irc.lua

local irc = safeinit(...)

local Gs = require "state"
local buffers = require "buffers"
local i18n = require "i18n"
local tests = require "tests"
local ui = require "ui"
local util = require "util"

irc.RPL_ISUPPORT = "005"
irc.RPL_LIST = "322"
irc.RPL_LISTEND = "323"
irc.RPL_TOPIC = "332"
irc.RPL_NAMREPLY = "353"
irc.RPL_ENDOFMOTD = "376"
irc.ERR_NOMOTD = "422"
irc.ERR_NICKNAMEINUSE = "433"

function irc.writecmd(...)
	local args = {...}
	if #args >= 2 then
		args[#args] = ":" .. args[#args]
	end

	local cmd = table.concat(args, " ")
	if config.debug then
		print("=>", ui.escape(cmd))
	end
	capi.writesock(cmd)
	irc.newcmd(":"..Gs.user.."!@ "..cmd, false)
end

function irc.parsecmd(line)
	local data = {}

	local pos = 1
	if string.sub(line, 1, 1) == ":" then
		pos = string.find(line, " ")
		if not pos then return end -- invalid message
		data.prefix = string.sub(line, 2, pos-1)
		pos = pos+1

		local excl = string.find(data.prefix, "!")
		if excl then
			data.user = string.sub(data.prefix, 1, excl-1)
		end
	end
	while pos <= string.len(line) do
		local nextpos = nil
		if string.sub(line, pos, pos) ~= ":" then
			nextpos = string.find(line, " ", pos+1)
		else
			pos = pos+1
		end
		if not nextpos then
			nextpos = string.len(line)+1
		end
		table.insert(data, string.sub(line, pos, nextpos-1))
		pos = nextpos+1
	end

	local cmd = string.upper(data[1])
	if (cmd == "PRIVMSG" or cmd == "NOTICE") and string.sub(data[3], 1, 1) == "\1" then
		data.ctcp = {}
		local inner = string.gsub(string.sub(data[3], 2), "\1$", "")
		local split = string.find(inner, " ", 2)
		if split then
			data.ctcp.cmd = string.upper(string.sub(inner, 1, split-1))
			data.ctcp.params = string.sub(inner, split+1)
		else
			data.ctcp.cmd = string.upper(inner)
		end
	end

	return data
end

-- Called for new commands, both from the server and from the client.
function irc.newcmd(line, remote)
	local args = irc.parsecmd(line)
	local from = args.user
	local cmd = string.upper(args[1])
	local to = args[2] -- not always valid!

	if not remote and not (cmd == "PRIVMSG" or cmd == "NOTICE" or cmd == "QUIT") then
		-- (afaik) all other messages are echoed back at us
		return
	end

	if cmd == "PRIVMSG" or cmd == "NOTICE" then
		if to == "*" then return end
		if string.match(to, Gs.prefix_pat) then
			to = string.sub(to, 2)
		end

		if not args.ctcp or args.ctcp.cmd == "ACTION" then
			if to == Gs.user then -- direct message
				buffers:push(from, line, {urgency=1})
			else
				local msg
				if not args.ctcp then
					msg = args[3]
				else
					msg = args.ctcp.params or ""
				end

				if string.match(msg, util.nick_pattern(Gs.user)) then
					buffers:push(to, line, {urgency=2})
				elseif from == Gs.user then
					buffers:push(to, line, {forceshow=true})
				else
					buffers:push(to, line)
				end
			end
		end

