# Copyright 2011 Citrix System.
# 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 urllib

from oslo_config import cfg
from oslo_log import log as logging
from webob import exc

from neutron.common import constants
from neutron.common import exceptions
from neutron.i18n import _LW


LOG = logging.getLogger(__name__)


def get_filters(request, attr_info, skips=[]):
    """Extracts the filters from the request string.

    Returns a dict of lists for the filters:
    check=a&check=b&name=Bob&
    becomes:
    {'check': [u'a', u'b'], 'name': [u'Bob']}
    """
    res = {}
    for key, values in request.GET.dict_of_lists().iteritems():
        if key in skips:
            continue
        values = [v for v in values if v]
        key_attr_info = attr_info.get(key, {})
        if 'convert_list_to' in key_attr_info:
            values = key_attr_info['convert_list_to'](values)
        elif 'convert_to' in key_attr_info:
            convert_to = key_attr_info['convert_to']
            values = [convert_to(v) for v in values]
        if values:
            res[key] = values
    return res


def get_previous_link(request, items, id_key):
    params = request.GET.copy()
    params.pop('marker', None)
    if items:
        marker = items[0][id_key]
        params['marker'] = marker
    params['page_reverse'] = True
    return "%s?%s" % (request.path_url, urllib.urlencode(params))


def get_next_link(request, items, id_key):
    params = request.GET.copy()
    params.pop('marker', None)
    if items:
        marker = items[-1][id_key]
        params['marker'] = marker
    params.pop('page_reverse', None)
    return "%s?%s" % (request.path_url, urllib.urlencode(params))


def get_limit_and_marker(request):
    """Return marker, limit tuple from request.

    :param request: `wsgi.Request` possibly containing 'marker' and 'limit'
                    GET variables. 'marker' is the id of the last element
                    the client has seen, and 'limit' is the maximum number
                    of items to return. If limit == 0, it means we needn't
                    pagination, then return None.
    """
    max_limit = _get_pagination_max_limit()
    limit = _get_limit_param(request, max_limit)
    if max_limit > 0:
        limit = min(max_limit, limit) or max_limit
    if not limit:
        return None, None
    marker = request.GET.get('marker', None)
    return limit, marker


def _get_pagination_max_limit():
    max_limit = -1
    if (cfg.CONF.pagination_max_limit.lower() !=
        constants.PAGINATION_INFINITE):
        try:
            max_limit = int(cfg.CONF.pagination_max_limit)
            if max_limit == 0:
                raise ValueError()
        except ValueError:
            LOG.warn(_LW("Invalid value for pagination_max_limit: %s. It "
                         "should be an integer greater to 0"),
                     cfg.CONF.pagination_max_limit)
    return max_limit


def _get_limit_param(request, max_limit):
    """Extract integer limit from request or fail."""
    try:
        limit = int(request.GET.get('limit', 0))
        if limit >= 0:
            return limit
    except ValueError:
        pass
    msg = _("Limit must be an integer 0 or greater and not '%d'")
    raise exceptions.BadRequest(resource='limit', msg=msg)


def list_args(request, arg):
    """Extracts the list of arg from request."""
    return [v for v in request.GET.getall(arg) if v]


def get_sorts(request, attr_info):
    """Extract sort_key and sort_dir from request.

    Return as: [(key1, value1), (key2, value2)]
    """
    sort_keys = list_args(request, "sort_key")
    sort_dirs = list_args(request, "sort_dir")
    if len(sort_keys) != len(sort_dirs):
        msg = _("The number of sort_keys and sort_dirs must be same")
        raise exc.HTTPBadRequest(explanation=msg)
    valid_dirs = [constants.SORT_DIRECTION_ASC, constants.SORT_DIRECTION_DESC]
    absent_keys = [x for x in sort_keys if x not in attr_info]
    if absent_keys:
        msg = _("%s is invalid attribute for sort_keys") % absent_keys
        raise exc.HTTPBadRequest(explanation=msg)
    invalid_dirs = [x for x in sort_dirs if x not in valid_dirs]
    if invalid_dirs:
        msg = (_("%(invalid_dirs)s is invalid value for sort_dirs, "
                 "valid value is '%(asc)s' and '%(desc)s'") %
               {'invalid_dirs': invalid_dirs,
                'asc': constants.SORT_DIRECTION_ASC,
                'desc': constants.SORT_DIRECTION_DESC})
        raise exc.HTTPBadRequest(explanation=msg)
    return zip(sort_keys,
               [x == constants.SORT_DIRECTION_ASC for x in sort_dirs])


