local reactor = peripheral.wrap("back")
local monitor = peripheral.wrap("monitor_0")

if reactor == nil then
	error("No reactor found")
end
if monitor == nil then
	error("No monitor found")
end

local energyStored = 0
local energyProduced = 0
local energyCapacity = 0
local fillPercentage = 0
local batteryWindowBG = window.create(monitor, 2, 2, 5, 10, true)
local batteryWindowFG = window.create(monitor, 2, 2, 5, 5, true)

batteryWindowBG.setBackgroundColor(colours.red)
batteryWindowBG.clear()
batteryWindowBG.redraw()

batteryWindowFG.setBackgroundColor(colours.green)
batteryWindowFG.clear()
batteryWindowFG.redraw()

local function round(num, numDecimalPlaces)
  local mult = 10^(numDecimalPlaces or 2)
  return math.floor(num * mult + 0.5) / mult
end

local function UpdateReactorStats()
	local stats = reactor.getEnergyStats()
	energyStored = stats["energyStored"]
	energyProduced = stats["energyProducedLastTick"]
	energyCapacity = stats["energyCapacity"]
	if energyStored == 0 then
		fillPercentage = 0
	else
		fillPercentage = energyStored / energyCapacity * 100
	end
end

local function ClearScreen()
	term.setBackgroundColor(colours.black)
	term.clear()
	term.setCursorPos(1,1)
end

local function ClearMonitor()
	monitor.setBackgroundColor(colours.black)
	monitor.clear()
	monitor.setCursorPos(1,1)
end

local function UpdateMonitorStats()
	batteryWindowFG.reposition(2, 2, 5, round(fillPercentage/10, 0))

	batteryWindowBG.redraw()
	batteryWindowFG.redraw()
	--monitor.write(fillPercentage)
end

ClearScreen()
ClearMonitor()
UpdateReactorStats()

while true do
	os.sleep(0.2)
	UpdateReactorStats()
	ClearScreen()
	ClearMonitor()
	UpdateMonitorStats()
end