Commands refactor, first pass.

- add API versionning
- changed error handling, based on exception
- commands moved/merged from mod_admin_p1 to mod_admin_extra
- command bufixes
- add some elixir unit test cases

Squashed commit of the following:

commit dd59855b3486f78a9349756e4f102e79b3accff8
Merge: 14e8ffc 506e08e
Author: Jerome Sautret <jerome.sautret@process-one.net>
Date:   Fri Oct 30 11:43:18 2015 +0100

    Merge branch '3.2.x' into api

commit 14e8ffce78cbea6c8605371d1fc50a0c1d1e012c
Author: Jerome Sautret <jerome.sautret@process-one.net>
Date:   Tue Oct 27 16:35:17 2015 +0100

    Added OAuth tests to ejabberd_commands

commit f81c550c14628edfe4861c228576cb767924366a
Author: Jerome Sautret <jerome.sautret@process-one.net>
Date:   Tue Oct 27 16:34:55 2015 +0100

    Added some mod_http_api tests

commit 6a64578d5b2ba532a2feb6503ed98561e56d5d53
Author: Jerome Sautret <jerome.sautret@process-one.net>
Date:   Mon Oct 26 15:29:36 2015 +0100

    Fix get_last command test

    Previous version won't work with dst.

commit 27e0cde9e9c1f001effe68f8424a365ad947c068
Author: Jerome Sautret <jerome.sautret@process-one.net>
Date:   Fri Oct 23 17:59:34 2015 +0200

    Add tests on admin command policy

commit 19dad8d54f54c9fabd454280483cccfb06c8e78a
Author: Jerome Sautret <jerome.sautret@process-one.net>
Date:   Fri Oct 23 16:49:36 2015 +0200

    Added command related tests (http api & user policy)

commit e0e596ab4a3f3a70aba5f374f028939ab794de33
Author: Jerome Sautret <jerome.sautret@process-one.net>
Date:   Fri Oct 23 16:49:16 2015 +0200

    Fix command call.

commit 128cd7d1ede3c47a34f8ec3a750c980ccad2c61d
Merge: 60c4c4c 447313c
Author: Jerome Sautret <jerome.sautret@process-one.net>
Date:   Thu Oct 22 14:48:39 2015 +0200

    Merge branch '3.2.x' into api

commit 60c4c4c0751302524c14219c6bc8c56a6069a689
Author: Jerome Sautret <jerome.sautret@process-one.net>
Date:   Thu Oct 22 14:45:57 2015 +0200

    Fix ejabberd_commands spec.

commit 8e145c28c5da762c2b93ee32327eff1db94ebfed
Merge: 397273a f13dc94
Author: Jerome Sautret <jerome.sautret@process-one.net>
Date:   Wed Oct 21 18:26:07 2015 +0200

    Merge branch '3.2.x' into api

commit 397273a23ed415feac87aed33da6452229793387
Merge: c30e89b f289e27
Author: Jerome Sautret <jerome.sautret@process-one.net>
Date:   Wed Oct 21 15:27:45 2015 +0200

    Merge branch '3.2.x' into api

commit c30e89bb8a0013bff37e61e4c6953350c9c1f313
Author: Jerome Sautret <jerome.sautret@process-one.net>
Date:   Wed Oct 21 12:47:02 2015 +0200

    Merge mod_http_api

commit 7b0db22b4acd48ff6fabce41c1b2525e6580a3c5
Author: Jerome Sautret <jerome.sautret@process-one.net>
Date:   Fri Oct 16 11:55:48 2015 +0200

    Fix exunit tests to run with common_test suites

commit d8b1a89800ac7379a57a7eb4a09c3c93c3e1e5eb
Merge: 2879ae8 63455b3
Author: Jerome Sautret <jerome.sautret@process-one.net>
Date:   Thu Oct 15 11:39:45 2015 +0200

    Merge branch '3.2.x' into api

commit 2879ae87ff3eee369ef3d780136b96ecff5285d1
Author: Jerome Sautret <jerome.sautret@process-one.net>
Date:   Wed Oct 14 14:53:44 2015 +0200

    Fix update_roster command.

commit a1d453dd7a3afda9861a8d747494a45057ad574b
Author: Jerome Sautret <jerome.sautret@process-one.net>
Date:   Tue Oct 13 16:14:28 2015 +0200

    API commands refactor

    Moving and/or merging commands from mod_admin_p1 to mod_admin_extra

commit b709ed26b0fc0ca4f3bdd5a59fa58ec7e3db97fa
Author: Jerome Sautret <jerome.sautret@process-one.net>
Date:   Wed Oct 7 15:10:01 2015 +0200

