%%-----------------------------------------------------------------------------
%% Copyright (c) 2012-2015, Feng Lee <feng@emqtt.io>
%% 
%% Permission is hereby granted, free of charge, to any person obtaining a copy
%% of this software and associated documentation files (the "Software"), to deal
%% in the Software without restriction, including without limitation the rights
%% to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
%% copies of the Software, and to permit persons to whom the Software is
%% furnished to do so, subject to the following conditions:
%% 
%% The above copyright notice and this permission notice shall be included in all
%% copies or substantial portions of the Software.
%% 
%% THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
%% IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
%% FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
%% AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
%% LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
%% OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
%% SOFTWARE.
%%------------------------------------------------------------------------------
-module(emqtt_queue).

-include("emqtt.hrl").

-export([new/1, new/2, in/3, all/1, clear/1]).

%%----------------------------------------------------------------------------

-ifdef(use_specs).

-type(mqtt_queue() :: #mqtt_queue_wrapper{}).

-spec(new(non_neg_intger()) -> mqtt_queue()).

-spec(in(binary(), mqtt_message(), mqtt_queue()) -> mqtt_queue()).

-spec(all(mqtt_queue()) -> list()).

-spec(clear(mqtt_queue()) -> mqtt_queue()).

-endif.

%%----------------------------------------------------------------------------

-define(DEFAULT_MAX_LEN, 1000).

-record(mqtt_queue_wrapper, { queue = queue:new(), max_len = ?DEFAULT_MAX_LEN, store_qos0 = false }). 

new(MaxLen) -> #mqtt_queue_wrapper{ max_len = MaxLen }.

new(MaxLen, StoreQos0) -> #mqtt_queue_wrapper{ max_len = MaxLen, store_qos0 = StoreQos0 }.

in(ClientId, Message = #mqtt_message{qos = Qos}, 
    Wrapper = #mqtt_queue_wrapper{ queue = Queue, max_len = MaxLen}) ->
    case queue:len(Queue) < MaxLen of
        true -> 
            Wrapper#mqtt_queue_wrapper{ queue = queue:in(Message, Queue) };
        false -> % full
            if
                Qos =:= ?QOS_0 ->
                    lager:warning("Queue ~s drop qos0 message: ~p", [ClientId, Message]),
                    Wrapper;
                true ->
                    {{value, Msg}, Queue1} = queue:drop(Queue),
                    lager:warning("Queue ~s drop message: ~p", [ClientId, Msg]),
                    Wrapper#mqtt_queue_wrapper{ queue = Queue1 }
            end
    end.

all(#mqtt_queue_wrapper { queue = Queue }) -> queue:to_list(Queue).

clear(Queue) -> Queue#mqtt_queue_wrapper{ queue = queue:new() }.