Basic main structure for centralized alarm handling.

code/modules/alarm/alarm.dm

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+/datum/alarm_source
+	var/source		= null	// The source trigger
+	var/source_name = ""	// The name of the source should it be lost (for example a destroyed camera)
+	var/duration	= 0		// How long this source will be alarming, 0 for indefinetely.
+	var/start_time	= 0		// When this source began alarming.
+	var/end_time	= 0		// Use to set when this trigger should clear, in case the source is lost.
+
+/datum/alarm_source/New(var/atom/source)
+	src.source = source
+	source_name = source.name
+	start_time = world.time
+
+/datum/alarm
+	var/atom/origin					//Used to identify the alarm area.
+	var/list/sources = new()		//List of sources triggering the alarm. Used to determine when the alarm should be cleared.
+	var/list/sources_assoc = new()	//Associative list of source triggers. Used to efficiently acquire the alarm source.
+	var/list/cameras				//List of cameras that can be switched to, if the player has that capability.
+	var/area/last_area				//The last acquired area, used should origin be lost (for example a destroyed borg containing an alarming camera).
+
+/datum/alarm/New(var/atom/origin, var/atom/source, var/duration)
+	src.origin = origin
+	last_area = alarm_area()
+	set_duration(source, duration)
+
+/datum/alarm/proc/set_duration(var/atom/source, var/duration)
+	var/datum/alarm_source/AS = sources[source]
+	if(!AS)
+		AS = new/datum/alarm_source(source)
+		sources += AS
+		sources_assoc[source] = AS
+	// Currently only non-0 durations can be altered (normal alarms VS EMP blasts)
+	if(AS.duration)
+		AS.duration = duration
+
+/datum/alarm/proc/clear(var/source)
+	var/datum/alarm_source/AS = sources[source]
+	sources -= AS
+	sources_assoc -= source
+
+/datum/alarm/proc/alarm_area()
+	if(!origin)
+		return last_area
+
+	last_area = origin.get_alarm_area()
+	return last_area
+
+/datum/alarm/proc/cameras()
+	if(!origin)
+		return list()
+
+	if(!cameras)
+		cameras = origin.get_alarm_cameras()
+
+	return cameras
+
+
+/atom/proc/get_alarm_area()
+	return get_area(src)
+
+/area/get_alarm_area()
+	return src
+
+/atom/proc/get_alarm_cameras()
+	var/area/A = get_area(src)
+	return A.get_cameras()
+
+/area/get_alarm_cameras()
+	return get_cameras()
+
+/mob/living/silicon/robot/get_alarm_cameras()
+	var/list/cameras = ..()
+	if(camera)
+		cameras += camera
+
+	return cameras
+
+/mob/living/silicon/robot/syndicate/get_alarm_cameras()
+	return list()

code/modules/alarm/alarm_handler.dm

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+#define ALARM_ORIGIN_LOST "Origin Lost"
+
+/datum/alarm_handler
+	var/category = ""
+	var/list/datum/alarm/alarms = new			// All alarms, to handle cases when origin has been deleted with one or more active alarms
+	var/list/datum/alarm/alarms_assoc = new		// Associative list of alarms, to efficiently acquire them based on origin.
+
+/datum/alarm_handler/proc/process()
+	/*
+	for(var/datum/alarm/A in alarms)
+		var/datum/alarm_source/AS = A.source
+		// Alarm owner has been deleted. Clean up in at most 15 seconds
+		if(!AS.owner && !AS.end_time)
+			AS.end_time = world.time + SecondsToTicks(15)
+		if(AS.duration || AS.end_time)
+			if(world.time > (AS.start_time + AS.duration) || world.time > AS.end_time)
+				//Somethingthing..
+	*/
+
+/datum/alarm_handler/proc/triggerAlarm(var/atom/origin, var/atom/source, var/duration = 0)
+	//Proper origin and source mandatory
+	if(!origin || !source)
+		return
+
+	//see if there is already an alarm of this origin
+	var/alarm_key = origin.get_alarm_key()
+	var/datum/alarm/existing = alarms_assoc[alarm_key]
+	if(existing)
+		existing.set_duration(source, duration)
+	else
+		existing = new/datum/alarm(origin, source, duration)
+
+	alarms |= existing
+	alarms_assoc[alarm_key] = existing
+
+/datum/alarm_handler/proc/cancelAlarm(var/atom/origin, var/source)
+	//Proper origin and source mandatory
+	if(!origin || !source)
+		return
+
+	var/alarm_key = origin.get_alarm_key()
+
+	var/datum/alarm/existing = alarms_assoc[alarm_key]
+	if(existing)
+		existing.clear(source)
+		if (!existing.sources.len)
+			alarms -= existing
+			alarms_assoc -= alarm_key
+
+/atom/proc/get_alarm_key()
+	return src
+
+/turf/get_alarm_key()
+	return get_area(src)
+
+/obj/item/device/alarm_debug
+	name = "An alarm debug tool - Self"
+	desc = "Alarm Up. Alarm Reset."
+	icon = 'icons/obj/radio.dmi'
+	icon_state = "beacon"
+	item_state = "signaler"
+
+/obj/item/device/alarm_debug/loc
+	name = "An alarm debug tool - Loc"
+
+/obj/item/device/alarm_debug/verb/alarm()
+	set name = "Alarm"
+	set category = "Debug"
+	usr << "Raising alarm"
+	camera_alarm.triggerAlarm(src, src)
+
+/obj/item/device/alarm_debug/verb/reset()
+	set name = "Reset"
+	set category = "Debug"
+	usr << "Raising alarm"
+	camera_alarm.triggerAlarm(src, src)
+
+/obj/item/device/alarm_debug/verb/tell_me()
+	set name = "Tell"
+	set category = "Debug"
+	usr << "Telling about alarms"
+
+	var/list/datum/alarm/alarms = camera_alarm.alarms
+	var/list/datum/alarm/alarms_assoc = camera_alarm.alarms_assoc
+
+	world << "List"
+	for(var/datum/alarm/A in alarms)
+		world << "Origin: [A.origin ? A.origin : ALARM_ORIGIN_LOST]"
+		world << "Alarm area: [A.alarm_area()]"
+		for(var/source in A.sources)
+			world << "Source: [source]"
+
+	world << "Assoc"
+
+	for(var/atom/origin in alarms_assoc)
+		world << "Origin: [origin ? origin : ALARM_ORIGIN_LOST]"
+		var/datum/alarm/A = alarms_assoc[origin]
+		world << "Alarm area: [A.alarm_area()]"
+		for(var/source in A.sources)
+			world << "Source: [source]"
+
+/obj/item/device/alarm_debug/loc/alarm()
+	set name = "Alarm"
+	set category = "Debug"
+	usr << "Raising alarm"
+	camera_alarm.triggerAlarm(src.loc, src)
+
+/obj/item/device/alarm_debug/loc/reset()
+	set name = "Reset"
+	set category = "Debug"
+	usr << "Clearing alarm"
+	camera_alarm.cancelAlarm(src.loc, src)

code/modules/alarm/atmosphere_alarm.dm

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+/datum/alarm_handler/atmosphere
+	category = "Atmosphere"

code/modules/alarm/camera_alarm.dm

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+/datum/alarm_handler/camera
+	category = "Camera"

code/modules/alarm/fire_alarm.dm

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+/datum/alarm_handler/fire_alarm
+	category = "Fire"

code/modules/alarm/motion_alarm.dm

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+/datum/alarm_handler/motion
+	category = "Motion"

code/modules/alarm/power_alarm.dm

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+/datum/alarm_handler/power
+	category = "Power"