From d208437c055d47a64306436a74097d168ec6ae29 Mon Sep 17 00:00:00 2001
From: buxxi <buxxi@omfilm.net>
Date: Sun, 22 Sep 2019 17:33:01 +0200
Subject: [PATCH] Changes to the clock module regarding the notifications sent.
 Disable sending of CLOCK_SECOND when displaySeconds not set. Avoid drifting
 by calculating the interval each time and use setTimeout instead of
 setInterval. Make sure the values sent with CLOCK_SECOND and CLOCK_MINUTE has
 the correct values instead of starting at 00:00 on startup

---
 CHANGELOG.md                   |  2 ++
 modules/default/clock/clock.js | 50 ++++++++++++++++++++++------------
 2 files changed, 34 insertions(+), 18 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index faba8887..79d1ebcc 100755
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -24,12 +24,14 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 ### Updated
 - Updatenotification module: Display update notification for a limited (configurable) time.
 - The css/custom.css will be rename after the next release. We've add into `run-start.sh` a instruction by GIT to ignore with `--skip-worktree` and `rm --cached`. The history about this change [#1540].
+- Disable sending of notification CLOCK_SECOND when displaySeconds is false
 
 ### Fixed
 - Updatenotification module: Properly handle race conditions, prevent crash.
 - Send `NEWS_FEED` notification also for the first news messages which are shown
 - Fixed issue where weather module would not refresh data after a network or API outage [#1722](https://github.com/MichMich/MagicMirror/issues/1722)
 - Fixed weatherforecast module not displaying rain amount on fallback endpoint
+- Notifications CLOCK_SECOND & CLOCK_MINUTE being from startup instead of matched against the clock and avoid drifting
 
 ## [2.8.0] - 2019-07-01
 
diff --git a/modules/default/clock/clock.js b/modules/default/clock/clock.js
index 00a71eaa..d566c52f 100644
--- a/modules/default/clock/clock.js
+++ b/modules/default/clock/clock.js
@@ -41,26 +41,40 @@ Module.register("clock",{
 
 		// Schedule update interval.
 		var self = this;
-		self.second = 0;
-		self.minute = 0;
-		self.lastDisplayedMinute = null;
-		setInterval(function() {
-			if (self.config.displaySeconds || self.lastDisplayedMinute !== moment().minute()) {
-				self.updateDom();
-			}
-			if (self.second === 59) {
-				self.second = 0;
-				if (self.minute === 59){
-					self.minute = 0;
-				} else {
-					self.minute++;
-				}
-				self.sendNotification("CLOCK_MINUTE", self.minute);
+		self.second = moment().second();
+		self.minute = moment().minute();
+
+		//Calculate how many ms should pass until next update depending on if seconds is displayed or not
+		var delayCalculator = function(reducedSeconds) {
+			if (self.config.displaySeconds) {
+				return 1000 - moment().milliseconds();
 			} else {
-				self.second++;
-				self.sendNotification("CLOCK_SECOND", self.second);
+				return ((60 - reducedSeconds) * 1000) - moment().milliseconds();
 			}
-		}, 1000);
+		};
+
+		//A recursive timeout function instead of interval to avoid drifting
+		var notificationTimer = function() {
+			self.updateDom();
+
+			//If seconds is displayed CLOCK_SECOND-notification should be sent (but not when CLOCK_MINUTE-notification is sent)
+			if (self.config.displaySeconds) {
+				self.second = (self.second + 1) % 60;
+				if (self.second !== 0) {
+					self.sendNotification("CLOCK_SECOND", self.second);
+					setTimeout(notificationTimer, delayCalculator(0));
+					return;
+				}
+			}
+
+			//If minute changed or seconds isn't displayed send CLOCK_MINUTE-notification
+			self.minute = (self.minute + 1) % 60;
+			self.sendNotification("CLOCK_MINUTE", self.minute);
+			setTimeout(notificationTimer, delayCalculator(0));
+		};
+
+		//Set the initial timeout with the amount of seconds elapsed as reducedSeconds so it will trigger when the minute changes
+		setTimeout(notificationTimer, delayCalculator(self.second));
 
 		// Set locale.
 		moment.locale(config.language);