GChat - chat with all your friends (in-game)

-- GChat - chat program
-- by MysticT

-- Config
local nMinNameLen = 3 -- minimum user name lenght
local nMaxNameLen = 8 -- maximum user name lenght
local nMaxHistory = 50 -- maximum chat history size, set to nil to disable

-- System vars
local nScreenW, nScreenH = term.getSize()
local tUsers = {}
-- User message vars
local sUsrName = ""
local sUsrMsg = ""
local nPos = 0
-- Received messages vars
local tMessages = {}
local nMsg = 1
-- Menu vars
local bMenu = false
local nSelected = 1
local tMenuFunctions = {}
local tMenuOptions = {}
-- Menu functions vars
-- Add any variable you need here
local bExit = false

local function Clear()
	term.clear()
	term.setCursorPos(1, 1)
end

local function OpenAll()
	for _,side in ipairs(rs.getSides()) do
		rednet.open(side)
	end
end

local function AddMessage(sMsg, sName)
	if #sMsg > 0 then
		local msg
		if sName then
			msg = sName..": "..sMsg
		else
			msg = "<"..sMsg..">"
		end
		table.insert(tMessages, msg)
		if #tMessages - nMsg >= nScreenH - 1 then
			nMsg = nMsg + 1
		end
		if nMaxHistory ~= nil and #tMessages > nMaxHistory then
			table.remove(tMessages, 1)
			if nMsg > 1 then
				nMsg = nMsg - 1
			end
		end
	end
end

local function AddUser(nID, sName)
	tUsers[nID] = sName
	AddMessage("User "..sName.." connected from "..tostring(nID))
end

local function RemoveUser(nID)
	AddMessage("User "..tUsers[nID].." disconnected")
	tUsers[nID] = nil
end

local function WriteMsg(sText)
	local x, y = term.getCursorPos()
	local function newLine()
		x = 1
		y = y + 1
		term.setCursorPos(x, y)
		if y < nScreenH - 2 then
			return true
		end
		return false
	end
	while #sText > 0 do
		local whitespace = string.match(sText, "^[ t]+")
		if whitespace then
			term.write(whitespace)
			x, y = term.getCursorPos()
			sText = string.sub(sText, #whitespace + 1)
		end
		local newline = string.match(sText, "^n")
		if newline then
			if not newLine() then
				return true
			end
			sText = string.sub(sText, 2)
		end
		local text = string.match(sText, "^[^ tn]+")
		if text then
			sText = string.sub(sText, #text + 1)
			if #text > nScreenW then
				while #text > 0 do
					if x > nScreenW then
						if not newLine() then
							return true
						end
					end
					term.write(text)
					text = string.sub(text, (nScreenW - x) + 2)
					x, y = term.getCursorPos()
				end
			else
				if x + #text > nScreenW then
					if not newLine() then
						return true
					end
				end
				term.write(text)
				x, y = term.getCursorPos()
			end
		end
	end
	return false
end

local function WriteMessages()
	local i = 0
	while nMsg + i <= #tMessages and i < nScreenH - 1 do
		if WriteMsg(tMessages[nMsg + i]) then
			break
		end
		local x, y = term.getCursorPos()
		term.setCursorPos(1, y + 1)
		i = i + 1
	end
end

local function RedrawUserMsg()
	local nScroll = 0
	if nPos + 3 >= nScreenW then
		nScroll = nPos + 3 - nScreenW
	end
	term.setCursorPos(1, nScreenH)
	write("> ")
	write(string.sub(sUsrMsg, nScroll + 1))
	term.setCursorPos(nPos + 3 - nScroll, nScreenH)
end

local function RedrawMenu()
	term.setCursorPos(1, nScreenH)
	for i, s in ipairs(tMenuOptions) do
		if i == nSelected then
			term.write("["..s.."]")
		else
			term.write(s)
		end
		term.write(" ")
	end
end

local function Redraw()
	Clear()
	WriteMessages()
	if bMenu then
		RedrawMenu()
	else
		RedrawUserMsg()
	end
end

