--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mod_groups_internal/mod_groups_internal.lua	Mon Jan 25 18:43:20 2021 +0100
@@ -0,0 +1,180 @@
+local rostermanager = require"core.rostermanager";
+local id = require "util.id";
+local jid = require "util.jid";
+local jid_join = jid.join;
+local host = module.host;
+
+local group_info_store = module:open_store("group_info");
+local group_members_store = module:open_store("groups");
+local group_memberships = module:open_store("groups", "map");
+
+local is_contact_subscribed = rostermanager.is_contact_subscribed;
+
+-- Make a *one-way* subscription. User will see when contact is online,
+-- contact will not see when user is online.
+local function subscribe(user, user_jid, contact, contact_jid)
+	-- Update user's roster to say subscription request is pending...
+	rostermanager.set_contact_pending_out(user, host, contact_jid);
+	-- Update contact's roster to say subscription request is pending...
+	rostermanager.set_contact_pending_in(contact, host, user_jid);
+	-- Update contact's roster to say subscription request approved...
+	rostermanager.subscribed(contact, host, user_jid);
+	-- Update user's roster to say subscription request approved...
+	rostermanager.process_inbound_subscription_approval(user, host, contact_jid);
+
+	-- Push updates to both rosters
+	rostermanager.roster_push(user, host, contact_jid);
+	rostermanager.roster_push(contact, host, user_jid);
+end
+
+local function user_groups(username)
+	return pairs(group_memberships:get_all(username) or {});
+end
+
+local function do_single_group_subscriptions(username, group_id)
+	local members = group_members_store:get(group_id);
+	if not members then return; end
+	local user_jid = jid_join(username, host);
+	for membername in pairs(members) do
+		if membername ~= username then
+			local member_jid = jid_join(membername, host);
+			if not is_contact_subscribed(username, host, member_jid) then
+				module:log("debug", "[group %s] Subscribing %s to %s", member_jid, user_jid);
+				subscribe(membername, member_jid, username, user_jid);
+			end
+			if not is_contact_subscribed(membername, host, user_jid) then
+				module:log("debug", "[group %s] Subscribing %s to %s", user_jid, member_jid);
+				subscribe(username, user_jid, membername, member_jid);
+			end
+		end
+	end
+end
+
+local function do_all_group_subscriptions_by_user(username)
+	for group_id in user_groups(username) do
+		do_single_group_subscriptions(username, group_id);
+	end
+end
+
+local function do_all_group_subscriptions_by_group(group_id)
+	for membername in pairs(get_members(group_id)) do
+		do_single_group_subscriptions(membername, group_id);
+	end
+end
+
+module:hook("resource-bind", function(event)
+	module:log("debug", "Updating group subscriptions...");
+	do_all_group_subscriptions_by_user(event.session.username);
+end);
+
+local function get_group_muc(group_id)
+	-- Group MUC
+	local group_info = group_info_store:get(group_id);
+	if group_info and group_info.muc_jid then
+		local muc_jid = group_info.muc_jid;
+		local mod_muc = hosts[jid.host(muc_jid)].modules.muc;
+		if mod_muc then
+			local room = mod_muc.get_room_from_jid(muc_jid);
+			if not room then
+				room = mod_muc.create_room(muc_jid);
+			end
+			return room;
+		end
+	end
+end
+
+--luacheck: ignore 131
+function create(group_info, create_muc)
+	if not group_info.name then
+		return nil, "group-name-required";
+	end
+	local group_id = id.short();
+
+	if create_muc then
+		return nil, "not-implemented";
+	end
+
+	local ok = group_info_store:set(group_id, {
+		name = group_info.name;
+	});
+	if not ok then
+		return nil, "internal-server-error";
+	end
+	return group_id;
+end
+
+function get_info(group_id)
+	return group_info_store:get(group_id);
+end
+
+function set_info(group_id, info)
+	if not info then
+		return nil, "bad-request"
+	end
+
+	if not info.name or #info.name == 0 then
+		return nil, "bad-request"
+	end
+
+	local ok = group_info_store:set(group_id, info);
+	if not ok then
+		return nil, "internal-server-error";
+	end
+	return true
+end
+
+function get_members(group_id)
+	return group_members_store:get(group_id);
+end
+
+function exists(group_id)
+	return not not get_info(group_id);
+end
+
+function get_user_groups(username)
+	local groups = {};
+	do
+		local group_set = group_memberships:get_all(username);
+		if group_set then
+			for group_id in pairs(group_set) do
+				table.insert(groups, group_id);
+			end
+		end
+	end
+	return groups;
+end
+
+function delete(group_id)
+	if group_members_store:set(group_id, nil) then
+		return group_info_store:set(group_id, nil);
+	end
+	return nil, "internal-server-error";
+end
+
+function add_member(group_id, username)
+	local group_info = group_info_store:get(group_id);
+	if not group_info then
+		return nil, "group-not-found";
+	end
+	if not group_memberships:set(group_id, username, {}) then
+		return nil, "internal-server-error";
+	end
+	do_all_group_subscriptions_by_group(group_id);
+	return true;
+end
+
+function remove_member(group_id, username)
+	local group_info = group_info_store:get(group_id);
+	if not group_info then
+		return nil, "group-not-found";
+	end
+	if not group_memberships:set(group_id, username, nil) then
+		return nil, "internal-server-error";
+	end
+	return true;
+end
+
+-- Returns iterator over group ids
+function groups()
+	return group_info_store:users();
+end