# -*- encoding: utf-8 -*-
# Copyright (c) 2016 b<>com
#
# 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:`Strategy <strategy_definition>` is an algorithm implementation which is
able to find a :ref:`Solution <solution_definition>` for a given
:ref:`Goal <goal_definition>`.

There may be several potential strategies which are able to achieve the same
:ref:`Goal <goal_definition>`. This is why it is possible to configure which
specific :ref:`Strategy <strategy_definition>` should be used for each goal.

Some strategies may provide better optimization results but may take more time
to find an optimal :ref:`Solution <solution_definition>`.
"""

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.common import utils as common_utils
from watcher.decision_engine import rpcapi
from watcher import objects


class Strategy(base.APIBase):
    """API representation of a strategy.

    This class enforces type checking and value constraints, and converts
    between the internal object model and the API representation of a strategy.
    """
    _goal_uuid = None
    _goal_name = None

    def _get_goal(self, value):
        if value == wtypes.Unset:
            return None
        goal = None
        try:
            if (common_utils.is_uuid_like(value) or
                    common_utils.is_int_like(value)):
                goal = objects.Goal.get(pecan.request.context, value)
            else:
                goal = objects.Goal.get_by_name(pecan.request.context, value)
        except exception.GoalNotFound:
            pass
        if goal:
            self.goal_id = goal.id
        return goal

    def _get_goal_uuid(self):
        return self._goal_uuid

    def _set_goal_uuid(self, value):
        if value and self._goal_uuid != value:
            self._goal_uuid = None
            goal = self._get_goal(value)
            if goal:
                self._goal_uuid = goal.uuid

    def _get_goal_name(self):
        return self._goal_name

    def _set_goal_name(self, value):
        if value and self._goal_name != value:
            self._goal_name = None
            goal = self._get_goal(value)
            if goal:
                self._goal_name = goal.name

    uuid = types.uuid
    """Unique UUID for this strategy"""

    name = wtypes.text
    """Name of the strategy"""

    display_name = wtypes.text
    """Localized name of the strategy"""

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

    goal_uuid = wsme.wsproperty(wtypes.text, _get_goal_uuid, _set_goal_uuid,
                                mandatory=True)
    """The UUID of the goal this audit refers to"""

    goal_name = wsme.wsproperty(wtypes.text, _get_goal_name, _set_goal_name,
                                mandatory=False)
    """The name of the goal this audit refers to"""

    parameters_spec = {wtypes.text: types.jsontype}
    """Parameters spec dict"""

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

        self.fields = []
        self.fields.append('uuid')
        self.fields.append('name')
        self.fields.append('display_name')
        self.fields.append('goal_uuid')
        self.fields.append('goal_name')
        self.fields.append('parameters_spec')
        setattr(self, 'uuid', kwargs.get('uuid', wtypes.Unset))
        setattr(self, 'name', kwargs.get('name', wtypes.Unset))
        setattr(self, 'display_name', kwargs.get('display_name', wtypes.Unset))
        setattr(self, 'goal_uuid', kwargs.get('goal_id', wtypes.Unset))
        setattr(self, 'goal_name', kwargs.get('goal_id', wtypes.Unset))
        setattr(self, 'parameters_spec', kwargs.get('parameters_spec',
                wtypes.Unset))

    @staticmethod
    def _convert_with_links(strategy, url, expand=True):
        if not expand:
            strategy.unset_fields_except(
                ['uuid', 'name', 'display_name', 'goal_uuid', 'goal_name'])

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

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

    @classmethod
    def sample(cls, expand=True):
        sample = cls(uuid='27e3153e-d5bf-4b7e-b517-fb518e17f34c',
                     name='DUMMY',
                     display_name='Dummy strategy')
        return cls._convert_with_links(sample, 'http://localhost:9322', expand)


class StrategyCollection(collection.Collection):
    """API representation of a collection of strategies."""

    strategies = [Strategy]
    """A list containing strategies objects"""

    def __init__(self, **kwargs):
        super(StrategyCollection, self).__init__()
        self._type = 'strategies'

