# Copyright 2016 VMware, Inc.
# 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.

import abc
import inspect
import re
import time

from oslo_log import log
import tenacity
from tenacity import _utils as tenacity_utils

from vmware_nsxlib._i18n import _
from vmware_nsxlib.v3 import exceptions as nsxlib_exceptions

LOG = log.getLogger(__name__)

MAX_RESOURCE_TYPE_LEN = 20
MAX_TAG_LEN = 40
DEFAULT_MAX_ATTEMPTS = 10
DEFAULT_CACHE_AGE_SEC = 600
INJECT_HEADERS_CALLBACK = None
IS_ATTR_SET_CALLBACK = None


def set_is_attr_callback(callback):
    global IS_ATTR_SET_CALLBACK
    IS_ATTR_SET_CALLBACK = callback


def is_attr_set(attr):
    if IS_ATTR_SET_CALLBACK:
        return IS_ATTR_SET_CALLBACK(attr)
    return attr is not None


def set_inject_headers_callback(callback):
    global INJECT_HEADERS_CALLBACK
    INJECT_HEADERS_CALLBACK = callback


def _validate_resource_type_length(resource_type):
    # Add in a validation to ensure that we catch this at build time
    if len(resource_type) > MAX_RESOURCE_TYPE_LEN:
        raise nsxlib_exceptions.NsxLibInvalidInput(
            error_message=(_('Resource type cannot exceed %(max_len)s '
                             'characters: %(resource_type)s') %
                           {'max_len': MAX_RESOURCE_TYPE_LEN,
                            'resource_type': resource_type}))


def add_v3_tag(tags, resource_type, tag):
    _validate_resource_type_length(resource_type)
    tags.append({'scope': resource_type, 'tag': tag[:MAX_TAG_LEN]})
    return tags


def update_v3_tags(current_tags, tags_update):
    current_scopes = set([tag['scope'] for tag in current_tags])
    updated_scopes = set([tag['scope'] for tag in tags_update])

    # All tags scopes which are either completely new or already defined on the
    # resource are left in place, unless the tag value is empty, in that case
    # it is ignored.
    tags = [{'scope': tag['scope'], 'tag': tag['tag']}
            for tag in (current_tags + tags_update)
            if tag['tag'] and
            tag['scope'] in (current_scopes ^ updated_scopes)]

    modified_scopes = current_scopes & updated_scopes
    for tag in tags_update:
        if tag['scope'] in modified_scopes:
            # If the tag value is empty or None, then remove the tag completely
            if tag['tag']:
                tag['tag'] = tag['tag'][:MAX_TAG_LEN]
                tags.append(tag)

    return tags


def _log_before_retry(func, trial_number):
    """Before call strategy that logs to some logger the attempt."""
    if trial_number > 1:
        LOG.warning("Retrying call to '%(func)s' for the %(num)s time",
                    {'func': tenacity_utils.get_callback_name(func),
                     'num': tenacity_utils.to_ordinal(trial_number)})


def _get_args_from_frame(frames, frame_num):
    if len(frames) > frame_num and frames[frame_num] and frames[frame_num][0]:
        argvalues = inspect.getargvalues(frames[frame_num][0])
        formated_args = inspect.formatargvalues(*argvalues)
        # remove the first 'self' arg from the log as it adds no information
        formated_args = re.sub(r'\(self=.*?, ', "(", formated_args)
        return formated_args


def _log_after_retry(func, trial_number, trial_time_taken):
    """After call strategy that logs to some logger the finished attempt."""
    # Using inspect to get arguments of the relevant call
    frames = inspect.trace()
    # Look at frame #2 first because of the internal functions _do_X
    formated_args = _get_args_from_frame(frames, 2)
    if not formated_args:
        formated_args = _get_args_from_frame(frames, 1)
    if not formated_args:
        formated_args = "Unknown"

