chat for computercraft

term.clear()
term.setCursorPos(1,1)
function LR()
local n=1
while true do
local x, y=term.getCursorPos()
term.clearLine()
if n==1 then write(">LEFT<   RIGHT") else write (" LEFT   >RIGHT<") end
term.setCursorPos(x, y)
a, b=os.pullEventRaw()
while a~="key" do a, b=os.pullEventRaw() end
if b==203 and n==2 then n=1 end
if b==205 and n==1 then n=2 end
if b==28 then print("") break end
end
if n==1 then return true end
if n==2 then return false end
return false
end
local chatTable = { [1] = "Welcome to DSC Chat! (/help for commands)" }
local chatLine = 1
local message = ""
local user = "???"
local compID = os.computerID()
local toID = ""
local msgMessage = ""
local msgSent = ""

function drawLine()
term.setCursorPos( 1, 17 )
term.clearLine()
for n=1,49 do
io.write("=")
end
term.setCursorPos(1,18)
term.clearLine()
write(username)
write(": ")
write(message)
end
function addChat(str)
if chatLine < 16 then
  table.insert(chatTable, str)
  chatLine = chatLine + 1
else
  for n=1,15 do
   chatTable[n] = chatTable[n+1]
  end
   chatTable[16] = str
  end
end
function quit()
os.exit()
end
function showChat()
term.setCursorPos( 1, 1 )
for n=1,chatLine do
  term.clearLine()
  print(chatTable[n])
end
end
print("Is your modem on the Left or the Right?")
term.setCursorPos(1,18)
if LR() == true then
rednet.open("left")
else
rednet.open("right")
end
term.clear()
repeat
term.setCursorPos(1,1)
print("Enter a username for yourself.")
term.setCursorPos(1,18)
user = read()
if string.len(user) > 9 then
term.setCursorPos(1,2)
print("Name too long! 9 character maximum.")
term.setCursorPos(1,18)
elseif string.len(user) > 0 then
write("Your username is ")
write(user)
print("")
print("Entering Chat...")
username = user
end
until string.len(user) ~=0
sleep(2.0)
term.clear()
drawLine()
rednet.broadcast("")
rednet.broadcast(username .. " enters the room!")
repeat

term.setCursorPos(1,1)
write(chatTable[chatLine] or "")
drawLine()
showChat()
term.setCursorPos((3 + string.len(username) + string.len(message)),18)
term.setCursorBlink( true )

