local get_time = os.clock
local sethook = xlua.sethook or debug.sethook
local func_info_map, start_time
local create_func_info = function(db_info)
	return {
		db_info = db_info,
		count = 0,
		total_time = 0
	}
end
local on_hook = function(event, func_info_id, source)
	if func_info_map == nil then
		return
	end
	local func_info = func_info_map[func_info_id]
	if not func_info then
		func_info = create_func_info(debug.getinfo(2, "nS"))
		func_info_map[func_info_id] = func_info
	end
	if event == "call" then
		func_info.call_time = get_time()
		func_info.count = func_info.count + 1
		func_info.return_time = nil
	elseif event == "return" or event == "tail return" then
		local now = get_time()
		if func_info.call_time then
			func_info.total_time = func_info.total_time + (now - func_info.call_time)
			func_info.call_time = nil
		else
			func_info.total_time = func_info.total_time + (now - (func_info.return_time or now))
			func_info.count = func_info.count + 1
		end
		func_info.return_time = now
		if source and func_info.count == 1 then
			func_info.db_info.short_src = source
		end
	end
end
local start = function()
	func_info_map = {}
	start_time = get_time()
	sethook(on_hook, "cr")
end
local pause = function()
	sethook()
end
local resume = function()
	sethook(on_hook, "cr")
end
local stop = function()
	sethook()
	func_info_map = nil
	start_time = nil
end
local report_output_line = function(rp, stat_interval)
	local source = rp.db_info.short_src or "[NA]"
	local linedefined = rp.db_info.linedefined and rp.db_info.linedefined >= 0 and string.format(":%i", rp.db_info.linedefined) or ""
	source = source .. linedefined
	local name = rp.db_info.name or "[anonymous]"
	local total_time = string.format("%04.3f", rp.total_time * 1000)
	local average_time = string.format("%04.3f", rp.total_time / rp.count * 1000)
	local relative_time = string.format("%03.2f%%", rp.total_time / stat_interval * 100)
	local count = string.format("%7i", rp.count)
	return string.format("|%-40.40s: %-50.50s: %-12s: %-12s: %-12s: %-12s|\n", name, source, total_time, average_time, relative_time, count)
end
local sort_funcs = {
	TOTAL = function(a, b)
		return a.total_time > b.total_time
	end,
	AVERAGE = function(a, b)
		return a.average > b.average
	end,
	CALLED = function(a, b)
		return a.count > b.count
	end
}
local report = function(sort_by)
	sethook()
	local sort_func = type(sort_by) == "function" and sort_by or sort_funcs[sort_by]
	local FORMAT_HEADER_LINE = "|%-40s: %-50s: %-12s: %-12s: %-12s: %-12s|\n"
	local header = string.format(FORMAT_HEADER_LINE, "FUNCTION", "SOURCE", "TOTAL(MS)", "AVERAGE(MS)", "RELATIVE", "CALLED")
	local stat_interval = get_time() - (start_time or get_time())
	local report_list = {}
	for _, rp in pairs(func_info_map or {}) do
		table.insert(report_list, {
			total_time = rp.total_time,
			count = rp.count,
			average = rp.total_time / rp.count,
			output = report_output_line(rp, stat_interval)
		})
	end
	table.sort(report_list, sort_func or sort_funcs.TOTAL)
	local output = header
	for i, rp in ipairs(report_list) do
		output = output .. rp.output
	end
	sethook(on_hook, "cr")
	return output
end
return {
	start = start,
	report = report,
	stop = stop
}