epns

%% MIT License

%% Copyright (c) 2021 Viacheslav Katsuba <v.katsuba.dev@gmail.com>

%% 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(epns_apns).

%%% ==================================================================
%%% Macro
%%% ==================================================================

-define(COMMAND_REQ, 1).
-define(COMMAND_RESP, 8).
-define(EXPIRY, (os:system_time(second) + 604800)).
-define(TOKEN_LENGTH, 32).
-define(TIMEOUT, 500).

%%% ==================================================================
%%% API
%%% ==================================================================

-export([push/1, recv/2]).

%% -------------------------------------------------------------------
%% @doc
%% Send APNS push notification
%% @end
%% -------------------------------------------------------------------
-spec push(Data :: maps:map()) -> Result :: tuple().

push(#{playload := P, key := K, cert := C, url := U, token := T}) ->
    case ssl:connect(U, 2195, [{certfile, C}, {keyfile, K}, {mode, binary}, {verify, verify_none}], ?TIMEOUT) of
        {ok, Socket} ->
            ID = rand:uniform(9999),
            Payload = jiffy:encode(P),
            PayloadLen = erlang:byte_size(Payload),
            DeviceToken = binary_to_integer(T, 16),
            Packet = <<?COMMAND_REQ:8, ID:32/big, ?EXPIRY:4/big-unsigned-integer-unit:8,
            ?TOKEN_LENGTH:16/big, DeviceToken:256/integer, PayloadLen:16/big, Payload/binary>>,
            ssl:send(Socket, Packet),
            ssl:close(Socket, 0),
            {ok, apns};
        {error, Reason} ->
            {error, Reason}
    end.

%% -------------------------------------------------------------------
%% @doc
%% Receive errors of APNS
%% Use inside of push/1: ssl:controlling_process(Socket, spawn(fun() -> recv(self(), 100) end))
%% @end
%% -------------------------------------------------------------------
-spec recv(Pid :: pid(), Timeout :: integer()) -> Result :: term().

recv(Pid, Timeout) ->
    receive
        {ssl, Sock, <<?COMMAND_RESP:8, Status, UserID:32/big>>} ->
            io:format("APNS Error: [~p:~p/1]: Reason: ~p, message ID: ~p~n", [?MODULE, push, convert_status(Status), UserID]),
            ssl:close(Sock),
            Pid ! {error, UserID};
        {ssl_closed, _} -> ok
            after Timeout -> exit(Pid, normal)
    end.

%% -------------------------------------------------------------------
%% @private
%% @doc
%% Handler for status code of response from APNS
%% @end
%% -------------------------------------------------------------------
-spec convert_status(StatusCode :: integer()) -> Result :: binary().

convert_status(0) ->
    <<"no errors">>;
convert_status(1) ->
    <<"processing error">>;
convert_status(2) ->
    <<"missing device token">>;
convert_status(3) ->
    <<"missing topic">>;
convert_status(4) ->
    <<"missing payload">>;
convert_status(5) ->
    <<"invalid token size">>;
convert_status(6) ->
    <<"invalid topic size">>;
convert_status(7) ->
    <<"invalid payload size">>;
convert_status(8) ->
    <<"invalid token">>;
convert_status(10) ->
    <<"shutdown">>;
convert_status(128) ->
    <<"protocol error">>;
convert_status(255) ->
    <<"unknown">>.