stopGap = {}
stopGap.version = "1.3.0"
stopGap.verbose = false 
stopGap.ssbEnabled = true  
stopGap.ignoreMe = "-sg"
stopGap.spIgnore = "-sp" -- only single-player ignored 
stopGap.noParking = false -- turn on to ignore all 'from parking' 
stopGap.isMP = false 
stopGap.running = true 
stopGap.refreshInterval = -1 -- seconds to refresh all statics. -1 = never, 3600 = once every hour 
stopGap.kickTheDead = true -- kick players to spectators on death to prevent re-entry issues

stopGap.requiredLibs = {
	"dcsCommon",
	"cfxZones", 
	"cfxMX",
}
--[[--
	Written and (c) 2023-2024 by Christian Franz 

	Replace all player units with static aircraft until the first time 
	that a player slots into that plane. Static is then replaced with live player unit. 
	
	For aircraft/helo carriers, no player planes are replaced with statics
	
	For multiplayer, StopGapGUI must run on the server (only server)

	STRONGLY RECOMMENDED FOR MISSION DESIGNERS:
	- Use single-unit player groups.
	- Use 'start from ground hot/cold' to be able to control initial aircraft orientation

	To selectively exempt player units from stopGap, add a '-sg' to their name. Alternatively, use stopGap zones 
	
	Version History
	1.0.0 - Initial version
    1.0.1 - update / replace statics after slots become free again
	1.0.2 - DML integration 
	      - SSB integration 
		  - on? 
		  - off?
		  - onStart
		  - stopGap Zones 
	1.0.3 - server plug-in logic
	1.0.4 - player units or groups that end in '-sg' are not stop-gapped
	1.0.5 - triggerMethod
	1.0.6 - spIgnore '-sp' 
	1.0.7 - migrated to OOP zones 
		  - corrected ssbEnabled config from sbb to ssb 
	1.0.8 - added refreshInterval option as requested 
		  - refresh attribute config zone 
	1.0.9 - in line with standalone (optimization not required for DML)
	1.0.10 - some more verbosity for spIgnore and sgIgnore zones (DML only)
	1.1.0 - kickTheDead option 
	1.1.1 - filter "from runway" clients 
	1.1.2 - allNeutral (DML only) 
	1.2.0 - DCS dynamic player spawn compatibility 
			stopGaps only works with MX data, so we are good, no changes 
			required 
	1.3.0 - carriers in shallow waters also no longer handled as viable 
		  - noParking option 
	1.3.1 - stronger guards on refresh 
--]]--

stopGap.standInGroups = {} -- idx by name, if set has a static 
stopGap.myGroups = {} -- for fast look-up of mx orig data 
stopGap.stopGapZones = {} -- DML only 

--
-- one-time start-up processing
--
-- in DCS, a group with one or more players only allocates when 
-- the first player in the group enters the game. 
--

function stopGap.staticMXFromUnitMX(theGroup, theUnit)
	-- enter with MX data blocks
	-- build a static object from mx unit data 
	local theStatic = {}
	theStatic.x = theUnit.x 
	theStatic.y = theUnit.y 
	theStatic.livery_id = theUnit.livery_id -- if exists 
	theStatic.heading = theUnit.heading -- may need some attention
	theStatic.type = theUnit.type 
	theStatic.name = theUnit.name  -- will magically be replaced with player unit 
	theStatic.cty = cfxMX.countryByName[theGroup.name]
	theStatic.payload = theUnit.payload -- not supported (yet) by DCS 
	theStatic.onboard_num = theUnit.onboard_num -- not supported 
	-- DML only: allNeutral 
	if stopGap.allNeutral then 
		theStatic.cty = dcsCommon.getACountryForCoalition(0)
	end
	return theStatic 
end

