-- Global Chat Client for ComputerCraft
-- Connects automatically to the "global" chat host
-- Remembers username, supports -log option, clears screen on start

term.clear()
term.setCursorPos(1,1)

local tArgs = { ... }

-- Logging feature
local bLogging = false
for i = 1, #tArgs do
    if tArgs[i] == "-log" then
        bLogging = true
        table.remove(tArgs, i)
        break
    end
end

local logFile
if bLogging then
    logFile = fs.open("chat_log.txt", "a")
    local oldPrint = print
    local oldWrite = write

    local function logWrite(text)
        if logFile then
            logFile.write(text)
            logFile.flush()
        end
    end

    function write(...)
        local t = table.pack(...)
        for i = 1, t.n do
            oldWrite(t[i])
            logWrite(t[i])
        end
    end

    function print(...)
        local t = table.pack(...)
        local text = table.concat(t, " ")
        oldPrint(text)
        logWrite(text .. "\n")
    end

    print("Logging enabled. Output will be written to chat_log.txt")
end

-- Utility functions
local sOpenedModem = nil
local function openModem()
    for _, sModem in ipairs(peripheral.getNames()) do
        if peripheral.getType(sModem) == "modem" then
            if not rednet.isOpen(sModem) then
                rednet.open(sModem)
                sOpenedModem = sModem
            end
            return true
        end
    end
    print("No modems found.")
    return false
end

local function closeModem()
    if sOpenedModem ~= nil then
        rednet.close(sOpenedModem)
        sOpenedModem = nil
    end
end

-- Colours
local highlightColour, textColour
if term.isColour() then
    textColour = colours.white
    highlightColour = colours.yellow
else
    textColour = colours.white
    highlightColour = colours.white
end

-- Always connect to global
local sHostname = "global"

-- Username handling
local sUsername
if fs.exists("chat_username.txt") then
    local f = fs.open("chat_username.txt", "r")
    sUsername = f.readAll()
    f.close()
    sUsername = sUsername:gsub("%s+$", "")
    print("Using saved username: " .. sUsername)
else
    write("Enter your username: ")
    sUsername = read()
    local f = fs.open("chat_username.txt", "w")
    f.write(sUsername)
    f.close()
end

-- Connect to global chat
if not openModem() then return end
write("Looking up " .. sHostname .. "... ")
local nHostID = rednet.lookup("chat", sHostname)
if not nHostID then
    print("Failed to find host '" .. sHostname .. "'.")
    return
else
    print("Success.")
end

-- Login
local nUserID = math.random(1, 2147483647)
rednet.send(nHostID, {
    sType = "login",
    nUserID = nUserID,
    sUsername = sUsername,
}, "chat")

-- Setup ping-pong to keep connection alive
local bPingPonged = true
local pingPongTimer = os.startTimer(0)
local function ping()
    rednet.send(nHostID, {
        sType = "ping to server",
        nUserID = nUserID,
    }, "chat")
    bPingPonged = false
    pingPongTimer = os.startTimer(15)
end

-- UI setup
local w, h = term.getSize()
local parentTerm = term.current()
local titleWindow = window.create(parentTerm, 1, 1, w, 1, true)
local historyWindow = window.create(parentTerm, 1, 2, w, h - 2, true)
local promptWindow = window.create(parentTerm, 1, h, w, 1, true)
historyWindow.setCursorPos(1, h - 2)

term.clear()
term.setTextColour(textColour)
term.redirect(promptWindow)
promptWindow.restoreCursor()

local function drawTitle()
    local w = titleWindow.getSize()
    local sTitle = sUsername .. " on " .. sHostname
    titleWindow.setTextColour(highlightColour)
    titleWindow.setCursorPos(math.floor(w / 2 - #sTitle / 2), 1)
    titleWindow.clearLine()
    titleWindow.write(sTitle)
    promptWindow.restoreCursor()
end

local function printMessage(sMessage)
    term.redirect(historyWindow)
    print()
    if string.match(sMessage, "^%*") then
        term.setTextColour(highlightColour)
        write(sMessage)
        term.setTextColour(textColour)
    else
        local sUsernameBit = string.match(sMessage, "^<[^>]*>")
        if sUsernameBit then
            term.setTextColour(highlightColour)
            write(sUsernameBit)
            term.setTextColour(textColour)
            write(string.sub(sMessage, #sUsernameBit + 1))
        else
            write(sMessage)
        end
    end
    term.redirect(promptWindow)
    promptWindow.restoreCursor()
end

drawTitle()

-- Run client logic
local ok, error = pcall(parallel.waitForAny,
    function() -- timer handler
        while true do
            local sEvent, timer = os.pullEvent()
            if sEvent == "timer" then
                if timer == pingPongTimer then
                    if not bPingPonged then
                        printMessage("Server timeout.")
                        return
                    else
                        ping()
                    end
                end
            elseif sEvent == "term_resize" then
                local w, h = parentTerm.getSize()
                titleWindow.reposition(1, 1, w, 1)
                historyWindow.reposition(1, 2, w, h - 2)
                promptWindow.reposition(1, h, w, 1)
            end
        end
    end,
    function() -- receive messages
        while true do
            local nSenderID, tMessage = rednet.receive("chat")
            if nSenderID == nHostID and type(tMessage) == "table" and tMessage.nUserID == nUserID then
                if tMessage.sType == "text" then
                    local sText = tMessage.sText
                    if sText then printMessage(sText) end
                elseif tMessage.sType == "ping to client" then
                    rednet.send(nSenderID, { sType = "pong to server", nUserID = nUserID }, "chat")
                elseif tMessage.sType == "pong to client" then
                    bPingPonged = true
                elseif tMessage.sType == "kick" then
                    return
                end
            end
        end
    end,
    function() -- send messages
        local tSendHistory = {}
        while true do
            promptWindow.setCursorPos(1, 1)
            promptWindow.clearLine()
            promptWindow.setTextColor(highlightColour)
            promptWindow.write(": ")
            promptWindow.setTextColor(textColour)

            local sChat = read(nil, tSendHistory)
            if string.match(sChat, "^/logout") then
                break
            else
                rednet.send(nHostID, {
                    sType = "chat",
                    nUserID = nUserID,
                    sText = sChat,
                }, "chat")
                table.insert(tSendHistory, sChat)
            end
        end
    end
)

term.redirect(parentTerm)
local _, h = term.getSize()
term.setCursorPos(1, h)
term.clearLine()
term.setCursorBlink(false)
if not ok then printError(error) end

-- Logout
rednet.send(nHostID, { sType = "logout", nUserID = nUserID }, "chat")
closeModem()
print("Disconnected.")