From cc44f3e0c6dc2e20abb06084aac1d37ce1fdc3b7 Mon Sep 17 00:00:00 2001
From: Alex Tselegidis <alextselegidis@gmail.com>
Date: Wed, 9 Dec 2020 14:07:14 +0200
Subject: [PATCH] Corrected timezone support when syncing events with Google
 Calendar

---
 application/libraries/Google_sync.php | 34 ++++++++++++++++-----------
 application/libraries/Timezones.php   |  2 +-
 2 files changed, 21 insertions(+), 15 deletions(-)

diff --git a/application/libraries/Google_sync.php b/application/libraries/Google_sync.php
index f6319247..a648d704 100644
--- a/application/libraries/Google_sync.php
+++ b/application/libraries/Google_sync.php
@@ -151,12 +151,14 @@ class Google_Sync {
         $event->setDescription($appointment['notes']);
         $event->setLocation(isset($appointment['location']) ? $appointment['location'] : $settings['company_name']);
 
+        $timezone = new DateTimeZone($provider['timezone']);
+
         $start = new Google_Service_Calendar_EventDateTime();
-        $start->setDateTime(date3339(strtotime($appointment['start_datetime'])));
+        $start->setDateTime((new DateTime($appointment['start_datetime'], $timezone))->format(DateTime::RFC3339));
         $event->setStart($start);
 
         $end = new Google_Service_Calendar_EventDateTime();
-        $end->setDateTime(date3339(strtotime($appointment['end_datetime'])));
+        $end->setDateTime((new DateTime($appointment['end_datetime'], $timezone))->format(DateTime::RFC3339));
         $event->setEnd($end);
 
         $event->attendees = [];
@@ -170,8 +172,7 @@ class Google_Sync {
         if ($customer != NULL)
         {
             $event_customer = new Google_Service_Calendar_EventAttendee();
-            $event_customer->setDisplayName($customer['first_name'] . ' '
-                . $customer['last_name']);
+            $event_customer->setDisplayName($customer['first_name'] . ' ' . $customer['last_name']);
             $event_customer->setEmail($customer['email']);
             $event->attendees[] = $event_customer;
         }
@@ -207,19 +208,20 @@ class Google_Sync {
         $event->setDescription($appointment['notes']);
         $event->setLocation(isset($appointment['location']) ? $appointment['location'] : $settings['company_name']);
 
+        $timezone = new DateTimeZone($provider['timezone']);
+
         $start = new Google_Service_Calendar_EventDateTime();
-        $start->setDateTime(date3339(strtotime($appointment['start_datetime'])));
+        $start->setDateTime((new DateTime($appointment['start_datetime'], $timezone))->format(DateTime::RFC3339));
         $event->setStart($start);
 
         $end = new Google_Service_Calendar_EventDateTime();
-        $end->setDateTime(date3339(strtotime($appointment['end_datetime'])));
+        $end->setDateTime((new DateTime($appointment['end_datetime'], $timezone))->format(DateTime::RFC3339));
         $event->setEnd($end);
 
         $event->attendees = [];
 
         $event_provider = new Google_Service_Calendar_EventAttendee();
-        $event_provider->setDisplayName($provider['first_name'] . ' '
-            . $provider['last_name']);
+        $event_provider->setDisplayName($provider['first_name'] . ' ' . $provider['last_name']);
         $event_provider->setEmail($provider['email']);
         $event->attendees[] = $event_provider;
 
@@ -273,12 +275,14 @@ class Google_Sync {
         $event->setSummary('Unavailable');
         $event->setDescription($unavailable['notes']);
 
+        $timezone = new DateTimeZone($provider['timezone']);
+
         $start = new Google_Service_Calendar_EventDateTime();
-        $start->setDateTime(date3339(strtotime($unavailable['start_datetime'])));
+        $start->setDateTime((new DateTime($unavailable['start_datetime'], $timezone))->format(DateTime::RFC3339));
         $event->setStart($start);
 
         $end = new Google_Service_Calendar_EventDateTime();
-        $end->setDateTime(date3339(strtotime($unavailable['end_datetime'])));
+        $end->setDateTime((new DateTime($unavailable['end_datetime'], $timezone))->format(DateTime::RFC3339));
         $event->setEnd($end);
 
         // Add the new event to the google calendar.
@@ -304,12 +308,14 @@ class Google_Sync {
             $unavailable['id_google_calendar']);
         $event->setDescription($unavailable['notes']);
 
+        $timezone = new DateTimeZone($provider['timezone']);
+
         $start = new Google_Service_Calendar_EventDateTime();
-        $start->setDateTime(date3339(strtotime($unavailable['start_datetime'])));
+        $start->setDateTime((new DateTime($unavailable['start_datetime'], $timezone))->format(DateTime::RFC3339));
         $event->setStart($start);
 
         $end = new Google_Service_Calendar_EventDateTime();
-        $end->setDateTime(date3339(strtotime($unavailable['end_datetime'])));
+        $end->setDateTime((new DateTime($unavailable['end_datetime'], $timezone))->format(DateTime::RFC3339));
         $event->setEnd($end);
 
         $updated_event = $this->service->events->update($provider['settings']['google_calendar'],
@@ -364,8 +370,8 @@ class Google_Sync {
         $this->CI->load->helper('general');
 
         $params = [
-            'timeMin' => date3339($start),
-            'timeMax' => date3339($end),
+            'timeMin' => date(DateTime::RFC3339, $start),
+            'timeMax' => date(DateTime::RFC3339, $end),
             'singleEvents' => TRUE,
         ];
 
diff --git a/application/libraries/Timezones.php b/application/libraries/Timezones.php
index f8e55ba0..1c2af09c 100644
--- a/application/libraries/Timezones.php
+++ b/application/libraries/Timezones.php
@@ -551,7 +551,7 @@ class Timezones {
      */
     public function convert($value, $from_timezone, $to_timezone)
     {
-        if ( ! $to_timezone)
+        if ( ! $to_timezone || $from_timezone === $to_timezone)
         {
             return $value;
         }