From 7564a4e95368e41cc9d63371d942ebca50f537ce Mon Sep 17 00:00:00 2001
From: Linus Jahn <lnj@kaidan.im>
Date: Sun, 12 Jun 2022 15:55:59 +0200
Subject: [PATCH] mod_mix_pam: Provide MIX channels as roster entries via hook

---
 include/mod_roster.hrl |  3 ++-
 src/mod_mix_pam.erl    | 26 ++++++++++++++++++++++++++
 src/mod_roster.erl     |  6 +++++-
 3 files changed, 33 insertions(+), 2 deletions(-)

diff --git a/include/mod_roster.hrl b/include/mod_roster.hrl
index 6ec05b3da..3f9a951c4 100644
--- a/include/mod_roster.hrl
+++ b/include/mod_roster.hrl
@@ -28,7 +28,8 @@
     ask = none                             :: ask() | '_',
     groups = []                            :: [binary()] | '_',
     askmessage = <<"">>                    :: binary() | '_',
-    xs = []                                :: [fxml:xmlel()] | '_'
+    xs = []                                :: [fxml:xmlel()] | '_',
+    mix_participant_id = <<>>              :: binary() | '_'
 }).
 
 -record(roster_version,
diff --git a/src/mod_mix_pam.erl b/src/mod_mix_pam.erl
index e67ae2c80..9bf75d1ba 100644
--- a/src/mod_mix_pam.erl
+++ b/src/mod_mix_pam.erl
@@ -32,11 +32,13 @@
 	 disco_sm_features/5,
 	 remove_user/2,
 	 process_iq/1,
+	 get_mix_roster_items/2,
 	 webadmin_user/4,
 	 webadmin_page/3]).
 
 -include_lib("xmpp/include/xmpp.hrl").
 -include("logger.hrl").
+-include("mod_roster.hrl").
 -include("translate.hrl").
 -include("ejabberd_http.hrl").
 -include("ejabberd_web_admin.hrl").
@@ -65,6 +67,7 @@ start(Host, Opts) ->
 	    ejabberd_hooks:add(bounce_sm_packet, Host, ?MODULE, bounce_sm_packet, 50),
 	    ejabberd_hooks:add(disco_sm_features, Host, ?MODULE, disco_sm_features, 50),
 	    ejabberd_hooks:add(remove_user, Host, ?MODULE, remove_user, 50),
+	    ejabberd_hooks:add(roster_get, Host, ?MODULE, get_mix_roster_items, 50),
 	    ejabberd_hooks:add(webadmin_user, Host, ?MODULE, webadmin_user, 50),
 	    ejabberd_hooks:add(webadmin_page_host, Host, ?MODULE, webadmin_page, 50),
 	    gen_iq_handler:add_iq_handler(ejabberd_sm, Host, ?NS_MIX_PAM_0,
@@ -77,6 +80,7 @@ stop(Host) ->
     ejabberd_hooks:delete(bounce_sm_packet, Host, ?MODULE, bounce_sm_packet, 50),
     ejabberd_hooks:delete(disco_sm_features, Host, ?MODULE, disco_sm_features, 50),
     ejabberd_hooks:delete(remove_user, Host, ?MODULE, remove_user, 50),
+    ejabberd_hooks:delete(roster_get, Host, ?MODULE, get_mix_roster_items, 50),
     ejabberd_hooks:delete(webadmin_user, Host, ?MODULE, webadmin_user, 50),
     ejabberd_hooks:delete(webadmin_page_host, Host, ?MODULE, webadmin_page, 50),
     gen_iq_handler:remove_iq_handler(ejabberd_sm, Host, ?NS_MIX_PAM_0).
@@ -208,6 +212,28 @@ process_iq(#iq{type = set,
 process_iq(IQ) ->
     xmpp:make_error(IQ, unsupported_query_error(IQ)).
 
+-spec get_mix_roster_items([#roster{}], {binary(), binary()}) -> [#roster{}].
+get_mix_roster_items(Acc, {LUser, LServer}) ->
+    JID = jid:make(LUser, LServer),
+    case get_channels(JID) of
+        {ok, Channels} ->
+            lists:map(
+                fun({#jid{luser=Channel, lserver=Service}, Id}) ->
+                    #roster{
+                        jid = {Channel, Service, <<>>},
+                        name = <<>>,
+                        subscription = both,
+                        ask = none,
+                        groups = [<<"Channels">>],
+                        askmessage = <<>>,
+                        xs = [],
+                        mix_participant_id = Id
+                    }
+                end, Channels);
+        _ ->
+            []
+    end ++ Acc.
+
 -spec remove_user(binary(), binary()) -> ok | {error, db_failure}.
 remove_user(LUser, LServer) ->
     Mod = gen_mod:db_mod(LServer, ?MODULE),
diff --git a/src/mod_roster.erl b/src/mod_roster.erl
index e2b176502..d3a0c6be2 100644
--- a/src/mod_roster.erl
+++ b/src/mod_roster.erl
@@ -426,7 +426,11 @@ encode_item(Item) ->
 			   both -> subscribe;
 			   _ -> undefined
 		       end,
-		 groups = Item#roster.groups}.
+		 groups = Item#roster.groups,
+		 mix_channel = case Item#roster.mix_participant_id of
+				   <<>> -> undefined;
+				   _ -> #mix_roster_channel{'participant-id' = Item#roster.mix_participant_id}
+			       end}.
 
 -spec decode_item(roster_item(), #roster{}, boolean()) -> #roster{}.
 decode_item(#roster_item{subscription = remove} = Item, R, _) ->