-- XEP-0280: Message Carbons implementation for Prosody
-- Copyright (C) 2011 Kim Alvefur
--
-- This file is MIT/X11 licensed.

local st = require "util.stanza";
local jid_bare = require "util.jid".bare;
local jid_split = require "util.jid".split;
local xmlns_carbons = "urn:xmpp:carbons:1";
local xmlns_forward = "urn:xmpp:forward:0";
local host_sessions = hosts[module.host].sessions;

module:hook("iq/self/"..xmlns_carbons..":enable", function(event)
	local origin, stanza = event.origin, event.stanza;
	if stanza.attr.type == "set" then
		module:log("debug", "%s enabled carbons", origin.full_jid);
		origin.want_carbons = true;
		origin.send(st.reply(stanza));
		return true
	end
end);

module:hook("iq/self/"..xmlns_carbons..":disable", function(event)
	local origin, stanza = event.origin, event.stanza;
	if stanza.attr.type == "set" then
		module:log("debug", "%s disabled carbons", origin.full_jid);
		origin.want_carbons = nil;
		origin.send(st.reply(stanza));
		return true
	end
end);

local function message_handler(event, c2s)
	local origin, stanza = event.origin, event.stanza;
	local orig_type = stanza.attr.type;
	local orig_to = stanza.attr.to;
	local orig_from = stanza.attr.from;
	
	if not (orig_type == nil
			or orig_type == "normal"
			or orig_type == "chat") then
		return -- No carbons for messages of type error or headline
	end

	local bare_jid, user_sessions;
	local no_carbon_to = {};
	module:log("debug", "Message from %s to %s", orig_from, orig_to);
	if c2s then -- Stanza sent by a local client
		bare_jid = (origin.username.."@"..origin.host)
		user_sessions = host_sessions[origin.username];
	else -- Stanza about to be delivered to a local client
		local username, hostname, resource = jid_split(orig_to);
		bare_jid = jid_bare(orig_to);
		user_sessions = host_sessions[username];
		if resource then
			module:log("debug", "Message was to resource %s, it will not get carbon", resource);
			no_carbon_to[resource] = true;
		elseif user_sessions then
			local top_resources = user_sessions.top_resources;
			if top_resources then
				for _, session in ipairs(top_resources) do
					module:log("debug", "Not sending carbons to top resource %s", session.resource);
					no_carbon_to[session.resource] = true;
				end
			end
		end
	end

	if not user_sessions then
		module:log("debug", "Skip carbons for offline user");
		return -- No use in sending carbons to an offline user
	end

	if not c2s and stanza:get_child("private", xmlns_carbons) then
		stanza:maptags(function(tag)
			return tag.attr.xmlns == xmlns_carbons
				and tag.name == "private" and tag or nil;
		end);
		module:log("debug", "Message tagged private, ignoring");
		return
	end

	if not stanza:get_child("forwarded", xmlns_forward) then
		user_sessions = user_sessions and user_sessions.sessions;
		for resource, session in pairs(user_sessions) do
			local full_jid = bare_jid .. "/" .. resource;
			module:log("debug", "%s wants carbons: %s", session.full_jid, tostring(session.want_carbons));
			if session.want_carbons then
				if c2s then
					module:log("debug", "Session is origin: %s", tostring(session == origin));
				else
					module:log("debug", "Session is in ignore list: %s", tostring(no_carbon_to[resource]));
				end
				if (c2s and session ~= origin) or (not c2s and not no_carbon_to[resource]) then
					local msg = st.clone(stanza);
					msg.attr.xmlns = msg.attr.xmlns or "jabber:client";
					local fwd = st.message{
								from = bare_jid,
								to = full_jid,
								type = orig_type,
							}
						:tag(c2s and "sent" or "received", { xmlns = xmlns_carbons }):up()
						:tag("forwarded", { xmlns = xmlns_forward })
							:add_child(msg);
					module:log("debug", "Sending carbon");
					session.send(fwd);
				end
			end
		end
	end
end

local function c2s_message_handler(event)
	return message_handler(event, true)
end

-- Stanzas sent by local clients
module:hook("pre-message/bare", c2s_message_handler, 1);
module:hook("pre-message/full", c2s_message_handler, 1);
-- Stanzas to local clients
module:hook("message/bare", message_handler, 1);
module:hook("message/full", message_handler, 1);

module:add_feature(xmlns_carbons);