1 files changed, 58 insertions, 0 deletions
diff --git a/src/rebar_prv_packages.erl b/src/rebar_prv_packages.erl
new file mode 100644
index 0000000..8b4a963
--- /dev/null
+++ b/src/rebar_prv_packages.erl
@@ -0,0 +1,58 @@
+-module(rebar_prv_packages).
+
+-behaviour(rebar_provider).
+
+-export([init/1,
+         do/1]).
+
+-include("rebar.hrl").
+
+-define(PROVIDER, pkgs).
+-define(DEPS, []).
+
+-spec init(rebar_state:t()) -> {ok, rebar_state:t()}.
+init(State) ->
+    State1 = rebar_state:add_provider(State, #provider{name = ?PROVIDER,
+                                                       provider_impl = ?MODULE,
+                                                       bare = false,
+                                                       deps = ?DEPS,
+                                                       example = "rebar pkgs",
+                                                       short_desc = "List available packages",
+                                                       desc = info("List available packages"),
+                                                       opts = []}),
+    {ok, State1}.
+
+-spec do(rebar_state:t()) -> {ok, rebar_state:t()}.
+do(State) ->
+    {Packages, _Graph} = rebar_packages:get_packages(State),
+    print_packages(Packages),
+    {ok, State}.
+
+print_packages(Packages) ->
+    Keys = lists:keysort(1, dict:fetch_keys(Packages)),
+    Pkgs = merge(Keys),
+    lists:foreach(fun({Name, Vsns}) ->
+                          VsnStr = join(Vsns, <<", ">>),
+                          io:format("~s:~n    Versions: ~s~n~n", [Name, VsnStr])
+                  end, Pkgs).
+
+-spec merge([{binary(), binary()}]) -> [{binary(), [binary()]}].
+merge(List) ->
+    merge([], List).
+
+merge(List, []) ->
+    List;
+merge([{Key, Values} | T], [{Key, Value} | Rest]) ->
+    merge([{Key, [Value | Values]} | T], Rest);
+merge(List, [{Key, Value} | Rest]) ->
+    merge([{Key, [Value]} | List], Rest).
+
+-spec join([binary()], binary()) -> binary().
+join([Bin], _Sep) ->
+    <<Bin/binary>>;
+join([Bin | T], Sep) ->
+    <<Bin/binary, Sep/binary, (join(T, Sep))/binary>>.
+
+
+info(Description) ->
+    io_lib:format("~s.~n", [Description]).