# Copyright 2010 Jacob Kaplan-Moss

# Copyright 2011 OpenStack Foundation
# 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.

"""
Base utilities to build API operation managers and objects on top of.
"""

import abc
import contextlib
import hashlib
import inspect
import os
import threading

import six

from novaclient import exceptions
from novaclient.openstack.common.apiclient import base
from novaclient import utils

Resource = base.Resource


def getid(obj):
    """
    Abstracts the common pattern of allowing both an object or an object's ID
    as a parameter when dealing with relationships.
    """
    try:
        return obj.id
    except AttributeError:
        return obj


class Manager(utils.HookableMixin):
    """
    Managers interact with a particular type of API (servers, flavors, images,
    etc.) and provide CRUD operations for them.
    """
    resource_class = None
    cache_lock = threading.RLock()

    def __init__(self, api):
        self.api = api

    def _list(self, url, response_key, obj_class=None, body=None):
        if body:
            _resp, body = self.api.client.post(url, body=body)
        else:
            _resp, body = self.api.client.get(url)

        if obj_class is None:
            obj_class = self.resource_class

        data = body[response_key]
        # NOTE(ja): keystone returns values as list as {'values': [ ... ]}
        #           unlike other services which just return the list...
        if isinstance(data, dict):
            try:
                data = data['values']
            except KeyError:
                pass

        with self.completion_cache('human_id', obj_class, mode="w"):
            with self.completion_cache('uuid', obj_class, mode="w"):
                return [obj_class(self, res, loaded=True)
                        for res in data if res]

    @contextlib.contextmanager
    def completion_cache(self, cache_type, obj_class, mode):
        """
        The completion cache store items that can be used for bash
        autocompletion, like UUIDs or human-friendly IDs.

        A resource listing will clear and repopulate the cache.

        A resource create will append to the cache.

        Delete is not handled because listings are assumed to be performed
        often enough to keep the cache reasonably up-to-date.
        """
        # NOTE(wryan): This lock protects read and write access to the
        # completion caches
        with self.cache_lock:
            base_dir = utils.env('NOVACLIENT_UUID_CACHE_DIR',
                                 default="~/.novaclient")

            # NOTE(sirp): Keep separate UUID caches for each username +
            # endpoint pair
            username = utils.env('OS_USERNAME', 'NOVA_USERNAME')
            url = utils.env('OS_URL', 'NOVA_URL')
            uniqifier = hashlib.md5(username.encode('utf-8') +
                                    url.encode('utf-8')).hexdigest()

            cache_dir = os.path.expanduser(os.path.join(base_dir, uniqifier))

            try:
                os.makedirs(cache_dir, 0o755)
            except OSError:
                # NOTE(kiall): This is typically either permission denied while
                #              attempting to create the directory, or the
                #              directory already exists. Either way, don't
                #              fail.
                pass

            resource = obj_class.__name__.lower()
            filename = "%s-%s-cache" % (resource, cache_type.replace('_', '-'))
            path = os.path.join(cache_dir, filename)

            cache_attr = "_%s_cache" % cache_type

            try:
                setattr(self, cache_attr, open(path, mode))
            except IOError:
                # NOTE(kiall): This is typically a permission denied while
                #              attempting to write the cache file.
                pass

            try:
                yield
            finally:
                cache = getattr(self, cache_attr, None)
                if cache:
                    cache.close()
                    delattr(self, cache_attr)

    def write_to_completion_cache(self, cache_type, val):
        cache = getattr(self, "_%s_cache" % cache_type, None)
        if cache:
            cache.write("%s\n" % val)

    def _get(self, url, response_key):
        _resp, body = self.api.client.get(url)
        return self.resource_class(self, body[response_key], loaded=True)

    def _create(self, url, body, response_key, return_raw=False, **kwargs):
        self.run_hooks('modify_body_for_create', body, **kwargs)
        _resp, body = self.api.client.post(url, body=body)
        if return_raw:
            return body[response_key]

        with self.completion_cache('human_id', self.resource_class, mode="a"):
            with self.completion_cache('uuid', self.resource_class, mode="a"):
                return self.resource_class(self, body[response_key])

    def _delete(self, url):
        _resp, _body = self.api.client.delete(url)

    def _update(self, url, body, response_key=None, **kwargs):
        self.run_hooks('modify_body_for_update', body, **kwargs)
        _resp, body = self.api.client.put(url, body=body)
        if body:
            if response_key:
                return self.resource_class(self, body[response_key])
            else:
                return self.resource_class(self, body)


@six.add_metaclass(abc.ABCMeta)
class ManagerWithFind(Manager):
    """
    Like a `Manager`, but with additional `find()`/`findall()` methods.
    """

    @abc.abstractmethod
    def list(self):
        pass

    def find(self, **kwargs):
        """
        Find a single item with attributes matching ``**kwargs``.

        This isn't very efficient: it loads the entire list then filters on
        the Python side.
        """
        matches = self.findall(**kwargs)
        num_matches = len(matches)
        if num_matches == 0:
            msg = "No %s matching %s." % (self.resource_class.__name__, kwargs)
            raise exceptions.NotFound(404, msg)
        elif num_matches > 1:
            raise exceptions.NoUniqueMatch
        else:
            return matches[0]

    def findall(self, **kwargs):
        """
        Find all items with attributes matching ``**kwargs``.

        This isn't very efficient: it loads the entire list then filters on
        the Python side.
        """
        found = []
        searches = kwargs.items()

        detailed = True
        list_kwargs = {}

        list_argspec = inspect.getargspec(self.list)
        if 'detailed' in list_argspec.args:
            detailed = ("human_id" not in kwargs and
                        "name" not in kwargs and
                        "display_name" not in kwargs)
            list_kwargs['detailed'] = detailed

        if 'is_public' in list_argspec.args and 'is_public' in kwargs:
            is_public = kwargs['is_public']
            list_kwargs['is_public'] = is_public
            if is_public is None:
                tmp_kwargs = kwargs.copy()
                del tmp_kwargs['is_public']
                searches = tmp_kwargs.items()

        listing = self.list(**list_kwargs)

        for obj in listing:
            try:
                if all(getattr(obj, attr) == value
                        for (attr, value) in searches):
                    if detailed:
                        found.append(obj)
                    else:
                        found.append(self.get(obj.id))
            except AttributeError:
                continue

        return found


class BootingManagerWithFind(ManagerWithFind):
    """Like a `ManagerWithFind`, but has the ability to boot servers."""

    def _parse_block_device_mapping(self, block_device_mapping):
        bdm = []

        for device_name, mapping in six.iteritems(block_device_mapping):
            #
            # The mapping is in the format:
            # <id>:[<type>]:[<size(GB)>]:[<delete_on_terminate>]
            #
            bdm_dict = {'device_name': device_name}

            mapping_parts = mapping.split(':')
            source_id = mapping_parts[0]
            if len(mapping_parts) == 1:
                bdm_dict['volume_id'] = source_id

            elif len(mapping_parts) > 1:
                source_type = mapping_parts[1]
                if source_type.startswith('snap'):
                    bdm_dict['snapshot_id'] = source_id
                else:
                    bdm_dict['volume_id'] = source_id

            if len(mapping_parts) > 2 and mapping_parts[2]:
                bdm_dict['volume_size'] = str(int(mapping_parts[2]))

            if len(mapping_parts) > 3:
                bdm_dict['delete_on_termination'] = mapping_parts[3]

            bdm.append(bdm_dict)
        return bdm
