Message System 2

--Coded by HPWebcamAble--
--Note: There are no variables that the user can change here!

--Variables--
local vers = "2.0"
local continue = true
local w,h = term.getSize()
local tID = os.getComputerID()
local x = 14
local y = 5
local cPos = 2
local tUser = nil
local users = {}
local hMessage = ""
local aMessage = ""
local messages = {}
local colorsT = {}
local menus = {
  ["main"] = {
    ["options"] = {"Online Users","Back","Quit"},
    ["pos"] = {y+3,y+4,y+5},
  },
  ["users"] = {
    ["options"] = {"Back"},
    ["pos"] = {y+10},
  },
  ["confirmQuit"] = {
    ["options"] = {"Yes","No"},
    ["pos"] = {y+3,y+4},
  }
}
local cMenu = "main"
local select = 1
local menuS = false

--Functions--
function clear()
  term.clear()
  term.setCursorPos(1,1)
end

function printCentered(text,ypos,color)
  if ypos == nil then
    error("Expected String, Number, got String, Nil")
  end
  if color ~= nil then
    term.setTextColor(color)
  end
  term.setCursorPos(w/2-#text/2,ypos)
  term.write(text)
end

function changeMenu()
  local selected = menus[cMenu]["options"][select]
  if cMenu == "main" then
    if selected == "Online Users" then
      cMenu = "users"
    elseif selected == "Back" then
      menuS = false
    elseif selected == "Quit" then
      cMenu = "confirmQuit"
    end
  elseif cMenu == "users" and selected == "Back" then
    cMenu = "main"
  elseif cMenu == "confirmQuit" then
    if selected == "Yes" then
      continue = false
    elseif selected == "No" then
      cMenu = "main"
    end
  end
  select = 1
end

function drawMenuBG(h)
  printCentered("+-----------------------------------+",y)
  for i = 1, h do
    printCentered("|                                   |",y+i)
  end
  printCentered("+-----------------------------------+",y+h+1)
end

function drawOptions()
  for i = 1, #menus[cMenu]["options"] do
    printCentered(menus[cMenu]["options"][i],menus[cMenu]["pos"][i])
  end
  if select > #menus[cMenu]["options"] then
    select = #menus[cMenu]["options"]
  end
  if select < 1 then
    select = 1
  end
  printCentered("[ "..menus[cMenu]["options"][select].." ]",menus[cMenu]["pos"][select])
end

function drawScreen()
  clear()
  while #messages > h-2 do
    table.remove(messages,1)
    table.remove(colorsT,1)
  end
  for i = 1, #messages do
    term.setCursorPos(1,i)
    term.setTextColor(colorsT[i])
    term.write(messages[i])
  end
  if menuS then
    term.setCursorBlink(false)
    term.setCursorPos(1,h)
    term.setTextColor(colors.black)
    term.write("Press Ctrl to close menu")
    if cMenu == "main" then
      drawMenuBG(5)
      printCentered("Menu",y+1)
      drawOptions()
    elseif cMenu == "users" then
      drawMenuBG(10)
      printCentered("Users Online",y+1)
      local t = 0
      for a,b in pairs(users) do
        printCentered(b,y+t+3)
        t = t+1
        if t == 5 then
          break
        end
      end
      term.setCursorPos(1,h-1)
      local numUsers = 0
      for a,b in pairs(users) do
        numUsers=numUsers+1
      end
      if numUsers > 5 then
        printCentered("+"..(numUsers-5).." more",y+8)
      end
      drawOptions()
    elseif cMenu == "confirmQuit" then
      drawMenuBG(4)
      printCentered("Quit?",y+1)
      drawOptions()
    end
  else
    term.setCursorPos(1,h)
    term.setTextColor(colors.orange)
    term.write(">")
    term.write(hMessage)
    term.setCursorPos(cPos,h)
    term.setCursorBlink(true)
  end
end

