local cellTable = {}
local isTE2 = false
local linesDrawn = 0

function detect()
  for per, side in pairs(rs.getSides()) do
    if peripheral.isPresent(side) then
      if peripheral.getType(side) == "monitor" then
        mon = peripheral.wrap(side)
      elseif peripheral.getType(side) == "modem" then
        modem = side
      end
    end
  end
  return mon, modem
end

function updateCells(_cell, _energy, _max, _state, _isTE2)
  cellTable[_cell] = {energy = _energy, cellMax = _max, state = _state, isTE2 = _isTE2}
end

function getEnergyStats()
  currentSum = 0
  maxSum = 0

  for cell, data in pairs(cellTable) do
    currentSum = currentSum + data.energy
    maxSum = maxSum + data.cellMax
  end
end

function updateStatus(cell, energy, state)
  if state == "EMPTY" then
    mon.write("Cell "..cell.." : ")
    mon.setTextColor(colors.red)
    mon.write("EMPTY")
  elseif state == "FULL" then
    mon.write("Cell "..cell.." : ")
    mon.setTextColor(colors.lightBlue)
    mon.write("FULL")
  elseif state == "CHARGING" then
    mon.write("Cell "..cell.." : ")
    mon.setTextColor(colors.lime)
    mon.write(energy.."%")
  elseif state == "DISCHARGING" then
    mon.write("Cell "..cell.." : ")
    mon.setTextColor(colors.orange)
    mon.write(energy.."%")
  elseif state == "NO CHANGE" then
    mon.write("Cell "..cell.." : "..energy.."%")
  else
    mon.setBackgroundColor(colors.red)
    mon.setTextColor(colors.black)
    mon.write("Cell "..cell.." : ERROR")
  end
  mon.setBackgroundColor(colors.black)
end

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

function getPercentage(current, max)
  return (current / max) * 100
end

function drawBar(val, x, y)
  local percent
  local modifier
  local color

  --If the monitor is 39 cols wide or wider
  --then extend the bar using a static modifier
  if monWidth >= 61 then
    percent = val * 0.025
    modifier = 4
  elseif monWidth >= 39 then
    percent = val * 0.05
    modifier = 2
  elseif monWidth < 39 then
    percent = val * 0.1
    modifier = 1
  end

  --Determine what color the bar should be
  if percent >= 10 / modifier then
    color = colors.lightBlue
  elseif percent >= 8 / modifier then
    color = colors.cyan
  elseif percent >= 6 / modifier then
    color = colors.lime
  elseif percent >= 4 / modifier then
    color = colors.yellow
  elseif percent >= 2 / modifier then
    color = colors.orange
  else
    color = colors.red
  end
  
  --Print bar "brackets"
  mon.setTextColor(colors.white)
  mon.setCursorPos(x, y)
  mon.write("[")

  --Raise modifier to the power of 2 if
  --monitor is large enough
  --[Monitor size to segment size:]
  --3m wide: 10% per segment
  --4m wide: 5% per segment
  --6m wide: 2.5% per segment
  for i = 1, percent * (modifier ^ 2) do
    mon.setTextColor(color)
    mon.write("#")
  end

  if monWidth >= 61 then
    mon.setCursorPos(x + 41, y)
  elseif monWidth >= 39 then
    mon.setCursorPos(x + 21, y)
  elseif monWidth < 39 then
    mon.setCursorPos(x + 11, y)
  end
  mon.setTextColor(colors.white)
  mon.write("]")  
end

--Draw all on-screen data
function draw(serverID)
  local header = "-- Energy Storage Status --"

  --Energy summary
  mon.setBackgroundColor(colors.black)
  mon.setTextColor(colors.white)
  mon.clear()
  mon.setCursorPos((monWidth / 2) - (#header / 2) + 1, 1)
  mon.setBackgroundColor(colors.gray)
  mon.clearLine()
  mon.write(header)
  mon.setCursorPos(1, 3)
  mon.setBackgroundColor(colors.black)
  mon.write("System Energy   : ")

  if isTE2 then
    mon.write(currentSum.." MJ")
  else
    mon.write(currentSum.." RF")
  end
  mon.setCursorPos(1, 4)
  mon.write("Max Sys. Energy : ")

  if isTE2 then
    mon.write(maxSum.." MJ")
  else
    mon.write(maxSum.." RF")
  end
  mon.setCursorPos(1, 6)

  --Render individual cell percentages,
  --states, and colored bars
  for cell, data in pairs(cellTable) do    
    mon.setCursorPos(1, 5 + cell)
    print(serverID.." -> Cell "..cell.." : "..data.energy.."/"..data.cellMax.." ["..data.state.."]")
    linesDrawn = linesDrawn + 1
    updateStatus(cell, round(getPercentage(data.energy, data.cellMax), 2), data.state)
    --mon.setCursorPos(17, 5 + cell)
    drawBar(round(getPercentage(data.energy, data.cellMax), 2), 17, 5 + cell)
  end

  --Bottom bar on monitor
  mon.setCursorPos(1, monHeight)
  mon.setBackgroundColor(colors.gray)
  mon.clearLine()
  --Reset button
  mon.setBackgroundColor(colors.red)
  mon.write(" RESET ")
  --Client ID
  local cidText = "Client ID: "..os.getComputerID()

  mon.setCursorPos(monWidth - #cidText, monHeight)
  mon.setBackgroundColor(colors.gray)
  mon.write(cidText)
end

function init()
  --Print client ID reminder in terminal
  term.clear()
  term.setCursorPos(1, 1)
  term.write("This client's ID is "..os.getComputerID()..".")
  term.setCursorPos(1, 3)
end

term.clear()
mon, modem = detect()
--Get initial monitor size
monWidth, monHeight = mon.getSize()
rednet.open(modem)
init()

--End program if screen is too small
--Screen must be 3 blocks wide by
--two blocks tall to display any info
if monWidth < 29 or monHeight < 12 then
  error("Monitor must be 3 blocks wide by 2 blocks high to display data.")
end

local idle = "No Signal"
mon.setCursorPos((monWidth / 2) - (#idle / 2) + 1, (monHeight / 2) + 1)
mon.setBackgroundColor(colors.red)
mon.write(idle)

while true do
  event, p1, p2, p3 = os.pullEvent()

  if event == "monitor_touch" then
    if p2 <= 7 and p3 == monHeight then
      term.setTextColor(colors.red)
      print("Reboot event requested by user.")
      os.sleep(2)
      os.reboot()
    end
  end
  local sender, message, dist = rednet.receive()
  local data = textutils.unserialize(message)
  --Get monitor size in case size changes while client is running
  monWidth, monHeight = mon.getSize()

  updateCells(data._cellNum, data._current, data._max, data._state, data._isTE2)
  getEnergyStats()
  isTE2 = data._isTE2
  draw(sender)
  
  if linesDrawn > 8 then
    term.clear()
    linesDrawn = 0
    init()
  end
end