From c0e717fe27cdba61c24627c04db3e54838163d41 Mon Sep 17 00:00:00 2001
From: Aaron Suen <warr1024@gmail.com>
Date: Tue, 20 Aug 2024 07:00:39 -0400
Subject: [PATCH] Publish lagometer JSON file

If the szutil_lagometer_publish_json setting is enabled, write a
JSON file to the world path with lagometer data every publish
cycle, so that external systems can access it.

Also fix formatting issues in the lagometer format string.
---
 szutil_lagometer/init.lua | 31 ++++++++++++++++++++++++-------
 1 file changed, 24 insertions(+), 7 deletions(-)

diff --git a/szutil_lagometer/init.lua b/szutil_lagometer/init.lua
index c859400..c3d98f0 100644
--- a/szutil_lagometer/init.lua
+++ b/szutil_lagometer/init.lua
@@ -1,10 +1,10 @@
 -- LUALOCALS < ---------------------------------------------------------
-local ipairs, loadstring, math, minetest, pairs, string, tonumber
-    = ipairs, loadstring, math, minetest, pairs, string, tonumber
-local math_ceil, math_floor, string_format, string_gsub, string_rep,
-      string_sub
-    = math.ceil, math.floor, string.format, string.gsub, string.rep,
-      string.sub
+local ipairs, loadstring, math, minetest, os, pairs, string, tonumber
+    = ipairs, loadstring, math, minetest, os, pairs, string, tonumber
+local math_ceil, math_floor, os_time, string_format, string_gsub,
+      string_rep, string_sub
+    = math.ceil, math.floor, os.time, string.format, string.gsub,
+      string.rep, string.sub
 -- LUALOCALS > ---------------------------------------------------------
 
 local modname = minetest.get_current_modname()
@@ -121,6 +121,7 @@ local graphbar = string_rep("|", graphbar_width)
 
 -- Function to publish current lag values to all receiving parties.
 local hud_elem_type = minetest.features.hud_def_type_field and "type" or "hud_elem_type"
+local meterfmt = "%2.2f %s %2.2f%s"
 local function publish()
 	-- Expire old periods, and accumulate current ones.
 	local accum = newperiod()
@@ -141,7 +142,7 @@ local function publish()
 	for bucket = 1, bucket_max do
 		local qty = accum[bucket]
 
-		local line = qty <= 0 and "" or string_format(" % 2.2f % s % 2.2f % s", qty,
+		local line = qty <= 0 and "" or string_format(meterfmt, qty,
 			-- Maximum width of a graph bar corresponds to 50% of the total
 			-- time in the window, so that there will never be 2 bars of the
 			-- same length that don't have the same amount of time, even if
@@ -194,6 +195,22 @@ local function publish()
 			end
 		end
 	end
+
+	-- Publish a JSON dump for external use.
+	if minetest.settings:get_bool(modname .. "_publish_json") then
+		minetest.safe_file_write(
+			minetest.get_worldpath() .. "/lagometer.json",
+			minetest.write_json({
+					timestamp = os_time(),
+					interval = interval,
+					period_length = period_length,
+					period_count = period_count,
+					bucket_step = bucket_step,
+					bucket_max = bucket_max,
+					buckets = accum
+				}))
+	end
+
 end
 
 -- Run the publish method on a timer, so that player displays