startup

local function rgb2hex(r,g,b)
    local t = string.format("0x%02X%02X%02X", r or 0, g or 0, b or 0)
    return tonumber(t)
end
local function getcolor(rat)
  local start_c = {255, 0, 0}
  local end_c = {0, 255, 0}
  local r_dist = end_c[1] - start_c[1]
  local g_dist = end_c[2] - start_c[2]
  local b_dist = end_c[3] - start_c[3]
  local r = start_c[1] + r_dist * rat
  local g = start_c[2] + g_dist * rat
  local b = start_c[3] + b_dist * rat

  return rgb2hex(r, g, b)
end
local p = peripheral.wrap("right")
local cell = peripheral.wrap("left")
p.clear()
local ox, oy = 5, 5
local width = 100
local box2 = p.addBox(ox, oy, 50, 14, 0x000000, 0.5)
local box = p.addBox(ox, oy, 0, 14, 0xFFFF00, 0.5)
local energy = p.addText(ox + 6, oy + 3, "", 0xFFFFFF)
while true do
  local ratio = cell.getEnergyStored()/cell.getMaxEnergyStored()
  box.setWidth(width * ratio)
  box2.setWidth(width * (1 - ratio))
  box2.setX(width * ratio)
  box.setColor(getcolor(ratio))
  energy.setText(math.floor(cell.getEnergyStored()) .. " / " .. cell.getMaxEnergyStored())
  os.sleep(0.1)
end