MAGETWO-51629: Incorrect current time in date pickers

Author: iivashchenko

app/code/Magento/Backend/view/adminhtml/templates/page/js/calendar.phtml

@@ -50,6 +50,7 @@ require([
             showTime: false,
             showHour: false,
             showMinute: false,
+            serverTimezoneOffset: <?php echo (int) $block->getTimezoneOffsetSeconds(); ?>,
             yearRange: '<?php /* @escapeNotVerified */ echo $block->getYearRange() ?>'
         }
     });

lib/web/mage/calendar.js

@@ -73,12 +73,15 @@
             var self = this;
 
             /**
-             * overwrite jQuery UI datepicker function.
+             * Overwrite jQuery UI datepicker function.
+             * Reason: magento date could be set before calendar show
+             * but local date will be styled as current in original _generateHTML
+             *
              * @param {Object} inst - instance datepicker.
              * @return {String} html template
              */
             $.datepicker.constructor.prototype._generateHTML = function (inst) {
-                var today = this._daylightSavingAdjust(self.getTimezoneDate()),
+                var today = self.getTimezoneDate(),
                     isRTL = this._get(inst, 'isRTL'),
                     showButtonPanel = this._get(inst, 'showButtonPanel'),
                     hideIfNoPrevNext = this._get(inst, 'hideIfNoPrevNext'),
@@ -313,17 +316,21 @@
 
         /**
          * If server timezone is defined then take to account server timezone shift
-         * @param {Object} date
          * @return {Object} date
          */
-        getTimezoneDate: function (date) {
-            date = date || new Date();
+        getTimezoneDate: function () {
 
-            if (this.options.serverTimezoneSeconds) {
-                date.setTime((this.options.serverTimezoneSeconds + date.getTimezoneOffset() * 60) * 1000);
+            // Get local time in ms
+            var ms = Date.now();
+
+            // Adjust milliseconds according to store timezone offset
+            // Mind the GMT zero offset
+            if (typeof this.options.serverTimezoneOffset !== 'undefined') {                
+                // Make UTC time and add store timezone offset in seconds
+                ms += (new Date().getTimezoneOffset() * 60 * 1000) + this.options.serverTimezoneOffset * 1000;
             }
 
-            return date;
+            return new Date(ms);
         },
 
         /**
@@ -515,9 +522,12 @@
      * @param {Object} el
      */
     $.datepicker._gotoToday = function (el) {
-        $.datepicker._gotoTodayOriginal.call(this, el);
-        $.datepicker._selectDate.call(this, el);
-        $(el).blur();   // To ensure that user can re-select date field without clicking outside it first.
+        var pickerObject = $(el);
+
+        // Set date/time according to timezone offset        
+        pickerObject.datepicker( "setDate", pickerObject.calendar("getTimezoneDate") )
+            // To ensure that user can re-select date field without clicking outside it first.
+            .blur();
     };
 
     return {