    Add tests on commands

commit 6711687bee9c672cb3d5aed0744e13420ecf6dbd
Author: Jerome Sautret <jerome.sautret@process-one.net>
Date:   Tue Sep 29 15:58:16 2015 +0200

    Add ejabberd_commands tests

commit df8682f419cf3877e77e36a19bca0fc55dc991f8
Author: Jerome Sautret <jerome.sautret@process-one.net>
Date:   Mon Sep 28 14:54:39 2015 +0200

    Added API versioning for ejabberdctl and rest commands

commit cd017b0e3aac431bc3ee807ceb7f8641e1523ef5
Author: Jerome Sautret <jerome.sautret@process-one.net>
Date:   Fri Sep 18 11:21:45 2015 +0200

    Better error handling of HTTP API commands.

commit ca5cb6acd8e4643f9d6c484d2277b0d7e88471e5
Author: Jerome Sautret <jerome.sautret@process-one.net>
Date:   Tue Sep 15 15:03:05 2015 +0200

    add commands to mod_admin_extra:
    - get_offline_count
    - get_presence
    - change_password

commit 7f583fa099e30ac2b0915669fd8f102ac565b833
Author: Jerome Sautret <jerome.sautret@process-one.net>
Date:   Tue Sep 15 15:02:16 2015 +0200

    Improve REST API error handling

commit 14753b1c02cdce434a786b7f80f6c09f0d210075
Author: Jerome Sautret <jerome.sautret@process-one.net>
Date:   Mon Sep 14 10:51:17 2015 +0200

    Change REST API return codes for integer type.

1 files changed, 106 insertions, 54 deletions

diff --git a/src/mod_http_api.erl b/src/mod_http_api.erl
index 15fe36364..f2b7a484b 100644
--- a/src/mod_http_api.erl
+++ b/src/mod_http_api.erl
@@ -29,6 +29,11 @@
 %%    request_handlers:
 %%      "/api": mod_http_api
 %%
+%% To use a specific API version N, add a vN element in the URL path:
+%%  in ejabberd_http listener
+%%    request_handlers:
+%%      "/api/v2": mod_http_api
+%%
 %% Access rights are defined with:
 %% commands_admin_access: configure
 %% commands:
@@ -76,6 +81,8 @@
 -include("logger.hrl").
 -include("ejabberd_http.hrl").
 
+-define(DEFAULT_API_VERSION, 0).
+
 -define(CT_PLAIN,
         {<<"Content-Type">>, <<"text/plain">>}).
 
@@ -179,7 +186,8 @@ check_permissions2(#request{ip={IP, _Port}}, Call) ->
                 true -> {allowed, Call, admin};
                 _ -> unauthorized_response()
             end;
-        _ ->
+        _E ->
+	    ?DEBUG("Unauthorized: ~p", [_E]),
             unauthorized_response()
     end.
 
@@ -192,10 +200,13 @@ oauth_check_token(Scope, Token) ->
 %% command processing
 %% ------------------
 
+%process(Call, Request) ->
+%    ?DEBUG("~p~n~p", [Call, Request]), ok;
 process(_, #request{method = 'POST', data = <<>>}) ->
     ?DEBUG("Bad Request: no data", []),
-    badrequest_response();
+    badrequest_response(<<"Missing POST data">>);
 process([Call], #request{method = 'POST', data = Data, ip = IP} = Req) ->
+    Version = get_api_version(Req),
     try
         Args = case jiffy:decode(Data) of
             List when is_list(List) -> List;
@@ -205,16 +216,20 @@ process([Call], #request{method = 'POST', data = Data, ip = IP} = Req) ->
         log(Call, Args, IP),
         case check_permissions(Req, Call) of
             {allowed, Cmd, Auth} ->
-                {Code, Result} = handle(Cmd, Auth, Args),
+                {Code, Result} = handle(Cmd, Auth, Args, Version),
                 json_response(Code, jiffy:encode(Result));
             ErrorResponse -> %% Should we reply 403 ?
                 ErrorResponse
         end
-    catch _:Error ->
-        ?DEBUG("Bad Request: ~p", [Error]),
+    catch _:{error,{_,invalid_json}} = _Err ->
+	    ?DEBUG("Bad Request: ~p", [_Err]),
+	    badrequest_response(<<"Invalid JSON input">>);
+	  _:_Error ->
+        ?DEBUG("Bad Request: ~p ~p", [_Error, erlang:get_stacktrace()]),
         badrequest_response()
     end;
 process([Call], #request{method = 'GET', q = Data, ip = IP} = Req) ->
+    Version = get_api_version(Req),
     try
         Args = case Data of
             [{nokey, <<>>}] -> [];
@@ -223,13 +238,13 @@ process([Call], #request{method = 'GET', q = Data, ip = IP} = Req) ->
         log(Call, Args, IP),
         case check_permissions(Req, Call) of
             {allowed, Cmd, Auth} ->
-                {Code, Result} = handle(Cmd, Auth, Args),
+                {Code, Result} = handle(Cmd, Auth, Args, Version),
                 json_response(Code, jiffy:encode(Result));
             ErrorResponse ->
                 ErrorResponse
         end
-    catch _:Error ->
-        ?DEBUG("Bad Request: ~p", [Error]),
+    catch _:_Error ->
+        ?DEBUG("Bad Request: ~p ~p", [_Error, erlang:get_stacktrace()]),
         badrequest_response()
     end;
 process([], #request{method = 'OPTIONS', data = <<>>}) ->
@@ -238,13 +253,28 @@ process(_Path, Request) ->
     ?DEBUG("Bad Request: no handler ~p", [Request]),
     badrequest_response().
 
