--- activate under main vhost
--- In /etc/hosts add:
--- vm1-ip-address visitors1.domain.com
--- vm1-ip-address conference.visitors1.domain.com
--- vm2-ip-address visitors2.domain.com
--- vm2-ip-address conference.visitors2.domain.com
--- Enable in global modules: 's2s_bidi' and 'certs_all'
--- Make sure 's2s' is not in modules_disabled
--- Open port 5269 on the provider side and on the firewall on the machine (iptables -I INPUT 4 -p tcp -m tcp --dport 5269 -j ACCEPT)
--- NOTE: Make sure all communication between prosodies is using the real jids ([foo]room1@muc.example.com)
local st = require 'util.stanza';
local jid = require 'util.jid';
local new_id = require 'util.id'.medium;
local util = module:require 'util';
local presence_check_status = util.presence_check_status;
local process_host_module = util.process_host_module;

local um_is_admin = require 'core.usermanager'.is_admin;
local function is_admin(jid)
    return um_is_admin(jid, module.host);
end

local MUC_NS = 'http://jabber.org/protocol/muc';

-- required parameter for custom muc component prefix, defaults to 'conference'
local muc_domain_prefix = module:get_option_string('muc_mapper_domain_prefix', 'conference');

local main_muc_component_config = module:get_option_string('main_muc');
if main_muc_component_config == nil then
    module:log('error', 'visitors rooms not enabled missing main_muc config');
    return ;
end

-- A list of domains which to be ignored for visitors. For occupants using those domain we do not propagate them
-- to visitor nodes and we do not update them with presence changes
local ignore_list = module:get_option_set('visitors_ignore_list', {});

-- Advertise the component for discovery via disco#items
module:add_identity('component', 'visitors', 'visitors.'..module.host);

local sent_iq_cache = require 'util.cache'.new(200);

-- visitors_nodes = {
--  roomjid1 = {
--    nodes = {
--      ['conference.visitors1.jid'] = 2, // number of main participants, on 0 we clean it
--      ['conference.visitors2.jid'] = 3
--    }
--  },
--  roomjid2 = {}
--}
local visitors_nodes = {};

-- sends connect or update iq
-- @parameter type - Type of iq to send 'connect' or 'update'
local function send_visitors_iq(conference_service, room, type)
    -- send iq informing the vnode that the connect is done and it will allow visitors to join
    local iq_id = new_id();
    sent_iq_cache:set(iq_id, socket.gettime());
    local connect_done = st.iq({
        type = 'set',
        to = conference_service,
        from = module.host,
        id = iq_id })
      :tag('visitors', { xmlns = 'jitsi:visitors',
                         room = jid.join(jid.node(room.jid), conference_service) })
      :tag(type, { xmlns = 'jitsi:visitors',
        password = type ~= 'disconnect' and room:get_password() or '',
        lobby = room._data.lobbyroom and 'true' or 'false',
        meetingId = room._data.meetingId,
        moderatorId = room._data.moderator_id, -- can be used from external modules to set single moderator for meetings
        createdTimestamp = room.created_timestamp and tostring(room.created_timestamp) or nil
      }):up();

      module:send(connect_done);
end

-- an event received from visitors component, which receives iqs from jicofo
local function connect_vnode(event)
    local room, vnode = event.room, event.vnode;
    local conference_service = muc_domain_prefix..'.'..vnode..'.meet.jitsi';

    if visitors_nodes[room.jid] and
        visitors_nodes[room.jid].nodes and
        visitors_nodes[room.jid].nodes[conference_service] then
        -- nothing to do
        return;
    end

    if visitors_nodes[room.jid] == nil then
        visitors_nodes[room.jid] = {};
    end
    if visitors_nodes[room.jid].nodes == nil then
        visitors_nodes[room.jid].nodes = {};
    end

    local sent_main_participants = 0;

    for _, o in room:each_occupant() do
        if not is_admin(o.bare_jid) then
            local fmuc_pr = st.clone(o:get_presence());
            local user, _, res = jid.split(o.nick);
            fmuc_pr.attr.to = jid.join(user, conference_service , res);
            fmuc_pr.attr.from = o.jid;
            -- add <x>
            fmuc_pr:tag('x', { xmlns = MUC_NS });

            -- if there is a password on the main room let's add the password for the vnode join
            -- as we will set the password to the vnode room and we will need it
            local pass = room:get_password();
            if pass and pass ~= '' then
                fmuc_pr:tag('password'):text(pass);
            end
            fmuc_pr:up();

            module:send(fmuc_pr);

            sent_main_participants = sent_main_participants + 1;
        end
    end
    visitors_nodes[room.jid].nodes[conference_service] = sent_main_participants;

    send_visitors_iq(conference_service, room, 'connect');
end
module:hook('jitsi-connect-vnode', connect_vnode);