function keyPress(cKey)
  if cKey == 29 then --Left ctrl
    menuS = not menuS
    if not menuS then
      cMenu = "main"
    end
  elseif cKey == 200 then --Up
    if menuS then
      select = select-1
    end
  elseif cKey == 208 then --Down
    if menuS then
      select = select+1
    end
  elseif cKey == 28 then --Enter
    if menuS then
      changeMenu()
    else
      if hMessage ~= "" then
        sendMsg()
      end
    end
  elseif cKey == 205 then --Right
    if not menuS then
      if cPos <= #hMessage+1 then
        cPos = cPos+1
      end
    end
  elseif cKey == 203 then --Left
    if not menuS then
      if cPos > 2 then
        cPos = cPos-1
      end
    end
  elseif cKey == 14 then --Backspace
    if not menuS and cPos > 2 then
      hMessage = string.sub(hMessage,1,cPos-3)..string.sub(hMessage,cPos-1)
      cPos = cPos-1
    end
  elseif cKey == 211 then --Delete
    if not menuS then
      hMessage = string.sub(hMessage,1,cPos-2)..string.sub(hMessage,cPos)
    end
  elseif cKey == 56 then --Alt
    if not menuS then
      hMessage = ""
      cPos = 2
    end
  end
end

function charPress(char)
  if not menuS then
    hMessage = string.sub(hMessage,1,cPos-2)..char..string.sub(hMessage,cPos-1)
    cPos = cPos+1
  end
end

function formatMessage(channel,aID,aMessage)
  if channel == 2 then
    if users[aID] == nil then
      if aMessage ~= "~offline~" then
        m.transmit(2,tID,tUser)
        users[aID] = aMessage
        table.insert(messages,"*"..aMessage.." is online*")
        table.insert(colorsT,colors.lime)
      end
    elseif aMessage == "~offline~" then
      table.insert(messages,"*"..users[aID].." is offline*")
      table.insert(colorsT,colors.red)
      users[aID] = nil
    end
  elseif channel == 1 then
    if users[aID] == nil then
      table.insert(messages,"Error: Channel has unknown interferrence")
      table.insert(messages,"Message:"..aMessage)
      table.insert(messages,"Reply Chanel:"..aID)
      for i = 1, 3 do
        table.insert(colorsT,colors.black)
      end
    else
      table.insert(messages,"<"..users[aID].."> "..aMessage)
      table.insert(colorsT,colors.blue)
    end
  end
end

function sendMsg()
  m.transmit(1,tID,hMessage)
  table.insert(messages,"<"..tUser.."> "..hMessage)
  table.insert(colorsT,colors.orange)
  hMessage = ""
  cPos = 2
end

--Program--
if not term.isColor() then
    clear()
    print("Message System "..vers.." requires and advanced computer")
    return
  elseif not fs.exists("msbg") then
    clear()
    print("'msbg' file not found, delete Message System and reinstall it with the installer")
    return
  elseif peripheral.getType("top") ~= "modem" then
    clear()
    print("To use Message System, please place a wireless modem on top of this computer")
    return
end
term.setBackgroundColor(colors.white)
term.clear()
paintutils.drawImage(paintutils.loadImage("msbg"),1,1)

sleep(2)

term.setTextColor(colors.black)
term.setBackgroundColor(colors.white)
term.setCursorPos(23,16)
term.write("Loading...")
m = peripheral.wrap("top")
m.open(1)
m.open(2)

sleep(4)

clear()
term.setCursorPos(x-1,y+1)
term.write("Welcome to ")
term.setTextColor(colors.orange)
print("Message System!")
term.setTextColor(colors.black)
printCentered("Enter a user name:",y+2,colors.blue)
term.setCursorPos(x+5,y+3)
term.setTextColor(colors.blue)
term.write(">")
printCentered("Version "..vers,h,colors.lightGray)
term.setCursorPos(x+6,y+3)
term.setTextColor(colors.black)
tUser = read()

m.transmit(2,tID,tUser)
clear()
table.insert(messages,"[Username:"..tUser.."]")
table.insert(messages,"[You are now online]")
table.insert(messages,"[Press Ctrl to access menu]")
table.insert(colorsT,colors.lightBlue)
table.insert(colorsT,colors.lime)
table.insert(colorsT,colors.black)
drawScreen()
term.setCursorBlink(true)

--Main loop
while continue do
  event,par1,par2,par3,par4,par5 = os.pullEvent()
  if event == "key" then
    keyPress(par1)
  elseif event == "char" then
    charPress(par1)
  elseif event == "modem_message" then
    formatMessage(par2,par3,par4)
  end
  drawScreen()
end

--Tell other computers  you are offline
--If you terminate the program before it does this, you may encounter weird errors when running it again
m.transmit(2,tID,"~offline~")
m.closeAll()
term.setTextColor(colors.white)
term.setBackgroundColor(colors.black)
clear()
print("Network Connections have been saftely closed")
term.write("Thank you for choosing")
term.setTextColor(colors.orange)
print(" Message System!")