Help with a typing program.

local cursorX = 1  --This is supposed to be a simple host/client chatroom program, so if it seems like it, it is.
local cursorY = 1  --I'll try to explain some of the parts
local hostID = 0
local clientID = 0
local username = tostring(hostID)
local cMessage = ""
local hMessage = ""
local letter = ""
local shift = false
function ClearScreen() --Nobody likes typing this s**t over and over again so I declared a function.
term.clear()
term.setCursorPos(1,1)
end
function AnyEvent()					 --The purpose of this program is to allow your program to keep running while accepting input. I don't
event, param1, param2 = os.pullEvent()  --like how io.read() halts your program and in a chatroom this command is
Decode()								--useless as you can't recieve new messages until you've pressed enter/return.
end
function Decode()  --This is how the program is supposed to decode os.pullEvent() events and prepare them for sending.
	if event == "key" and param1 == "42" and shift == false then shift = true  --Allows shift key functionality.
	elseif event == "key" and param1 == "42" and shift == true then shift = false
	end
if event == "char" and param1 == "1" and shift == false then letter = "1"  --Lots of code here but it's all exactly the same.
elseif event == "char" and param1 == "2" and shift == false then letter = "2"
elseif event == "char" and param1 == "3" and shift == false then letter = "3"
elseif event == "char" and param1 == "4" and shift == false then letter = "4"
elseif event == "char" and param1 == "5" and shift == false then letter = "5"
elseif event == "char" and param1 == "6" and shift == false then letter = "6"
elseif event == "char" and param1 == "7" and shift == false then letter = "7"
elseif event == "char" and param1 == "8" and shift == false then letter = "8"
elseif event == "char" and param1 == "9" and shift == false then letter = "9"
elseif event == "char" and param1 == "0" and shift == false then letter = "0"
elseif event == "char" and param1 == "1" and shift == true then letter = "!"  --Added a little part to test shift key, doesn't work.
elseif event == "char" and param1 == "2" and shift == true then letter = "@"
elseif event == "char" and param1 == "3" and shift == true then letter = "#"
elseif event == "char" and param1 == "4" and shift == true then letter = "$"
elseif event == "char" and param1 == "5" and shift == true then letter = "%"
elseif event == "char" and param1 == "6" and shift == true then letter = "^"
elseif event == "char" and param1 == "7" and shift == true then letter = "&"
elseif event == "char" and param1 == "8" and shift == true then letter = "*"
elseif event == "char" and param1 == "9" and shift == true then letter = "("
elseif event == "char" and param1 == "0" and shift == true then letter = ")"
elseif event == "char" and param1 == "a" and shift == false then letter = "a"
elseif event == "char" and param1 == "b" and shift == false then letter = "b"
elseif event == "char" and param1 == "c" and shift == false then letter = "c"
elseif event == "char" and param1 == "d" and shift == false then letter = "d"
elseif event == "char" and param1 == "e" and shift == false then letter = "e"
elseif event == "char" and param1 == "f" and shift == false then letter = "f"
elseif event == "char" and param1 == "g" and shift == false then letter = "g"
elseif event == "char" and param1 == "h" and shift == false then letter = "h"
elseif event == "char" and param1 == "i" and shift == false then letter = "i"
elseif event == "char" and param1 == "j" and shift == false then letter = "j"
elseif event == "char" and param1 == "k" and shift == false then letter = "k"
elseif event == "char" and param1 == "l" and shift == false then letter = "l"
elseif event == "char" and param1 == "m" and shift == false then letter = "m"
elseif event == "char" and param1 == "n" and shift == false then letter = "n"
elseif event == "char" and param1 == "o" and shift == false then letter = "o"
elseif event == "char" and param1 == "p" and shift == false then letter = "p"
elseif event == "char" and param1 == "q" and shift == false then letter = "q"
elseif event == "char" and param1 == "r" and shift == false then letter = "r"
elseif event == "char" and param1 == "s" and shift == false then letter = "s"
elseif event == "char" and param1 == "t" and shift == false then letter = "t"
elseif event == "char" and param1 == "u" and shift == false then letter = "u"
elseif event == "char" and param1 == "v" and shift == false then letter = "v"
elseif event == "char" and param1 == "w" and shift == false then letter = "w"
elseif event == "char" and param1 == "x" and shift == false then letter = "x"
elseif event == "char" and param1 == "y" and shift == false then letter = "y"
elseif event == "char" and param1 == "z" and shift == false then letter = "z"
elseif event == "key" and param1 == "1" then letter = "message received!"  --Little rednet testing.
																		   --(Early signs of a chat program)
end
end
ClearScreen()  --One line of code.
while true do  --Two lines of code.
term.write(letter)  --Three lines of code.
AnyEvent()  --Four lines of code.
end  --Five lines of code. (Yes it counts because without it your program will not work.)