-- listens for responses to the iq sent for connecting vnode
local function stanza_handler(event)
    local origin, stanza = event.origin, event.stanza;

    if stanza.name ~= 'iq' then
        return;
    end

    -- we receive error from vnode for our disconnect message as the room was already destroyed (all visitors left)
    if (stanza.attr.type == 'result' or stanza.attr.type == 'error') and sent_iq_cache:get(stanza.attr.id) then
        sent_iq_cache:set(stanza.attr.id, nil);
        return true;
    end
end
module:hook('iq/host', stanza_handler, 10);

-- an event received from visitors component, which receives iqs from jicofo
local function disconnect_vnode(event)
    local room, vnode = event.room, event.vnode;

    if visitors_nodes[event.room.jid] == nil then
        -- maybe the room was already destroyed and vnodes cleared
        return;
    end

    local conference_service = muc_domain_prefix..'.'..vnode..'.meet.jitsi';

    visitors_nodes[room.jid].nodes[conference_service] = nil;

    send_visitors_iq(conference_service, room, 'disconnect');
end
module:hook('jitsi-disconnect-vnode', disconnect_vnode);

-- takes care when the visitor nodes destroys the room to count the leaving participants from there, and if its really destroyed
-- we clean up, so if we establish again the connection to the same visitor node to send the main participants
module:hook('presence/full', function(event)
    local stanza = event.stanza;
    local room_name, from_host = jid.split(stanza.attr.from);
    if stanza.attr.type == 'unavailable' and from_host ~= main_muc_component_config then
        local room_jid = jid.join(room_name, main_muc_component_config); -- converts from visitor to main room jid

        local x = stanza:get_child('x', 'http://jabber.org/protocol/muc#user');
        if not presence_check_status(x, '110') then
            return;
        end

        if visitors_nodes[room_jid] and visitors_nodes[room_jid].nodes
                and visitors_nodes[room_jid].nodes[from_host] then
            visitors_nodes[room_jid].nodes[from_host] = visitors_nodes[room_jid].nodes[from_host] - 1;
            -- we clean only on disconnect coming from jicofo
        end
    end
end, 900);

process_host_module(main_muc_component_config, function(host_module, host)
    -- detects presence change in a main participant and propagate it to the used visitor nodes
    host_module:hook('muc-occupant-pre-change', function (event)
        local room, stanza, occupant = event.room, event.stanza, event.dest_occupant;

        -- filter focus and configured domains (used for jibri and transcribers)
        if is_admin(stanza.attr.from) or visitors_nodes[room.jid] == nil
            or ignore_list:contains(jid.host(occupant.bare_jid)) then
            return;
        end

        local vnodes = visitors_nodes[room.jid].nodes;
        local user, _, res = jid.split(occupant.nick);
        -- a change in the presence of a main participant we need to update all active visitor nodes
        for k in pairs(vnodes) do
            local fmuc_pr = st.clone(stanza);
            fmuc_pr.attr.to = jid.join(user, k, res);
            fmuc_pr.attr.from = occupant.jid;
            module:send(fmuc_pr);
        end
    end);

    -- when a main participant leaves inform the visitor nodes
    host_module:hook('muc-occupant-left', function (event)
        local room, stanza, occupant = event.room, event.stanza, event.occupant;

        -- ignore configured domains (jibri and transcribers)
        if is_admin(occupant.bare_jid) or visitors_nodes[room.jid] == nil or visitors_nodes[room.jid].nodes == nil
            or ignore_list:contains(jid.host(occupant.bare_jid)) then
            return;
        end

        --this is probably participant kick scenario, create an unavailable presence and send to vnodes.
        if not stanza then
            stanza = st.presence {from = occupant.nick; type = "unavailable";};
        end

        -- we want to update visitor node that a main participant left or kicked.
        if stanza then
            local vnodes = visitors_nodes[room.jid].nodes;
            local user, _, res = jid.split(occupant.nick);
            for k in pairs(vnodes) do
                local fmuc_pr = st.clone(stanza);
                fmuc_pr.attr.to = jid.join(user, k, res);
                fmuc_pr.attr.from = occupant.jid;
                module:send(fmuc_pr);
            end
        end
    end);

    -- cleanup cache
    host_module:hook('muc-room-destroyed',function(event)
        local room = event.room;

