# vim: tabstop=4 shiftwidth=4 softtabstop=4

# Copyright 2010 United States Government as represented by the
# Administrator of the National Aeronautics and Space Administration.
# All Rights Reserved.
#
#    Licensed under the Apache License, Version 2.0 (the "License"); you may
#    not use this file except in compliance with the License. You may obtain
#    a copy of the License at
#
#         http://www.apache.org/licenses/LICENSE-2.0
#
#    Unless required by applicable law or agreed to in writing, software
#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
#    License for the specific language governing permissions and limitations
#    under the License.

"""
Helper methods for commonly used operations.
"""

from django.conf import settings
from django.core.cache import cache
from django.core.exceptions import PermissionDenied
from django.http import Http404
from django_nova import manager
from django_nova.connection import get_nova_admin_connection
from django_nova.exceptions import wrap_nova_error


@wrap_nova_error
def get_project_or_404(request, project_id):
    """
    Returns a project or 404s if it doesn't exist.
    """

    # Ensure that a connection is never attempted for a user that is unauthenticated.
    if not request.user.is_authenticated:
        raise PermissionDenied('User not authenticated')

    nova = get_nova_admin_connection()
    project = nova.get_project(project_id)
    region = get_current_region(request)

    if not project:
        raise Http404('Project %s does not exist.' % project_id)

    return manager.ProjectManager(request.user, project, region)


@wrap_nova_error
def get_projects(user):
    """
    Returns a list of projects for a user.
    """
    #key = 'projects.%s' % user
    #projects = cache.get(key)

    #if not projects:
    #    nova = get_nova_admin_connection()
    #    projects = nova.get_projects(user=user)
    #    cache.set(key, projects, 30)

    #return projects
    nova = get_nova_admin_connection()
    return nova.get_projects(user=user)


@wrap_nova_error
def get_all_regions():
    """
    Returns a list of all regions.
    """
    regions = cache.get('regions')

    if not regions:
        nova = get_nova_admin_connection()
        conn = nova.connection_for(settings.NOVA_ADMIN_USER, settings.NOVA_PROJECT)
        results = conn.get_all_regions()
        regions = [{'name': r.name, 'endpoint': r.endpoint} for r in results]
        cache.set('regions', regions, 60 * 60 * 24)

    return regions


def get_region(region_name):
    regions = get_all_regions()
    try:
        return [r for r in regions if r['name'] == region_name][0]
    except IndexError:
        return None


def get_current_region(request):
    """
    Returns the currently selected region for a user.
    """
    region_name = request.session.get('region', settings.NOVA_DEFAULT_REGION)
    return get_region(region_name)


def set_current_region(request, region_name):
    """
    Sets the current region selection for a user.
    """
    request.session['region'] = region_name


@wrap_nova_error
def get_user_image_permissions(username, project_name):
    """
    Returns true if user is a sysadmin and can modify image attributes.
    """
    nova = get_nova_admin_connection()
    user_has_modify_permissions = False

    # checks global roles, if user is a sysadmin they can modify image attribtues.
    if not user_has_modify_permissions:
        for role in nova.get_user_roles(username):
            if role.role == "sysadmin":
                user_has_modify_permissions = True

    # checks project roles, if user is a sysadmin they can modify image attribtues.
    if not user_has_modify_permissions:
        for role in nova.get_user_roles(username, project_name):
            if role.role == "sysadmin":
                user_has_modify_permissions = True

    return user_has_modify_permissions