Advanced Chat Monitor

--[[
Name: Advanced Chat Box
Description: Monitor chat on your server or in predefined of your chatbox.
Usage: chat <chatbox side> <lines of history to keep>
]]

local chat = {}
local maxX, maxY = term.getSize()
local position = 1

function cls()
    term.clear()
    term.setCursorPos(1,1)
end

function updateScrn()
  cls()
  for i=position,position+maxY-1 do -- -1 to prevent writing on last line
      if chat[i] then
          print(chat[i])
      end
  end
  term.setCursorPos(maxX-7,maxY)
  term.write("down up")
end

args = {...}

if #args < 2 then
    print ("Usage:")
    print ("chat <side> <history>")
    print()
    print("Where <side> is the position of the chatbox in relation to the computer and <history> is the amount of chat lines to buffer.")
    return --exit the program because the user failed
end

local side,lines = args[1],tonumber(args[2])

_ = peripheral.wrap(side)

cls()
while true do
    -- update screen
    updateScrn()

    local event, p1, p2, p3 = os.pullEvent()

    if event == "chat" then
      table.insert(chat,"<".. p1 .."> " .. p2) -- add it to the chat table

      if #chat > lines then
          -- limit size of history
          table.remove(chat,1) -- removes the first entry
      end

      if #chat > maxY - 1 then -- only update position if the screen is not full
        position = position + 1
      end

    elseif event == "monitor_touch" then

      x,y=tonumber(p2),tonumber(p3)

      if y == maxY then -- first test for y (row)

            if x <= maxX and x >= maxX - 1 then -- up was clicked
              position = position -1
            elseif x <= maxX - 3 and x >= maxX - 7 then -- down was clicked
              position = position + 1
            end

      end

    end

    if position < 0 then
      position = 0
    elseif position > lines then
      position = lines
    elseif position > #chat then
      position = #chat
    end

end