ComputerCraft Info Screen v3

--Resolution 57x24
local params = {...}

if #params < 3 then
  error("Use: info monitor_id filename(.txt) filename(.col)")
end

local linkColor = colors.red
local monitorId = params[1]
local textFile = params[2] .. ".txt"
local colorFile = params[3] .. ".col"
local monitor
local width, height
local palette = {
  text = nil,
  background = nil,
  header = nil
}

local function fileExists(filename)
  local file = fs.open(filename, "r")

  if file then
    file.close()

    return true
  end

  return false
end

local function checkFile (filename)
  if not fileExists(filename) then
    error("File '" .. filename .. "' not found")
  end
end

local function getMonitor (sideOrId)
  if not peripheral.getType(sideOrId) == "monitor" then
    error("No monitor found")
  end

  print("Monitor found: " .. sideOrId)
  monitor = peripheral.wrap(sideOrId)
  monitor.setTextScale(0.5)
  width, height = monitor.getSize()
  monitor.clear()
  monitor.setCursorPos(1, 1)
end

local function loadColors ()
  local file = fs.open(colorFile, "r")

  for lineNumber = 1, 3 do
    local line = file.readLine()

    if not line then
      error(
        colorFile .. ": No line "
          .. lineNumber .. " found"
      )
    end

    if lineNumber == 1 then
      palette.text = tonumber(line)
    elseif lineNumber == 2 then
      palette.background = tonumber(line)
    else
      palette.header = tonumber(line)
    end
  end
end

local function newLine ()
  local x, y = monitor.getCursorPos()

  monitor.setCursorPos(1, y + 1)
end

local function wordWrap (text)
  local remainingSpace = width - 2

  monitor.write(" ")

  for word in text:gmatch("[a-zA-Z0-9()'\"@!:*/.,_-]+") do
    wordIsLink = false

    if word:match("[A-Za-z0-9%.%%%+%-]+@[A-Za-z0-9%.%%%+%-]+%.%w%w%w?%w?")
    or word:sub(1, 7) == "http://" then
      wordIsLink = true
      monitor.setTextColor(linkColor)
    end

    if #word > remainingSpace then
      newLine()
      monitor.write(" " .. word .. " ")
      remainingSpace = width - #word - 3
    else
      monitor.write(word .. " ")
      remainingSpace = remainingSpace - #word - 1
    end

    if wordIsLink then
      monitor.setTextColor(palette.text)
    end
  end
end

local function drawBackground (color)
  monitor.setBackgroundColor(color)
  monitor.clear()
end

local function centerPrint (lineNumber, textColor, text)
  monitor.setCursorPos((width - #text) / 2, lineNumber)
  monitor.setTextColor(textColor)
  monitor.write(text)
end

local function getData ()
  local info = fs.open(textFile, "r")
  local infoData = {}

  repeat
    line = info.readLine()

    if line then
      table.insert(infoData, line)
    end
  until line == nil

  info.close()

  return infoData
end

--Draw a filled box for e.g. a button or shadow
local function drawBox (x, y, width, height, color)
  monitor.setBackgroundColor(color)
  monitor.setTextColor(color)

  for i = 0, height - 1 do
    monitor.setCursorPos(x, y + i)

    for j = 1, width do
      monitor.write(" ")
    end
  end
end

local function drawHeader (text)
  --Draw shadow
  drawBox(4, 3, width - 5, 3, colors.lightGray)

  --Draw header box
  drawBox(3, 2, width - 5, 3, colors.white)

  --Write text
  centerPrint(3, palette.header, text)
  monitor.setCursorPos(1, 6)
end

local function displayInfo ()
  local text = getData()

  drawBackground(palette.background)

  for lineNumber, line in ipairs(text) do
    if lineNumber == 1 then
      drawHeader(line:upper())
      monitor.setTextColor(palette.text)
      monitor.setBackgroundColor(palette.background)
    else
      wordWrap(line)
    end

    newLine()
  end
end

--Main program
checkFile(textFile)
checkFile(colorFile)
getMonitor(monitorId)
loadColors()
displayInfo()