function stopGap.isGroundStart(theGroup)
	-- look at route 
	if not theGroup.route then return false end 
	local route = theGroup.route 
	local points = route.points 
	if not points then return false end
	local ip = points[1]
	if not ip then return false end 
	local action = ip.action 
	if action == "Fly Over Point" then return false end 
	if action == "Turning Point" then return false end 	
	if action == "Landing" then return false end 	
	if action == "From Runway" then return false end 
	if stopGap.noParking then
		local loAct = string.lower(action)
		if loAct == "from parking area" or 
		   loAct == "from parking area hot" then 
			if stopGap.verbose then 
				trigger.action.outText("StopG: Player Group <" .. theGroup.name .. "> NOPARKING: [" .. action .. "] must be skipped.", 30)
			end 
			return false 
		end
	end
	-- looks like aircraft is on the ground
	-- but is it in water (carrier)? 
	local u1 = theGroup.units[1]
	local sType = land.getSurfaceType(u1) -- has fields x and y
	if sType == 3 or sType == 2 then 
		if stopGap.verbose then 
			trigger.action.outText("StopG: Player Group <" .. theGroup.name .. "> SEA BASED: [" .. action .. "], land type " .. sType .. " should be skipped.", 30)
		end
		return false 
	end -- water & shallow water a no-go
	if stopGap.verbose then 
		trigger.action.outText("StopG: Player Group <" .. theGroup.name .. "> GROUND BASED: " .. action .. ", land type " .. sType, 30)
	end 
	return true
end

function stopGap.ignoreMXUnit(theUnit) -- DML-only 
	local p = {x=theUnit.x, y=0, z=theUnit.y}
	for idx, theZone in pairs(stopGap.stopGapZones) do 
		if theZone.sgIgnore and cfxZones.pointInZone(p, theZone) then 
			return true
		end
		-- only single-player: exclude units in spIgnore zones 
		if (not stopGap.isMP) and
			theZone.spIgnore and cfxZones.pointInZone(p, theZone) then 
			return true
		end
	end
	return false
end

function stopGap.createStandInsForMXGroup(group)
	local allUnits = group.units
	if group.name:sub(-#stopGap.ignoreMe) == stopGap.ignoreMe then 
		if stopGap.verbose then 
			trigger.action.outText("+++StopG: <<skipping group " .. group.name .. ">>", 30)
		end
		return nil 
	end
	if (not stopGap.isMP) and group.name:sub(-#stopGap.spIgnore) == stopGap.spIgnore then 
		if stopGap.verbose then 
			trigger.action.outText("<<'-sp' !SP! skipping group " .. group.name .. ">>", 30)
		end
		return nil 
	end
	
	local theStaticGroup = {}
	for idx, theUnit in pairs (allUnits) do 
		local sgMatch = theUnit.name:sub(-#stopGap.ignoreMe) == stopGap.ignoreMe
		local spMatch = theUnit.name:sub(-#stopGap.spIgnore) == stopGap.spIgnore
		local zoneIgnore = stopGap.ignoreMXUnit(theUnit)
		if stopGap.isMP then spMatch = false end -- only single-player
		if (theUnit.skill == "Client" or theUnit.skill == "Player") 
		   and (not sgMatch)
		   and (not spMatch)
		   and (not zoneIgnore)
		then
			local theStaticMX = stopGap.staticMXFromUnitMX(group, theUnit)
			local theStatic = coalition.addStaticObject(theStaticMX.cty, theStaticMX)
			theStaticGroup[theUnit.name] = theStatic -- remember me
			if stopGap.verbose then 
				trigger.action.outText("+++StopG: adding static for <" .. theUnit.name .. ">", 30)
			end
		else 
			if stopGap.verbose then 
				trigger.action.outText("+++StopG: <<skipping unit " .. theUnit.name .. ">>", 30)
			end
		end 
	end
	return theStaticGroup
end

function stopGap.initGaps()
	-- turn on. May turn on any time, even during game 
	-- when we enter, all slots should be emptry 
	-- and we populate all slots. If slot in use, don't populate
	-- with their static representations 
	for name, group in pairs (cfxMX.playerGroupByName) do 
		-- check to see if this group is on the ground at parking 
		-- by looking at the first waypoint 
		if stopGap.isGroundStart(group) then 
			-- this is one of ours!
			group.sgName = "SG"..group.name -- flag name for MP
			trigger.action.setUserFlag(group.sgName, 0) -- mark unengaged
			stopGap.myGroups[name] = group

