local stats = require "util.statistics".new();

local config = require "core.configmanager";

local log = require "util.logger".init("stats");

local timer = require "util.timer";

local fire_event = prosody.events.fire_event;

local stats_config = config.get("*", "statistics_interval");

local stats_interval = tonumber(stats_config);

if stats_config and not stats_interval then

	log("error", "Invalid 'statistics_interval' setting, statistics will be disabled");

end

local measure, collect;

local latest_stats = {};

local changed_stats = {};

local stats_extra = {};

if stats_interval then

	log("debug", "Statistics collection is enabled every %d seconds", stats_interval);

	function measure(type, name)

		local f = assert(stats[type], "unknown stat type: "..type);

		return f(name);

	end

	local mark_collection_start = measure("duration", "stats.collection_time");

	local mark_processing_start = measure("duration", "stats.processing_time");

	function collect()

		local mark_collection_done = mark_collection_start();

		changed_stats, stats_extra = {}, {};

		for name, getter in pairs(stats.get_stats()) do

			local type, value, extra = getter();

			local stat_name = name..":"..type;

			local old_value = latest_stats[stat_name];

			latest_stats[stat_name] = value;

			if value ~= old_value then

				changed_stats[stat_name] = value;

			end

			if extra then

				print(stat_name, extra)

				stats_extra[stat_name] = extra;

				if type == "duration" then

					local rate = extra.rate;

					local rate_name = name..":rate";

					latest_stats[rate_name] = rate;

					changed_stats[rate_name] = rate;

				end

			end

		end

		mark_collection_done();

		local mark_processing_done = mark_processing_start();

		fire_event("stats-updated", { stats = latest_stats, changed_stats = changed_stats, stats_extra = stats_extra });

		mark_processing_done();

		return stats_interval;

	end

	timer.add_task(stats_interval, collect);

else

	log("debug", "Statistics collection is disabled");

	-- nop

	function measure()

		return measure;

	end

	function collect()

	end

end

return {

	measure = measure;

	collect = collect;

	get_stats = function ()

		return latest_stats, changed_stats, stats_extra;

	end;

};