    LOG.warning("Finished retry of %(func)s for the %(num)s time after "
                "%(time)0.3f(s) with args: %(args)s",
                {'func': tenacity_utils.get_callback_name(func),
                 'num': tenacity_utils.to_ordinal(trial_number),
                 'time': trial_time_taken,
                 'args': formated_args})


def retry_upon_exception(exc, delay=0.5, max_delay=2,
                         max_attempts=DEFAULT_MAX_ATTEMPTS):
    return tenacity.retry(reraise=True,
                          retry=tenacity.retry_if_exception_type(exc),
                          wait=tenacity.wait_exponential(
                              multiplier=delay, max=max_delay),
                          stop=tenacity.stop_after_attempt(max_attempts),
                          before=_log_before_retry, after=_log_after_retry)


def list_match(list1, list2):
    # Check if list1 and list2 have identical elements, but relaxed on
    # dict elements where list1's dict element can be a subset of list2's
    # corresponding element.
    if (not isinstance(list1, list) or not isinstance(list2, list) or
        len(list1) != len(list2)):
        return False
    list1 = sorted(list1)
    list2 = sorted(list2)
    for (v1, v2) in zip(list1, list2):
        if isinstance(v1, dict):
            if not dict_match(v1, v2):
                return False
        elif isinstance(v1, list):
            if not list_match(v1, v2):
                return False
        elif v1 != v2:
            return False
    return True


def dict_match(dict1, dict2):
    # Check if dict1 is a subset of dict2.
    if not isinstance(dict1, dict) or not isinstance(dict2, dict):
        return False
    for k1, v1 in dict1.items():
        if k1 not in dict2:
            return False
        v2 = dict2[k1]
        if isinstance(v1, dict):
            if not dict_match(v1, v2):
                return False
        elif isinstance(v1, list):
            if not list_match(v1, v2):
                return False
        elif v1 != v2:
            return False
    return True


def get_name_and_uuid(name, uuid, tag=None, maxlen=80):
    short_uuid = '_' + uuid[:5] + '...' + uuid[-5:]
    maxlen = maxlen - len(short_uuid)
    if tag:
        maxlen = maxlen - len(tag) - 1
        return name[:maxlen] + '_' + tag + short_uuid
    else:
        return name[:maxlen] + short_uuid


def build_extra_args(body, extra_args, **kwargs):
    for arg in extra_args:
        if arg in kwargs:
            body[arg] = kwargs[arg]
    return body


def escape_tag_data(data):
    # ElasticSearch query_string requires slashes and dashes to
    # be escaped. We assume no other reserved characters will be
    # used in tag scopes or values
    return data.replace('/', '\\/').replace('-', '\\-')


class NsxLibCache(object):
    def __init__(self, timeout):
        self.timeout = timeout
        self._cache = {}
        super(NsxLibCache, self).__init__()

    def expired(self, entry):
        return (time.time() - entry['time']) > self.timeout

    def get(self, key):
        if key in self._cache:
            # check that the value is still valid
            if self.expired(self._cache[key]):
                # this entry has expired
                self.remove(key)
            else:
                return self._cache[key]['value']

    def update(self, key, value):
        self._cache[key] = {'time': time.time(),
                            'value': value}

    def remove(self, key):
        if key in self._cache:
            del self._cache[key]


class NsxLibApiBase(object):
    """Base class for nsxlib api """
    def __init__(self, client, nsxlib_config=None, nsxlib=None):
        self.client = client
        self.nsxlib_config = nsxlib_config
        self.nsxlib = nsxlib
        super(NsxLibApiBase, self).__init__()
        self.cache = NsxLibCache(self.cache_timeout)

    @abc.abstractproperty
    def uri_segment(self):
        pass

    @abc.abstractproperty
    def resource_type(self):
        pass

    @property
    def use_cache_for_get(self):
        """By default no caching is used"""
        return False

