local tankChestSide = "left"
local drumName = "thermalexpansion_tank"
local drumRefillDuration = 8
local sleepDuration = 4
local drumRefillTrigger = 0.9
local redstoneSide = ""
local redstoneColor = colors.red

local pDrums = peripheral.getNames()
local pChest = peripheral.wrap(tankChestSide)

-- in world tanks
local drums = {}
--refill Tanks
local tanksChest = {}

local refillingFluid
local isRefilling = false


function scanDrums()
	print("scanning connected drums...")
	for i,j in pairs(pDrums) do
		if peripheral.getType(j) == drumName then
			local tankInfo = peripheral.call(j,"getTankInfo")[1]
			local fluid = tankInfo["contents"]
			if fluid ~= nil then
				print("...found: ", fluid["rawName"] , " Drum")
				drums[i] = fluid["rawName"]
			else
				print("...found empty drum-ignore!")
			end
		end
	end
end

function scanTanksChest()
	print("scanning chest for refill tanks...")
	if pChest ~= nil then
		local stackCount = pChest.getInventorySize()
		--print(stackCount)
		for i=1,stackCount do
			local stack = pChest.getStackInSlot(i)
			if stack ~= nil then
				local fluidC = stack["fluid_container"]
				if fluidC ~= nil then
					local fluid = fluidC["contents"]
					if fluid == nil then
						print("...found an empty tank in slot ", i)
					else
						print("...found a Tank with ", fluid["rawName"], " in slot ",i)
						tanksChest[fluid["rawName"]] = i
					end
				end
			end
		end
	else
		print("...no chest found")
	end
end

local function round(num, n)
	local mult = 10^(n or 0)
	return math.floor(num * mult + 0.5) / mult
end

local function persistRefill(name)
	local file = fs.open("refill", "w")
	file.write(name)
	file.close()
end

local function unpersistRefill()
	local file = fs.open("refill", "w")
	file.write("")
	file.close()
end

local function readPersistendRefill()
	local file = fs.open("refill", "r")
	local fluidName = fs.readLine()
	file.close()
	return fluidName
end

local function moveToRefillChest(name)
	local slot = tonumber(tanksChest[name])
	print(slot)
	pChest.pushItem("up", slot)
	refillingFluid = name
	isRefilling = true
	persistRefill(name)
end

print("init tanks and drums...")
print("")
scanDrums()
scanTanksChest()

print("")
print("...init done")

local function testFluid(pName)
	local tankInfo = peripheral.call(j, "getTankInfo")[1]
	local fluidMax = tankInfo["capacity"]
	local fluid = tankInfo["contents"]
	local fluidCur = 0.01
	if fluid ~= nil then
		fluidCur = fluid["amount"]
	end
	return round(fluidCur / fluidMax, 2) <= drumRefillTrigger
end


while true do
	term.clear()
	term.setCursorPos(1,1)
	if isRefilling == false then
		print("checking fluids...")
		for i,j in pairs(pDrums) do
			if peripheral.getType(j) == drumName then
				local tankInfo = peripheral.call(j, "getTankInfo")[1]
				local fluidMax = tankInfo["capacity"]
				local fluid = tankInfo["contents"]
				local fluidCur = 0.01
				if fluid ~= nil then
					fluidCur = fluid["amount"]
				end
				local fillLevel = round(fluidCur / fluidMax, 2)
				print("...fluid: ", fluid["rawName"] , " ", fluidCur, " / ", fluidMax, " (", fillLevel*100, "%)")
				if fillLevel <= drumRefillTrigger then
					moveToRefillChest(fluid["rawName"])
					break
				end
			end
		end
		sleep(sleepDuration)
	else
		print("refilling ", refillingFluid, "...")
		while testFluid(refillingFluid) == false do
			print("...filling drum")
			sleep(drumRefillDuration)
		end
		refillingFluid = ""
		unpersistRefill()
		isRefilling = false
		--break tank via redstone signal
		rs.setBundledOuput(redstoneSide, redstoneColor)
		sleep(1.5)
		rs.setBundledOuput(redstoneSide, 0)
		print("...drum filled!")
		sleep(sleepDuration)
	end
end