From 6435c751b7d24d40376c5841fdb9cdc9d1883687 Mon Sep 17 00:00:00 2001
From: campbell-m <87438215+campbell-m@users.noreply.github.com>
Date: Fri, 1 Sep 2023 07:32:27 +0100
Subject: [PATCH 1/4] Fix problem with getting ISO Date strings in timezones
 other than UTC.

---
 web/js/datepicker.js.php | 31 ++++++++++++++++++++++++++-----
 1 file changed, 26 insertions(+), 5 deletions(-)

diff --git a/web/js/datepicker.js.php b/web/js/datepicker.js.php
index 6b118159b0..d96ffb42e8 100644
--- a/web/js/datepicker.js.php
+++ b/web/js/datepicker.js.php
@@ -42,6 +42,27 @@ function getISODate(year, month, day)
   return date.toISOString().split('T')[0];
 }
 
+
+function getLocalISODateString(date)
+{
+  var month = (date.getMonth() + 1).toString();
+  var day = date.getDate().toString();
+  var year = date.getFullYear().toString();
+
+  if (month.length < 2)
+  {
+    month = '0' + month;
+  }
+  if (day.length < 2)
+  {
+    day = '0' + day;
+  }
+
+  return [year, month, day].join('-');
+}
+
+
+
 <?php
 // Functions to find the start and end dates of a week and month given a
 // date in YYYY-MM-DD format.
@@ -58,26 +79,26 @@ function weekStart(date, weekStarts) {
     diff += 7;
   }
   d.setDate(d.getDate() - diff);
-  return d.toISOString().split('T')[0];
+  return getLocalISODateString(d);
 }
 
 function weekEnd(date, weekStarts) {
   var d = new Date(weekStart(date, weekStarts));
   d.setDate(d.getDate() + 6);
-  return d.toISOString().split('T')[0];
+  return getLocalISODateString(d);
 }
 
 function monthStart(date) {
   var d = new Date(date);
   d.setDate(1);
-  return d.toISOString().split('T')[0];
+  return getLocalISODateString(d);
 }
 
 function monthEnd(date) {
   var d = new Date(date);
   d.setMonth(d.getMonth() + 1);
   d.setDate(0);
-  return d.toISOString().split('T')[0];
+  return getLocalISODateString(d);
 }
 
 
@@ -95,7 +116,7 @@ function datesInRange(startDate, endDate, excludeHiddenDays) {
     {
       continue;
     }
-    result.push(d.toISOString().split('T')[0]);
+    result.push(getLocalISODateString(d));
   }
 
   return result;

From 2cf3eb7606e528a4c28102914b8bfa49683afe13 Mon Sep 17 00:00:00 2001
From: campbell-m <87438215+campbell-m@users.noreply.github.com>
Date: Fri, 1 Sep 2023 08:06:26 +0100
Subject: [PATCH 2/4] Add comments

---
 web/js/datepicker.js.php | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/web/js/datepicker.js.php b/web/js/datepicker.js.php
index 66c5edd2ef..d7adc2bffc 100644
--- a/web/js/datepicker.js.php
+++ b/web/js/datepicker.js.php
@@ -38,11 +38,14 @@ function iPadMobileFix() {
 ?>
 function getISODate(year, month, day)
 {
+  <?php // toISOString() converts to UTC, so make the date a UTC date ?>
   var date = new Date(Date.UTC(year, month, day));
   return date.toISOString().split('T')[0];
 }
 
 
+// Given a JavaScript Date object returns a date string in YYYY-MM-DD
+// format.  (Note that toISOString() returns a date in UTC time).
 function getLocalISODateString(date)
 {
   var month = (date.getMonth() + 1).toString();

From 7275c1b77f2938ef4168d42bdf9f59f56d98db18 Mon Sep 17 00:00:00 2001
From: campbell-m <87438215+campbell-m@users.noreply.github.com>
Date: Sat, 2 Sep 2023 06:23:24 +0100
Subject: [PATCH 3/4] Simplify code

