local U = require "scriptbank\\utillib"
local lightNum = {}
local attachTo = {}
local offx,offy,offz,offax,offay,offaz = {},{},{},{},{},{}
attachLightToMe = {}
local _rad = math.rad
function light_npc_init(e)
  lightNum[e] = GetEntityLightNumber(e)--change 2 to the entity number of the light
	--change 'nil' to the entity number of the npc
	--or place the light next to entity for automatic assignment
	--*make sure entity has 'attachLightToMe[e] = e' in the script*
	attachTo[e] = nil 	
end
function light_npc_main(e)
	if attachTo[e] == nil then 
		local x1,y1,z1 = GetLightPosition(lightNum[e])
		local dist1 = 999999
		for a,_ in pairs (attachLightToMe) do 
			local x2,y2,z2 = GetEntityPosAng(a)
			local dist2 = sqrd(x1,z1,x2,z2)
			if dist2 < dist1 then 
				attachTo[e] = a 
				dist1 = dist2
			end 
		end
		if attachTo[e] == nil then 
			attachTo[e] = -1
			return 
		end 
		--get the entity pos & angles values we are attaching too
		local x, y, z, Ax, Ay, Az = GetEntityPosAng(attachTo[e])
		--get our own (light) values 
		local lx,ly,lz = GetLightPosition(lightNum[e])
		local lax,lay,laz = GetEntityAngleX(e),GetEntityAngleY(e),GetEntityAngleZ(e)
		--work out the offsets (done once at map start)
		offx[e] = lx-x
		offy[e] = ly-y 
		offz[e] = lz-z 
		--store the angle offset as a radian for vector use for later
		offax[e] = _rad(lax-Ax)
		offay[e] = _rad(lay-Ay)
		offaz[e] = _rad(laz-Az)
	else 
		--this part is run during the update
		if attachTo[e] == -1 then 
			return 
		end
		--get the new values for our attached entity
		local x, y, z, Ax, Ay, Az = GetEntityPosAng(attachTo[e])
		--place the light based on the new position + our offset
		SetLightPosition ( lightNum[e], x+offx[e], y+offy[e], z+offz[e] )		
		--work out the angle of the entity + our angle offset
		local xv, yv, zv = U.Rotate3D( 0, 0, 1, _rad(Ax)+offax[e], _rad(Ay)+offay[e], _rad(Az)+offaz[e] )
		SetLightAngle( lightNum[e], xv, yv, zv )
		--just to move the prompt
		SetPosition(e, x+offx[e], y+offy[e], z+offz[e])		
		ResetPosition(e, x+offx[e], y+offy[e], z+offz[e])		
		--shows the light's angle vectors
		PromptLocal(e,xv.."  "..yv.."   "..zv)
	end 
end 

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