Moderation delay WIP (#132):

* mod_muc_moderation_delay, first shot.

prosody-modules/mod_muc_moderation_delay/README.md

@@ -0,0 +1,25 @@
+<!--
+SPDX-FileCopyrightText: 2024 John Livingston <https://www.john-livingston.fr/>
+SPDX-License-Identifier: AGPL-3.0-only
+-->
+# mod_muc_moderation_delay
+
+With this module, you can apply a delay to groupchat messages delivery, so that room moderators can moderate them before other participants receives them.
+
+This module is part of peertube-plugin-livechat, and is under the same LICENSE.
+This module can work on any Prosody server (version >= 0.12.x).
+
+## Configuration
+
+Just enable the module on your MUC component.
+The feature will be accessible throught the room configuration form.
+
+The position in the room config form can be changed be setting the option `moderation_delay_form_position`.
+This value will be passed as priority for the "muc-config-form" hook.
+By default, the field will be between muc#roomconfig_changesubject and muc#roomconfig_moderatedroom.
+
+``` lua
+VirtualHost "muc.example.com"
+  modules_enabled = { "muc_moderation_delay" }
+  moderation_delay_form_position = 96
+```

prosody-modules/mod_muc_moderation_delay/config.lib.lua

@@ -0,0 +1,61 @@
+-- SPDX-FileCopyrightText: 2024 John Livingston <https://www.john-livingston.fr/>
+-- SPDX-License-Identifier: AGPL-3.0-only
+
+-- Getter/Setter
+local function get_moderation_delay(room)
+  return room._data.moderation_delay or nil;
+end
+
+local function set_moderation_delay(room, delay)
+  if delay == 0 then
+    delay = nil;
+  end
+  if delay ~= nil then
+    delay = assert(tonumber(delay), "Moderation delay is not a valid number");
+    if delay < 0 then
+      delay = nil;
+    end
+  end
+
+  if get_moderation_delay(room) == delay then return false; end
+
+  room._data.moderation_delay = delay;
+  return true;
+end
+
+-- Discovering support
+local function add_disco_form(event)
+  table.insert(event.form, {
+    name = "muc#roominfo_moderation_delay";
+    value = "";
+  });
+  event.formdata["muc#roominfo_moderation_delay"] = get_moderation_delay(event.room);
+end
+
+
+-- Config form declaration
+local function add_form_option(event)
+  table.insert(event.form, {
+    name = "muc#roomconfig_moderation_delay";
+    type = "text-single";
+    datatype = "xs:integer";
+    range_min = 0;
+    range_max = 60; -- do not allow too big values, it does not make sense.
+    label = "Moderation delay (0=disabled, any positive integer= messages will be delayed for X seconds for non-moderator participants.)";
+    -- desc = "";
+    value = get_moderation_delay(event.room);
+  });
+end
+
+local function config_submitted(event)
+  set_moderation_delay(event.room, event.value);
+  -- no need to 104 status, this feature is invisible for regular participants.
+end
+
+return {
+  set_moderation_delay = set_moderation_delay;
+  get_moderation_delay = get_moderation_delay;
+  add_disco_form = add_disco_form;
+  add_form_option = add_form_option;
+  config_submitted = config_submitted;
+}

prosody-modules/mod_muc_moderation_delay/delay.lib.lua

@@ -0,0 +1,59 @@
+-- SPDX-FileCopyrightText: 2024 John Livingston <https://www.john-livingston.fr/>
+-- SPDX-License-Identifier: AGPL-3.0-only
+local async = require "util.async";
+local get_moderation_delay = module:require("config").get_moderation_delay;
+
+local muc_util = module:require "muc/util";
+local valid_roles = muc_util.valid_roles;
+
+local function handle_broadcast_message(event)
+  local room, stanza = event.room, event.stanza;
+  local delay = get_moderation_delay(room);
+  if delay == nil then
+    return;
+  end
+
+  -- only delay groupchat messages with body.
+  if stanza.attr.type ~= "groupchat" then
+    return;
+  end
+  if not stanza:get_child("body") then
+    return;
+  end
+
+  local id = stanza.attr.id;
+  if not id then
+    -- message should alway have an id, but just in case...
+    module:log("warn", "Message has no id, wont delay it.");
+    return;
+  end
+
+  -- TODO: detect message retractation, and stop broadcast for any waiting message.
+
+  -- Message must be delayed, except for:
+  -- * room moderators
+  -- * the user that sent the message (if they don't get the echo quickly, their clients could have weird behaviours)
+
+  module:log("debug", "Message must be delayed by %i seconds, sending first broadcast wave.", delay);
+  local moderator_role_value = valid_roles["moderator"];
+  local func = function (nick, occupant)
+    if valid_roles[occupant.role or "none"] >= moderator_role_value then
+      return true;
+    end
+    if nick == stanza.attr.from then
+      return true;
+    end
+    return false;
+  end;
+  room:broadcast(stanza, func);
+  async.sleep(delay);
+  module:log("debug", "Message has been delayed, sending to remaining participants.");
+  room:broadcast(stanza, function (nick, occupant)
+    return not func(nick, occupant);
+  end);
+  return true; -- stop the default process
+end
+
+return {
+  handle_broadcast_message = handle_broadcast_message;
+};

prosody-modules/mod_muc_moderation_delay/mod_muc_moderation_delay.lua

@@ -0,0 +1,30 @@
+-- mod_muc_moderation_delay
+--
+-- SPDX-FileCopyrightText: 2024 John Livingston <https://www.john-livingston.fr/>
+-- SPDX-License-Identifier: AGPL-3.0-only
+--
+-- This file is AGPL-v3 licensed.
+-- Please see the Peertube livechat plugin copyright information.
+-- https://livingston.frama.io/peertube-plugin-livechat/credits/
+--
+
+local add_disco_form = module:require("config").add_disco_form;
+local config_submitted = module:require("config").config_submitted;
+local add_form_option = module:require("config").add_form_option;
+local handle_broadcast_message = module:require("delay").handle_broadcast_message;
+
+-- form_position: the position in the room config form (this value will be passed as priority for the "muc-config-form" hook).
+-- By default, field will be between muc#roomconfig_changesubject and muc#roomconfig_moderatedroom
+local form_position = module:get_option_number("moderation_delay_form_position") or 80-2;
+
+-- Plugin dependencies
+local mod_muc = module:depends "muc";
+
+-- muc-disco and muc-config to configure the feature:
+module:hook("muc-disco#info", add_disco_form);
+module:hook("muc-config-submitted/muc#roomconfig_moderation_delay", config_submitted);
+module:hook("muc-config-form", add_form_option, form_position);
+
+-- intercept muc-broadcast-message, and broadcast with delay if required.
+-- Priority is negative, as we want it to be the last handler.
+module:hook("muc-broadcast-message", handle_broadcast_message, -1000);

server/lib/prosody/config/content.ts

@@ -249,6 +249,9 @@ class ProsodyConfigContent {
     if (chatTerms) {
       this.muc.set('muc_terms_global', new ConfigEntryValueMultiLineString(chatTerms))
     }
+
+    this.muc.add('modules_enabled', 'muc_moderation_delay')
+    this.muc.add('moderation_delay_form_position', 118)
   }
 
   useAnonymous (autoBanIP: boolean): void {