# HG changeset patch
# User Kim Alvefur <zash@zash.se>
# Date 1629031461 -7200
# Node ID e6a5f196fc1f5e41c8a09ad8f312f2e9d48e7787
# Parent  a27a329e93cabf7ed148a59b5657b55e46c50a17
util.uuid: Add UUIDv7

Allows sorting by id as a substitute for sorting by timestamp since it
has the timestamp in the encoded in the first part, and only things that
happen extremely close together may get out of order by such a sort,
which might not matter.

From draft-ietf-uuidrev-rfc4122bis formerly draft-peabody-dispatch-new-uuid-format

diff -r a27a329e93ca -r e6a5f196fc1f spec/util_uuid_spec.lua
--- a/spec/util_uuid_spec.lua	Sat Nov 11 21:33:53 2023 +0100
+++ b/spec/util_uuid_spec.lua	Sun Aug 15 14:44:21 2021 +0200
@@ -20,6 +20,28 @@
 			for _ = 1, 100 do
 				assert.is_string(uuid.generate():match(pattern));
 			end
+
+			assert.truthy(uuid.generate() ~= uuid.generate(), "does not generate the same UUIDv4 twice")
+		end);
+	end);
+	describe("#v7", function()
+		it("should also follow the UUID pattern", function()
+			local pattern = "^" .. table.concat({
+					string.rep("%x", 8),
+					string.rep("%x", 4),
+					"7" .. -- version
+					string.rep("%x", 3),
+					"[89ab]" .. -- reserved bits of 1 and 0
+					string.rep("%x", 3),
+					string.rep("%x", 12),
+				}, "%-") .. "$";
+
+			local one = uuid.v7(); -- one before the loop to ensure some time passes
+			for _ = 1, 100 do
+				assert.is_string(uuid.v7():match(pattern));
+			end
+			-- one after the loop when some time should have passed
+			assert.truthy(one < uuid.v7(), "should be ordererd")
 		end);
 	end);
 end);
diff -r a27a329e93ca -r e6a5f196fc1f util/uuid.lua
--- a/util/uuid.lua	Sat Nov 11 21:33:53 2023 +0100
+++ b/util/uuid.lua	Sun Aug 15 14:44:21 2021 +0200
@@ -8,8 +8,10 @@
 
 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);
@@ -24,7 +26,22 @@
 	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