-- XEP-0313: Message Archive Management for Prosody
-- Copyright (C) 2011-2012 Kim Alvefur
--
-- This file is MIT/X11 licensed.

local xmlns_mam     = "urn:xmpp:mam:tmp";
local xmlns_delay   = "urn:xmpp:delay";
local xmlns_forward = "urn:xmpp:forward:0";

local st = require "util.stanza";
local rsm = module:require "rsm";
local prefs = module:require"mamprefs";
local set_prefs, get_prefs = prefs.set, prefs.get;
local jid_bare = require "util.jid".bare;
local jid_split = require "util.jid".split;
local jid_prep = require "util.jid".prep;
local host = module.host;

local dm_list_load = require "util.datamanager".list_load;
local dm_list_append = require "util.datamanager".list_append;
local rm_load_roster = require "core.rostermanager".load_roster;

local tostring = tostring;
local time_now = os.time;
local m_min = math.min;
local t_insert = table.insert;
local timestamp, timestamp_parse = require "util.datetime".datetime, require "util.datetime".parse;
local uuid = require "util.uuid".generate;
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", false);
-- TODO Should be possible to enforce it too


-- For translating preference names from string to boolean and back
local default_attrs = {
	always = true, [true] = "always",
	never = false, [false] = "never",
	roster = "roster",
}

local archive_store = "archive2";

-- 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 = get_prefs(user);
		local default = prefs[false];
		default = default ~= nil and default_attrs[default] or global_default_policy;
		local reply = st.reply(stanza):tag("prefs", { xmlns = xmlns_mam, default = default })
		local always = st.stanza("always");
		local never = st.stanza("never");
		for k,v in pairs(prefs) do
			if k then
				(v and always or never):tag("jid"):text(k):up();
			end
		end
		reply:add_child(always):add_child(never);
		origin.send(reply);
		return true
	else -- type == "set"
		local prefs = {};
		local new_prefs = stanza:get_child("prefs", xmlns_mam);
		local new_default = new_prefs.attr.default;
		if new_default then
			prefs[false] = default_attrs[new_default];
		end

		local always = new_prefs:get_child("always");
		if always then
			for rule in always:childtags("jid") do
				local jid = rule:get_text();
				prefs[jid] = true;
			end
		end

		local never = new_prefs:get_child("never");
		if never then
			for rule in never:childtags("jid") do
				local jid = rule:get_text();
				prefs[jid] = false;
			end
		end

		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
		return true
	end
end);

-- Handle archive queries
module:hook("iq-get/self/"..xmlns_mam..":query", function(event)
	local origin, stanza = event.origin, event.stanza;
	local query = stanza.tags[1];
	local qid = query.attr.queryid;

	-- Search query parameters
	local qwith = query:get_child_text("with");
	local qstart = query:get_child_text("start");
	local qend = query:get_child_text("end");
	local qset = rsm.get(query);
	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");

	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

	local qres;
	if qwith then -- Validate the 'with' jid
		local pwith = qwith and jid_prep(qwith);
		if pwith and not qwith then -- it failed prepping
			origin.send(st.error_reply(stanza, "modify", "bad-request", "Invalid JID"))
			return true
		end
		local _, _, resource = jid_split(qwith);
		qwith = jid_bare(pwith);
		qres = resource;
	end

	-- Load all the data!
	local data, err = dm_list_load(origin.username, origin.host, archive_store);
	if not data then
		if (not err) then
			module:log("debug", "The archive was empty.");
			origin.send(st.reply(stanza));
		else
			origin.send(st.error_reply(stanza, "cancel", "internal-server-error", "Error loading archive: "..tostring(err)));
		end
		return true
	end

	-- RSM stuff
	local qmax = m_min(qset and qset.max or default_max_items, max_max_items);
	local qset_matches = not (qset and qset.after);
	local first, last, index;
	local n = 0;
	local start = qset and qset.index or 1;
	local results = {};
	-- An empty <before/> means: give the last n items. So we loop backwards.
	local reverse = qset and qset.before or false;

	module:log("debug", "Loaded %d items, about to filter", #data);
	for i=(reverse and #data or start),(reverse and start or #data),(reverse and -1 or 1) do
		local item = data[i];
		local when, with, resource = item.when, item.with, item.resource;
		local id = item.id;
		--module:log("debug", "id is %s", id);

