-- README
-- Squish verse into this dir, then squish them into one, which you move
-- and rename to mod_ircd.lua in your prosody modules/plugins dir.
--
-- IRC spec:
-- http://tools.ietf.org/html/rfc2812

local _module = module
module = _G.module
local module = _module
local client_xmlns = "jabber:client"

local component_jid, component_secret, muc_server, port_number =
      module.host, nil, module:get_option_string("conference_server"), module:get_option_number("listener_port", 7000);

if not muc_server then
        module:log ("error", "You need to set the MUC server! halting.")
        return false;
end

package.loaded["util.sha1"] = require "util.encodings";
local verse = require "verse"
require "verse.component"
require "socket"
c = verse.new(); -- something interferes with prosody's console logging
c:add_plugin("groupchat");

local function verse2prosody(e)
        return c:event("stanza", e.stanza) or true;
end
module:hook("message/bare", verse2prosody);
module:hook("message/full", verse2prosody);
module:hook("presence/bare", verse2prosody);
module:hook("presence/full", verse2prosody);
c.type = "component";
c.send = core_post_stanza;

local jid = require "util.jid";
local nodeprep = require "util.encodings".stringprep.nodeprep;

local function utf8_clean (s)
        local push, join = table.insert, table.concat;
        local r, i = {}, 1;
        if not(s and #s > 0) then
                return ""
        end
        while true do
                local c = s:sub(i,i)
                local b = c:byte();
                local w = (
                        (b >= 9   and b <= 10  and 0) or
                        (b >= 32  and b <= 126 and 0) or
                        (b >= 192 and b <= 223 and 1) or
                        (b >= 224 and b <= 239 and 2) or
                        (b >= 240 and b <= 247 and 3) or
                        (b >= 248 and b <= 251 and 4) or
                        (b >= 251 and b <= 252 and 5) or nil
                )
                if not w then
                        push(r, "?")
                else
                        local n = i + w;
                        if w == 0 then
                                push(r, c);
                        elseif n > #s then
                                push(r, ("?"):format(b));
                        else
                                local e = s:sub(i+1,n);
                                if e:match('^[\128-\191]*$') then
                                        push(r, c);
                                        push(r, e);
                                        i = n;
                                else
                                        push(r, ("?"):format(b));
                                end
                        end
                end
                i = i + 1;
                if i > #s then
                        break
                end
        end
        return join(r);
end

local function parse_line(line)
        local ret = {};
        if line:sub(1,1) == ":" then
                ret.from, line = line:match("^:(%w+)%s+(.*)$");
        end
        for part in line:gmatch("%S+") do
                if part:sub(1,1) == ":" then
                        ret[#ret+1] = line:match(":(.*)$");
                        break
                end
                ret[#ret+1]=part;
        end
        return ret;
end

local function build_line(parts)
        if #parts > 1 then
                parts[#parts] = ":" ..  parts[#parts];
        end
        return (parts.from and ":"..parts.from.." " or "")..table.concat(parts, " ");
end

local function irc2muc(channel, nick)
        local room = channel and nodeprep(channel:match("^#(%w+)")) or nil;
        if not nick then
                return jid.join(room, muc_server);
        else
                return jid.join(room, muc_server, nick);
        end
end
local function muc2irc(room)
        local channel, _, nick = jid.split(room);
        return "#"..channel, nick;
end
local role_map = {
        moderator = "@",
        participant = "",
        visitor = "",
        none = ""
}
local aff_map = {
        owner = "~",
        administrator = "&",
        member = "+",
        none = ""
}
local role_modemap = {
        moderator = "o",
        participant = "",
        visitor = "",
        none = ""
}
local aff_modemap = {
        owner = "q",
        administrator = "a",
        member = "v",
        none = ""
}

local irc_listener = { default_port = port_number, default_mode = "*l" };

local sessions = {};
local jids = {};
local commands = {};

local nicks = {};
local usernames = {};

local st = require "util.stanza";

local conference_server = muc_server;

local function irc_close_session(session)
        session.conn:close();
end

function irc_listener.onincoming(conn, data)
        local session = sessions[conn];
        if not session then
                session = { conn = conn, host = component_jid, reset_stream = function () end,
                        close = irc_close_session, log = logger.init("irc"..(conn.id or "1")),
                        rooms = {}, roster = {}, has_un = false };
                sessions[conn] = session;
               