local function ParseMsg(nID, sMsg)
	local sAction, sArgs = string.match(sMsg, "(%a+): (.+)")
	if sAction == "MSG" then
		AddMessage(sArgs, tUsers[nID])
	elseif sAction == "PONG" then
		AddUser(nID, sArgs)
	elseif sAction == "PING" then
		AddUser(nID, sArgs)
		rednet.send(nID, "PONG: "..sUsrName)
	elseif sAction == "QUIT" then
		RemoveUser(nID)
	end
end

local function Ping()
	rednet.broadcast("PING: "..sUsrName)
end

local function Disconnect()
	for id,_ in pairs(tUsers) do
		rednet.send(id, "QUIT: "..sUsrName)
	end
end

local function SendMsg()
	AddMessage(sUsrMsg, sUsrName)
	for id,_ in pairs(tUsers) do
		rednet.send(id, "MSG: "..sUsrMsg)
	end
	sUsrMsg = ""
	nPos = 0
end

local function DoMenuItem()
	tMenuFunctions[nSelected]()
	nSelected = 1
end

function KeyPress(key)
	if key == 28 then -- Enter
		if bMenu then
			DoMenuItem()
		else
			SendMsg()
		end
	elseif key == 203 then -- Left
		if bMenu then
			if nSelected > 1 then
				nSelected = nSelected - 1
			end
		else
			if nPos > 0 then
				nPos = nPos - 1
			end
		end
	elseif key == 205 then -- Right
		if bMenu then
			if nSelected < #tMenuOptions then
				nSelected = nSelected + 1
			end
		else
			if nPos < #sUsrMsg then
				nPos = nPos + 1
			end
		end
	elseif key == 14 then -- Backspace
		if not bMenu then
			if nPos > 0 then
				sUsrMsg = string.sub(sUsrMsg, 1, nPos - 1)..string.sub(sUsrMsg, nPos + 1)
				nPos = nPos - 1
			end
		end
	elseif key == 211 then -- Delete
		if not bMenu then
			sUsrMsg = string.sub(sUsrMsg, 1, nPos)..string.sub(sUsrMsg, nPos + 2)
		end
	elseif key == 199 then -- Start
		if bMenu then
			nSelected = 1
		else
			nPos = 0
		end
	elseif key == 207 then -- End
		if bMenu then
			nSelected = #tMenuOptions
		else
			nPos = #sUsrMsg
		end
	elseif key == 200 then -- Up
		if nMsg > 1 then
			nMsg = nMsg - 1
		end
	elseif key == 208 then -- Down
		if nMsg < #tMessages then
			nMsg = nMsg + 1
		end
	elseif key == 29 then -- Ctrl
		bMenu = not bMenu
		term.setCursorBlink(not bMenu)
	end
end

local function AddChar(sChar)
	sUsrMsg = string.sub(sUsrMsg, 1, nPos)..sChar..string.sub(sUsrMsg, nPos + 1)
	nPos = nPos + 1
end

local function CheckUserName()
	if #sUsrName < nMinNameLen then
		return false, "Name too short."
	elseif #sUsrName > nMaxNameLen then
		return false, "Name too long."
	end
	return true
end

-- Menu

-- Add Menu functions here --
--[[
tMenuOptions[n] = "your option name"
tMenuFunctions[n] = function()
	-- Your code here
end
--]]

table.insert(tMenuOptions, "Exit")
table.insert(tMenuFunctions, function()
	bExit = true
end )

-- Main loop

repeat
	Clear()
	print("- Welcome to GChat -")
	write("Enter your name: ")
	sUsrName = read()
	local bValid, err = CheckUserName()
	if not bValid then
		print(err)
		sleep(2)
	end
until bValid
OpenAll()
Ping()
term.setCursorBlink(true)

while not bExit do
	Redraw()
	local evt, arg1, arg2 = os.pullEvent()
	if evt == "key" then
		KeyPress(arg1)
	elseif evt == "char" then
		AddChar(arg1)
	elseif evt == "rednet_message" then
		ParseMsg(arg1, arg2)
	end
end
Disconnect()
Clear()