-- Prosody IM

-- Copyright (C) 2008-2010 Matthew Wild

-- Copyright (C) 2008-2010 Waqas Hussain

--

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

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

--

local random = require "prosody.util.random";

local random_bytes = random.bytes;

local time = require "prosody.util.time";

local hex = require "prosody.util.hex".encode;

local m_ceil = math.ceil;

local m_floor = math.floor;

local function get_nibbles(n)

	return hex(random_bytes(m_ceil(n/2))):sub(1, n);

end

local function get_twobits()

	return ("%x"):format(random_bytes(1):byte() % 4 + 8);

end

local function generate()

	-- generate RFC 4122 complaint UUIDs (version 4 - random)

	return get_nibbles(8).."-"..get_nibbles(4).."-4"..get_nibbles(3).."-"..(get_twobits())..get_nibbles(3).."-"..get_nibbles(12);

end

local function generate_v7()

	-- Sortable based on time and random

	-- https://datatracker.ietf.org/doc/html/draft-peabody-dispatch-new-uuid-format-01#section-4.4

	local t = time.now();

	local unixts = m_floor(t);

	local unixts_a = m_floor(unixts / 16);

	local unixts_b = m_floor(unixts % 16);

	local subsec = t % 1;

	local subsec_a = m_floor(subsec * 0x1000);

	local subsec_b = m_floor(subsec * 0x1000000) % 0x1000;

	return ("%08x-%x%03x-7%03x-%4s-%12s"):format(unixts_a, unixts_b, subsec_a, subsec_b, get_twobits() .. get_nibbles(3), get_nibbles(12));

end

return {

	v4 = generate;

	v7 = generate_v7;

	get_nibbles=get_nibbles;

	generate = generate ;

	-- COMPAT

	seed = random.seed;

};