Client: add form interception

register_on_receiving_inventory_form(function(formname, formspec))
    intercepts forms sent from the server
register_on_open_nodemeta_form(function(pos, formname, formspec))
    intercepts forms that are to be shown locally

nodemeta intecept probably doesn't intercept all ways it can be opened

builtin/client/register.lua

@@ -94,3 +94,5 @@ core.registered_on_item_use, core.register_on_item_use = make_registration()
 core.registered_on_modchannel_message, core.register_on_modchannel_message = make_registration()
 core.registered_on_modchannel_signal, core.register_on_modchannel_signal = make_registration()
 core.registered_on_inventory_open, core.register_on_inventory_open = make_registration()
+core.registered_on_receiving_inventory_form, core.register_on_receiving_inventory_form = make_registration()
+core.registered_on_open_nodemeta_form, core.register_on_open_nodemeta_form = make_registration()

src/client/game.cpp

@@ -2624,6 +2624,8 @@ bool Game::nodePlacement(const ItemDefinition &selected_def,
 		if (nodedef_manager->get(map.getNode(nodepos)).rightclickable)
 			client->interact(INTERACT_PLACE, pointed);
 
+		std::string formspec_str = meta->getString("formspec");
+		if (!client->getScript()->on_nodemeta_form_open(nodepos, "", formspec_str)) {
 			infostream << "Launching custom inventory view" << std::endl;
 
 			InventoryLocation inventoryloc;
@@ -2637,7 +2639,8 @@ bool Game::nodePlacement(const ItemDefinition &selected_def,
 			GUIFormSpecMenu::create(formspec, client, &input->joystick, fs_src,
 				txt_dst, client->getFormspecPrepend());
 
-		formspec->setFormSpec(meta->getString("formspec"), inventoryloc);
+			formspec->setFormSpec(formspec_str, inventoryloc);
+		}
 		return false;
 	}
 

src/network/clientpackethandler.cpp

@@ -979,6 +979,7 @@ void Client::handleCommand_ShowFormSpec(NetworkPacket* pkt)
 
 	*pkt >> formname;
 
+	if (!m_script->on_receiving_inventory_form(formname, formspec)) {
 		ClientEvent *event = new ClientEvent();
 		event->type = CE_SHOW_FORMSPEC;
 		// pointer is required as event is a struct only!
@@ -987,6 +988,7 @@ void Client::handleCommand_ShowFormSpec(NetworkPacket* pkt)
 		event->show_formspec.formname = new std::string(formname);
 		m_client_event_queue.push(event);
 	}
+}
 
 void Client::handleCommand_SpawnParticle(NetworkPacket* pkt)
 {

src/script/cpp_api/s_client.cpp

@@ -248,6 +248,35 @@ void ScriptApiClient::open_special_inventory()
 		lua_pcall(L, 0, 0, error_handler);
 }
 
+bool ScriptApiClient::on_receiving_inventory_form(std::string formname, std::string formspec)
+{
+	SCRIPTAPI_PRECHECKHEADER
+
+	lua_getglobal(L, "core");
+	lua_getfield(L, -1, "registered_on_receiving_inventory_form");
+
+	lua_pushstring(L, formname.c_str());
+	lua_pushstring(L, formspec.c_str());
+
+	runCallbacks(2, RUN_CALLBACKS_MODE_OR);
+	return readParam<bool>(L, -1);
+}
+
+bool ScriptApiClient::on_nodemeta_form_open(v3s16 position, std::string formname, std::string formspec)
+{
+	SCRIPTAPI_PRECHECKHEADER
+
+	lua_getglobal(L, "core");
+	lua_getfield(L, -1, "registered_on_nodemeta_form_open");
+
+	push_v3s16(L, position);
+	lua_pushstring(L, formname.c_str());
+	lua_pushstring(L, formspec.c_str());
+
+	runCallbacks(2, RUN_CALLBACKS_MODE_OR);
+	return readParam<bool>(L, -1);
+}
+
 void ScriptApiClient::setEnv(ClientEnvironment *env)
 {
 	ScriptApiBase::setEnv(env);

src/script/cpp_api/s_client.h

@@ -61,5 +61,8 @@ public:
 	bool on_inventory_open(Inventory *inventory);
 	void open_special_inventory();
 
+	bool on_receiving_inventory_form(std::string formname, std::string formspec);
+	bool on_nodemeta_form_open(v3s16 position, std::string formname, std::string formspec);
+
 	void setEnv(ClientEnvironment *env);
 };