    @property
    def cache_timeout(self):
        """the default cache aging time in seconds"""
        return DEFAULT_CACHE_AGE_SEC

    def get_path(self, resource=None):
        if resource:
            return '%s/%s' % (self.uri_segment, resource)
        return self.uri_segment

    def list(self):
        return self.client.list(self.uri_segment)

    def get(self, uuid, silent=False):
        if self.use_cache_for_get:
            # try to get it from the cache
            result = self.cache.get(uuid)
            if result:
                if not silent:
                    LOG.debug("Getting %s from cache.", self.get_path(uuid))
                return result
        # call the client
        result = self.client.get(self.get_path(uuid), silent=silent)
        if result and self.use_cache_for_get:
            # add the result to the cache
            self.cache.update(uuid, result)
        return result

    def delete(self, uuid):
        if self.use_cache_for_get:
            self.cache.remove(uuid)
        return self.client.delete(self.get_path(uuid))

    def find_by_display_name(self, display_name):
        found = []
        for resource in self.list()['results']:
            if resource['display_name'] == display_name:
                found.append(resource)
        return found

    def _update_with_retry(self, uuid, payload):
        if self.use_cache_for_get:
            self.cache.remove(uuid)
        return self._update_resource_with_retry(self.get_path(uuid), payload)

    def _update_resource_with_retry(self, resource, payload):
        # Using internal method so we can access max_attempts in the decorator
        @retry_upon_exception(nsxlib_exceptions.StaleRevision,
                              max_attempts=self.nsxlib_config.max_attempts)
        def do_update():
            revised_payload = self.client.get(resource)
            for key_name in payload.keys():
                revised_payload[key_name] = payload[key_name]
            return self.client.update(resource, revised_payload)

        return do_update()

    def _get_resource_by_name_or_id(self, name_or_id, resource):
        all_results = self.client.list(resource)['results']
        matched_results = []
        for rs in all_results:
            if rs.get('id') == name_or_id:
                # Matched by id - must be unique
                return name_or_id

            if rs.get('display_name') == name_or_id:
                # Matched by name - add to the list to verify it is unique
                matched_results.append(rs)

        if len(matched_results) == 0:
            err_msg = (_("Could not find %(resource)s %(name)s") %
                       {'name': name_or_id, 'resource': resource})
            # TODO(aaron): improve exception handling...
            raise nsxlib_exceptions.ManagerError(details=err_msg)
        elif len(matched_results) > 1:
            err_msg = (_("Found multiple %(resource)s named %(name)s") %
                       {'name': name_or_id, 'resource': resource})
            # TODO(aaron): improve exception handling...
            raise nsxlib_exceptions.ManagerError(details=err_msg)

        return matched_results[0].get('id')

    def get_id_by_name_or_id(self, name_or_id):
        """Get a resource by it's display name or uuid

        Return the resource data, or raise an exception if not found or
        not unique
        """

        return self._get_resource_by_name_or_id(name_or_id,
                                                self.get_path())

    def build_v3_api_version_tag(self):
        """Some resources are created on the manager

        that do not have a corresponding plugin resource.

        """
        return [{'scope': self.nsxlib_config.plugin_scope,
                 'tag': self.nsxlib_config.plugin_tag},
                {'scope': "os-api-version",
                 'tag': self.nsxlib_config.plugin_ver}]

    def is_internal_resource(self, nsx_resource):
        """Indicates whether the passed nsx-resource is internal

        owned by the plugin for internal use.

        """
        for tag in nsx_resource.get('tags', []):
            if tag['scope'] == self.nsxlib_config.plugin_scope:
                return tag['tag'] == self.nsxlib_config.plugin_tag
        return False

    def build_v3_tags_payload(self, resource, resource_type, project_name):
        """Construct the tags payload that will be pushed to NSX-v3

        Add <resource_type>:<resource-id>, os-project-id:<project-id>,
        os-project-name:<project_name> os-api-version:<plugin-api-version>

        """
        _validate_resource_type_length(resource_type)
        # There may be cases when the plugin creates the port, for example DHCP
        if not project_name:
            project_name = self.nsxlib_config.plugin_tag
        project_id = (resource.get('project_id', '') or
                      resource.get('tenant_id', ''))
        # If project_id is present in resource and set to None, explicitly set
        # the project_id in tags as ''.
        if project_id is None:
            project_id = ''
        return [{'scope': resource_type,
                 'tag': resource.get('id', '')[:MAX_TAG_LEN]},
                {'scope': 'os-project-id',
                 'tag': project_id[:MAX_TAG_LEN]},
                {'scope': 'os-project-name',
                 'tag': project_name[:MAX_TAG_LEN]},
                {'scope': 'os-api-version',
                 'tag': self.nsxlib_config.plugin_ver}]