                function session.data(data)
                        local parts = parse_line(data);
                        module:log("debug", require"util.serialization".serialize(parts));
                        local command = table.remove(parts, 1);
                        if not command then
                                return;
                        end
                        command = command:upper();
                        if not session.username and not session.nick then
                                if not (command == "USER" or command == "NICK") then
                                        module:log("debug", "Client tried to send command %s before registering", command);
                                        return session.send{from=muc_server, "451", command, "You have not completed the registration."}
                                end
                        end
                        if commands[command] then
                                local ret = commands[command](session, parts);
                                if ret then
                                        return session.send(ret);
                                end
                        else
                                session.send{from=muc_server, "421", session.nick, command, "Unknown command"};
                                return module:log("debug", "Unknown command: %s", command);
                        end
                end
               
                function session.send(data)
                        if type(data) == "string" then
                                return conn:write(data.."\r\n");
                        elseif type(data) == "table" then
                                local line = build_line(data);
                                module:log("debug", line);
                                conn:write(line.."\r\n");
                        end
                end
        end

        if data then
                session.data(data);
        end
end

function irc_listener.ondisconnect(conn, error)
        local session = sessions[conn];

        if session then
                for _, room in pairs(session.rooms) do
                        room:leave("Disconnected");
                end
                if session.nick then
                        nicks[session.nick] = nil;
                end
                if session.full_jid then
                        jids[session.full_jid] = nil;
                end
                if session.username then
                        usernames[session.username] = nil;
                end
        end
        sessions[conn] = nil;
end

local function nick_inuse(nick)
        if nicks[nick] then return true else return false end
end
local function check_username(un)
        local count = 0;
        local result;

        for name, given in pairs(usernames) do
                if un == given then count = count + 1; end
        end
       
        result = count + 1;
       
        if count > 0 then return tostring(un)..tostring(result); else return tostring(un); end
end
local function set_t_data(session, full_jid)
        session.full_jid = full_jid;
        jids[full_jid] = session;
        jids[full_jid]["ar_last"] = {};
        jids[full_jid]["nicks_changing"] = {};

        if session.nick then nicks[session.nick] = session; end
end
local function send_motd(session)
        local nick = session.nick;

        if session.username and session.nick then -- send MOTD only if username and nick are set
                session.send{from = muc_server, "001", nick, "Welcome in the IRC to MUC XMPP Gateway, "..nick};
                session.send{from = muc_server, "002", nick, "Your host is "..muc_server.." running Prosody "..prosody.version};
                session.send{from = muc_server, "003", nick, "This server was created the "..os.date(nil, prosody.start_time)}
                session.send{from = muc_server, "004", nick, table.concat({muc_server, "mod_ircd(alpha-0.8)", "i", "aoqv"}, " ")};
                session.send((":%s %s %s %s :%s"):format(muc_server, "005", nick, "CHANTYPES=# PREFIX=(qaov)~&@+", "are supported by this server"));
                session.send((":%s %s %s %s :%s"):format(muc_server, "005", nick, "STATUSMSG=~&@+", "are supported by this server"));
                session.send{from = muc_server, "375", nick, "- "..muc_server.." Message of the day -"};
                session.send{from = muc_server, "372", nick, "-"};
                session.send{from = muc_server, "372", nick, "- Please be warned that this is only a partial irc implementation,"};
                session.send{from = muc_server, "372", nick, "- it's made to facilitate users transiting away from irc to XMPP."};
                session.send{from = muc_server, "372", nick, "-"};
                session.send{from = muc_server, "372", nick, "- Prosody is _NOT_ an IRC Server and it never will."};
                session.send{from = muc_server, "372", nick, "- We also would like to remind you that this plugin is provided as is,"};
                session.send{from = muc_server, "372", nick, "- it's still an Alpha and it's still a work in progress, use it at your sole"};
                session.send{from = muc_server, "372", nick, "- risk as there's a not so little chance something will break."};
                session.send{from = nick, "MODE", nick, "+i"};  -- why -> Invisible mode setting,
        end                                                     --        enforce by default on most servers (since the source host doesn't show it's sensible to have it "set")
end

function commands.NICK(session, args)
        local nick = args[1];
        nick = nick:gsub("[^%w_]","");
       
        if session.nick and not nick_inuse(nick) then -- changing nick
                local oldnick = session.nick;
                           