+% get API version N from last "vN" element in URL path
+get_api_version(#request{path = Path}) ->
+    get_api_version(lists:reverse(Path));
+get_api_version([<<"v", String/binary>> | Tail]) ->
+    case catch jlib:binary_to_integer(String) of
+	N when is_integer(N) ->
+	    N;
+	_ ->
+	    get_api_version(Tail)
+    end;
+get_api_version([_Head | Tail]) ->
+    get_api_version(Tail);
+get_api_version([]) ->
+    ?DEFAULT_API_VERSION.
+
 %% ----------------
 %% command handlers
 %% ----------------
 
 % generic ejabberd command handler
-handle(Call, Auth, Args) when is_atom(Call), is_list(Args) ->
-    case ejabberd_commands:get_command_format(Call, Auth) of
+handle(Call, Auth, Args, Version) when is_atom(Call), is_list(Args) ->
+    case ejabberd_commands:get_command_format(Call, Auth, Version) of
         {ArgsSpec, _} when is_list(ArgsSpec) ->
             Args2 = [{jlib:binary_to_atom(Key), Value} || {Key, Value} <- Args],
             Spec = lists:foldr(
@@ -259,22 +289,51 @@ handle(Call, Auth, Args) when is_atom(Call), is_list(Args) ->
                         ({Key, atom}, Acc) ->
                             [{Key, undefined}|Acc]
                     end, [], ArgsSpec),
-            handle2(Call, Auth, match(Args2, Spec));
+	    try
+		handle2(Call, Auth, match(Args2, Spec), Version)
+	    catch throw:not_found ->
+		    {404, <<"not_found">>};
+		  throw:{not_found, Why} when is_atom(Why) ->
+		    {404, jlib:atom_to_binary(Why)};
+		  throw:{not_found, Msg} ->
+		    {404, iolist_to_binary(Msg)};
+		  throw:not_allowed ->
+		    {401, <<"not_allowed">>};
+		  throw:{not_allowed, Why} when is_atom(Why) ->
+		    {401, jlib:atom_to_binary(Why)};
+		  throw:{not_allowed, Msg} ->
+		    {401, iolist_to_binary(Msg)};
+		  throw:{invalid_parameter, Msg} ->
+		    {400, iolist_to_binary(Msg)};
+		  throw:{error, Why} when is_atom(Why) ->
+		    {400, jlib:atom_to_binary(Why)};
+		  throw:{error, Msg} ->
+		    {400, iolist_to_binary(Msg)};
+		  throw:Error when is_atom(Error) ->
+		    {400, jlib:atom_to_binary(Error)};
+		  throw:Msg when is_list(Msg); is_binary(Msg) ->
+		    {400, iolist_to_binary(Msg)};
+		  _Error ->
+		    ?ERROR_MSG("REST API Error: ~p ~p", [_Error, erlang:get_stacktrace()]),
+		    {500, <<"internal_error">>}
+	    end;
         {error, Msg} ->
+	    ?ERROR_MSG("REST API Error: ~p", [Msg]),
             {400, Msg};
         _Error ->
+	    ?ERROR_MSG("REST API Error: ~p", [_Error]),
             {400, <<"Error">>}
     end.
 