			-- see if this group exists in-game already 
			local existing = Group.getByName(name)
			if existing and Group.isExist(existing) then 
				if stopGap.verbose then 
					trigger.action.outText("+++stopG: group <" .. name .. "> already slotted, skipping", 30)
				end
			else 
				-- replace all groups entirely with static objects 
				---local allUnits = group.units
				local theStaticGroup = stopGap.createStandInsForMXGroup(group)
				-- remember this static group by its real name 
				stopGap.standInGroups[group.name] = theStaticGroup
			end
		end -- if groundtstart
	end
end

function stopGap.turnOff()
	-- remove all stand-ins
	for gName, standIn in pairs (stopGap.standInGroups) do 
		for name, theStatic in pairs(standIn) do 
			StaticObject.destroy(theStatic)
		end
	end
	stopGap.standInGroups = {}
	stopGap.running = false 
end

function stopGap.turnOn()
	-- populate all empty (non-taken) slots with stand-ins
	stopGap.initGaps()
	stopGap.running = true 
end

function stopGap.refreshAll() -- restore all statics 
	if stopGap.refreshInterval > 0 then 
		-- re-schedule invocation 
		timer.scheduleFunction(stopGap.refreshAll, {}, timer.getTime() + stopGap.refreshInterval)
		if not stopGap.enabled then return end -- why do we have enabled and running?		
		if stopGap.running then 
			stopGap.turnOff() -- kill all statics 
			-- turn back on in half a second 
			timer.scheduleFunction(stopGap.turnOn, {}, timer.getTime() + 0.5)
		end
		if stopGap.verbose then 
			trigger.action.outText("+++stopG: refreshing all static", 30)
		end
	end
end
-- 
-- event handling 
--
function stopGap.removeStaticGapGroupNamed(gName)
	for name, theStatic in pairs(stopGap.standInGroups[gName]) do 
		StaticObject.destroy(theStatic)
	end
	stopGap.standInGroups[gName] = nil
end

function stopGap:onEvent(event)
	if not event then return end 
	if not event.id then return end 
	if not event.initiator then return end 
	local theUnit = event.initiator 
	if (not theUnit.getPlayerName) or (not theUnit:getPlayerName()) then 
		return 
	end -- no player unit.
	local id = event.id 
	if id == 15 then 
		local uName = theUnit:getName()
		local theGroup = theUnit:getGroup() 
		local gName = theGroup:getName()
		
		if stopGap.myGroups[gName] then
			-- in case there were more than one units in this group, 
			-- also clear out the others. better safe than sorry
			if stopGap.standInGroups[gName] then 
				stopGap.removeStaticGapGroupNamed(gName)
			end
		end		
		-- erase stopGapGUI flag, no longer required, unit 
		-- is now slotted into 
		trigger.action.setUserFlag("SG"..gName, 0)
	end
	if id == 6 then -- eject
--		trigger.action.outText("+++SG: not handled: Eject Eject Eject!", 30)
	end
	if 	(id == 9) or (id == 30) or (id == 5) then -- dead, lost, crash 
--		trigger.action.outText("+++sg: event <" .. id .. ">, handing off to kicker", 30)
		local pName = theUnit:getPlayerName()
		timer.scheduleFunction(stopGap.kickplayer, pName, timer.getTime() + 1)
	end
	
end

stopGap.kicks = {}
function stopGap.kickplayer(args)
--	trigger.action.outText("+++sg: enter kicker!", 30)
	if not stopGap.kickTheDead then return end 
	local pName = args 
	for i,slot in pairs(net.get_player_list()) do
		local nn = net.get_name(slot)
		if nn == pName then
			if stopGap.kicks[nn] then 
				if timer.getTime() < stopGap.kicks[nn] then return end 
			end 
			net.force_player_slot(slot, 0, '')
			stopGap.kicks[nn] = timer.getTime() + 5 -- avoid too many kicks in 5 seconds
		end
	end
end

