GLOBAL_DATUM_INIT(ntnet_global, /datum/ntnet, new)


/// This is the NTNet datum. There can be only one NTNet datum in game at once. Modular computers read data from this.
/datum/ntnet
	var/list/relays = list()
	var/list/logs = list()
	var/list/messages = list()
	var/list/available_station_software = list()
	var/list/available_antag_software = list()
	var/list/available_software = list()
	var/list/available_software_presets = list()
	var/list/available_news = list()
	var/list/fileservers = list()
	var/list/datum/ntnet_account/users = list()
	/// Amount of logs the system tries to keep in memory. Keep below 999 to prevent byond from acting weirdly.
	/// High values make displaying logs much laggier.
	var/setting_maxlogcount = 100

	/// These only affect wireless. LAN (consoles) are unaffected since it would be possible to create scenario where someone turns off NTNet, and is unable to turn it back on since it refuses connections
	var/setting_softwaredownload = TRUE
	var/setting_peertopeer = TRUE
	var/setting_communication = TRUE
	var/setting_systemcontrol = TRUE
	/// Setting to 1 will disable all wireless, independently on relays status.
	var/setting_disabled = FALSE
	/// Whether the IDS warning system is enabled
	var/intrusion_detection_enabled = TRUE
	/// Set when there is an IDS warning due to malicious (antag) software.
	var/intrusion_detection_alarm = FALSE


/// If new NTNet datum is spawned, it replaces the old one.
/datum/ntnet/New()
	if(GLOB.ntnet_global && (GLOB.ntnet_global != src))
		GLOB.ntnet_global = src // There can be only one.
	for(var/obj/structure/machinery/ntnet_relay/R in SSmachinery.machinery)
		relays.Add(R)
		R.NTNet = src
	build_software_lists()
	build_news_list()

	//add some default channels
	new /datum/ntnet_conversation("NTNet Relay", TRUE)

/// Simplified logging: Adds a log. log_string is mandatory parameter, source is optional.
/datum/ntnet/proc/add_log(var/log_string, var/obj/item/computer_hardware/network_card/source = null, var/messaging=FALSE)
	var/log_text = "[worldtime2text()] - "
	if(source)
		log_text += "[source.get_network_tag()] - "
	else
		log_text += "*SYSTEM* - "
	log_text += log_string
	if(!messaging)
		logs.Add(log_text)
	else
		messages.Add(log_text)

	if(logs.len > setting_maxlogcount)
		// We have too many logs, remove the oldest entries until we get into the limit
		for(var/L in logs)
			if(logs.len > setting_maxlogcount)
				logs.Remove(L)
			else
				break

/// Checks whether NTNet's core service operates. If parameter is passed checks whether specific function is enabled.
/datum/ntnet/proc/check_function(var/specific_action = 0)
	var/operating = has_operable_core()

	if(setting_disabled)
		return FALSE

	if(specific_action == NTNET_SOFTWAREDOWNLOAD)
		return (operating && setting_softwaredownload)
	if(specific_action == NTNET_PEERTOPEER)
		return (operating && setting_peertopeer)
	if(specific_action == NTNET_COMMUNICATION)
		return (operating && setting_communication)
	if(specific_action == NTNET_SYSTEMCONTROL)
		return (operating && setting_systemcontrol)
	return operating

/datum/ntnet/proc/check_endpoint_function(var/specific_action = 0, var/ethernet = FALSE)
	// Wireless firewall toggles do not affect wired endpoints, but wired endpoints still need a live core service
	if(ethernet)
		return has_operable_core()
	return check_function(specific_action)

/datum/ntnet/proc/has_operable_core()
	if(!relays || !relays.len)
		return FALSE

	for(var/obj/structure/machinery/ntnet_relay/R in relays)
		if(R.provides_core_service())
			return TRUE
	return FALSE

/// 'For endpoint' signifies that sometimes we will abstract a device as being a modular computer when really all we care about is whether it is networked.
/// This will likely need to be simplified in future.
/datum/ntnet/proc/get_signal_for_endpoint(var/atom/endpoint, var/specific_action = 0, var/ethernet = FALSE, var/long_range = FALSE)
	if(!istype(endpoint))
		return 0

	var/turf/endpoint_turf = get_turf(endpoint)
	if(SSatlas.current_map.is_always_available_network_level(endpoint_turf?.z))
		if(ethernet)
			return 3
		if(long_range)
			return 2
		return 1

	if(!check_endpoint_function(specific_action, ethernet))
		return 0

	var/area/A = get_area(endpoint)
	if(A?.centcomm_area && ethernet)
		return 3

	var/signal = 0
	for(var/obj/structure/machinery/ntnet_relay/R in relays)
		signal = max(signal, R.get_signal_for_endpoint(endpoint, ethernet, long_range))
	return signal

