import requests
from django.conf import settings
from django.db import models
from django.db.models import JSONField
from oauth2_provider.models import AbstractApplication, AbstractAccessToken, AbstractGrant, AbstractRefreshToken
from oauth2_provider.scopes import get_scopes_backend
from oauth2_provider.settings import oauth2_settings
import uuid


class Resource(models.Model):
    uuid = models.UUIDField(primary_key=True, editable=False, default=uuid.uuid4, unique=True, db_index=True)
    name = models.CharField(max_length=255)

    user = models.ForeignKey(
        settings.AUTH_USER_MODEL, on_delete=models.CASCADE, blank=True, null=True,
        related_name="resources"
    )
    expires = models.DateTimeField()

    def __str__(self):
        return self.name


class Application(AbstractApplication):
    """
    Application model for use with Django OAuth Toolkit that allows the scopes
    available to an application to be restricted on a per-application basis.
    """
    user = models.ForeignKey(
        settings.AUTH_USER_MODEL,
        related_name="%(app_label)s_%(class)s",
        on_delete=models.PROTECT
    )
    allowed_scope = models.TextField(blank=True)
    resource = models.OneToOneField(
        Resource,
        models.PROTECT,
        blank=True, null=True,
        help_text='The resource of application.',
        related_name='application'
    )

    @property
    def allowed_scopes(self):
        """
        Returns the set of allowed scope names for this application.
        """
        all_scopes = set(get_scopes_backend().get_all_scopes().keys())
        app_scopes = set(self.allowed_scope.split())
        return app_scopes.intersection(all_scopes)


class Scope(models.Model):
    """
    Django model for an OAuth scope.
    """
    #: The application that created the scope
    # NOTE: This is not used to limit access to the scope in any way - we want the
    #       scope to be available to other applications in order to request access
    #       to the resource it protects!
    application = models.ForeignKey(
        oauth2_settings.APPLICATION_MODEL,
        models.CASCADE,
        # This field is nullable because it is only set for scopes created by
        # external resource servers, which have a corresponding OAuth application
        # record on the authorisation server
        blank=True, null=True,
        help_text='The application to which the scope belongs.',
        related_name='scopes'
    )
    resource = models.ForeignKey(
        Resource,
        models.PROTECT,
        blank=True, null=True,
        help_text='The resource of scope.',
        related_name='scopes'
    )
    #: The name of the scope
    name = models.CharField(
        max_length=255,
        unique=True,
        help_text='The name of the scope.'
    )
    #: A brief description of the scope
    description = models.TextField(
        help_text='A brief description of the scope. This text is displayed '
                  'to users when authorising access for the scope.'
    )
    #: Indicates if the scope should be included in the default scopes
    is_default = models.BooleanField(
        default=False,
        help_text='Indicates if this scope should be included in the default scopes.'
    )

    @property
    def final_name(self):
        args = []
        if self.resource:
            args.append(self.resource.name)

        args.append(self.name)
        return '.'.join(args)

    @property
    def final_description(self):
        resource_name = self.resource and self.resource.name

        if resource_name:
            return f"{resource_name} -> {self.description}"
        return self.description

    @classmethod
    def register(cls, name, description, is_default=False):
        """
        Registers a scope with the given values. It always creates an instance in
        the local database, but if this resource server has an external authorisation
        server, it will also register the scope there.

        Returns ``True`` on success. Should raise on failure.
        """
        endpoint = settings.RESOURCE_SERVER_REGISTER_SCOPE_URL
        if endpoint:
            #  If the endpoint is set, make the callout to the authz server
            token = "Bearer {}".format(oauth2_settings.RESOURCE_SERVER_AUTH_TOKEN)
            #  Let any failures bubble up
            # The idea is to call this method during deployment as a post-migrate
            #  hook, so we want failures to halt the deployment
            response = requests.post(
                endpoint,
                json={
                    'name': name,
                    'description': description,
                    'is_default': is_default
                },
                headers={"Authorization": token}
            )
            #  Raise the exception for anything other than 20x responses
            response.raise_for_status()
        #  Always create/update the scope record locally
        _ = Scope.objects.update_or_create(
            name=name,
            defaults={'description': description, 'is_default': is_default}
        )
        return True


class Grant(AbstractGrant):
    application = models.ForeignKey(
        oauth2_settings.APPLICATION_MODEL, on_delete=models.CASCADE, related_name='grants'
    )


class RefreshToken(AbstractRefreshToken):
    application = models.ForeignKey(
        oauth2_settings.APPLICATION_MODEL, on_delete=models.CASCADE, related_name='refresh_tokens')


class AccessToken(AbstractAccessToken):
    detail = JSONField(null=True, blank=True)
    application = models.ForeignKey(
        oauth2_settings.APPLICATION_MODEL, on_delete=models.CASCADE, blank=True, null=True, related_name='access_tokens'
    )