-- XEP-0313: Message Archive Management for Prosody

-- Copyright (C) 2011-2016 Kim Alvefur

--

-- This file is MIT/X11 licensed.

local xmlns_mam     = "urn:xmpp:mam:1";

local xmlns_delay   = "urn:xmpp:delay";

local xmlns_forward = "urn:xmpp:forward:0";

local um = require "core.usermanager";

local st = require "util.stanza";

local rsm = require "rsm";

local get_prefs = module:require"mamprefs".get;

local set_prefs = module:require"mamprefs".set;

local prefs_to_stanza = module:require"mamprefsxml".tostanza;

local prefs_from_stanza = module:require"mamprefsxml".fromstanza;

local jid_bare = require "util.jid".bare;

local jid_split = require "util.jid".split;

local jid_prepped_split = require "util.jid".prepped_split;

local dataform = require "util.dataforms".new;

local host = module.host;

local rm_load_roster = require "core.rostermanager".load_roster;

local is_stanza = st.is_stanza;

local tostring = tostring;

local time_now = os.time;

local m_min = math.min;

local timestamp, timestamp_parse = require "util.datetime".datetime, require "util.datetime".parse;

local default_max_items, max_max_items = 20, module:get_option_number("max_archive_query_results", 50);

local global_default_policy = module:get_option("default_archive_policy", true);

if global_default_policy ~= "roster" then

	global_default_policy = module:get_option_boolean("default_archive_policy", global_default_policy);

end

local strip_tags = module:get_option_set("dont_archive_namespaces", { "http://jabber.org/protocol/chatstates" });

local archive = assert(module:open_store(archive_store, "archive"));

if archive.name == "null" or not archive.find then

	if not archive.find then

		module:log("debug", "Attempt to open archive storage returned a valid driver but it does not seem to implement the storage API");

		module:log("debug", "mod_%s does not support archiving", archive._provided_by or archive.name and "storage_"..archive.name.."(?)" or "<unknown>");

	else

		module:log("debug", "Attempt to open archive storage returned null driver");

	end

	module:log("debug", "See https://prosody.im/doc/storage and https://prosody.im/doc/archiving for more information");

	module:log("info", "Using in-memory fallback archive driver");

	archive = module:require "fallback_archive";

end

local cleanup;

-- Handle prefs.

module:hook("iq/self/"..xmlns_mam..":prefs", function(event)

	local origin, stanza = event.origin, event.stanza;

	local user = origin.username;

	if stanza.attr.type == "get" then

		local prefs = prefs_to_stanza(get_prefs(user));

		local reply = st.reply(stanza):add_child(prefs);

		origin.send(reply);

	else -- type == "set"

		local new_prefs = stanza:get_child("prefs", xmlns_mam);

		local prefs = prefs_from_stanza(new_prefs);

		local ok, err = set_prefs(user, prefs);

		if not ok then

			origin.send(st.error_reply(stanza, "cancel", "internal-server-error", "Error storing preferences: "..tostring(err)));

		else

			origin.send(st.reply(stanza));

		end

	end

	return true;

end);

local query_form = dataform {

	{ name = "FORM_TYPE"; type = "hidden"; value = xmlns_mam; };

	{ name = "with"; type = "jid-single"; };

	{ name = "start"; type = "text-single" };

	{ name = "end"; type = "text-single"; };

};

-- Serve form

module:hook("iq-get/self/"..xmlns_mam..":query", function(event)

	local origin, stanza = event.origin, event.stanza;

	origin.send(st.reply(stanza):add_child(query_form:form()));

	return true;

end);

-- Handle archive queries

module:hook("iq-set/self/"..xmlns_mam..":query", function(event)

	local origin, stanza = event.origin, event.stanza;

	local query = stanza.tags[1];

	local qid = query.attr.queryid;

	if cleanup then cleanup[origin.username] = true; end

	-- Search query parameters

	local qwith, qstart, qend;

	local form = query:get_child("x", "jabber:x:data");

	if form then

		local err;

		form, err = query_form:data(form);

		if err then

			origin.send(st.error_reply(stanza, "modify", "bad-request", select(2, next(err))));

			return true;

		end

		qwith, qstart, qend = form["with"], form["start"], form["end"];