---
 web/js/datepicker.js.php | 13 ++-----------
 1 file changed, 2 insertions(+), 11 deletions(-)

diff --git a/web/js/datepicker.js.php b/web/js/datepicker.js.php
index d7adc2bffc..b6b622fd77 100644
--- a/web/js/datepicker.js.php
+++ b/web/js/datepicker.js.php
@@ -48,19 +48,10 @@ function getISODate(year, month, day)
 // format.  (Note that toISOString() returns a date in UTC time).
 function getLocalISODateString(date)
 {
-  var month = (date.getMonth() + 1).toString();
-  var day = date.getDate().toString();
+  var month = (date.getMonth() + 1).toString().padStart(2, '0');
+  var day = date.getDate().toString().padStart(2, '0');
   var year = date.getFullYear().toString();
 
-  if (month.length < 2)
-  {
-    month = '0' + month;
-  }
-  if (day.length < 2)
-  {
-    day = '0' + day;
-  }
-
   return [year, month, day].join('-');
 }
 

From 349ee9c91e02711fcea5db293e8cd8564c407073 Mon Sep 17 00:00:00 2001
From: campbell-m <87438215+campbell-m@users.noreply.github.com>
Date: Mon, 11 Sep 2023 05:23:02 -1000
Subject: [PATCH 4/4] Fix properly.

---
 web/js/datepicker.js.php | 22 ++++++++++++++++------
 1 file changed, 16 insertions(+), 6 deletions(-)

diff --git a/web/js/datepicker.js.php b/web/js/datepicker.js.php
index b6b622fd77..5f6c272642 100644
--- a/web/js/datepicker.js.php
+++ b/web/js/datepicker.js.php
@@ -66,7 +66,13 @@ function getLocalISODateString(date)
 ?>
 
 function weekStart(date, weekStarts) {
-  var d = new Date(date);
+  <?php
+  // Need to add a time to make sure the date is interpreted as local rather than UTC.
+  // "When the time zone offset is absent, date-only forms are interpreted as a UTC time and
+  // date-time forms are interpreted as local time. This is due to a historical spec error
+  // that was not consistent with ISO 8601 but could not be changed due to web compatibility."
+  ?>
+  var d = new Date(date + "T00:00:00");
   var diff = d.getDay() - weekStarts;
   if (diff < 0)
   {
@@ -77,19 +83,22 @@ function weekStart(date, weekStarts) {
 }
 
 function weekEnd(date, weekStarts) {
-  var d = new Date(weekStart(date, weekStarts));
+  <?php // Need to add a time to make sure the date is interpreted as local rather than UTC. ?>
+  var d = new Date(weekStart(date, weekStarts) + "T00:00:00");
   d.setDate(d.getDate() + 6);
   return getLocalISODateString(d);
 }
 
 function monthStart(date) {
-  var d = new Date(date);
+  <?php // Need to add a time to make sure the date is interpreted as local rather than UTC. ?>
+  var d = new Date(date + "T00:00:00");
   d.setDate(1);
   return getLocalISODateString(d);
 }
 
 function monthEnd(date) {
-  var d = new Date(date);
+  <?php // Need to add a time to make sure the date is interpreted as local rather than UTC. ?>
+  var d = new Date(date + "T00:00:00");
   <?php
   // Set the date to the first of the month, because otherwise we will
   // advance by two months when incrementing the month below if we're at the
@@ -106,11 +115,12 @@ function monthEnd(date) {
 // excluding hidden days.
 function datesInRange(startDate, endDate, excludeHiddenDays) {
   var result=[];
-  var e=new Date(endDate);
+  <?php // Need to add a time to make sure the date is interpreted as local rather than UTC. ?>
+  var e=new Date(endDate + "T00:00:00");
   var hiddenDays = [<?php echo implode(',', $hidden_days)?>];
 
   <?php // dates can be compared using > and < but not == or === ?>
-  for (var d=new Date(startDate); !(d>e); d.setDate(d.getDate()+1))
+  for (var d=new Date(startDate + "T00:00:00"); !(d>e); d.setDate(d.getDate()+1))
   {
     if (excludeHiddenDays && (hiddenDays.indexOf(d.getDay()) >= 0))
     {