[mqtt] Interpet incoming NaN as UNDEF for NumberValues

Since DecimalType and QuantityType don't support NaN, but
when you're linking to a topic that the device is using
floating point, NaN might happen.

Signed-off-by: Cody Cutrer <cody@cutrer.us>

bundles/org.openhab.binding.mqtt.generic/src/main/java/org/openhab/binding/mqtt/generic/ChannelState.java

@@ -32,6 +32,7 @@
 import org.openhab.core.thing.ChannelUID;
 import org.openhab.core.types.Command;
 import org.openhab.core.types.State;
+import org.openhab.core.types.Type;
 import org.openhab.core.types.TypeParser;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -198,29 +199,31 @@ public void processMessage(String topic, byte[] payload) {
             return;
         }
 
-        Command parsedCommand;
+        Type parsedType;
         // Map the string to a command, update the cached value and post the command to the framework
         try {
-            parsedCommand = cachedValue.parseMessage(command);
+            parsedType = cachedValue.parseMessage(command);
         } catch (IllegalArgumentException | IllegalStateException e) {
             logger.warn("Command '{}' from channel '{}' not supported by type '{}': {}", strValue, channelUID,
                     cachedValue.getClass().getSimpleName(), e.getMessage());
             receivedOrTimeout();
             return;
         }
 
-        // things that are only Commands _must_ be posted as a command (like STOP)
-        if (!(parsedCommand instanceof State)) {
-            channelStateUpdateListener.postChannelCommand(channelUID, parsedCommand);
+        if (parsedType instanceof State parsedState) {
+            cachedValue.update(parsedState);
+        } else {
+            // things that are only Commands _must_ be posted as a command (like STOP)
+            channelStateUpdateListener.postChannelCommand(channelUID, (Command) parsedType);
             receivedOrTimeout();
             return;
         }
-        cachedValue.update((State) parsedCommand);
 
-        if (config.postCommand) {
-            channelStateUpdateListener.postChannelCommand(channelUID, (Command) cachedValue.getChannelState());
+        State newState = cachedValue.getChannelState();
+        if (config.postCommand && newState instanceof Command newCommand) {
+            channelStateUpdateListener.postChannelCommand(channelUID, newCommand);
         } else {
-            channelStateUpdateListener.updateChannelState(channelUID, cachedValue.getChannelState());
+            channelStateUpdateListener.updateChannelState(channelUID, newState);
         }
         receivedOrTimeout();
     }

bundles/org.openhab.binding.mqtt.generic/src/main/java/org/openhab/binding/mqtt/generic/values/NumberValue.java

@@ -23,10 +23,13 @@
 import org.openhab.core.library.types.DecimalType;
 import org.openhab.core.library.types.IncreaseDecreaseType;
 import org.openhab.core.library.types.QuantityType;
+import org.openhab.core.library.types.StringType;
 import org.openhab.core.library.types.UpDownType;
 import org.openhab.core.library.unit.Units;
 import org.openhab.core.types.Command;
 import org.openhab.core.types.StateDescriptionFragmentBuilder;
+import org.openhab.core.types.Type;
+import org.openhab.core.types.UnDefType;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -43,6 +46,8 @@
  */
 @NonNullByDefault
 public class NumberValue extends Value {
+    private static final String NAN = "NaN";
+
     private final Logger logger = LoggerFactory.getLogger(NumberValue.class);
     private final @Nullable BigDecimal min;
     private final @Nullable BigDecimal max;
@@ -112,6 +117,14 @@ public Command parseCommand(Command command) throws IllegalArgumentException {
         }
     }
 
+    @Override
+    public Type parseMessage(Command command) throws IllegalArgumentException {
+        if (command instanceof StringType && command.toString().equalsIgnoreCase(NAN)) {
+            return UnDefType.UNDEF;
+        }
+        return parseCommand(command);
+    }
+
     private BigDecimal getOldValue() {
         BigDecimal val = BigDecimal.ZERO;
         if (state instanceof DecimalType decimalCommand) {

bundles/org.openhab.binding.mqtt.generic/src/main/java/org/openhab/binding/mqtt/generic/values/Value.java

@@ -27,6 +27,7 @@
 import org.openhab.core.types.CommandDescriptionBuilder;
 import org.openhab.core.types.State;
 import org.openhab.core.types.StateDescriptionFragmentBuilder;
+import org.openhab.core.types.Type;
 import org.openhab.core.types.UnDefType;
 
 /**
@@ -145,7 +146,7 @@ public void update(State newState) throws IllegalArgumentException {
      * @param command The command to parse.
      * @exception IllegalArgumentException Thrown if for example a text is assigned to a number type.
      */
-    public Command parseMessage(Command command) throws IllegalArgumentException {
+    public Type parseMessage(Command command) throws IllegalArgumentException {
         return parseCommand(command);
     }
 

bundles/org.openhab.binding.mqtt.generic/src/test/java/org/openhab/binding/mqtt/generic/values/ValueTests.java

@@ -37,6 +37,7 @@
 import org.openhab.core.types.Command;
 import org.openhab.core.types.State;
 import org.openhab.core.types.TypeParser;
+import org.openhab.core.types.UnDefType;
 
 /**
  * Test cases for the value classes. They should throw exceptions if the wrong command type is used
@@ -175,6 +176,9 @@ public void numberUpdate() {
         command = v.parseCommand(new QuantityType<>("20"));
         assertThat(command, is(new QuantityType<>(20, Units.WATT)));
         assertThat(v.getMQTTpublishValue(command, null), is("20"));
+
+        assertThat(v.parseMessage(new StringType("NaN")), is(UnDefType.UNDEF));
+        assertThat(v.parseMessage(new StringType("nan")), is(UnDefType.UNDEF));
     }
 
     @Test