event, param = os.pullEventRaw()
if event == "key" then
  if param == 28 then
   if string.sub(message,1,1) == "/" then
        if string.sub(message,1,6) == "/name " then
         if string.len(message) > 6 then
          if string.len(message) < 16 then
           user = username
           username = string.sub(message,7,string.len(message))
           message = "User '" .. user .. "' is now called '" .. username .. "'!"
           rednet.broadcast("")
           rednet.broadcast(message)
           addChat(message)
           message = ""
           drawLine()
          else
           addChat("<SYS> Name too long! Maximum 9 characters.")
           message = ""
          end
         end
        elseif string.sub(message,1,4) == "/me " then
         local meMessage = string.sub(message,4,string.len(message))
         message = "*" .. username .. meMessage
         rednet.broadcast("")
         rednet.broadcast(message)
         addChat(message)
         message = ""
         drawLine()
        elseif string.sub(message,1,5) == "/list" then
         rednet.broadcast("")
         rednet.broadcast(message)
         message = ""
        elseif string.sub(message,1,5) == "/exit" then
         addChat("<SYS> Goodbye!")
         rednet.broadcast("")
         rednet.broadcast("User '" .. username .. "' exits the room.")
         sleep(1.0)
         term.clear()
         term.setCursorPos(1,1)
         break
        elseif string.sub(message,1,5) == "/quit" then
         addChat("<SYS> Goodbye!")
         rednet.broadcast("")
         rednet.broadcast("User '" .. username .. "' exits the room.")
         sleep(1.0)
         term.clear()
         term.setCursorPos(1,1)
         break
        elseif string.sub(message,1,5) == "/help" then
         addChat("/help - lists programs")
         addChat("/name <name> - changes username")
         addChat("/list - lists connected users, and console IDs")
         addChat("/me - used as emote")
         addChat("/clear - clears the screen")
         addChat("/msg <ID> <message> - sends a private message")
         addChat("/exit - exits the program")
         message = ""
        elseif string.sub(message,1,5) == "/msg " then
         if string.len(message) > 5 then
          if string.sub(message,7,7) == " " then
           toID = string.sub(message,6,6)
           msgMessage = string.sub(message,8,string.len(message))
           addChat("You whisper to #" .. toID .. ": " .. msgMessage)
           message = username .. " whispers to you: " .. msgMessage
           toID = tonumber(toID)
           rednet.send(toID,"")
           rednet.send(toID,message)
           message = ""
          elseif string.sub(message, 8,8) == " " then
           toID = string.sub(message,6,7)
           msgMessage = string.sub(message,9,string.len(message))
           addChat("You whisper to #" .. toID .. ": " .. msgMessage)
           message = username .. " whispers to you: " .. msgMessage
           toID = tonumber(toID)
           rednet.send(toID,"")
           rednet.send(toID,message)
           message = ""
          elseif string.sub(message, 9,9) == " " then
           toID = string.sub(message,6,8)
           msgMessage = string.sub(message,10,string.len(message))
           addChat("You whisper to #" .. toID .. ": " .. msgMessage)
           message = username .. " whispers to you: " .. msgMessage
           toID = tonumber(toID)
           rednet.send(toID,"")
           rednet.send(toID,message)
           message = ""
          elseif string.sub(message,10,10) == " " then
           toID = string.sub(message,6,9)
           msgMessage = string.sub(message,11,string.len(message))
           addChat("You whisper to #" .. toID .. ": " .. msgMessage)
           message = username .. " whispers to you: " .. msgMessage
           toID = tonumber(toID)
           rednet.send(toID,"")
           rednet.send(toID,message)
           message = ""
          end
         end
        elseif string.sub(message,1,3) == "/m " then
         if string.len(message) > 3 then
          if string.sub(message,5,5) == " " then
           toID = string.sub(message,4,4)
           msgMessage = string.sub(message,6,string.len(message))
           addChat("You whisper to #" .. toID .. ": " .. msgMessage)
           message = username .. " whispers to you: " .. msgMessage
           toID = tonumber(toID)
           rednet.send(toID,"")
           rednet.send(toID,message)
           message = ""
          elseif string.sub(message, 6,6) == " " then
           toID = string.sub(message,4,5)
           msgMessage = string.sub(message,7,string.len(message))
           addChat("You whisper to #" .. toID .. ": " .. msgMessage)
           message = username .. " whispers to you: " .. msgMessage
           toID = tonumber(toID)
           rednet.send(toID,"")
           rednet.send(toID,message)
           message = ""
          elseif string.sub(message, 7,7) == " " then
           toID = string.sub(message,4,6)
           msgMessage = string.sub(message,8,string.len(message))
           addChat("You whisper to #" .. toID .. ": " .. msgMessage)
           message = username .. " whispers to you: " .. msgMessage
           toID = tonumber(toID)
           rednet.send(toID,"")
           rednet.send(toID,message)
           message = ""
          elseif string.sub(message,8,8) == " " then
           toID = string.sub(message,4,7)
           msgMessage = string.sub(message,9,string.len(message))
           addChat("You whisper to #" .. toID .. ": " .. msgMessage)
           message = username .. " whispers to you: " .. msgMessage
           toID = tonumber(toID)
           rednet.send(toID,"")
           rednet.send(toID,message)
           message = ""
          end
         end
        elseif string.sub(message,1,6) == "/clear" then
         term.clear()
         for n=1,16 do
          addChat(" ")
         end
         chatTable = {}
         chatLine = 1
         message = ""
        else
         message = ""
        end
   else
        if string.len(message) > 0 then
          username = tostring(username)
          message = tostring(message)
          message = "<" .. username .. "> " .. message
          rednet.broadcast("")
          rednet.broadcast(message)
          addChat(message)
          message = ""
          drawLine()
        end
   end
  elseif param == 14 then
   message = string.sub(message,1,string.len(message)-1)
   drawLine()
  end
end

if event == "char" then
  if string.len(message) < 40 then
        message = message .. param
  end
  drawLine()
end

if event == "rednet_message" then
  id, incoming = rednet.receive(0.5)

  if incoming == "/list" then
   rednet.send(id,"")
   rednet.send(id,"User '" .. username .. "' is connected at terminal #" .. compID)
  else
   addChat(incoming)
  end
end

until message == "override"