% 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.

-module(mango_idx_special).


-export([
    validate/1,
    add/2,
    remove/2,
    from_ddoc/1,
    to_json/1,
    columns/1,
    is_usable/2,
    start_key/1,
    end_key/1
]).


-include_lib("couch/include/couch_db.hrl").
-include("mango_idx.hrl").


validate(_) ->
    erlang:exit(invalid_call).


add(_, _) ->
    erlang:exit(invalid_call).


remove(_, _) ->
    erlang:exit(invalid_call).


from_ddoc(_) ->
    erlang:exit(invalid_call).


to_json(#idx{def=all_docs}) ->
    {[
        {ddoc, null},
        {name, <<"_all_docs">>},
        {type, <<"special">>},
        {def, {[
            {<<"fields">>, [{[
                {<<"_id">>, <<"asc">>}
            ]}]}
        ]}}
    ]}.


columns(#idx{def=all_docs}) ->
    [<<"_id">>].


is_usable(#idx{def=all_docs}, Selector) ->
    Fields = mango_idx_view:indexable_fields(Selector),
    lists:member(<<"_id">>, Fields).


start_key([{'$gt', Key, _, _}]) ->
    case mango_json:special(Key) of
        true ->
            ?MIN_STR;
        false ->
            Key
    end;
start_key([{'$gte', Key, _, _}]) ->
    false = mango_json:special(Key),
    Key;
start_key([{'$eq', Key, '$eq', Key}]) ->
    false = mango_json:special(Key),
    Key.


end_key([{_, _, '$lt', Key}]) ->
    case mango_json:special(Key) of
        true ->
            ?MAX_STR;
        false ->
            Key
    end;
end_key([{_, _, '$lte', Key}]) ->
    false = mango_json:special(Key),
    Key;
end_key([{'$eq', Key, '$eq', Key}]) ->
    false = mango_json:special(Key),
    Key.