def get_page_reverse(request):
    data = request.GET.get('page_reverse', 'False')
    return data.lower() == "true"


def get_pagination_links(request, items, limit,
                         marker, page_reverse, key="id"):
    key = key if key else 'id'
    links = []
    if not limit:
        return links
    if not (len(items) < limit and not page_reverse):
        links.append({"rel": "next",
                      "href": get_next_link(request, items,
                                            key)})
    if not (len(items) < limit and page_reverse):
        links.append({"rel": "previous",
                      "href": get_previous_link(request, items,
                                                key)})
    return links


class PaginationHelper(object):

    def __init__(self, request, primary_key='id'):
        self.request = request
        self.primary_key = primary_key

    def update_fields(self, original_fields, fields_to_add):
        pass

    def update_args(self, args):
        pass

    def paginate(self, items):
        return items

    def get_links(self, items):
        return {}


class PaginationEmulatedHelper(PaginationHelper):

    def __init__(self, request, primary_key='id'):
        super(PaginationEmulatedHelper, self).__init__(request, primary_key)
        self.limit, self.marker = get_limit_and_marker(request)
        self.page_reverse = get_page_reverse(request)

    def update_fields(self, original_fields, fields_to_add):
        if not original_fields:
            return
        if self.primary_key not in original_fields:
            original_fields.append(self.primary_key)
            fields_to_add.append(self.primary_key)

    def paginate(self, items):
        if not self.limit:
            return items
        i = -1
        if self.marker:
            for item in items:
                i = i + 1
                if item[self.primary_key] == self.marker:
                    break
        if self.page_reverse:
            return items[i - self.limit:i]
        return items[i + 1:i + self.limit + 1]

    def get_links(self, items):
        return get_pagination_links(
            self.request, items, self.limit, self.marker,
            self.page_reverse, self.primary_key)


class PaginationNativeHelper(PaginationEmulatedHelper):

    def update_args(self, args):
        if self.primary_key not in dict(args.get('sorts', [])).keys():
            args.setdefault('sorts', []).append((self.primary_key, True))
        args.update({'limit': self.limit, 'marker': self.marker,
                     'page_reverse': self.page_reverse})

    def paginate(self, items):
        return items


class NoPaginationHelper(PaginationHelper):
    pass


class SortingHelper(object):

    def __init__(self, request, attr_info):
        pass

    def update_args(self, args):
        pass

    def update_fields(self, original_fields, fields_to_add):
        pass

    def sort(self, items):
        return items


class SortingEmulatedHelper(SortingHelper):

    def __init__(self, request, attr_info):
        super(SortingEmulatedHelper, self).__init__(request, attr_info)
        self.sort_dict = get_sorts(request, attr_info)

    def update_fields(self, original_fields, fields_to_add):
        if not original_fields:
            return
        for key in dict(self.sort_dict).keys():
            if key not in original_fields:
                original_fields.append(key)
                fields_to_add.append(key)

    def sort(self, items):
        def cmp_func(obj1, obj2):
            for key, direction in self.sort_dict:
                ret = cmp(obj1[key], obj2[key])
                if ret:
                    return ret * (1 if direction else -1)
            return 0
        return sorted(items, cmp=cmp_func)


class SortingNativeHelper(SortingHelper):

    def __init__(self, request, attr_info):
        self.sort_dict = get_sorts(request, attr_info)

    def update_args(self, args):
        args['sorts'] = self.sort_dict


class NoSortingHelper(SortingHelper):
    pass


class NeutronController(object):
    """Base controller class for Neutron API."""
    # _resource_name will be redefined in sub concrete controller
    _resource_name = None

    def __init__(self, plugin):
        self._plugin = plugin
        super(NeutronController, self).__init__()

    def _prepare_request_body(self, body, params):
        """Verifies required parameters are in request body.

        Sets default value for missing optional parameters.
        Body argument must be the deserialized body.
        """
        try:
            if body is None:
                # Initialize empty resource for setting default value
                body = {self._resource_name: {}}
            data = body[self._resource_name]
        except KeyError:
            # raise if _resource_name is not in req body.
            raise exc.HTTPBadRequest(_("Unable to find '%s' in request body") %
                                     self._resource_name)
        for param in params:
            param_name = param['param-name']
            param_value = data.get(param_name)
            # If the parameter wasn't found and it was required, return 400
            if param_value is None and param['required']:
                msg = (_("Failed to parse request. "
                         "Parameter '%s' not specified") % param_name)
                LOG.error(msg)
                raise exc.HTTPBadRequest(msg)
            data[param_name] = param_value or param.get('default-value')
        return body
