# 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 contextlib
import copy
import hashlib
import os

from manilaclient import api_versions
from manilaclient.common import cliutils
from manilaclient import exceptions
from manilaclient import utils


def getid(obj):
    """Return id if argument is a Resource.

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


class Manager(utils.HookableMixin):
    """Manager for CRUD operations.

    Managers interact with a particular type of API (shares, snapshots,
    etc.) and provide CRUD operations for them.
    """
    resource_class = None

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

    @property
    def api_version(self):
        return self.api.api_version

    def _list(self, url, response_key, manager=None, body=None):
        """List the collection.

        :param url: a partial URL, e.g., '/shares'
        :param response_key: the key to be looked up in response dictionary,
            e.g., 'shares'. If response_key is None - all response body
            will be used.
        :param manager: manager instance for constructing the returned objects
            (self will be used by default)
        :param body: data that will be encoded as JSON and passed in POST
            request (GET will be sent by default)
        """
        resp = None
        if body:
            resp, body = self.api.client.post(url, body=body)
        else:
            resp, body = self.api.client.get(url)

        if manager is None:
            manager = self

        obj_class = manager.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"):
                resource = [obj_class(manager, res, loaded=True)
                            for res in data if res]
                if 'count' in body:
                    return resource, body['count']
                else:
                    return resource

    @contextlib.contextmanager
    def completion_cache(self, cache_type, obj_class, mode):
        """Bash autocompletion items storage.

        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.
        """
        base_dir = cliutils.env('manilaclient_UUID_CACHE_DIR',
                                'MANILACLIENT_UUID_CACHE_DIR',
                                default="~/.cache/manilaclient")

        # NOTE(sirp): Keep separate UUID caches for each username + endpoint
        # pair
        username = cliutils.env('OS_USERNAME', 'MANILA_USERNAME')
        url = cliutils.env('OS_URL', 'MANILA_URL')
        uniqifier = hashlib.sha1(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:
            try:
                cache.write("%s\n" % val)
            except UnicodeEncodeError:
                pass

    def _get(self, url, response_key=None):
        resp, body = self.api.client.get(url)
        if response_key:
            return self.resource_class(self, body[response_key], loaded=True)
        else:
            return self.resource_class(self, body, loaded=True)

    def _get_with_base_url(self, url, response_key=None):
        resp, body = self.api.client.get_with_base_url(url)
        if response_key:
            return [self.resource_class(self, res, loaded=True)
                    for res in body[response_key] if res]
        else:
            return self.resource_class(self, body, 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)

    def _build_query_string(self, search_opts):
        search_opts = search_opts or {}
        params = sorted(
            [(k, v) for (k, v) in search_opts.items() if v])
        query_string = "?%s" % utils.safe_urlencode(params) if params else ''
        return query_string


class ManagerWithFind(Manager):
    """Like a `Manager`, but with additional `find()`/`findall()` methods."""
    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 = list(kwargs.items())

        search_opts = {'all_tenants': 1}
        resources = self.list(search_opts=search_opts)
        if ('v2.shares.ShareManager' in str(self.__class__) and
                self.api_version >= api_versions.APIVersion("2.69")):
            search_opts_2 = {'all_tenants': 1,
                             'is_soft_deleted': True}
            shares_soft_deleted = self.list(search_opts=search_opts_2)
            resources += shares_soft_deleted
        for obj in resources:
            try:
                if all(getattr(obj, attr) == value
                       for (attr, value) in searches):
                    found.append(obj)
            except AttributeError:
                continue

        return found

    def list(self, search_opts=None):
        raise NotImplementedError


class Resource(object):
    """Base class for OpenStack resources (tenant, user, etc.).

    This is pretty much just a bag for attributes.
    """

    HUMAN_ID = False
    NAME_ATTR = 'name'

    def __init__(self, manager, info, loaded=False):
        """Populate and bind to a manager.

        :param manager: BaseManager object
        :param info: dictionary representing resource attributes
        :param loaded: prevent lazy-loading if set to True
        """
        self.manager = manager
        self._info = info
        self._add_details(info)
        self._loaded = loaded

    def __repr__(self):
        reprkeys = sorted(k
                          for k in self.__dict__.keys()
                          if k[0] != '_' and k != 'manager')
        info = ", ".join("%s=%s" % (k, getattr(self, k)) for k in reprkeys)
        return "<%s %s>" % (self.__class__.__name__, info)

    @property
    def human_id(self):
        """Human-readable ID which can be used for bash completion."""
        if self.HUMAN_ID:
            name = getattr(self, self.NAME_ATTR, None)
            if name is not None:
                return strutils.to_slug(name)
        return None

    def _add_details(self, info):
        for (k, v) in info.items():
            try:
                setattr(self, k, v)
                self._info[k] = v
            except AttributeError:
                # In this case we already defined the attribute on the class
                pass

    def __getattr__(self, k):
        if k not in self.__dict__:
            # NOTE(bcwaldon): disallow lazy-loading if already loaded once
            if not self.is_loaded():
                self.get()
                return self.__getattr__(k)

            raise AttributeError(k)
        else:
            return self.__dict__[k]

    def get(self):
        """Support for lazy loading details.

        Some clients, such as novaclient have the option to lazy load the
        details, details which can be loaded with this function.
        """
        # set_loaded() first ... so if we have to bail, we know we tried.
        self.set_loaded(True)
        if not hasattr(self.manager, 'get'):
            return

        new = self.manager.get(self.id)
        if new:
            self._add_details(new._info)

    def __eq__(self, other):
        if not isinstance(other, Resource):
            return NotImplemented
        # two resources of different types are not equal
        if not isinstance(other, self.__class__):
            return False
        if hasattr(self, 'id') and hasattr(other, 'id'):
            return self.id == other.id
        return self._info == other._info

    def __ne__(self, other):
        return not self == other

    def is_loaded(self):
        return self._loaded

    def set_loaded(self, val):
        self._loaded = val

    def to_dict(self):
        return copy.deepcopy(self._info)
