Emergency shuttle is aware of security level (#78271)

## About The Pull Request

The emergency shuttle maintains its security level coefficient and does
the calculation instead of outside procs that aren't aware of what alert
it was when the shuttle was first called.

If the shuttle auto-call timer should be capped at the current security
level timer, that can be done in a different PR.

## Why It's Good For The Game

Fixes https://github.com/tgstation/tgstation/issues/78159

## Changelog

🆑 LT3
fix: Emergency shuttle should correctly scale timer up/down when
changing security levels
/🆑

code/__DEFINES/shuttles.dm

@@ -63,6 +63,14 @@
 #define ENGINE_COEFF_MAX 2
 #define ENGINE_DEFAULT_MAXSPEED_ENGINES 5
 
+// Alert level related
+#define ALERT_COEFF_AUTOEVAC_NORMAL 2.5
+#define ALERT_COEFF_GREEN 2
+#define ALERT_COEFF_BLUE 1
+#define ALERT_COEFF_RED 0.5
+#define ALERT_COEFF_AUTOEVAC_CRITICAL 0.4
+#define ALERT_COEFF_DELTA 0.25
+
 //Docking error flags
 #define DOCKING_SUCCESS 0
 #define DOCKING_BLOCKED (1<<0)

code/controllers/subsystem/security_level.dm

@@ -41,8 +41,6 @@ SUBSYSTEM_DEF(security_level)
 
 	announce_security_level(selected_level) // We want to announce BEFORE updating to the new level
 
-	var/old_shuttle_call_time_mod = current_security_level.shuttle_call_time_mod // Need this before we set the new one
-
 	SSsecurity_level.current_security_level = selected_level
 
 	if(selected_level.looping_sound)
@@ -52,9 +50,7 @@ SUBSYSTEM_DEF(security_level)
 		can_fire = FALSE
 
 	if(SSshuttle.emergency.mode == SHUTTLE_CALL || SSshuttle.emergency.mode == SHUTTLE_RECALL) // By god this is absolutely shit
-		old_shuttle_call_time_mod = 1 / old_shuttle_call_time_mod
-		SSshuttle.emergency.modTimer(old_shuttle_call_time_mod)
-		SSshuttle.emergency.modTimer(selected_level.shuttle_call_time_mod)
+		SSshuttle.emergency.alert_coeff_change(selected_level.shuttle_call_time_mod)
 
 	SEND_SIGNAL(src, COMSIG_SECURITY_LEVEL_CHANGED, selected_level.number_level)
 	SSnightshift.check_nightshift()

code/controllers/subsystem/shuttle.dm

@@ -262,8 +262,8 @@ SUBSYSTEM_DEF(shuttle)
 		log_shuttle("[msg] Alive: [alive], Roundstart: [total], Threshold: [threshold]")
 		emergency_no_recall = TRUE
 		priority_announce("Catastrophic casualties detected: crisis shuttle protocols activated - jamming recall signals across all frequencies.")
-		if(emergency.timeLeft(1) > emergency_call_time * 0.4)
-			emergency.request(null, set_coefficient = 0.4)
+		if(emergency.timeLeft(1) > emergency_call_time * ALERT_COEFF_AUTOEVAC_CRITICAL)
+			emergency.request(null, set_coefficient = ALERT_COEFF_AUTOEVAC_CRITICAL)
 
 /datum/controller/subsystem/shuttle/proc/block_recall(lockout_timer)
 	if(admin_emergency_no_recall)
@@ -457,7 +457,7 @@ SUBSYSTEM_DEF(shuttle)
 
 	if(callShuttle)
 		if(EMERGENCY_IDLE_OR_RECALLED)
-			emergency.request(null, set_coefficient = 2.5)
+			emergency.request(null, set_coefficient = ALERT_COEFF_AUTOEVAC_NORMAL)
 			log_shuttle("There is no means of calling the emergency shuttle anymore. Shuttle automatically called.")
 			message_admins("All the communications consoles were destroyed and all AIs are inactive. Shuttle called.")
 

