tdz = {}
tdz.version = "0.9.0dev"
tdz.requiredLibs = {
	"dcsCommon", -- always
	"cfxZones", -- Zones, of course 
}
tdz.allTdz = {}
tdz.watchlist = {}
tdz.watching = false 
tdz.timeoutAfter = 120 -- seconds.
-- 
-- rwy draw procs
--
function tdz.rotateXZPolyInRads(thePoly, rads)
	if not rads then 
		trigger.action.outText("rotateXZPolyInRads (inner): no rads", 30)
		return 
	end 
	local c = math.cos(rads)
	local s = math.sin(rads)
	for idx, p in pairs(thePoly) do 	
		local nx = p.x * c - p.z * s
		local nz = p.x * s + p.z * c
		p.x = nx
		p.z = nz 
	end 
end

function tdz.rotateXZPolyAroundCenterInRads(thePoly, center, rads)
	if not rads then 
		trigger.action.outText("rotateXZPolyAroundCenterInRads: no rads", 30)
		return 
	end 
	local negCtr = {x = -center.x, y = -center.y, z = -center.z}
	tdz.translatePoly(thePoly, negCtr)
	if not rads then 
		trigger.action.outText("WHOA! rotateXZPolyAroundCenterInRads: no rads", 30)
		return 
	end 
	tdz.rotateXZPolyInRads(thePoly, rads)
	tdz.translatePoly(thePoly, center)
end

function tdz.rotateXZPolyAroundCenterInDegrees(thePoly, center, degrees)
	tdz.rotateXZPolyAroundCenterInRads(thePoly, center, degrees * 0.0174533)
end

function tdz.translatePoly(thePoly, v) -- straight rot, translate to 0 first
	for idx, aPoint in pairs(thePoly) do 
		aPoint.x = aPoint.x + v.x 
		if aPoint.y then aPoint.y = aPoint.y + v.y end 
		if aPoint.z then aPoint.z = aPoint.z + v.z end  
	end
end
--[[--
function tdz.frameRwy(center, length, width, rads, a, b) -- bearing in rads 
	if not a then a = 0 end 
	if not b then b = 1 end 
	
	-- create a 0-rotated centered poly 
	local poly = {}
	local half = length / 2
	local leftEdge = -half
	poly[4] = { x = leftEdge + a * length, z = width / 2, y = 0}
	poly[3] = { x = leftEdge + b * length, z = width / 2, y = 0}
	poly[2] = { x = leftEdge + b * length, z = -width / 2, y = 0}
	poly[1] = { x = leftEdge + a * length, z = -width / 2, y = 0}
	-- move it to center in map 
	tdz.translatePoly(poly, center)
	
	-- rotate it 
	tdz.rotateXZPolyAroundCenterInRads(poly, center, rads)
	
	-- frame it 
	local mId = dcsCommon.numberUUID()
	 trigger.action.quadToAll(-1, mId, poly[1], poly[2], poly[3], poly[4], {1, 0, 0, 1}, {1, 0, 0, .5}, 3) -- dotted line, red
	 
end
--]]--
function tdz.calcTDZone(name, center, length, width, rads, a, b)
	if not a then a = 0 end 
	if not b then b = 1 end 
	-- create a 0-rotated centered poly 
	local poly = {}
	local half = length / 2
	local leftEdge = -half
	poly[1] = { x = leftEdge + a * length, z = width / 2, y = 0}
	poly[2] = { x = leftEdge + b * length, z = width / 2, y = 0}
	poly[3] = { x = leftEdge + b * length, z = -width / 2, y = 0}
	poly[4] = { x = leftEdge + a * length, z = -width / 2, y = 0}
	-- move it to center in map 
	tdz.translatePoly(poly, center)	
	-- rotate it 
	tdz.rotateXZPolyAroundCenterInRads(poly, center, rads)
	-- make it a dml zone 
	local theNewZone = cfxZones.createSimplePolyZone(name, center, poly)
	return theNewZone--, left, right 
end