local cursorY = 17
local username = tostring(os.getComputerLabel)
local cMessage = ""
local hMessage = ""
local charNum = 1
local message = {}
local pastCount = 1
local pastMess = {}
local capOn = false
rednet.open("right")

for i = 1, 48 do
	message[i] = ""
end
for i = 1, 12 do
	pastMess[i] = ""
end

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

function resetMessage()
	for i = 1, 48 do
		message[i] = ""
	end
charNum = 1
end

function updatePast(newMess)
	for i = 1, 11 do
   pastMess[i] = pastMess[i + 1]
end
pastMess[12] = newMess
updateScreen()
end

function updateScreen()
for i = 4, 15 do
   term.setCursorPos(1, i)
term.clearLine()
end
for i = 4, 15 do
   term.setCursorPos(1, i)
term.write("|")
term.setCursorPos(50, i)
term.write("|")
end
	for i = 12, 1, -1 do
   term.setCursorPos(2, i + 3)
   term.write(pastMess[i])
end
end

function Border()
clearScreen()
	for i = 2, 49 do
		term.setCursorPos(i, 1)
		term.write("-")
term.setCursorPos(i, 3)
term.write("-")
		term.setCursorPos(i, 16)
		term.write("-")
term.setCursorPos(i, 18)
term.write("-")
	end
	for i = 1, 18 do
		term.setCursorPos(1, i)
		term.write("|")
		term.setCursorPos(50, i)
		term.write("|")
	end
	term.setCursorPos(2, 2)
	term.write("BossChat v.005")
end

function handleBackspace()
	if charNum + 1 >= 3 then
   charNum = charNum - 1
   message[charNum] = " "
   term.setCursorPos(charNum + 1, cursorY)
   term.write(" ")
   term.setCursorPos(charNum + 1, cursorY)
elseif charNum <= 1 then
charNum = 1
end
end

function handleSend(message)
for i = 1, charNum do
   hMessage = hMessage .. message[i]
end
term.setCursorPos(1, 17)
term.clearLine()
term.setCursorPos(1, 17)
term.write("|")
term.setCursorPos(50, 17)
term.write("|")
resetMessage()
if string.find(hMessage, "/") == 1 then
   handleCommand(hMessage)
elseif hMessage ~= "" then
   updatePast(hMessage)
   messageSend(hMessage)
end
return hMessage
end

function handleCaps(capOn)
	if capOn == false then
   term.setCursorPos(20, 2)
term.write("CAPS ON")
capOn = true
elseif capOn == true then
   term.setCursorPos(20, 2)
term.write("	   ")
capOn = false
end
end

function handleCommand(command)
	if command == "/exit" or command == "/Exit" or command == "/EXIT" then
   term.setCursorPos(2, 17)
   term.write("Thank you for using. Rebooting")
for i = 1, 5 do
   term.write(".")
sleep(0.30)
end
hMessage = ""
os.reboot()
end
end

function writeChar(char)
	term.setCursorPos(charNum + 1, cursorY)
	if charNum <= 48 then
		term.write(char)
message[charNum] = char
   charNum = charNum + 1
end
end

function handleKey(key)
	if key == 58 then
   handleCaps(capOn)
elseif key == 14 then
   handleBackspace()
elseif key == 28 then
		hMessage = handleSend(message)
hMessage = ""
end
end

function messageReceive(id, message)
	cMessage = message
updatePast(cMessage)
end

function messageSend(hMessage)
	rednet.broadcast(hMessage)
end

function handleEvent()
	evt, p1, p2 = os.pullEvent()
if evt == "char" then
   writeChar(p1)
	elseif evt == "key" then
   handleKey(p1)
elseif evt == "rednet_message" then
   messageReceive(p1, p2)
end
end

clearScreen()
Border()
term.setCursorPos(2, 17)

while true do
	handleEvent()
end