		qwith = qwith and jid_bare(qwith); -- dataforms does jidprep

	end

	if qstart or qend then -- Validate timestamps

		local vstart, vend = (qstart and timestamp_parse(qstart)), (qend and timestamp_parse(qend));

		if (qstart and not vstart) or (qend and not vend) then

			origin.send(st.error_reply(stanza, "modify", "bad-request", "Invalid timestamp"))

			return true;

		end

		qstart, qend = vstart, vend;

	end

	module:log("debug", "Archive query, id %s with %s from %s until %s)",

		tostring(qid), qwith or "anyone", qstart or "the dawn of time", qend or "now");

	-- RSM stuff

	local qset = rsm.get(query);

	local qmax = m_min(qset and qset.max or default_max_items, max_max_items);

	local reverse = qset and qset.before or false;

	local before, after = qset and qset.before, qset and qset.after;

	if type(before) ~= "string" then before = nil; end

	-- Load all the data!

	local data, err = archive:find(origin.username, {

		start = qstart; ["end"] = qend; -- Time range

		with = qwith;

		limit = qmax + 1;

		before = before; after = after;

		reverse = reverse;

		total = true;

	});

	if not data then

		origin.send(st.error_reply(stanza, "cancel", "internal-server-error", err));

		return true;

	end

	local total = tonumber(err);

	local msg_reply_attr = { to = stanza.attr.from, from = stanza.attr.to };

	local results = {};

	-- Wrap it in stuff and deliver

	local first, last;

	local count = 0;

	local complete = "true";

	for id, item, when in data do

		count = count + 1;

		if count > qmax then

			complete = nil;

			break;

		end

		local fwd_st = st.message(msg_reply_attr)

			:tag("result", { xmlns = xmlns_mam, queryid = qid, id = id })

				:tag("forwarded", { xmlns = xmlns_forward })

					:tag("delay", { xmlns = xmlns_delay, stamp = timestamp(when) }):up();

		if not is_stanza(item) then

			item = st.deserialize(item);

		end

		item.attr.xmlns = "jabber:client";

		fwd_st:add_child(item);

		if not first then first = id; end

		last = id;

		if reverse then

			results[count] = fwd_st;

		else

			origin.send(fwd_st);

		end

	end

	if reverse then

		for i = #results, 1, -1 do

			origin.send(results[i]);

		end

		first, last = last, first;

	end

	-- That's all folks!

	module:log("debug", "Archive query %s completed", tostring(qid));

	origin.send(st.reply(stanza)

		:tag("fin", { xmlns = xmlns_mam, queryid = qid, complete = complete })

			:add_child(rsm.generate {

				first = first, last = last, count = total }));

	return true;

end);

local function has_in_roster(user, who)

	local roster = rm_load_roster(user, host);

	module:log("debug", "%s has %s in roster? %s", user, who, roster[who] and "yes" or "no");

	return roster[who];

end

local function shall_store(user, who)

	-- TODO Cache this?

	if not um.user_exists(user, host) then

		return false;

	end

	local prefs = get_prefs(user);

	local rule = prefs[who];

	module:log("debug", "%s's rule for %s is %s", user, who, tostring(rule));

	if rule ~= nil then

		return rule;

	end

	-- Below could be done by a metatable

	local default = prefs[false];

	module:log("debug", "%s's default rule is %s", user, tostring(default));

	if default == nil then

		default = global_default_policy;

		module:log("debug", "Using global default rule, %s", tostring(default));

	end

	if default == "roster" then

		return has_in_roster(user, who);

	end

	return default;

end

-- Handle messages

local function message_handler(event, c2s)

	local origin, stanza = event.origin, event.stanza;

	local log = c2s and origin.log or module._log;

	local orig_type = stanza.attr.type or "normal";

	local orig_from = stanza.attr.from;

	local orig_to = stanza.attr.to or orig_from;

	-- Stanza without 'to' are treated as if it was to their own bare jid

	-- Whos storage do we put it in?

	local store_user = c2s and origin.username or jid_split(orig_to);

	-- And who are they chatting with?

	local with = jid_bare(c2s and orig_to or orig_from);