/datum/ntnet/proc/get_signal(var/obj/item/computer_hardware/network_card/card, var/specific_action = 0)
	if(!istype(card) || !card.parent_computer)
		return 0
	return get_signal_for_endpoint(card.parent_computer, specific_action, card.ethernet, card.long_range)

/datum/ntnet/proc/get_reachable_z_levels_for_endpoint(var/atom/endpoint, var/specific_action = 0, var/ethernet = FALSE, var/long_range = FALSE)
	. = list()
	var/turf/endpoint_turf = get_turf(endpoint)
	if(SSatlas.current_map.is_always_available_network_level(endpoint_turf?.z))
		. |= endpoint_turf.z
		return
	if(get_signal_for_endpoint(endpoint, specific_action, ethernet, long_range) <= 0)
		return

	for(var/obj/structure/machinery/ntnet_relay/R in relays)
		if(R.can_route_to_core())
			. |= R.get_covered_z_levels()

/datum/ntnet/proc/get_reachable_z_levels(var/obj/item/computer_hardware/network_card/card, var/specific_action = 0)
	. = list()
	var/turf/endpoint_turf = get_turf(card?.parent_computer)
	if(SSatlas.current_map.is_always_available_network_level(endpoint_turf?.z))
		. |= endpoint_turf.z
		return
	if(get_signal(card, specific_action) <= 0)
		return

	for(var/obj/structure/machinery/ntnet_relay/R in relays)
		if(R.can_route_to_core())
			. |= R.get_covered_z_levels()

/// Builds lists that contain downloadable software.
/datum/ntnet/proc/build_software_lists()
	available_station_software = list()
	available_antag_software = list()
	available_software = list()
	for(var/F in typesof(/datum/computer_file/program))
		var/datum/computer_file/program/prog = new F("Compless")
		// Invalid type (shouldn't be possible but just in case), invalid filetype (not executable program) or invalid filename (unset program)
		if(!prog || !istype(prog) || prog.filename == "UnknownProgram" || prog.filetype != "PRG")
			continue

		available_software.Add(prog)
		// Check whether the program should be available for station/antag download, if yes, add it to lists.
		if(prog.available_on_ntnet)
			available_station_software.Add(prog)
		if(prog.available_on_syndinet)
			available_antag_software.Add(prog)
	for(var/path in typesof(/datum/modular_computer_app_presets))
		var/datum/modular_computer_app_presets/prs = new path()
		available_software_presets.Add(prs)

/// Builds lists that contain downloadable software.
/datum/ntnet/proc/build_news_list()
	available_news = list()
	for(var/F in typesof(/datum/computer_file/data/news_article/))
		var/datum/computer_file/data/news_article/news = new F(1)
		if(news.stored_data)
			available_news.Add(news)

/// Attempts to find a downloadable file according to filename var
/datum/ntnet/proc/find_ntnet_file_by_name(var/filename)
	for(var/datum/computer_file/program/P in available_software)
		if(filename == P.filename)
			return P

/// Resets the IDS alarm
/datum/ntnet/proc/resetIDS()
	intrusion_detection_alarm = FALSE

/datum/ntnet/proc/toggleIDS()
	resetIDS()
	intrusion_detection_enabled = !intrusion_detection_enabled

/// Removes all logs
/datum/ntnet/proc/purge_logs()
	logs = list()
	messages = list()
	add_log("-!- LOGS DELETED BY SYSTEM OPERATOR -!-")

/// Updates maximal amount of stored logs. Use this instead of setting the number, it performs required checks.
/datum/ntnet/proc/update_max_log_count(var/lognumber)
	if(!lognumber)
		return FALSE
	// Trim the value if necessary
	lognumber = between(MIN_NTNET_LOGS, lognumber, MAX_NTNET_LOGS)
	setting_maxlogcount = lognumber
	add_log("Configuration Updated. Now keeping [setting_maxlogcount] logs in system memory.")

/datum/ntnet/proc/toggle_function(var/function)
	if(!function)
		return
	function = text2num(function)
	switch(function)
		if(NTNET_SOFTWAREDOWNLOAD)
			setting_softwaredownload = !setting_softwaredownload
			add_log("Configuration Updated. Wireless network firewall now [setting_softwaredownload ? "allows" : "disallows"] connection to software repositories.")
		if(NTNET_PEERTOPEER)
			setting_peertopeer = !setting_peertopeer
			add_log("Configuration Updated. Wireless network firewall now [setting_peertopeer ? "allows" : "disallows"] peer to peer network traffic.")
		if(NTNET_COMMUNICATION)
			setting_communication = !setting_communication
			add_log("Configuration Updated. Wireless network firewall now [setting_communication ? "allows" : "disallows"] instant messaging and similar communication services.")
		if(NTNET_SYSTEMCONTROL)
			setting_systemcontrol = !setting_systemcontrol
			add_log("Configuration Updated. Wireless network firewall now [setting_systemcontrol ? "allows" : "disallows"] remote control of the station's systems.")