-- Prosody IM

-- Copyright (C) 2008-2010 Matthew Wild

-- Copyright (C) 2008-2010 Waqas Hussain

-- Copyright (C) 2014 Daurnimator

--

-- This project is MIT/X11 licensed. Please see the

-- COPYING file in the source package for more information.

--

local gettime = os.time;

local datetime = require "util.datetime";

local st = require "util.stanza";

local default_history_length = 20;

local max_history_length = module:get_option_number("max_history_messages", math.huge);

local function set_max_history_length(_max_history_length)

	max_history_length = _max_history_length or math.huge;

end

local function get_historylength(room)

	return math.min(room._data.history_length or default_history_length, max_history_length);

end

local function set_historylength(room, length)

	if length then

		length = assert(tonumber(length), "Length not a valid number");

	end

	if length == default_history_length then length = nil; end

	room._data.history_length = length;

	return true;

end

module:hook("muc-config-form", function(event)

	table.insert(event.form, {

		name = "muc#roomconfig_historylength";

		type = "text-single";

		label = "Maximum Number of History Messages Returned by Room";

		value = tostring(get_historylength(event.room));

	});

end, 100-10);

module:hook("muc-config-submitted/muc#roomconfig_historylength", function(event)

	if set_historylength(event.room, event.value) then

		event.status_codes["104"] = true;

	end

end);

local function parse_history(stanza)

	local x_tag = stanza:get_child("x", "http://jabber.org/protocol/muc");

	local history_tag = x_tag and x_tag:get_child("history", "http://jabber.org/protocol/muc");

	if not history_tag then

		return nil, default_history_length, nil;

	end

	local maxchars = tonumber(history_tag.attr.maxchars);

	local maxstanzas = tonumber(history_tag.attr.maxstanzas);

	-- messages received since the UTC datetime specified

	local since = history_tag.attr.since;

	if since then

		since = datetime.parse(since);

	end

	-- messages received in the last "X" seconds.

	local seconds = tonumber(history_tag.attr.seconds);

	if seconds then

		seconds = gettime() - seconds;

		if since then

			since = math.max(since, seconds);

		else

			since = seconds;

		end

	end

	return maxchars, maxstanzas, since;

end

module:hook("muc-get-history", function(event)

	local room = event.room;

	local history = room._history; -- send discussion history

	if not history then return nil end

	local history_len = #history;

	local to = event.to;

	local maxchars = event.maxchars;

	local maxstanzas = event.maxstanzas or history_len;

	local since = event.since;

	local n = 0;

	local charcount = 0;

	for i=history_len,1,-1 do

		local entry = history[i];

		if maxchars then

			if not entry.chars then

				entry.stanza.attr.to = "";

				entry.chars = #tostring(entry.stanza);

			end

			charcount = charcount + entry.chars + #to;

			if charcount > maxchars then break; end

		end

		if since and since > entry.timestamp then break; end

		if n + 1 > maxstanzas then break; end

		n = n + 1;

	end

	local i = history_len-n+1

	function event.next_stanza()

		if i > history_len then return nil end

		local entry = history[i];

		local msg = entry.stanza;

		msg.attr.to = to;

		i = i + 1;

		return msg;

	end

	return true;

end, -1);

local function send_history(room, stanza)

	local maxchars, maxstanzas, since = parse_history(stanza);

	local event = {

		room = room;

		to = stanza.attr.from; -- `to` is required to calculate the character count for `maxchars`

		maxchars = maxchars, maxstanzas = maxstanzas, since = since;

		next_stanza = function() end; -- events should define this iterator

	};

	module:fire_event("muc-get-history", event);

	for msg in event.next_stanza, event do

		room:route_stanza(msg);

	end

end

-- Send history on join

module:hook("muc-occupant-session-new", function(event)

	send_history(event.room, event.stanza);

end, 50); -- Before subject(20)

-- add to history

module:hook("muc-add-history", function(event)

	local historic = event.stanza:get_child("body");

	if historic then

		local room = event.room

		local history = room._history;

		if not history then history = {}; room._history = history; end

		local stanza = st.clone(event.stanza);

		stanza.attr.to = "";

		local ts = gettime();

		local stamp = datetime.datetime(ts);

		stanza:tag("delay", {xmlns = "urn:xmpp:delay", from = module.host, stamp = stamp}):up(); -- XEP-0203

		stanza:tag("x", {xmlns = "jabber:x:delay", from = module.host, stamp = datetime.legacy()}):up(); -- XEP-0091 (deprecated)

		local entry = { stanza = stanza, timestamp = ts };

		table.insert(history, entry);

		while #history > get_historylength(room) do table.remove(history, 1) end

	end

	return true;

end, -1);

-- Have a single muc-add-history event, so that plugins can mark it

-- as handled without stopping other muc-broadcast-message handlers

module:hook("muc-broadcast-message", function(event)

	module:fire_event("muc-add-history", event);

end);

return {

	set_max_length = set_max_history_length;

	parse_history = parse_history;

	send = send_history;

	get_length = get_historylength;

	set_length = set_historylength;

};