                -- update and replace session data
                session.nick = nick;
                nicks[oldnick] = nil;
                nicks[nick] = session;
               
                session.send{from=oldnick.."!"..nicks[nick].username, "NICK", nick};
               
                -- broadcast changes if required
                if session.rooms then
                        session.nicks_changing[nick] = { oldnick, session.username };
                        
                        for id, room in pairs(session.rooms) do room:change_nick(nick); end
                        
                        session.nicks_changing[nick] = nil;
                end
               
                return;
        elseif nick_inuse(nick) then
                session.send{from=muc_server, "433", nick, "The nickname "..nick.." is already in use"}; return;
        end
       
        session.nick = nick;
        session.type = "c2s";
        nicks[nick] = session;
       
        -- Some choppy clients send in NICK before USER, that needs to be handled
        if session.username then
                set_t_data(session, jid.join(session.username, component_jid, "ircd"));
        end

        send_motd(session);
end

function commands.USER(session, params)
        local username = params[1];

        if not session.has_un then
                local un_checked = check_username(username);
       
                usernames[un_checked] = username;
                session.username = un_checked;
                session.has_un = true;
               
                if not session.full_jid then
                        set_t_data(session, jid.join(session.username, component_jid, "ircd"));
                end
        else
                return session.send{from=muc_server, "462", "USER", "You may not re-register."}
        end
       
        send_motd(session);
end

function commands.USERHOST(session, params) -- can show only users on the gateway. Needed for some clients to determinate self hostmask.
        local nick = params[1];

        if not nick then session.send{from=muc_server, "461", "USERHOST", "Not enough parameters"}; return; end

        if nicks[nick] and nicks[nick].nick and nicks[nick].username then
                session.send{from=muc_server, "302", session.nick, nick.."=+"..nicks[nick].username}; return;
        else
                return;
        end
end

local function mode_map(am, rm, nicks)
        local rnick;
        local c_modes;
        c_modes = aff_modemap[am]..role_modemap[rm]
        rnick = string.rep(nicks.." ", c_modes:len())
        if c_modes == "" then return nil, nil end
        return c_modes, rnick
end

function commands.JOIN(session, args)
        local channel = args[1];
        if not channel then return end
        local room_jid = irc2muc(channel);

        if not jids[session.full_jid].ar_last[room_jid] then jids[session.full_jid].ar_last[room_jid] = {}; end
        local room, err = c:join_room(room_jid, session.nick, { source = session.full_jid } );
        if not room then
                return ":"..muc_server.." ERR :Could not join room: "..err
        end

        session.rooms[channel] = room;
        room.session = session;
       
        if session.nicks_changing[session.nick] then -- my own nick is changing
                commands.NAMES(session, channel);
        else
                session.send{from=session.nick.."!"..session.username, "JOIN", channel};
                if room.subject then
                        session.send{from=muc_server, 332, session.nick, channel, room.subject};
                end
                commands.NAMES(session, channel);
        end
       
        room:hook("subject-changed", function(changed)
                session.send{from=changed.by.nick, "TOPIC", channel, changed.to or ""}
        end);
       
        room:hook("message", function(event)
                if not event.body then return end
                local nick, body = event.nick, event.body;
                if nick ~= session.nick then
                        if body:sub(1,4) == "/me " then
                                body = "\1ACTION ".. body:sub(5) .. "\1"
                        end
                        local type = event.stanza.attr.type;
                        session.send{from=nick, "PRIVMSG", type == "groupchat" and channel or nick, body};
                        --FIXME PM's probably won't work
                end
        end);
       