code/modules/security_levels/security_level_datums.dm

@@ -45,7 +45,7 @@
 	sound = 'sound/misc/notice2.ogg' // Friendly beep
 	number_level = SEC_LEVEL_GREEN
 	lowering_to_configuration_key = /datum/config_entry/string/alert_green
-	shuttle_call_time_mod = 2
+	shuttle_call_time_mod = ALERT_COEFF_GREEN
 
 /**
  * BLUE
@@ -58,7 +58,7 @@
 	number_level = SEC_LEVEL_BLUE
 	lowering_to_configuration_key = /datum/config_entry/string/alert_blue_downto
 	elevating_to_configuration_key = /datum/config_entry/string/alert_blue_upto
-	shuttle_call_time_mod = 1
+	shuttle_call_time_mod = ALERT_COEFF_BLUE
 
 /**
  * RED
@@ -71,7 +71,7 @@
 	number_level = SEC_LEVEL_RED
 	lowering_to_configuration_key = /datum/config_entry/string/alert_red_downto
 	elevating_to_configuration_key = /datum/config_entry/string/alert_red_upto
-	shuttle_call_time_mod = 0.5
+	shuttle_call_time_mod = ALERT_COEFF_RED
 
 /**
  * DELTA
@@ -83,4 +83,4 @@
 	sound = 'sound/misc/airraid.ogg' // Air alarm to signify importance
 	number_level = SEC_LEVEL_DELTA
 	elevating_to_configuration_key = /datum/config_entry/string/alert_delta
-	shuttle_call_time_mod = 0.25
+	shuttle_call_time_mod = ALERT_COEFF_DELTA

code/modules/shuttle/emergency.dm

@@ -339,15 +339,9 @@
 
 /obj/docking_port/mobile/emergency/request(obj/docking_port/stationary/S, area/signal_origin, reason, red_alert, set_coefficient=null)
 	if(!isnum(set_coefficient))
-		var/security_num = SSsecurity_level.get_current_level_as_number()
-		switch(security_num)
-			if(SEC_LEVEL_GREEN)
-				set_coefficient = 2
-			if(SEC_LEVEL_BLUE)
-				set_coefficient = 1
-			else
-				set_coefficient = 0.5
-	var/call_time = SSshuttle.emergency_call_time * set_coefficient * engine_coeff
+		set_coefficient = SSsecurity_level.current_security_level.shuttle_call_time_mod
+	alert_coeff = set_coefficient
+	var/call_time = SSshuttle.emergency_call_time * alert_coeff * engine_coeff
 	switch(mode)
 		// The shuttle can not normally be called while "recalling", so
 		// if this proc is called, it's via admin fiat

code/modules/shuttle/shuttle.dm

@@ -439,7 +439,8 @@
 	var/current_engine_power = 0
 	///How much engine power (thrust) the shuttle starts with at mapload.
 	var/initial_engine_power = 0
-
+	///Speed multiplier based on station alert level
+	var/alert_coeff = ALERT_COEFF_BLUE
 	///used as a timer (if you want time left to complete move, use timeLeft proc)
 	var/timer
 	var/last_timer_length
@@ -927,6 +928,20 @@
 	last_timer_length *= multiple
 	setTimer(time_remaining)
 
+/obj/docking_port/mobile/proc/alert_coeff_change(new_coeff)
+	if(isnull(new_coeff))
+		return
+
+	var/time_multiplier = new_coeff / alert_coeff
+	var/time_remaining = timer - world.time
+	if(time_remaining < 0 || !last_timer_length)
+		return
+
+	time_remaining *= time_multiplier
+	last_timer_length *= time_multiplier
+	alert_coeff = new_coeff
+	setTimer(time_remaining)
+
 /obj/docking_port/mobile/proc/invertTimer()
 	if(!last_timer_length)
 		return