Allow lookup for a recent match of an alarm

ChangeLog

@@ -1,3 +1,10 @@
+2021-12-19 Richard Frith-Macdonald <rfm@gnu.org>
+
+	* EcAlarmDestination.h:
+	* EcAlarmDestination.m:
+	Add (-latest:) method to find the most recent match for an alarm
+	in the queue/active/cleared data structures.
+
 2021-12-16 Richard Frith-Macdonald <rfm@gnu.org>
 
 	* EcCommand.m:

EcAlarmDestination.h

@@ -184,6 +184,14 @@
  */
 - (BOOL) isRunning;
 
+/** Finds and returns the most recent alarm in the system which matches
+ * (is equal to) toFind.  This searches the queue of alarms to be processed,
+ * the set of active alarms, and the set of cleared alarms (in that order)
+ * returning the first match found.  If no match is found the method
+ * returns nil.
+ */
+- (EcAlarm*) latest: (EcAlarm*)toFind;
+
 /** Returns an array containing the known managed objects.
  */
 - (NSArray*) managed;

EcAlarmDestination.m

@@ -374,6 +374,39 @@
   return result;
 }
 
+- (EcAlarm*) latest: (EcAlarm*)toFind
+{
+  EcAlarm	*found = nil;
+  NSUInteger	index;
+
+  [_alarmLock lock];
+  /* First try to find the most recent match in the queue
+   */
+  index = [_alarmQueue count];
+  while (index-- > 0)
+    {
+      EcAlarm	*a = [_alarmQueue objectAtIndex: index];
+
+      if ([a isEqual: toFind])
+	{
+	  found = RETAIN(a);
+	  break;
+	}
+    }
+  if (nil == found)
+    {
+      /* Not in queue ... try active alarms or clears
+       */
+      found = RETAIN([_alarmsActive member: toFind]);
+      if (nil == found)
+	{
+	  found = RETAIN([_alarmsCleared member: toFind]);
+	}
+    }
+  [_alarmLock unlock];
+  return AUTORELEASE(found);  
+}
+
 - (NSArray*) managed
 {
   NSArray	*a;