		-- RSM pre-send-checking
		if qset then
			if qset.before == id then
				module:log("debug", "End of matching range found");
				qset_matches = false;
				break;
			end
		end

		--module:log("debug", "message with %s at %s", with, when or "???");
		-- Apply query filter
		if (not qwith or ((qwith == with) and (not qres or qres == resource)))
				and (not qstart or when >= qstart)
				and (not qend or when <= qend)
				and (not qset or qset_matches) then
			local fwd_st = st.message{ to = origin.full_jid }
				:tag("result", { xmlns = xmlns_mam, queryid = qid, id = id })
					:tag("forwarded", { xmlns = xmlns_forward })
						:tag("delay", { xmlns = xmlns_delay, stamp = timestamp(when) }):up();
			local orig_stanza = st.deserialize(item.stanza);
			orig_stanza.attr.xmlns = "jabber:client";
			fwd_st:add_child(orig_stanza);
			if reverse then
				t_insert(results, 1, fwd_st);
			else
				results[#results + 1] = fwd_st;
			end
			if not first then
				index = i;
				first = id;
			end
			last = id;
			n = n + 1;
		elseif (qend and when > qend) then
			module:log("debug", "We have passed into messages more recent than requested");
			break -- We have passed into messages more recent than requested
		end

		-- RSM post-send-checking
		if qset then
			if qset.after == id then
				module:log("debug", "Start of matching range found");
				qset_matches = true;
			end
		end
		if n >= qmax then
			module:log("debug", "Max number of items matched");
			break
		end
	end
	for _,v in pairs(results) do
		origin.send(v);
	end
	-- That's all folks!
	module:log("debug", "Archive query %s completed", tostring(qid));

	return origin.send(st.reply(stanza)
		:query(xmlns_mam):add_child(rsm.generate {
			first = (reverse and last or first), last = (reverse and first or last), count = #data}));
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?
	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;
	else -- 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
end

-- Handle messages
local function message_handler(event, c2s)
	local origin, stanza = event.origin, event.stanza;
	local orig_type = stanza.attr.type or "normal";
	local orig_to = stanza.attr.to;
	local orig_from = stanza.attr.from;

	if not orig_from and c2s then
		orig_from = origin.full_jid;
	end
	orig_to = orig_to or orig_from; -- Weird corner cases

	-- Don't store messages of these types
	if orig_type == "error"
	or orig_type == "headline"
	or orig_type == "groupchat"
	or not stanza:get_child("body") then
		return;
		-- TODO Maybe headlines should be configurable?
		-- TODO Write a mod_mam_muc for groupchat messages.
	end

	local store_user, store_host = jid_split(c2s and orig_from or orig_to);
	local target_jid = c2s and orig_to or orig_from;
	local target_bare = jid_bare(target_jid);
	local _, _, target_resource = jid_split(target_jid);

	if shall_store(store_user, target_bare) then
		module:log("debug", "Archiving stanza: %s", stanza:top_tag());

		local id = uuid();
		local when = time_now();
		-- And stash it
		local ok, err = dm_list_append(store_user, store_host, archive_store, {
			-- WARNING This format may change.
			id = id,
			when = when,
			with = target_bare,
			resource = target_resource,
			stanza = st.preserialize(stanza)
		});
		if ok and not c2s then
			stanza:tag("archived", { xmlns = xmlns_mam, by = jid_bare(orig_to), id = id }):up();
		end
	else
		module:log("debug", "Not archiving stanza: %s", stanza:top_tag());
	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, 2);
module:hook("pre-message/full", c2s_message_handler, 2);
-- Stanszas to local clients
module:hook("message/bare", message_handler, 2);
module:hook("message/full", message_handler, 2);

module:add_feature(xmlns_mam);