mapgen = {}

function mapgen:apollo_gen(area, data, pos)--minetest.register_on_generated(function(minp, maxp, seed)

	--local vm, emin, emax = minetest.get_mapgen_object("voxelmanip")
	--local area = VoxelArea:new{MinEdge=emin, MaxEdge=emax}
	--local data = vm:get_data()

	--local y1 = maxp.y
	--local y0 = minp.y

	local px = pos.x
	local py = pos.y
	local pz = pos.z
	--fire up the voxel manipulator
	local vm = minetest.get_voxel_manip()
	local p1 = {x=px-16,y=py-16,z=pz-16}
	local p2 = {x=px+16,y=py+16,z=pz+16}

	pmin, pmax = vm:read_from_map(p1,p2)
	local area = VoxelArea:new{MinEdge=pmin, MaxEdge=pmax}
	local data = vm:get_data()

	print("generating APOLLO MODULE")
	--moontest node content_ids
	local c_dust = minetest.get_content_id("moontest:dust")
	local c_bas = minetest.get_content_id("moontest:basalt")
	local c_hl = minetest.get_content_id("moontest:hlsource")
	local c_msto = minetest.get_content_id("moontest:stone")
	local c_vac = minetest.get_content_id("moontest:vacuum")
	local c_mair = minetest.get_content_id("moontest:air")
	local c_ashield = minetest.get_content_id("moontest:air_shield")
	--default node content_ids
	local c_sto = minetest.get_content_id("default:stone")
	local c_wood = minetest.get_content_id("default:wood")
	local c_glass = minetest.get_content_id("default:glass")
	local c_sblock = minetest.get_content_id("default:steelblock")
	local c_gblock = minetest.get_content_id("default:goldblock")
	local c_cblock = minetest.get_content_id("default:copperblock")
	--mesecons node content_ids
	local c_mesecon = minetest.get_content_id("mesecons:wire_00000000_off")
	local c_lamp = minetest.get_content_id("mesecons_lamp:lamp_off")
	local c_power = minetest.get_content_id("mesecons_powerplant:power_plant")
	--air
	local c_air = minetest.get_content_id("air")

	local yasurf = 0 -- y of above surface node at center of moon
	local stable = true -- is ground solid or liquid?
	for y = py + 16, py - 10, -1 do
		local vi = area:index(px, y, pz)
		local c_node = data[vi]
		if y == py+16 and c_node ~= c_vac and c_node ~= c_air then -- if top node solid
			break
		elseif c_node == c_hl then
			yasurf = y + 1
			stable = false
			break
		elseif c_node == c_dust or c_node == c_msto or c_node == c_bas then --if first surface node
			yasurf = y + 1 --set the position of the surface
			break
		end
	end
	yasurf = py
	--clear out an area for the apollo module
	for x = pmin.x, pmax.x do--px - 13, px + 13 do
		for z = pmin.z, pmax.z do--pz - 13, pz + 13 do
			for y = yasurf, yasurf + 16 do
				local vi = area:index(x, y, z)
				data[vi] = c_vac
			end
		end
	end
	--add a layer ground beneath of it
	for x = px - 15, px + 15 do
		for z = pz - 15, pz + 15 do
			for y = yasurf - 10, yasurf do
				local vi = area:index(x, y, z)
				data[vi] = c_msto
			end
		end
	end
	--create the module
	--start with gold base
	for y = yasurf + 4, yasurf + 6 do
		for x = px-4, px+4 do
			for z = pz - 4, pz + 4 do
				local vi = area:index(x, y, z)
				data[vi] = c_gblock
			end
		end
		for x = px - 2, px + 2 do
			local vi = area:index(x, y, pz + 5)
			data[vi] = c_gblock
			local vi = area:index(x, y, pz - 5)
			data[vi] = c_gblock
		end
		for z = pz - 2, pz + 2 do
			local vi = area:index(px + 5, y, z)
			data[vi] = c_gblock
			local vi = area:index(px - 5, y, z)
			data[vi] = c_gblock
		end
	end
	--create air
	for y = yasurf + 7, yasurf + 13 do
		for x = px - 3, px + 3 do
			for z = pz - 3, pz + 3 do
				local vi = area:index(x,y,z)
				data[vi] = c_mair
			end
		end
	end
	--create cabin
	for y = yasurf + 9, yasurf + 10 do
		for x = px - 2, px + 2 do
			z = pz - 5
			local vi = area:index(x,y,z)
			data[vi] = c_sblock
			z =pz + 5
			local vi = area:index(x,y,z)
			data[vi] = c_sblock
		end
		for z = pz - 2, pz + 2 do
			x = px - 5
			local vi = area:index(x,y,z)
			data[vi] = c_sblock
			x = px + 5
			local vi = area:index(x,y,z)
			data[vi] = c_sblock
		end
	end
	for y = yasurf + 8, yasurf + 11 do
		for x = px - 3, px + 3 do
			z = pz - 4
			local vi = area:index(x,y,z)
			data[vi] = c_sblock
			z =pz + 4
			local vi = area:index(x,y,z)
			data[vi] = c_sblock
		end
		for z = pz - 3, pz + 3 do
			x = px - 4
			local vi = area:index(x,y,z)
			data[vi] = c_sblock
			x = px + 4
			local vi = area:index(x,y,z)
			data[vi] = c_sblock
		end
	end

	--write the voxel manipulator data back to world
	vm:set_data(data)
	vm:write_to_map(data)
	vm:update_map()
end

minetest.register_on_newplayer(function(player)
	pos = player:getpos()
	mapgen:apollo_gen(area, data, pos)
end)