--
-- create a tdz
--
function tdz.createTDZ(theZone)
	local p = theZone:getPoint()
	local theBase = dcsCommon.getClosestAirbaseTo(p) -- never get FARPS
	theZone.base = theBase 
	theZone.baseName = theBase:getName()
	
	-- get closest runway to TDZ
	-- may get a bit hairy, so let's find a good way 
	local allRwys = theBase:getRunways()
	local nearestRwy = nil 
	local minDist = math.huge
	for idx, aRwy in pairs(allRwys) do 
		local rp = aRwy.position
		local dist = dcsCommon.distFlat(p, rp)
		if dist < minDist then 
			nearestRwy = aRwy 
			minDist = dist
		end
	end
	local bearing = nearestRwy.course * (-1)
	theZone.bearing = bearing 
	rwname = math.floor(dcsCommon.bearing2degrees(bearing)/10 + 0.5) -- nice number
	degrees = math.floor(dcsCommon.bearing2degrees(bearing) * 10) / 10
	if degrees < 0 then degrees = degrees + 360 end 
	if degrees > 360 then degrees = degrees - 360 end 
	if rwname < 0 then rwname = rwname + 36 end 
	if rwname > 36 then rwname = rwname - 36 end 
	local opName = rwname + 18 
	if opName > 36 then opName = opName - 36 end 
	if rwname < 10 then rwname = "0"..rwname end 
	if opName < 10 then opName = "0" .. opName end  
	theZone.rwName = rwname .. "/" .. opName	
	theZone.opName = opName .. "/" .. rwname
	local rwLen = nearestRwy.length
	local rwWid = nearestRwy.width 
	local pos = nearestRwy.position
	-- p1 is for distance to centerline calculation, defining a point 
	-- length away in direction bearing, setting up the line
	-- theZone.rwCenter, theZone.p1
	theZone.rwCenter = pos 
	local p1 = {x = pos.x + math.cos(bearing) * rwLen, y = 0, z = pos.z + math.sin(bearing) * rwLen}
	theZone.rwP1 = p1 
	theZone.starts = theZone:getNumberFromZoneProperty("starts", 0)
	theZone.ends = theZone:getNumberFromZoneProperty("ends", 610) -- m = 2000 ft
	theZone.opposing = theZone:getBoolFromZoneProperty("opposing", true)

	theZone.runwayZone = tdz.calcTDZone(theZone.name .. "-" .. rwname .. "main", pos, rwLen, rwWid, bearing)
	theZone.runwayZone:drawZone({0, 0, 0, 1}, {0, 0, 0, 0}) -- black outline 
	local theTDZone = tdz.calcTDZone(theZone.name .. "-" .. rwname, pos, rwLen, rwWid, bearing, theZone.starts / rwLen, theZone.ends/rwLen)
	-- to do: mark the various zones of excellence in different colors, or at least the excellent one with more color
	theTDZone:drawZone({0, 1, 0, 1}, {0, 1, 0, .25})
	theZone.normTDZone = theTDZone
	if theZone.opposing then 
		theTDZone = tdz.calcTDZone(theZone.name .. "-" .. opName, pos, rwLen, rwWid, bearing + math.pi, theZone.starts / rwLen, theZone.ends/rwLen)
		theTDZone:drawZone({0, 1, 0, 1}, {0, 1, 0, .25})
		theZone.opTDZone = theTDZone
		theZone.opBearing = bearing + math.pi
	end
	if theZone:hasProperty("landed!") then 
		theZone.landedFlag = theZone:getStringFromZoneProperty("landed!", "none")
	end
	if theZone:hasProperty("touchdown!") then 
		theZone.touchDownFlag = theZone:getStringFromZoneProperty("touchDown!", "none")
	end
	if theZone:hasProperty("fail!") then 
		theZone.failFlag = theZone:getStringFromZoneProperty("fail!", "none")
	end

	theZone.method = theZone:getStringFromZoneProperty("method", "inc")
end

--
-- event handler
--

function tdz.playerLanded(theUnit, playerName)
	if tdz.watchlist[playerName] then 
		-- this is not a new landing, for now ignore, increment bump count 
		-- make sure unit names match?
		local entry = tdz.watchlist[playerName]
		entry.hops = entry.hops + 1 -- uh oh. 
--		trigger.action.outText("Bump!")
	end 
	
