--rewritten better chat !
term.clear()
x,y=term.getSize()
midX=x/2
midY=y/2
history={}


function setUsername()
	term.setCursorPos(14,10)
	write("Your username: ")
	usr=read()
	term.setCursorPos(14,11)
	write("Channel:")
	channel=tonumber(read())
	term.clear()
end




function showBar()

	term.setCursorPos(1,1)
	term.setBackgroundColor(colors.white)
	for i=1,x do
		write(" ")
	end
	term.setCursorPos(1,1)
	term.setTextColor(colors.black)

	print("You are chatting in channel: "..channel)
	term.setCursorPos(x-2,1)
	write("[X]")

	term.setTextColor(colors.white)
	term.setBackgroundColor(colors.black)
	term.setCursorPos(1,2)
	for i=1,x do
		write("-")
	end



end



function exit()

	local event, button, xPos, yPos = os.pullEvent("mouse_click")

	if yPos==1 and xPos==x-1 then
		term.clear()
		os.shutdown()
	end
end










function drawmessages()
term.setCursorPos(1,3)
	for k,v in pairs(history) do
		term.clearLine()
		term.setCursorPos(1,k+2)
		print(v)
	end
end

function openSide()
        for _,side in ipairs({"top", "bottom", "front", "left", "right", "back"}) do
                if peripheral.isPresent(side)
                        then
                                if peripheral.getType(side)=="modem"
                                        then
                                                modemside=side
                                                rednet.open(modemside)
                                end
                end
        end
end
openSide()
function receive()

	local id,message=rednet.receive("chatmessage/"..channel)
	if message ~="" then table.insert(history,message)
	drawmessages()

	end
end


function sendMessage()
	showBar()
	drawmessages()
	term.setCursorPos(1,y-1)
	term.clearLine()
	term.setCursorPos(1,y)
	write(">>")

	msg=read()
	if msg~="" then
		msg="["..usr.."]:"..msg
	table.insert(history,msg)

	rednet.broadcast(msg,"chatmessage/"..channel)
end
end

setUsername()

while true do
parallel.waitForAny(sendMessage,receive,exit)

end