	-- Filter out <stanza-id> that claim to be from us

	stanza:maptags(function (tag)

		if tag.name == "stanza-id" and tag.attr.xmlns == "urn:xmpp:sid:0" then

			local by_user, by_host, res = prepped_split(tag.attr.by);

			if not res and by_host == module.host and by_user == store_user then

				return nil;

			end

		end

		return tag;

	end);

	-- We store chat messages or normal messages that have a body

	if not(orig_type == "chat" or (orig_type == "normal" and stanza:get_child("body")) ) then

		log("debug", "Not archiving stanza: %s (type)", stanza:top_tag());

		return;

	end

	-- or if hints suggest we shouldn't

	if not stanza:get_child("store", "urn:xmpp:hints") then -- No hint telling us we should store

		if stanza:get_child("no-permanent-store", "urn:xmpp:hints")

			or stanza:get_child("no-store", "urn:xmpp:hints") then -- Hint telling us we should NOT store

			log("debug", "Not archiving stanza: %s (hint)", stanza:top_tag());

			return;

		end

	end

	if not strip_tags:empty() then

		stanza = st.clone(stanza);

		stanza:maptags(function (tag)

			if strip_tags:contains(tag.attr.xmlns) then

				return nil;

			else

				return tag;

			end

		end);

		if #stanza.tags == 0 then

			return;

		end

	end

	-- Check with the users preferences

	if shall_store(store_user, with) then

		log("debug", "Archiving stanza: %s", stanza:top_tag());

		-- And stash it

		local ok, id = archive:append(store_user, nil, stanza, time_now(), with);

		if ok then

			stanza:tag("stanza-id", { xmlns = "urn:xmpp:sid:0", by = store_user.."@"..host, id = id }):up();

			if cleanup then cleanup[store_user] = true; end

			module:fire_event("archive-message-added", { origin = origin, stanza = stanza, for_user = store_user, id = id });

		end

	else

		log("debug", "Not archiving stanza: %s (prefs)", stanza:top_tag());

	end

end

local function c2s_message_handler(event)

	return message_handler(event, true);

end

local cleanup_after = module:get_option_string("archive_expires_after", "1w");

local cleanup_interval = module:get_option_number("archive_cleanup_interval", 4 * 60 * 60);

if cleanup_after ~= "never" then

	local day = 86400;

	local multipliers = { d = day, w = day * 7, m = 31 * day, y = 365.2425 * day };

	local n, m = cleanup_after:lower():match("(%d+)%s*([dwmy]?)");

	if not n then

		module:log("error", "Could not parse archive_expires_after string %q", cleanup_after);

		return false;

	end

	cleanup_after = tonumber(n) * ( multipliers[m] or 1 );

	module:log("debug", "archive_expires_after = %d -- in seconds", cleanup_after);

	if not archive.delete then

		module:log("error", "archive_expires_after set but mod_%s does not support deleting", archive._provided_by);

		return false;

	end

	-- Set of known users to do message expiry for

	-- Populated either below or when new messages are added

	cleanup = {};

	-- Iterating over users is not supported by all authentication modules

	-- Catch and ignore error if not supported

	pcall(function ()

		-- If this works, then we schedule cleanup for all known known

		for user in um.users(module.host) do

			cleanup[user] = true;

		end

	end);

	-- At odd intervals, delete old messages for one user

	module:add_timer(math.random(10, 60), function()

		local user = next(cleanup);

		if user then

			module:log("debug", "Removing old messages for user %q", user);

			local ok, err = archive:delete(user, { ["end"] = os.time() - cleanup_after; })

			if not ok then

				module:log("warn", "Could not expire archives for user %s: %s", user, err);

			elseif type(ok) == "number" then

				module:log("debug", "Removed %d messages", ok);

			end

			cleanup[user] = nil;

		end

		return math.random(cleanup_interval, cleanup_interval * 2);

	end);

end

-- Stanzas sent by local clients

module:hook("pre-message/bare", c2s_message_handler, 0);

module:hook("pre-message/full", c2s_message_handler, 0);

-- Stanszas to local clients

module:hook("message/bare", message_handler, 0);

module:hook("message/full", message_handler, 0);

module:hook("account-disco-info", function(event)

	(event.reply or event.stanza):tag("feature", {var=xmlns_mam}):up();

end);