# -*- encoding: utf-8 -*-
# Copyright 2016 Intel
# 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.

"""
A :ref:`Scoring Engine <scoring_engine_definition>` is an executable that has
a well-defined input, a well-defined output, and performs a purely mathematical
task. That is, the calculation does not depend on the environment in which it
is running - it would produce the same result anywhere.

Because there might be multiple algorithms used to build a particular data
model (and therefore a scoring engine), the usage of scoring engine might
vary. A metainfo field is supposed to contain any information which might
be needed by the user of a given scoring engine.
"""

import pecan
from pecan import rest
import wsme
from wsme import types as wtypes
import wsmeext.pecan as wsme_pecan

from watcher.api.controllers import base
from watcher.api.controllers import link
from watcher.api.controllers.v1 import collection
from watcher.api.controllers.v1 import types
from watcher.api.controllers.v1 import utils as api_utils
from watcher.common import exception
from watcher.common import policy
from watcher import objects


class ScoringEngine(base.APIBase):
    """API representation of a scoring engine.

    This class enforces type checking and value constraints, and converts
    between the internal object model and the API representation of a scoring
    engine.
    """

    uuid = types.uuid
    """Unique UUID of the scoring engine"""

    name = wtypes.text
    """The name of the scoring engine"""

    description = wtypes.text
    """A human readable description of the Scoring Engine"""

    metainfo = wtypes.text
    """A metadata associated with the scoring engine"""

    links = wsme.wsattr([link.Link], readonly=True)
    """A list containing a self link and associated action links"""

    def __init__(self, **kwargs):
        super(ScoringEngine, self).__init__()

        self.fields = []
        self.fields.append('uuid')
        self.fields.append('name')
        self.fields.append('description')
        self.fields.append('metainfo')
        setattr(self, 'uuid', kwargs.get('uuid', wtypes.Unset))
        setattr(self, 'name', kwargs.get('name', wtypes.Unset))
        setattr(self, 'description', kwargs.get('description', wtypes.Unset))
        setattr(self, 'metainfo', kwargs.get('metainfo', wtypes.Unset))

    @staticmethod
    def _convert_with_links(se, url, expand=True):
        if not expand:
            se.unset_fields_except(
                ['uuid', 'name', 'description', 'metainfo'])

        se.links = [link.Link.make_link('self', url,
                                        'scoring_engines', se.uuid),
                    link.Link.make_link('bookmark', url,
                                        'scoring_engines', se.uuid,
                                        bookmark=True)]
        return se

    @classmethod
    def convert_with_links(cls, scoring_engine, expand=True):
        scoring_engine = ScoringEngine(**scoring_engine.as_dict())
        return cls._convert_with_links(
            scoring_engine, pecan.request.host_url, expand)

    @classmethod
    def sample(cls, expand=True):
        sample = cls(uuid='81bbd3c7-3b08-4d12-a268-99354dbf7b71',
                     name='sample-se-123',
                     description='Sample Scoring Engine 123 just for testing')
        return cls._convert_with_links(sample, 'http://localhost:9322', expand)


class ScoringEngineCollection(collection.Collection):
    """API representation of a collection of scoring engines."""

    scoring_engines = [ScoringEngine]
    """A list containing scoring engine objects"""

    def __init__(self, **kwargs):
        super(ScoringEngineCollection, self).__init__()
        self._type = 'scoring_engines'

    @staticmethod
    def convert_with_links(scoring_engines, limit, url=None, expand=False,
                           **kwargs):

        collection = ScoringEngineCollection()
        collection.scoring_engines = [ScoringEngine.convert_with_links(
            se, expand) for se in scoring_engines]

        if 'sort_key' in kwargs:
            reverse = False
            if kwargs['sort_key'] == 'name':
                if 'sort_dir' in kwargs:
                    reverse = True if kwargs['sort_dir'] == 'desc' else False
                collection.goals = sorted(
                    collection.scoring_engines,
                    key=lambda se: se.name,
                    reverse=reverse)

        collection.next = collection.get_next(limit, url=url, **kwargs)
        return collection

    @classmethod
    def sample(cls):
        sample = cls()
        sample.scoring_engines = [ScoringEngine.sample(expand=False)]
        return sample


class ScoringEngineController(rest.RestController):
    """REST controller for Scoring Engines."""
    def __init__(self):
        super(ScoringEngineController, self).__init__()

    from_scoring_engines = False
    """A flag to indicate if the requests to this controller are coming
    from the top-level resource Scoring Engines."""

    _custom_actions = {
        'detail': ['GET'],
    }

    def _get_scoring_engines_collection(self, marker, limit,
                                        sort_key, sort_dir, expand=False,
                                        resource_url=None):

        limit = api_utils.validate_limit(limit)
        api_utils.validate_sort_dir(sort_dir)

        marker_obj = None
        if marker:
            marker_obj = objects.ScoringEngine.get_by_uuid(
                pecan.request.context, marker)

        filters = {}

        sort_db_key = sort_key

        scoring_engines = objects.ScoringEngine.list(
            context=pecan.request.context,
            limit=limit,
            marker=marker_obj,
            sort_key=sort_db_key,
            sort_dir=sort_dir,
            filters=filters)

        return ScoringEngineCollection.convert_with_links(
            scoring_engines,
            limit,
            url=resource_url,
            expand=expand,
            sort_key=sort_key,
            sort_dir=sort_dir)

    @wsme_pecan.wsexpose(ScoringEngineCollection, wtypes.text,
                         int, wtypes.text, wtypes.text)
    def get_all(self, marker=None, limit=None, sort_key='id',
                sort_dir='asc'):
        """Retrieve a list of Scoring Engines.

        :param marker: pagination marker for large data sets.
        :param limit: maximum number of resources to return in a single result.
        :param sort_key: column to sort results by. Default: name.
        :param sort_dir: direction to sort. "asc" or "desc". Default: asc.
        """
        context = pecan.request.context
        policy.enforce(context, 'scoring_engine:get_all',
                       action='scoring_engine:get_all')

        return self._get_scoring_engines_collection(
            marker, limit, sort_key, sort_dir)

    @wsme_pecan.wsexpose(ScoringEngineCollection, wtypes.text,
                         int, wtypes.text, wtypes.text)
    def detail(self, marker=None, limit=None, sort_key='id', sort_dir='asc'):
        """Retrieve a list of Scoring Engines with detail.

        :param marker: pagination marker for large data sets.
        :param limit: maximum number of resources to return in a single result.
        :param sort_key: column to sort results by. Default: name.
        :param sort_dir: direction to sort. "asc" or "desc". Default: asc.
        """
        context = pecan.request.context
        policy.enforce(context, 'scoring_engine:detail',
                       action='scoring_engine:detail')

        parent = pecan.request.path.split('/')[:-1][-1]
        if parent != "scoring_engines":
            raise exception.HTTPNotFound
        expand = True
        resource_url = '/'.join(['scoring_engines', 'detail'])
        return self._get_scoring_engines_collection(
            marker, limit, sort_key, sort_dir, expand, resource_url)

    @wsme_pecan.wsexpose(ScoringEngine, wtypes.text)
    def get_one(self, scoring_engine):
        """Retrieve information about the given Scoring Engine.

        :param scoring_engine_name: The name of the Scoring Engine.
        """
        context = pecan.request.context
        policy.enforce(context, 'scoring_engine:get',
                       action='scoring_engine:get')

        if self.from_scoring_engines:
            raise exception.OperationNotPermitted

        rpc_scoring_engine = api_utils.get_resource(
            'ScoringEngine', scoring_engine)

        return ScoringEngine.convert_with_links(rpc_scoring_engine)
