From e0136a01cde7e2bd0f9efff8ffddd4786c871119 Mon Sep 17 00:00:00 2001
From: Parnic <github@parnic.com>
Date: Fri, 15 Apr 2022 16:17:18 -0500
Subject: [PATCH] Fix SLDateTime day-of-week calculation

Turns out we were offsetting the wrong direction. This offsets the correct way (verified against a Wireshark capture of the official app).
---
 README.md              | 2 +-
 messages/SLMessage.js  | 6 +++---
 test/slmessage.spec.js | 4 ++--
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/README.md b/README.md
index 2c8831d..10be86c 100755
--- a/README.md
+++ b/README.md
@@ -581,7 +581,7 @@ Contains information about the system's current time and date. Passed as an argu
 * `year` - short representing current system year
 * `month` - short representing current system month (where 1 is January, 2 is February, etc.)
 * `day` - short representing current system day of the month
-* `dayOfWeek` - short representing current system day of the week (where 0 is Sunday and 6 is Sunday)
+* `dayOfWeek` - short representing current system day of the week (where 1 is Sunday and 7 is Saturday)
 * `hour` - short representing current system hour (24-hour time where 0 is midnight, 13 is 1PM, etc.)
 * `minute` - short representing current system minute
 * `second` - short representing current system second
diff --git a/messages/SLMessage.js b/messages/SLMessage.js
index 89dab34..5b23a0b 100644
--- a/messages/SLMessage.js
+++ b/messages/SLMessage.js
@@ -153,9 +153,9 @@ exports.SLMessage = class SLMessage extends SmartBuffer {
   writeSLDateTime(date) {
     this.writeInt16LE(date.getFullYear());
     this.writeInt16LE(date.getMonth() + 1);
-    var dayOfWeek = date.getDay() - 1;
-    if (dayOfWeek < 0) {
-      dayOfWeek = 6;
+    var dayOfWeek = date.getDay() + 1;
+    if (dayOfWeek == 7) {
+      dayOfWeek = 0;
     }
     this.writeInt16LE(dayOfWeek);
     this.writeInt16LE(date.getDate());
diff --git a/test/slmessage.spec.js b/test/slmessage.spec.js
index ee67215..981fdb9 100644
--- a/test/slmessage.spec.js
+++ b/test/slmessage.spec.js
@@ -181,8 +181,8 @@ describe('SLMessage utilities', function() {
     assert.equal(decodedMsg.readUInt16LE(), 2021);
     // javascript Date() month is 0-based, ScreenLogic month matches the calendar
     assert.equal(decodedMsg.readUInt16LE(), 9);
-    // ScreenLogic day-of-week starts with Monday as 0
-    assert.equal(decodedMsg.readUInt16LE(), 0);
+    // ScreenLogic day-of-week starts with Sunday as 1
+    assert.equal(decodedMsg.readUInt16LE(), 2);
     assert.equal(decodedMsg.readUInt16LE(), 6);
     assert.equal(decodedMsg.readUInt16LE(), 22);
     assert.equal(decodedMsg.readUInt16LE(), 8);