		if cmd == "PRIVMSG" and args.ctcp and remote then
			if args.ctcp.cmd == "VERSION" then
				irc.writecmd("NOTICE", from, "\1VERSION hewwo\1")
			elseif args.ctcp.cmd == "PING" then
				irc.writecmd("NOTICE", from, args[3])
			end
		end
	elseif cmd == "JOIN" then
		buffers:push(to, line, {urgency=-1})
		if from == Gs.user then
			Gs.buffers[to].connected = true
		end
		Gs.buffers[to].users[from] = true
	elseif cmd == "PART" then
		buffers:push(to, line, {urgency=-1})
		buffers:leave(to, from)
	elseif cmd == "KICK" then
		buffers:push(to, line)
		buffers:leave(to, args[3])
	elseif cmd == "INVITE" then
		buffers:push(from, line, {urgency=2})
	elseif cmd == "QUIT" then
		local forceshow = (from == Gs.user)
		local bufs = {}
		for chan,buf in pairs(Gs.buffers) do
			if buf.users[from] then
				table.insert(bufs, chan)
				buf.users[from] = nil
			end
		end
		buffers:push(bufs, line, {forceshow=forceshow, urgency=-1})
	elseif cmd == "NICK" then
		local forceshow = false
		local bufs = {}
		if from == Gs.user then
			forceshow = true
			Gs.user = to
		end
		for chan,buf in pairs(Gs.buffers) do
			if buf.users[from] then
				table.insert(bufs, chan)
				buf.users[from] = nil
				buf.users[to] = true
			end
		end
		buffers:push(bufs, line, {forceshow=forceshow, urgency=-1})
	elseif cmd == irc.RPL_ISUPPORT then
		for i=3,(#args-1) do
			local token = args[i]
			local minus = string.match(token, "^-")
			local key = string.match(token, "^-?(%w+)")
			local value = string.match(token, "=(.*)") or true
			-- for now i don't support escapes, they're not used on town anyways
			if minus then value = nil end
			Gs.ISUPPORT[key] = value
			if key == "PREFIX" then
				local prefixes = string.match(value, "%)(.*)") or "@"
				Gs.prefix_pat = "^["..util.patescape(prefixes).."]"
			end
		end
	elseif cmd == irc.RPL_ENDOFMOTD or cmd == irc.ERR_NOMOTD then
		Gs.active = true
		print(i18n.connected)
		print()
	elseif cmd == irc.RPL_TOPIC then
		Gs.topics[args[3]] = args[4]
		buffers:push(args[3], line, {urgency=-1})
	elseif cmd == "TOPIC" then
		local forceshow = (from == Gs.user)
		buffers:push(to, line, {forceshow=forceshow, oldtopic=Gs.topics[to]})
		Gs.topics[to] = args[3]
	elseif cmd == irc.RPL_LIST or cmd == irc.RPL_LISTEND then
		-- TODO list output should probably be pushed into a server buffer
		-- but switching away from the current buffer could confuse users?

		if ext.reason == "list" then ext.setpipe(true) end
		ui.printcmd({line=line, ts=os.time()})
		if ext.reason == "list" then ext.setpipe(false) end
	elseif cmd == irc.ERR_NICKNAMEINUSE then
		local hi = ui.highlight
		if Gs.active then
			printf("%s is taken, leaving your nick as %s", hi(args[3]), hi(Gs.user))
		else
			local new = util.nicksucc(Gs.user)
			printf("%s is taken, trying %s", hi(Gs.user), hi(new))
			Gs.user = new
			irc.writecmd("NICK", new)
		end
	elseif string.sub(cmd, 1, 1) == "4" then
		-- TODO the user should never see this. they should instead see friendlier
		-- messages with instructions how to proceed
		printf("irc error %s: %s", cmd, args[#args])
	elseif cmd == "PING" then
		irc.writecmd("PONG", to)
	elseif cmd == irc.RPL_NAMREPLY then
		to = args[4]
		buffers:make(to)
		for nick in string.gmatch(args[5], "[^ ]+") do
			if string.match(nick, Gs.prefix_pat) then
				nick = string.sub(nick, 2)
			end
			Gs.buffers[to].users[nick] = true
		end
	end
end

-- NOTE: for incoming data, prefer `not irc.is_channel`
function irc.is_nick(s)
	-- https://modern.ircdocs.horse/#clients implemented verbatim
	-- with the exception of CHANTYPES, because taken literally, that would
	-- imply that on some servers "#tildetown" is a nickname, and "dzwdz" is
	-- a channel. I assume it's #&.
	-- In Soviet Russia, #tildetown joins you!
	if not s or s == "" then return false end
	if string.find(s, "[ ,*?!@]") then return false end
	if string.find(s, "^[$:#&]") then return false end
	return true
end
function irc.is_channel(s)
	-- https://modern.ircdocs.horse/#channels
	-- ignoring CHANTYPES for the reasons mentioned in irc.is_nick
	if not s then return false end
	if not string.find(s, "^[&#]") then return false end
	if string.find(s, "[ \x07,]") then return false end
	return true
end
tests.run(function(t)
	local chans = {
		"#tildetown", "#", "##",
	}
	local nicks = {
		"bx", "cymen", "dzwdz", "ixera", "juspib", "natalia",
		"x",
		"dzwdz[m]",
		"a$woo",
	}
	local neither = {
		"",
		"dzwdz [m]", " dzwdz[m]",
		"panic!atthedisco", "panic!", "!panic",
		"$woo",
		" #hello", "# hello", "#hello ",
		"#a,#b",
	}
	for _,v in ipairs(chans) do
		t(irc.is_nick(v), false)
		t(irc.is_channel(v), true)
	end
	for _,v in ipairs(nicks) do
		t(irc.is_nick(v), true)
		t(irc.is_channel(v), false)
	end
	for _,v in ipairs(neither) do
		t(irc.is_nick(v), false)
		t(irc.is_channel(v), false)
	end
end)

return irc