        room:hook("presence", function(ar)
                local c_modes;
                local rnick;
                if ar.nick and not jids[session.full_jid].ar_last[ar.room_jid][ar.nick] then jids[session.full_jid].ar_last[ar.room_jid][ar.nick] = {} end
                local x_ar = ar.stanza:get_child("x", "http://jabber.org/protocol/muc#user")
                if x_ar then
                        local xar_item = x_ar:get_child("item")
                        if xar_item and xar_item.attr and ar.stanza.attr.type ~= "unavailable" then
                                if xar_item.attr.affiliation and xar_item.attr.role then
                                        if not jids[session.full_jid].ar_last[ar.room_jid][ar.nick]["affiliation"] and
                                           not jids[session.full_jid].ar_last[ar.room_jid][ar.nick]["role"] then
                                                jids[session.full_jid].ar_last[ar.room_jid][ar.nick]["affiliation"] = xar_item.attr.affiliation
                                                jids[session.full_jid].ar_last[ar.room_jid][ar.nick]["role"] = xar_item.attr.role
                                                n_self_changing = nicks[ar.nick] and nicks[ar.nick].nicks_changing and nicks[ar.nick].nicks_changing[ar.nick]
                                                if n_self_changing then return; end                                               
                                                c_modes, rnick = mode_map(xar_item.attr.affiliation, xar_item.attr.role, ar.nick);
                                                if c_modes and rnick then session.send((":%s MODE %s +%s"):format(muc_server, channel, c_modes.." "..rnick)); end
                                        else
                                                c_modes, rnick = mode_map(jids[session.full_jid].ar_last[ar.room_jid][ar.nick]["affiliation"], jids[session.full_jid].ar_last[ar.room_jid][ar.nick]["role"], ar.nick);
                                                if c_modes and rnick then session.send((":%s MODE %s -%s"):format(muc_server, channel, c_modes.." "..rnick)); end
                                                jids[session.full_jid].ar_last[ar.room_jid][ar.nick]["affiliation"] = xar_item.attr.affiliation
                                                jids[session.full_jid].ar_last[ar.room_jid][ar.nick]["role"] = xar_item.attr.role
                                                n_self_changing = nicks[ar.nick] and nicks[ar.nick].nicks_changing and nicks[ar.nick].nicks_changing[ar.nick]
                                                if n_self_changing then return; end                                                
                                                c_modes, rnick = mode_map(xar_item.attr.affiliation, xar_item.attr.role, ar.nick);
                                                if c_modes and rnick then session.send((":%s MODE %s +%s"):format(muc_server, channel, c_modes.." "..rnick)); end
                                        end
                                end
                        end
                 end
        end, -1);
end

c:hook("groupchat/joined", function(room)
        local session = room.session or jids[room.opts.source];
        local channel = "#"..room.jid:match("^(.*)@");
       
        room:hook("occupant-joined", function(nick)
                if session.nicks_changing[nick.nick] then
                        session.send{from=session.nicks_changing[nick.nick][1].."!"..(session.nicks_changing[nick.nick][2] or "xmpp"), "NICK", nick.nick};
                        session.nicks_changing[nick.nick] = nil;
                else
                        session.send{from=nick.nick.."!"..(nicks[nick.nick] and nicks[nick.nick].username or "xmpp"), "JOIN", channel};
                end
        end);
        room:hook("occupant-left", function(nick)
                if jids[session.full_jid] then jids[session.full_jid].ar_last[nick.jid:match("^(.*)/")][nick.nick] = nil; end
                local status_code =
                nick.presence:get_child("x","http://jabber.org/protocol/muc#user") and
                nick.presence:get_child("x","http://jabber.org/protocol/muc#user"):get_child("status") and
                nick.presence:get_child("x","http://jabber.org/protocol/muc#user"):get_child("status").attr.code;
               
               
                if status_code == "303" then
                        local newnick =
                        nick.presence:get_child("x","http://jabber.org/protocol/muc#user") and
                        nick.presence:get_child("x","http://jabber.org/protocol/muc#user"):get_child("item") and
                        nick.presence:get_child("x","http://jabber.org/protocol/muc#user"):get_child("item").attr.nick;
                       
