CamingLord: Resident List

-- Residental List Monitor by csmit195

local monitor = peripheral.wrap('right')
local residentList = 'residents.txt'
local authorisedTablet = 476
local cur

-- Design Options
monitor.setTextScale(2)
monitor.setBackgroundColor(colors.white)
monitor.clear()

-- Important Codes
local termX, termY = term.getSize()
rednet.open('bottom')

function showList()
  -- Does List Exist
  if ( fs.exists(residentList) ) then
    local listHandle = fs.open(residentList, 'r')
    local nativeTerm = term.redirect(monitor)
    paintutils.drawFilledBox(1, 1, termX, 3, colors.lightBlue)
    term.setCursorPos(1,2)
    centerText('Current Residents')
    term.setCursorPos(3,5)
    monitor.setBackgroundColor(colors.white)
    monitor.setTextColor(colors.black)
    write(listHandle.readAll():gsub('\n','\n  '))
    term.redirect(nativeTerm)
    listHandle.close()
  else
    local newList = fs.open(residentList, 'w')
    newList.writeLine('ExampleUser1\nExampleUser2\nExampleUser3')
    newList.close()
    error('Resident List: residents.txt could not be found, one has been created, type "edit residents.txt" to modify it, and press Left+CTRL then Enter to bring up the save menu.')
  end
end

function waitForTablet()
    local senderId, message, protocol = rednet.receive('resident_controller')
    print(senderId..', '..message..', '..protocol)
    if ( senderId == authorisedTablet ) then
        if ( message == "rc_load" ) then
            local residentFile = fs.open(residentList, 'r')
            local residents = residentFile.readAll()
            residentFile.close()
            rednet.send(authorisedTablet, residents, 'resident_controller')
        else
            local residentFile = fs.open(residentList, 'w')
            residentFile.write(message)
            residentFile.close()
            monitor.clear()
            showList()
        end
    end
    waitForTablet()
end

-- Utility Functions
function centerText(text)
  local x, y = term.getSize()
  local cX, cY = term.getCursorPos()
  term.setCursorPos(math.ceil((x / 2) - (text:len() / 2)), cY)
  write(text)
end
showList()
waitForTablet()