rebar_yang.erl

-module(rebar_yang).
-compile(export_all).
%% Add to rebar.config
%% {plugins, [rebar_yang]}.

pre_compile(_Config,AppFile) ->
    rebar_log:log(info, "rebar_yang: ~p~n", [rebar_utils:get_cwd()]),
    scan_files(rebar_utils:get_cwd()),

    ok.

pre_rebar_yang(_,_) ->
    ok.

post_rebar_yang(_,_) ->
    ok.
is_base_dir() ->
    rebar_utils:get_cwd() == rebar_config:get_global(base_dir, undefined).

last_mod(File) ->
    calendar:datetime_to_gregorian_seconds(filelib:last_modified(File)).

make_hrl_file(YangFile,Dir) ->    
    BaseName = filename:basename(YangFile, ".yang"),
    HRLFile  = filename:flatten([Dir,"/", BaseName, ".hrl"]),
    HRLFile.

yang_needs_build(YangFile, Dir) ->
    HRLFile = make_hrl_file(YangFile,Dir),
    rebar_log:log(info, "COMPILE ~s -> ~s ~n", [YangFile,HRLFile]),
    case filelib:is_file(HRLFile) of
        false ->
            true;
        true ->
            last_mod(YangFile) > last_mod(HRLFile)
    end.

scan_files(Dir) ->
    ToBuild = filelib:fold_files(Dir ++ "/src/", 
                                 "\.yang$",
                                 false, 
                                 fun(YangFile, Acc) ->
                                         case yang_needs_build(YangFile, Dir) of
                                             true ->
                                                 [YangFile|Acc];
                                             false -> Acc
                                         end
                                 end,
                                 []),
    [build_yang(File, Dir) || File <- ToBuild].


build_yang(File,Dir) ->
    rebar_log:log(info, "Building Yang File ~s~n", [File]),
    case yang:deep_parse_file(File) of
         {ok, Yang} ->
            Ts = yang:typespec(Yang),
            HRLFile = make_hrl_file(File,Dir),
            
            file:write_file(HRLFile, yang_typespec:hrl(Ts));
         {error, Error} ->
            rebar_log:log(error, "Unable to build Yang file ~s due to ~s",[File, Error])
                
    end,
    ok.