	-- we may want to filter helicopters
	
	-- see if we touched down inside of one of our watched zones 
	local p = theUnit:getPoint()
	local theGroup = theUnit:getGroup()
	local gID = theGroup:getID()
	local msg = ""
	local theZone = nil 
	for idx, aRunway in pairs(tdz.allTdz) do 
		local theRunway = aRunway.runwayZone 
		if theRunway:pointInZone(p) then 
			-- touchdown!
			theZone = aRunway 
			if theZone.touchDownFlag then 
				theZone.pollFlag(theZone.touchDownFlag, theZone.method)
			end
			trigger.action.outTextForGroup(gID, "Touchdown! Come to a FULL STOP for evaluation", 30)
		end 
	end
	if not theZone then return end -- no landing eval zone hit 
	
	-- start a new watchlist entry 
	local entry = {}
	entry.msg = ""
	entry.playerName = playerName 
	entry.unitName = theUnit:getName()
	entry.theType = theUnit:getTypeName()
	entry.gID = gID 
	entry.theTime = timer.getTime() 
	entry.tdPoint = p 
	entry.tdVel = theUnit:getVelocity() -- vector 
	entry.hops = 1
	entry.theZone = theZone
	
	-- see if we are in main or opposite direction 
	local hdg = dcsCommon.getUnitHeading(theUnit)
	local dHdg = math.abs(theZone.bearing - hdg) -- 0..Pi
	local dOpHdg = math.abs(theZone.opBearing - hdg)
	local opposite = false 
	if dOpHdg < dHdg then 
		opposite = true 
		dHdg = dOpHdg
		trigger.action.outText("opposite rwy detected", 30)
	end 
	if dHdg > math.pi * 1.5 then -- > 270+ 
		dHdg = dHdg - math.pi * 1.5
	elseif dHdg > math.pi / 2 then -- > 90+ 
		dHdg = dHdg - math.pi / 2 
	end
	dHdg = math.floor(dHdg * 572.958) / 10 -- in degrees
	local lHdg = math.floor(hdg * 572.958) / 10 -- also in deg 
	-- now see how far off centerline. 
	local offcenter = dcsCommon.distanceOfPointPToLineXZ(p, theZone.rwCenter, theZone.rwP1)
	offcenter = math.floor(offcenter * 10)/10 
	local vel = dcsCommon.vMag(entry.tdVel)
	local vkm = math.floor(vel * 36) / 10 
	local kkm = math.floor(vel * 19.4383) / 10
	entry.msg = entry.msg .. "\nLanded heading " .. lHdg .. "°, diverging by " .. dHdg .. "° from runway heading, velocity at touchdown " .. vkm .. " kmh/" .. kkm .. " kts, touchdown " .. offcenter ..  " m off centerline\n"
	
	-- inside TDZ?
	local tdZone = theZone.normTDZone
	if opposite and theZone.opposing then 
		
		tdZone = theZone.opTDZone
	end 
	if tdZone:pointInZone(p) then 
		-- yes, how far behind threshold
		-- project point onto line to see how far inside 
		local distBehind = dcsCommon.distanceOfPointPToLineXZ(p, tdZone.poly[1], tdZone.poly[4])
		local zonelen = math.abs(theZone.starts-theZone.ends)
		local percentile = math.floor(distBehind / zonelen * 100)
		local rating = ""
		if percentile < 5 or percentile > 90 then rating = "marginal"
		elseif percentile < 15 or percentile > 80 then rating = "pass"
		elseif percentile < 25 or percentile > 60 then rating = "good"
		else rating = "excellent" end 
		entry.msg = entry.msg .. "Touchdown inside TD-Zone, <" .. math.floor(distBehind) .. " m> behind threshold, rating = " .. rating .. "\n"	
	end
	
	tdz.watchlist[playerName] = entry 
	if not tdz.watching then 
		tdz.watching = true 
		timer.scheduleFunction(tdz.watchLandings, {}, timer.getTime() + 0.2)
	end
end 

function tdz:onEvent(event)
	if not event.initiator then return end 
	local theUnit = event.initiator 
	if not theUnit.getPlayerName then return end 
	local playerName = theUnit:getPlayerName() 
	if not playerName then return end 
	if event.id == 4 then 
		-- player landed 
		tdz.playerLanded(theUnit, playerName) 
	end
end

