first attempt. partial copy and stuff.

code/modules/modular_computers/NTNet/NTNRC/conversation.dm

@@ -0,0 +1,68 @@
+var/global/ntnrc_uid = 0
+
+/datum/ntnet_conversation/
+	var/id = null
+	var/title = "Untitled Conversation"
+	var/datum/computer_file/program/chatclient/operator // "Administrator" of this channel. Creator starts as channel's operator,
+	var/list/messages = list()
+	var/list/clients = list()
+	var/password
+
+/datum/ntnet_conversation/New()
+	id = ntnrc_uid
+	ntnrc_uid++
+	if(ntnet_global)
+		ntnet_global.chat_channels.Add(src)
+	..()
+
+/datum/ntnet_conversation/proc/add_message(var/message, var/username)
+	message = "[stationtime2text()] [username]: [message]"
+	messages.Add(message)
+	trim_message_list()
+
+/datum/ntnet_conversation/proc/add_status_message(var/message)
+	messages.Add("[stationtime2text()] -!- [message]")
+	trim_message_list()
+
+/datum/ntnet_conversation/proc/trim_message_list()
+	if(messages.len <= 50)
+		return
+	for(var/message in messages)
+		messages -= message
+		if(messages <= 50)
+			return
+
+/datum/ntnet_conversation/proc/add_client(var/datum/computer_file/program/chatclient/C)
+	if(!istype(C))
+		return
+	clients.Add(C)
+	add_status_message("[C.username] has joined the channel.")
+	// No operator, so we assume the channel was empty. Assign this user as operator.
+	if(!operator)
+		changeop(C)
+
+/datum/ntnet_conversation/proc/remove_client(var/datum/computer_file/program/chatclient/C)
+	if(!istype(C) || !(C in clients))
+		return
+	clients.Remove(C)
+	add_status_message("[C.username] has left the channel.")
+
+	// Channel operator left, pick new operator
+	if(C == operator)
+		operator = null
+		if(clients.len)
+			var/datum/computer_file/program/chatclient/newop = pick(clients)
+			changeop(newop)
+
+
+/datum/ntnet_conversation/proc/changeop(datum/computer_file/program/chatclient/newop)
+	if(istype(newop))
+		operator = newop
+		add_status_message("Channel operator status transferred to [newop.username].")
+
+/datum/ntnet_conversation/proc/change_title(var/newtitle, var/datum/computer_file/program/chatclient/client)
+	if(operator != client)
+		return 0 // Not Authorised
+
+	add_status_message("[client.username] has changed channel title from [title] to [newtitle]")
+	title = newtitle