--
-- update, includes MP client check code
--
function stopGap.update()
	-- check every second. 
	timer.scheduleFunction(stopGap.update, {}, timer.getTime() + 1)

	if not stopGap.isMP then 
		local sgDetect = trigger.misc.getUserFlag("stopGapGUI")
		if sgDetect > 0 then 
			trigger.action.outText("stopGap: MP activated <" .. sgDetect .. ">, will re-init", 30) 
			stopGap.turnOff()
			stopGap.isMP = true 
			if stopGap.enabled then 
				stopGap.turnOn()
			end
			return 
		end  
	end

		-- check if signal for on? or off? 
	if stopGap.turnOn and cfxZones.testZoneFlag(stopGap, stopGap.turnOnFlag, stopGap.triggerMethod, "lastTurnOnFlag") -- warning: stopGap is NOT dmlZone, requires cfxZone invocation 
	then
		if not stopGap.enabled then 
			stopGap.turnOn()
		end
		stopGap.enabled = true 
	end
	
	if stopGap.turnOff and cfxZones.testZoneFlag(stopGap, stopGap.turnOffFlag, stopGap.triggerMethod, "lastTurnOffFlag") then
		if stopGap.enabled then 
			stopGap.turnOff()
		end
		stopGap.enabled = false 
	end
	
	if not stopGap.enabled then return end 
	
	-- check if slots can be refilled or need to be vacated (MP) 
	for name, theGroup in pairs(stopGap.myGroups) do 
		if not stopGap.standInGroups[name] then 
			-- if there is no stand-in group, that group was slotted
			-- or removed for ssb
			local busy = true 
			local pGroup = Group.getByName(name)
			if pGroup then 
				if Group.isExist(pGroup) then 
				else
					busy = false -- no longer exists
				end
			else 
				busy = false -- nil group 
			end 
			
			-- now conduct ssb checks if enabled 
			if stopGap.ssbEnabled then 
				local ssbState = trigger.misc.getUserFlag(name)
				if ssbState > 0 then 
					busy = true -- keep busy 
				end
			end
			
			-- check if StopGapGUI wants a word 
			local sgState = trigger.misc.getUserFlag(theGroup.sgName)
			if sgState < 0 then 
				busy = true 
				-- count up for auto-release after n seconds
				trigger.action.setUserFlag(theGroup.sgName, sgState + 1)
			end
			
			if busy then 
				-- players active in this group 
			else 
				local theStaticGroup = stopGap.createStandInsForMXGroup(theGroup)
				stopGap.standInGroups[name] = theStaticGroup
			end	
		else 
			-- plane is currently static and visible
			-- check if this needs to change			
			local removeMe = false 
			if stopGap.ssbEnabled then 
				local ssbState = trigger.misc.getUserFlag(name)
				if ssbState > 0 then removeMe = true end 
			end
			local sgState = trigger.misc.getUserFlag(theGroup.sgName)
			if sgState < 0 then removeMe = true end 
			if removeMe then 
				stopGap.removeStaticGapGroupNamed(name) -- also nils entry
				if stopGap.verbose then 
					trigger.action.outText("+++StopG: [server command] remove static group <" .. name .. "> for SSB/SG server", 30)
				end 				
			end
		end
	end
end

-- 
-- read stopGapZone 
--
function stopGap.createStopGapZone(theZone)
	local sg = theZone:getBoolFromZoneProperty("stopGap", true)
	if sg then theZone.sgIgnore = false else 
		if theZone.verbose or stopGap.verbose then 
			trigger.action.outText("++sg: Ignoring player craft in zone <" ..theZone.name  .."> for all modes", 30)
		end
		theZone.sgIgnore = true 
	end 
end

function stopGap.createStopGapSPZone(theZone)
	local sp = theZone:getBoolFromZoneProperty("stopGapSP", true)
	if sp then theZone.spIgnore = false else 
		if theZone.verbose or stopGap.verbose then 
			trigger.action.outText("++sg: Ignoring player craft in zone <" ..theZone.name  .."> for single-player mode", 30)
		end
		theZone.spIgnore = true 
	end 
end

