Fix instance of Item checks don't work (#290)

Fixes an issue, where the webpacked, globals injected
`time.toZDT(items.Item)` did not work,
because #283 did revert
#273 and therefore constructor
names are not kept.

This introduces a `_isItem` helper method, which checks both constructor
name or unique properties (`rawItem`).

Signed-off-by: Florian Hotze <florianh_dev@icloud.com>

helpers.js

@@ -6,6 +6,21 @@ function _getItemName (itemOrName) {
   return itemOrName;
 }
 
+/**
+ * Checks whether the given object is an instance of {@link items.Item}.
+ *
+ * To be used when instanceof checks don't work because of circular dependencies.
+ * Checks constructor name or unique properties, because constructor name does not work for the webpacked globals injection.
+ *
+ * @param o {*}
+ * @returns {boolean}
+ * @private
+ */
+function _isItem (o) {
+  return ((o.constructor && o.constructor.name === 'Item') || typeof o.rawItem === 'object');
+}
+
 module.exports = {
-  _getItemName
+  _getItemName,
+  _isItem
 };

quantity.js

@@ -1,3 +1,4 @@
+const { _isItem } = require('./helpers');
 const QuantityType = Java.type('org.openhab.core.library.types.QuantityType');
 /**
  * @type {JavaBigDecimal}
@@ -20,7 +21,7 @@ const BigDecimal = Java.type('java.math.BigDecimal');
  * @private
  */
 function _toBigDecimalOrQtyType (value) {
-  if (value.constructor && value.constructor.name === 'Item' && value.rawState.getClass().getSimpleName() === 'DecimalType') {
+  if (_isItem(value) && value.rawState.getClass().getSimpleName() === 'DecimalType') {
     try {
       value = value.rawState.toBigDecimal();
     } catch (e) {
@@ -48,7 +49,7 @@ function _toBigDecimalOrQtyType (value) {
  * @private
  */
 function _toQtyType (value, errorMsg = 'Argument of wrong type provided, required Item, string or Quantity.') {
-  if (value.constructor && value.constructor.name === 'Item') {
+  if (_isItem(value)) {
     if (value.rawState.getClass().getSimpleName() === 'QuantityType') {
       value = value.rawState;
     } else {

time.js

@@ -9,6 +9,7 @@ require('@js-joda/timezone');
 const time = require('@js-joda/core');
 const items = require('./items');
 const utils = require('./utils');
+const { _isItem } = require('./helpers');
 
 const javaZDT = Java.type('java.time.ZonedDateTime');
 const javaDuration = Java.type('java.time.Duration');
@@ -254,11 +255,11 @@ function toZDT (when) {
 
   // GenericItem
   if (when instanceof ohItem) {
-    return _convertItem(items.getItem(when.name));
+    return _convertItem(items.getItem(when.getName()));
   }
 
   // items.Item
-  if (when.constructor.name === 'Item') {
+  if (_isItem(when)) {
     return _convertItem(when);
   }