From 692aa7bbb80044d68af28775c5512dbaabb14756 Mon Sep 17 00:00:00 2001
From: Houston4444 <picotmathieu@gmail.com>
Date: Thu, 2 Dec 2021 14:34:58 +0100
Subject: [PATCH] Add NSM ':switch:' capability

This allows to switch from one Ardour session to another without
application restart.

This also include some minor related NSM fixes.
---
 gtk2_ardour/ardour_ui.cc         |  1 +
 gtk2_ardour/ardour_ui.h          |  3 ++-
 gtk2_ardour/ardour_ui_dialogs.cc |  4 ++--
 gtk2_ardour/ardour_ui_startup.cc | 15 ++++++++++-----
 gtk2_ardour/nsm.cc               |  1 +
 5 files changed, 16 insertions(+), 8 deletions(-)

diff --git a/gtk2_ardour/ardour_ui.cc b/gtk2_ardour/ardour_ui.cc
index c7dae3edf3..85eb525e9d 100644
--- a/gtk2_ardour/ardour_ui.cc
+++ b/gtk2_ardour/ardour_ui.cc
@@ -369,6 +369,7 @@ ARDOUR_UI::ARDOUR_UI (int *argcp, char **argvp[], const char* localedir)
 	, prefs_visibility_button (S_("Window|Prefs"))
 	, recorder_visibility_button (S_("Window|Rec"))
 	, trigger_page_visibility_button (S_("Window|Trig"))
+	, nsm_first_session_opened (false)
 {
 	Gtkmm2ext::init (localedir);
 
diff --git a/gtk2_ardour/ardour_ui.h b/gtk2_ardour/ardour_ui.h
index fdd9aa359a..a6f06d649c 100644
--- a/gtk2_ardour/ardour_ui.h
+++ b/gtk2_ardour/ardour_ui.h
@@ -238,7 +238,7 @@ public:
 	int load_session_from_startup_fsm ();
 
 	/// @return true if session was successfully unloaded.
-	int unload_session (bool hide_stuff = false);
+	int unload_session (bool hide_stuff = false, bool force_unload = false);
 	void close_session();
 
 	int  save_state_canfail (std::string state_name = "", bool switch_to_it = false);
@@ -927,6 +927,7 @@ private:
 	void action_script_changed (int i, const std::string&);
 
 	void ask_about_scratch_deletion ();
+	bool nsm_first_session_opened;
 };
 
 #endif /* __ardour_gui_h__ */
diff --git a/gtk2_ardour/ardour_ui_dialogs.cc b/gtk2_ardour/ardour_ui_dialogs.cc
index a8a5bcdddf..f8b9c34982 100644
--- a/gtk2_ardour/ardour_ui_dialogs.cc
+++ b/gtk2_ardour/ardour_ui_dialogs.cc
@@ -287,7 +287,7 @@ ARDOUR_UI::set_session (Session *s)
 }
 
 int
-ARDOUR_UI::unload_session (bool hide_stuff)
+ARDOUR_UI::unload_session (bool hide_stuff, bool force_unload)
 {
 	if (_session) {
 		ARDOUR_UI::instance()->video_timeline->sync_session_state();
@@ -303,7 +303,7 @@ ARDOUR_UI::unload_session (bool hide_stuff)
 		save_ardour_state ();
 	}
 
-	if (_session && _session->dirty()) {
+	if (!force_unload && _session && _session->dirty()) {
 		std::vector<std::string> actions;
 		actions.push_back (_("Don't close"));
 		if (_session->unnamed()) {
diff --git a/gtk2_ardour/ardour_ui_startup.cc b/gtk2_ardour/ardour_ui_startup.cc
index a5145ec3eb..8e320567d1 100644
--- a/gtk2_ardour/ardour_ui_startup.cc
+++ b/gtk2_ardour/ardour_ui_startup.cc
@@ -428,7 +428,7 @@ ARDOUR_UI::nsm_init ()
 	 * The wrapper startup script should set the environment variable 'ARDOUR_SELF'
 	 */
 	const char *process_name = g_getenv ("ARDOUR_SELF");
-	nsm->announce (PROGRAM_NAME, ":dirty:", process_name ? process_name : "ardour6");
+	nsm->announce (PROGRAM_NAME, ":dirty:switch:", process_name ? process_name : "ardour7");
 
 	unsigned int i = 0;
 	// wait for announce reply from nsm server
@@ -751,7 +751,9 @@ ARDOUR_UI::load_from_application_api (const std::string& path)
 	}
 
 	if (nsm) {
-		if (!AudioEngine::instance()->set_backend("JACK", "", "")) {
+		unload_session(false, true);
+
+		if (!AudioEngine::instance()->set_backend("JACK", ARDOUR_COMMAND_LINE::backend_client_name, "")) {
 			error << _("NSM: The JACK backend is mandatory and can not be loaded.") << endmsg;
 			return;
 		}
@@ -775,10 +777,13 @@ ARDOUR_UI::load_from_application_api (const std::string& path)
 			}
 		}
 
-		PluginScanDialog psd (true, false);
-		psd.start ();
+		if (!nsm_first_session_opened) {
+			PluginScanDialog psd (true, false);
+			psd.start ();
 
-		post_engine ();
+			post_engine ();
+			nsm_first_session_opened = true;
+		}
 	}
 
 	/* the mechanisms that can result is this being called are only
diff --git a/gtk2_ardour/nsm.cc b/gtk2_ardour/nsm.cc
index e29af11f12..30e64455b8 100644
--- a/gtk2_ardour/nsm.cc
+++ b/gtk2_ardour/nsm.cc
@@ -50,6 +50,7 @@ NSM_Client::command_open(const char* name,
 	int r = ERR_OK;
 
 	ARDOUR_COMMAND_LINE::backend_client_name = client_id;
+	ARDOUR_COMMAND_LINE::session_name = "";
 
 	/* this appears asynchronous, but almost certainly is
 	 * synchronous. However, there's no return value available.