        -- room is destroyed let's disconnect all vnodes
        if visitors_nodes[room.jid] then
            local vnodes = visitors_nodes[room.jid].nodes;
            for conference_service in pairs(vnodes) do
                send_visitors_iq(conference_service, room, 'disconnect');
            end

            visitors_nodes[room.jid] = nil;
        end
    end);

    -- detects new participants joining main room and sending them to the visitor nodes
    host_module:hook('muc-occupant-joined', function (event)
        local room, stanza, occupant = event.room, event.stanza, event.occupant;

        -- filter focus, ignore configured domains (jibri and transcribers)
        if is_admin(stanza.attr.from) or visitors_nodes[room.jid] == nil
            or ignore_list:contains(jid.host(occupant.bare_jid)) then
            return;
        end

        local vnodes = visitors_nodes[room.jid].nodes;
        local user, _, res = jid.split(occupant.nick);
        -- a main participant we need to update all active visitor nodes
        for k in pairs(vnodes) do
            local fmuc_pr = st.clone(stanza);
            fmuc_pr.attr.to = jid.join(user, k, res);
            fmuc_pr.attr.from = occupant.jid;
            module:send(fmuc_pr);
        end
    end);
    -- forwards messages from main participants to vnodes
    host_module:hook('muc-occupant-groupchat', function(event)
        local room, stanza, occupant = event.room, event.stanza, event.occupant;

        -- filter sending messages from transcribers/jibris to visitors
        if not visitors_nodes[room.jid] or ignore_list:contains(jid.host(occupant.bare_jid)) then
            return;
        end

        local vnodes = visitors_nodes[room.jid].nodes;
        local user = jid.node(occupant.nick);
        -- a main participant we need to update all active visitor nodes
        for k in pairs(vnodes) do
            local fmuc_msg = st.clone(stanza);
            fmuc_msg.attr.to = jid.join(user, k);
            fmuc_msg.attr.from = occupant.jid;
            module:send(fmuc_msg);
        end
    end);
    -- receiving messages from visitor nodes and forward them to local main participants
    -- and forward them to the rest of visitor nodes
    host_module:hook('muc-occupant-groupchat', function(event)
        local occupant, room, stanza = event.occupant, event.room, event.stanza;
        local to = stanza.attr.to;
        local from = stanza.attr.from;
        local from_vnode = jid.host(from);

        if occupant or not (visitors_nodes[to]
                            and visitors_nodes[to].nodes
                            and visitors_nodes[to].nodes[from_vnode]) then
            return;
        end

        -- a message from visitor occupant of known visitor node
        stanza.attr.from = to;
        for _, o in room:each_occupant() do
            -- send it to the nick to be able to route it to the room (ljm multiple rooms) from unknown occupant
            room:route_to_occupant(o, stanza);
        end
        -- let's add the message to the history of the room
        host_module:fire_event("muc-add-history", { room = room; stanza = stanza; from = from; visitor = true; });

        -- now we need to send to rest of visitor nodes
        local vnodes = visitors_nodes[room.jid].nodes;
        for k in pairs(vnodes) do
            if k ~= from_vnode then
                local st_copy = st.clone(stanza);
                st_copy.attr.to = jid.join(jid.node(room.jid), k);
                module:send(st_copy);
            end
        end

        return true;
    end, 55); -- prosody check for unknown participant chat is prio 50, we want to override it

    host_module:hook('muc-config-submitted/muc#roomconfig_roomsecret', function(event)
        if event.status_codes['104'] then
            local room = event.room;

            if visitors_nodes[room.jid] then
                -- we need to update all vnodes
                local vnodes = visitors_nodes[room.jid].nodes;
                for conference_service in pairs(vnodes) do
                    send_visitors_iq(conference_service, room, 'update');
                end
            end
        end
    end, -100); -- we want to run last in order to check is the status code 104
end);

module:hook('jitsi-lobby-enabled', function(event)
    local room = event.room;
    if visitors_nodes[room.jid] then
        -- we need to update all vnodes
        local vnodes = visitors_nodes[room.jid].nodes;
        for conference_service in pairs(vnodes) do
            send_visitors_iq(conference_service, room, 'update');
        end
    end
end);
module:hook('jitsi-lobby-disabled', function(event)
local room = event.room;
    if visitors_nodes[room.jid] then
        -- we need to update all vnodes
        local vnodes = visitors_nodes[room.jid].nodes;
        for conference_service in pairs(vnodes) do
            send_visitors_iq(conference_service, room, 'update');
        end
    end
end);