    @staticmethod
    def convert_with_links(strategies, limit, url=None, expand=False,
                           **kwargs):
        strategy_collection = StrategyCollection()
        strategy_collection.strategies = [
            Strategy.convert_with_links(g, expand) for g in strategies]

        if 'sort_key' in kwargs:
            reverse = False
            if kwargs['sort_key'] == 'strategy':
                if 'sort_dir' in kwargs:
                    reverse = True if kwargs['sort_dir'] == 'desc' else False
                strategy_collection.strategies = sorted(
                    strategy_collection.strategies,
                    key=lambda strategy: strategy.uuid,
                    reverse=reverse)

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

    @classmethod
    def sample(cls):
        sample = cls()
        sample.strategies = [Strategy.sample(expand=False)]
        return sample


class StrategiesController(rest.RestController):
    """REST controller for Strategies."""
    def __init__(self):
        super(StrategiesController, self).__init__()

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

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

    def _get_strategies_collection(self, filters, marker, limit, sort_key,
                                   sort_dir, expand=False, resource_url=None):
        api_utils.validate_search_filters(
            filters, list(objects.strategy.Strategy.fields) +
            ["goal_uuid", "goal_name"])
        limit = api_utils.validate_limit(limit)
        api_utils.validate_sort_dir(sort_dir)

        sort_db_key = (sort_key if sort_key in objects.Strategy.fields
                       else None)

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

        strategies = objects.Strategy.list(
            pecan.request.context, limit, marker_obj, filters=filters,
            sort_key=sort_db_key, sort_dir=sort_dir)

        return StrategyCollection.convert_with_links(
            strategies, limit, url=resource_url, expand=expand,
            sort_key=sort_key, sort_dir=sort_dir)

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

        :param goal: goal UUID or name to filter by.
        :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: id.
        :param sort_dir: direction to sort. "asc" or "desc". Default: asc.
        """
        context = pecan.request.context
        policy.enforce(context, 'strategy:get_all',
                       action='strategy:get_all')
        filters = {}
        if goal:
            if common_utils.is_uuid_like(goal):
                filters['goal_uuid'] = goal
            else:
                filters['goal_name'] = goal

        return self._get_strategies_collection(
            filters, marker, limit, sort_key, sort_dir)

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

        :param goal: goal UUID or name to filter by.
        :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: id.
        :param sort_dir: direction to sort. "asc" or "desc". Default: asc.
        """
        context = pecan.request.context
        policy.enforce(context, 'strategy:detail',
                       action='strategy:detail')
        # NOTE(lucasagomes): /detail should only work agaist collections
        parent = pecan.request.path.split('/')[:-1][-1]
        if parent != "strategies":
            raise exception.HTTPNotFound
        expand = True
        resource_url = '/'.join(['strategies', 'detail'])

        filters = {}
        if goal:
            if common_utils.is_uuid_like(goal):
                filters['goal_uuid'] = goal
            else:
                filters['goal_name'] = goal

        return self._get_strategies_collection(
            filters, marker, limit, sort_key, sort_dir, expand, resource_url)

    @wsme_pecan.wsexpose(wtypes.text, wtypes.text)
    def state(self, strategy):
        """Retrieve a inforamation about strategy requirements.

        :param strategy: name of the strategy.
        """
        context = pecan.request.context
        policy.enforce(context, 'strategy:state', action='strategy:state')
        parents = pecan.request.path.split('/')[:-1]
        if parents[-2] != "strategies":
            raise exception.HTTPNotFound
        rpc_strategy = api_utils.get_resource('Strategy', strategy)
        de_client = rpcapi.DecisionEngineAPI()
        strategy_state = de_client.get_strategy_info(context,
                                                     rpc_strategy.name)
        strategy_state.extend([{
            'type': 'Name', 'state': rpc_strategy.name,
            'mandatory': '', 'comment': ''}])
        return strategy_state

    @wsme_pecan.wsexpose(Strategy, wtypes.text)
    def get_one(self, strategy):
        """Retrieve information about the given strategy.

        :param strategy: UUID or name of the strategy.
        """
        if self.from_strategies:
            raise exception.OperationNotPermitted

        context = pecan.request.context
        rpc_strategy = api_utils.get_resource('Strategy', strategy)
        policy.enforce(context, 'strategy:get', rpc_strategy,
                       action='strategy:get')

        return Strategy.convert_with_links(rpc_strategy)