-handle2(Call, Auth, Args) when is_atom(Call), is_list(Args) ->
-    {ArgsF, _ResultF} = ejabberd_commands:get_command_format(Call, Auth),
+handle2(Call, Auth, Args, Version) when is_atom(Call), is_list(Args) ->
+    {ArgsF, _ResultF} = ejabberd_commands:get_command_format(Call, Auth, Version),
     ArgsFormatted = format_args(Args, ArgsF),
-    case ejabberd_command(Auth, Call, ArgsFormatted, 400) of
-        0 -> {200, <<"OK">>};
-        1 -> {500, <<"500 Internal server error">>};
-        400 -> {400, <<"400 Bad Request">>};
-        404 -> {404, <<"404 Not found">>};
-        Res -> format_command_result(Call, Auth, Res)
+    case ejabberd_commands:execute_command(undefined, Auth, 
+					   Call, ArgsFormatted, Version) of
+	{error, Error} ->
+	    throw(Error);
+	Res ->
+	    format_command_result(Call, Auth, Res, Version)
     end.
 
 get_elem_delete(A, L) ->
@@ -339,7 +398,9 @@ format_arg(undefined, binary) -> <<>>;
 format_arg(undefined, string) -> <<>>;
 format_arg(Arg, Format) ->
     ?ERROR_MSG("don't know how to format Arg ~p for format ~p", [Arg, Format]),
-    error.
+    throw({invalid_parameter,
+	   io_lib:format("Arg ~p is not in format ~p",
+			 [Arg, Format])}).
 
 process_unicode_codepoints(Str) ->
     iolist_to_binary(lists:map(fun(X) when X > 255 -> unicode:characters_to_binary([X]);
@@ -353,36 +414,26 @@ process_unicode_codepoints(Str) ->
 match(Args, Spec) ->
     [{Key, proplists:get_value(Key, Args, Default)} || {Key, Default} <- Spec].
 
-ejabberd_command(Auth, Cmd, Args, Default) ->
-    Access = case Auth of
-                 admin -> [];
-                 _ -> undefined
-             end,
-    case catch ejabberd_commands:execute_command(Access, Auth, Cmd, Args) of
-        {'EXIT', _} -> Default;
-        {error, _} -> Default;
-        Result -> Result
-    end.
 
-format_command_result(Cmd, Auth, Result) ->
-    {_, ResultFormat} = ejabberd_commands:get_command_format(Cmd, Auth),
+format_command_result(Cmd, Auth, Result, Version) ->
+    {_, ResultFormat} = ejabberd_commands:get_command_format(Cmd, Auth, Version),
     case {ResultFormat, Result} of
-        {{_, rescode}, V} when V == true; V == ok ->
-            {200, <<"">>};
-        {{_, rescode}, _} ->
-            {500, <<"">>};
-        {{_, restuple}, {V1, Text1}} when V1 == true; V1 == ok ->
-            {200, iolist_to_binary(Text1)};
-        {{_, restuple}, {_, Text2}} ->
-            {500, iolist_to_binary(Text2)};
-        {{_, {list, _}}, _V} ->
-            {_, L} = format_result(Result, ResultFormat),
-            {200, L};
-        {{_, {tuple, _}}, _V} ->
-            {_, T} = format_result(Result, ResultFormat),
-            {200, T};
-        _ ->
-            {200, {[format_result(Result, ResultFormat)]}}
+	{{_, rescode}, V} when V == true; V == ok ->
+	    {200, 0};
+	{{_, rescode}, _} ->
+	    {200, 1};
+	{{_, restuple}, {V1, Text1}} when V1 == true; V1 == ok ->
+	    {200, iolist_to_binary(Text1)};
+	{{_, restuple}, {_, Text2}} ->
+	    {500, iolist_to_binary(Text2)};
+	{{_, {list, _}}, _V} ->
+	    {_, L} = format_result(Result, ResultFormat),
+	    {200, L};
+	{{_, {tuple, _}}, _V} ->
+	    {_, T} = format_result(Result, ResultFormat),
+	    {200, T};
+	_ ->
+	    {200, {[format_result(Result, ResultFormat)]}}
     end.
 
 format_result(Atom, {Name, atom}) ->
@@ -421,14 +472,15 @@ format_result(404, {_Name, _}) ->
     "not_found".
 
 unauthorized_response() ->
-    {401, ?HEADER(?CT_XML),
-     #xmlel{name = <<"h1">>, attrs = [],
-            children = [{xmlcdata, <<"401 Unauthorized">>}]}}.
+    unauthorized_response(<<"401 Unauthorized">>).
+unauthorized_response(Body) ->
+    json_response(401, jiffy:encode(Body)).
 
 badrequest_response() ->
-    {400, ?HEADER(?CT_XML),
-     #xmlel{name = <<"h1">>, attrs = [],
-            children = [{xmlcdata, <<"400 Bad Request">>}]}}.
+    badrequest_response(<<"400 Bad Request">>).
+badrequest_response(Body) ->
+    json_response(400, jiffy:encode(Body)).
+
 json_response(Code, Body) when is_integer(Code) ->
     {Code, ?HEADER(?CT_JSON), Body}.