local U = require "scriptbank\\utillib"
local lights = {}

attachLightToMe = attachLightToMe or {}

local rad = math.rad

function light_npc_init( e )
	lights[ e ] = { 
					lightNum = GetEntityLightNumber( e ),
					attachTo = nil
				  }
end

local function sqrd( x1, z1, x2, z2 )
	local dx, dz = x1 - x2, z1 - z2
	return dx * dx + dz * dz
end

function light_npc_main( e )
	local light = lights[ e ]
	
	if light == nil then return end
	
	if light.attachTo == nil then 
		local x1, y1, z1 = GetLightPosition( light.lightNum )
		
		local dist1 = math.huge
		local closest = nil
		
		for _, v in pairs( attachLightToMe ) do
			if v ~= nil then
				local x2, y2, z2 = GetEntityPosAng( v )
				local dist2 = sqrd( x1, z1, x2, z2 )
				if dist2 < dist1 then 
					closest = v 
					dist1 = dist2
				end
			end
		end
		
		if closest == nil then
			light.attachTo = -1
			return 
		end

		attachLightToMe[ closest ] = nil
		light.attachTo = closest
		
 		--get the entity pos & angles values we are attaching too
		local x, y, z, Ax, Ay, Az = GetEntityPosAng( closest )
		--get our own (light) values 
		local lx, ly, lz, lax, lay, laz = GetEntityPosAng( e )
		
		--work out the offsets (done once at map start)
		light.offx = lx - x
		light.offy = ly - y 
		light.offz = lz - z
		
		--store the angle offset as a radian for vector use for later
		light.offax = rad( lax - Ax )
		light.offay = rad( lay - Ay )
		light.offaz = rad( laz - Az )
		
	elseif 
	   light.attachTo ~= -1 then 
		--this part is run during the update
	
		--get the new values for our attached entity
		local x, y, z, Ax, Ay, Az = GetEntityPosAng( light.attachTo )
		
		--place the light based on the new position + our offset
		local xA, yA, zA = rad( Ax ), rad( Ay ), rad( Az )
		local xo, yo, zo =  U.Rotate3D( light.offx, light.offy, light.offz, xA, yA, zA )
		
		SetLightPosition ( light.lightNum, x + xo, y + yo, z + zo )		
		--work out the angle of the entity + our angle offset
		local xv, yv, zv = U.Rotate3D( 0, 0, 1, xA + light.offax, yA + light.offay, zA + light.offaz )
		SetLightAngle( light.lightNum, xv, yv, zv )
	end 
end