                        session.nicks_changing[newnick] = { nick.nick, (nicks[nick.nick] and nicks[nick.nick].username or "xmpp") }; return;
                end
               
                for id, data in pairs(session.nicks_changing) do
                        if data[1] == nick.nick then return; end
                end
                session.send{from=nick.nick.."!"..(nicks[nick.nick] and nicks[nick.nick].username or "xmpp"), "PART", channel};
        end);
end);

function commands.NAMES(session, channel)
        local nicks = { };
        if type(channel) == "table" then channel = channel[1] end
       
        local room = session.rooms[channel];
       
        local symbols_map = {
                owner = "~",
                administrator = "&",
                moderator = "@",
                member = "+"
        }
               
        if not room then return end
        -- TODO Break this out into commands.NAMES
        for nick, n in pairs(room.occupants) do
                if n.affiliation == "owner" and n.role == "moderator" then
                        nick = symbols_map[n.affiliation]..nick;
                elseif n.affiliation == "administrator" and n.role == "moderator" then
                        nick = symbols_map[n.affiliation]..nick;
                elseif n.affiliation == "member" and n.role == "moderator" then
                        nick = symbols_map[n.role]..nick;
                elseif n.affiliation == "member" and n.role == "partecipant" then
                        nick = symbols_map[n.affiliation]..nick;
                elseif n.affiliation == "none" and n.role == "moderator" then
                        nick = symbols_map[n.role]..nick;
                end
                table.insert(nicks, nick);
        end
        nicks = table.concat(nicks, " ");
        session.send((":%s 353 %s = %s :%s"):format(muc_server, session.nick, channel, nicks));
        session.send((":%s 366 %s %s :End of /NAMES list."):format(muc_server, session.nick, channel));
        session.send(":"..muc_server.." 353 "..session.nick.." = "..channel.." :"..nicks);
end

function commands.PART(session, args)
        local channel, part_message = unpack(args);
        local room = channel and nodeprep(channel:match("^#(%w+)")) or nil;
        if not room then return end
        channel = channel:match("^([%S]*)");
        session.rooms[channel]:leave(part_message);
        jids[session.full_jid].ar_last[room.."@"..muc_server] = nil;
        session.send{from=session.nick.."!"..session.username, "PART", channel};
end

function commands.PRIVMSG(session, args)
        local channel, message = unpack(args);
        if message and #message > 0 then
                if message:sub(1,8) == "\1ACTION " then
                        message = "/me ".. message:sub(9,-2)
                end
                message = utf8_clean(message);
                if channel:sub(1,1) == "#" then
                        if session.rooms[channel] then
                                module:log("debug", "%s sending PRIVMSG \"%s\" to %s", session.nick, message, channel);
                                session.rooms[channel]:send_message(message);
                        end
                else -- private message
                        local nick = channel;
                        module:log("debug", "PM to %s", nick);
                        for channel, room in pairs(session.rooms) do
                                module:log("debug", "looking for %s in %s", nick, channel);
                                if room.occupants[nick] then
                                        module:log("debug", "found %s in %s", nick, channel);
                                        local who = room.occupants[nick];
                                        -- FIXME PMs in verse
                                        --room:send_private_message(nick, message);
                                        local pm = st.message({type="chat",to=who.jid}, message);
                                        module:log("debug", "sending PM to %s: %s", nick, tostring(pm));
                                        room:send(pm)
                                        break
                                end
                        end
                end
        end
end

function commands.PING(session, args)
        session.send{from=muc_server, "PONG", args[1]};
end

function commands.TOPIC(session, message)
        if not message then return end
        local channel, topic = message[1], message[2];
        channel = utf8_clean(channel);
        topic = utf8_clean(topic);
        if not channel then return end
        local room = session.rooms[channel];

        if topic then room:set_subject(topic); end
end

function commands.WHO(session, args)
        local channel = args[1];
        if session.rooms[channel] then
                local room = session.rooms[channel]
                for nick in pairs(room.occupants) do
                        session.send{from=muc_server, 352, session.nick, channel, nick, nick, muc_server, nick, "H", "0 "..nick}
                end
                session.send{from=muc_server, 315, session.nick, channel, "End of /WHO list"};
        end
end

function commands.MODE(session, args) -- Empty command
end

function commands.QUIT(session, args)
        session.send{"ERROR", "Closing Link: "..session.nick};
        for _, room in pairs(session.rooms) do
                room:leave(args[1]);
        end
        jids[session.full_jid] = nil;
        nicks[session.nick] = nil;
        usernames[session.username] = nil;
        sessions[session.conn] = nil;
        session:close();
end

function commands.RAW(session, data) -- Empty command
end

local function desetup()
        require "net.connlisteners".deregister("irc");
end

require "net.connlisteners".register("irc", irc_listener);
require "net.connlisteners".start("irc");

module:hook("module-unloaded", desetup)