--
-- Monitor landings in progress
--
function tdz.watchLandings() 
	local filtered = {}
	local count = 0
	local transfer = false
	local success = false	
	local now = timer.getTime() 
	for playerName, aLanding in pairs (tdz.watchlist) do 
		-- see if landing timed out 
		local tdiff = now - aLanding.theTime 
		if tdiff < tdz.timeoutAfter then 
			local theUnit = Unit.getByName(aLanding.unitName)
			if theUnit and Unit.isExist(theUnit) then 
				local vel = theUnit:getVelocity()
				local vel = dcsCommon.vMag(vel)
				local p = theUnit:getPoint() 
				if aLanding.theZone.runwayZone:pointInZone(p) then 	
					-- we must slow down to below 3.6 km/h 
					if vel < 1 then 
						-- make sure that we are still inside the runway 
						success = true 
					else 
						transfer = true 
					end
				else 
					trigger.action.outTextForGroup(aLanding.gID, "Ran off runway.", 30)
				end
			end 
		end 
		if transfer then 
			count = count + 1
			filtered[playerName] = aLanding
		else 
			local theZone = aLanding.theZone
			if success then
				local theUnit = Unit.getByName(aLanding.unitName)
				local p = theUnit:getPoint()
				local tdist = math.floor(dcsCommon.distFlat(p, aLanding.tdPoint))
				aLanding.msg = aLanding.msg .."\nSuccessful landing for " .. aLanding.playerName .." in a " .. aLanding.theType .. ". Landing run = <" .. tdist .. " m>, <" .. math.floor(tdiff*10)/10 .. "> seconds from touch-down to standstill."

				if aLanding.hops > 1 then 
					aLanding.msg = aLanding.msg .. "\nNumber of hops: " .. aLanding.hops
				end 
				if theZone.landedFlag then 
					theZone:pollFlag(theZone.landedFlag, theZone.method)
				end
				aLanding.msg = aLanding.msg .."\n"
				trigger.action.outTextForGroup(aLanding.gID, aLanding.msg, 30)
			else 
				if theZone.failFlag then 
					theZone:pollFlag(theZone.failFlag, theZone.method)
				end
				trigger.action.outTextForGroup(aLanding.gID, "Landing for " .. aLanding.playerName .." incomplete.", 30)
			end 
		end
	end
	
	tdz.watchlist = filtered
	
	if count > 0 then 
		timer.scheduleFunction(tdz.watchLandings, {}, timer.getTime() + 0.2)
	else 
		tdz.watching = false
	end
end
--
-- Start
--
function tdz.readConfigZone()
end 

function tdz.start()
	if not dcsCommon.libCheck("cfx TDZ", 
		tdz.requiredLibs) then
		return false 
	end
	
	-- read config 
	tdz.readConfigZone()

	-- collect all wp target zones 
	local attrZones = cfxZones.getZonesWithAttributeNamed("TDZ")
	
	for k, aZone in pairs(attrZones) do 
		tdz.createTDZ(aZone) -- process attribute and add to zone
		table.insert(tdz.allTdz, aZone) -- remember it so we can smoke it
	end
		
	-- add event handler
	world.addEventHandler(tdz)

	trigger.action.outText("cf/x TDZ version " .. tdz.version .. " running", 30)
	return true 
end 

if not tdz.start() then 
	trigger.action.outText("cf/x TDZ aborted: missing libraries", 30)
	tdz = nil 
end