--
-- Read Config Zone
--
stopGap.name = "stopGapConfig" -- cfxZones compatibility here 
function stopGap.readConfigZone(theZone)
	-- currently nothing to do 
	stopGap.verbose = theZone.verbose 
	stopGap.ssbEnabled = theZone:getBoolFromZoneProperty("ssb", true)
	stopGap.enabled = theZone:getBoolFromZoneProperty("onStart", true)
	stopGap.noParking = theZone:getBoolFromZoneProperty("noParking", false)
	if theZone:hasProperty("on?") then 
		stopGap.turnOnFlag = theZone:getStringFromZoneProperty("on?", "*<none>")
		stopGap.lastTurnOnFlag = trigger.misc.getUserFlag(stopGap.turnOnFlag)
	end
	if theZone:hasProperty("off?") then 
		stopGap.turnOffFlag = theZone:getStringFromZoneProperty("off?", "*<none>")
		stopGap.lastTurnOffFlag = trigger.misc.getUserFlag(stopGap.turnOffFlag)
	end
	stopGap.triggerMethod = theZone:getStringFromZoneProperty( "triggerMethod", "change")
	if stopGap.verbose then 
		trigger.action.outText("+++StopG: config read, verbose = YES", 30)
		if stopGap.enabled then 
			trigger.action.outText("+++StopG: enabled", 30)
		else 
			trigger.action.outText("+++StopG: turned off", 30)		
		end 
	end
	
	stopGap.refreshInterval = theZone:getNumberFromZoneProperty("refresh", -1) -- default: no refresh
	stopGap.kickTheDead = theZone:getBoolFromZoneProperty("kickDead", true)
	stopGap.allNeutral = theZone:getBoolFromZoneProperty("allNeutral", false)
end

--
-- get going 
--
function stopGap.start()
	if not dcsCommon.libCheck("cfx StopGap", 
							  stopGap.requiredLibs) 
	then return false end
	
	local sgDetect = trigger.misc.getUserFlag("stopGapGUI")
	stopGap.isMP = sgDetect > 0 
	
	local theZone = cfxZones.getZoneByName("stopGapConfig") 
	if not theZone then 
		theZone = cfxZones.createSimpleZone("stopGapConfig")
	end
	stopGap.readConfigZone(theZone)
	
	-- collect exclusion zones
	local pZones = cfxZones.zonesWithProperty("stopGap")
	for k, aZone in pairs(pZones) do
		stopGap.createStopGapZone(aZone)
		stopGap.stopGapZones[aZone.name] = aZone
	end
	
	-- collect single-player exclusion zones
	local pZones = cfxZones.zonesWithProperty("stopGapSP")
	for k, aZone in pairs(pZones) do
		stopGap.createStopGapSPZone(aZone)
		stopGap.stopGapZones[aZone.name] = aZone
	end
	
	-- fill player slots with static objects 
	if stopGap.enabled then 
		stopGap.initGaps()
	end 
	
	-- connect event handler
	world.addEventHandler(stopGap)
	
	-- start update in 1 second 
	timer.scheduleFunction(stopGap.update, {}, timer.getTime() + 1)
	
	-- start refresh cycle if refresh (>0)
	if stopGap.refreshInterval > 0 then 
		timer.scheduleFunction(stopGap.refreshAll, {}, timer.getTime() + stopGap.refreshInterval)
	end
	
	-- say hi!
	local mp = " (SP - <" .. sgDetect .. ">)"
	if sgDetect > 0 then mp = " -- MP GUI Detected (" .. sgDetect .. ")!" end
	trigger.action.outText("stopGap v" .. stopGap.version .. "  running" .. mp, 30)	

	return true 
end

if not stopGap.start() then 
	trigger.action.outText("+++ aborted stopGap v" .. stopGap.version .. "  -- startup failed", 30)
	stopGap = nil 
end