-- 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, "^[^ \t\n]+")
                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
        clearArea()
        print("- CC IRC -")
        write("Enter your nick: ")
        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()