-- SPDX-FileCopyrightText: 2017 Daniel Ratcliffe
--
-- SPDX-License-Identifier: LicenseRef-CCPL

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

local function printUsage()
    local programName = arg[0] or fs.getName(shell.getRunningProgram())
    print("Usages:")
    print(programName .. " host")
    print(programName .. " join")
end

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

local sCommand = tArgs[1]
if sCommand == "host" then
    -- "chat host"
    local sHostname = "global"

    if not openModem() then
        return
    end
    rednet.host("chat", sHostname)
    print("Hosting global chat...")
    print("0 users connected.")

    -- Load chat history
    local chatHistory = {}
    if fs.exists("chat_history.txt") then
        local f = fs.open("chat_history.txt", "r")
        for line in f.readLine do
            table.insert(chatHistory, line)
        end
        f.close()
    end

    local function saveMessage(sMessage)
        table.insert(chatHistory, sMessage)
        local f = fs.open("chat_history.txt", "a")
        f.writeLine(sMessage)
        f.close()
    end

    local tUsers = {}
    local nUsers = 0

    local function send(sText, nUserID)
        if nUserID then
            local tUser = tUsers[nUserID]
            if tUser then
                rednet.send(tUser.nID, {
                    sType = "text",
                    nUserID = nUserID,
                    sText = sText,
                }, "chat")
            end
        else
            for nUserID, tUser in pairs(tUsers) do
                rednet.send(tUser.nID, {
                    sType = "text",
                    nUserID = nUserID,
                    sText = sText,
                }, "chat")
            end
        end
    end

    local tPingPongTimer = {}
    local function ping(nUserID)
        local tUser = tUsers[nUserID]
        if not tUser then return end
        rednet.send(tUser.nID, {
            sType = "ping to client",
            nUserID = nUserID,
        }, "chat")
        local timer = os.startTimer(15)
        tUser.bPingPonged = false
        tPingPongTimer[timer] = nUserID
    end

    local function printUsers()
        local _, y = term.getCursorPos()
        term.setCursorPos(1, y - 1)
        term.clearLine()
        if nUsers == 1 then
            print(nUsers .. " user connected.")
        else
            print(nUsers .. " users connected.")
        end
    end

    local ok, error = pcall(parallel.waitForAny,
        function()
            while true do
                local _, timer = os.pullEvent("timer")
                local nUserID = tPingPongTimer[timer]
                if nUserID and tUsers[nUserID] then
                    local tUser = tUsers[nUserID]
                    if not tUser.bPingPonged then
                        send("* " .. tUser.sUsername .. " has timed out")
                        tUsers[nUserID] = nil
                        nUsers = nUsers - 1
                        printUsers()
                    else
                        ping(nUserID)
                    end
                end
            end
        end,
        function()
            while true do
                local nSenderID, tMessage = rednet.receive("chat")
                if type(tMessage) == "table" then
                    if tMessage.sType == "login" then
                        local nUserID = tMessage.nUserID
                        local sUsername = tMessage.sUsername
                        if nUserID and sUsername then
                            tUsers[nUserID] = {
                                nID = nSenderID,
                                nUserID = nUserID,
                                sUsername = sUsername,
                            }
                            nUsers = nUsers + 1
                            printUsers()

                            -- Send chat history to new user
                            for _, line in ipairs(chatHistory) do
                                rednet.send(nSenderID, {
                                    sType = "text",
                                    nUserID = nUserID,
                                    sText = line,
                                }, "chat")
                            end

                            send("* " .. sUsername .. " has joined the chat")
                            saveMessage("* " .. sUsername .. " has joined the chat")
                            ping(nUserID)
                        end
                    else
                        local nUserID = tMessage.nUserID
                        local tUser = tUsers[nUserID]
                        if tUser and tUser.nID == nSenderID then
                            if tMessage.sType == "logout" then
                                send("* " .. tUser.sUsername .. " has left the chat")
                                saveMessage("* " .. tUser.sUsername .. " has left the chat")
                                tUsers[nUserID] = nil
                                nUsers = nUsers - 1
                                printUsers()

                          elseif tMessage.sType == "chat" then
    local sMessage = tMessage.sText
    if sMessage then
        local sCommand = string.match(sMessage, "^/([a-z]+)")
        if sCommand then
            local sContent = string.sub(sMessage, #sCommand + 3)
            if sCommand == "me" then
                if #sContent > 0 then
                    local msg = "* " .. tUser.sUsername .. " " .. sContent
                    send(msg)
                    saveMessage(msg)
                else
                    send("* Usage: /me [action]", tUser.nUserID)
                end

            elseif sCommand == "nick" then
                if #sContent > 0 then
                    local sOld = tUser.sUsername
                    tUser.sUsername = sContent
                    local msg = "* " .. sOld .. " is now known as " .. tUser.sUsername
                    send(msg)
                    saveMessage(msg)
                else
                    send("* Usage: /nick [new name]", tUser.nUserID)
                end

            elseif sCommand == "users" then
                send("* Connected users:", tUser.nUserID)
                local sUsers = "*"
                for _, u in pairs(tUsers) do
                    sUsers = sUsers .. " " .. u.sUsername
                end
                send(sUsers, tUser.nUserID)

            elseif sCommand == "help" then
                send("* Available commands:", tUser.nUserID)
                send("*/me  /nick  /users  /msg  /help  /logout", tUser.nUserID)

            elseif sCommand == "msg" then
    local targetName, message = sContent:match("^(%S+)%s+(.+)$")
    if not targetName or not message then
        send("* Usage: /msg <username> <message>", tUser.nUserID)
    else
        local found = false
        for _, targetUser in pairs(tUsers) do
            if targetUser.sUsername:lower() == targetName:lower() then
                found = true
                local fromMsg = "[From " .. tUser.sUsername .. "] " .. message
                local toMsg = "[To " .. targetUser.sUsername .. "] " .. message
                send(fromMsg, targetUser.nUserID)
                send(toMsg, tUser.nUserID)
                break
            end
        end
        if not found then
            send("* User '" .. targetName .. "' not found.", tUser.nUserID)
        end
    end

                send("* Unknown command: /" .. sCommand, tUser.nUserID)
            end
        else
            local sFull = "<" .. tUser.sUsername .. "> " .. sMessage
            send(sFull)
            saveMessage(sFull)
        end
    end


                            elseif tMessage.sType == "ping to server" then
                                rednet.send(tUser.nID, {
                                    sType = "pong to client",
                                    nUserID = nUserID,
                                }, "chat")

                            elseif tMessage.sType == "pong to server" then
                                tUser.bPingPonged = true
                            end
                        end
                    end
                end
            end
        end
    )
    if not ok then printError(error) end

    for nUserID, tUser in pairs(tUsers) do
        rednet.send(tUser.nID, { sType = "kick", nUserID = nUserID }, "chat")
    end
    rednet.unhost("chat")
    closeModem()

elseif sCommand == "join" then
    local sHostname = "global"

    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

    if not openModem() then return end
    write("Looking up " .. sHostname .. "... ")
    local nHostID = rednet.lookup("chat", sHostname)
    if not nHostID then print("Failed.") return else print("Success.") end

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

    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

    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()

    local ok, error = pcall(parallel.waitForAny,
        function()
            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()
            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()
            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

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

else
    printUsage()
end