
        null=True,
    )
    client_secret = OAuth2ClientSecretField(
        max_length=1024, 
        blank=True, 
        default=generate_client_secret, 
        db_index=True,
        help_text=_('Used for more stringent verification of access to an application when creating a token.')
    )
    client_type = models.CharField(
        max_length=32, 
        choices=CLIENT_TYPES,
        help_text=_('Set to Public or Confidential depending on how secure the client device is.')
    )
    skip_authorization = models.BooleanField(
        default=False,
        help_text=_('Set True to skip authorization step for completely trusted applications.')
    )
    authorization_grant_type = models.CharField(
        max_length=32, 
        choices=GRANT_TYPES,
        help_text=_('The Grant type the user must use for acquire tokens for this application.')
    )


class OAuth2AccessToken(AbstractAccessToken):

    class Meta:
        app_label = 'main'
        verbose_name = _('access token')

    user = models.ForeignKey(
        settings.AUTH_USER_MODEL, 
        on_delete=models.CASCADE, 
        blank=True, 
        null=True,
        related_name="%(app_label)s_%(class)s",
        help_text=_('The user representing the token owner')
    )
    description = models.CharField(
        max_length=200,
        default='',
        blank=True,
    )
    last_used = models.DateTimeField(
        null=True,
        default=None,
        editable=False,
    )
    scope = models.TextField(
        blank=True,
        default='write',
        help_text=_('Allowed scopes, further restricts user\'s permissions. Must be a simple space-separated string with allowed scopes [\'read\', \'write\'].')
    )
    modified = models.DateTimeField(
        editable=False,
        auto_now=True
    )

    def is_valid(self, scopes=None):
        valid = super(OAuth2AccessToken, self).is_valid(scopes)
        if valid:
            self.last_used = now()
            self.save(update_fields=['last_used'])
        return valid

    def save(self, *args, **kwargs):
        if self.user and settings.ALLOW_OAUTH2_FOR_EXTERNAL_USERS is False:
            external_account = get_external_account(self.user)
            if external_account is not None:
                raise oauth2.AccessDeniedError(_(
                    'OAuth2 Tokens cannot be created by users associated with an external authentication provider ({})'
                ).format(external_account))
        super(OAuth2AccessToken, self).save(*args, **kwargs)
