Fix rules stay uninitialized when using Java 17

On Java 17 there is no Nashorn scripting engine so it takes a bit longer before ScriptEngines are available.
Rules would stay uninitialized forever because the ScriptModuleTypeProvider did not notify its listeners whenever script.ScriptAction, script.ScriptCondition became available.

Signed-off-by: Wouter Born <github@maindrain.net>

Author: wborn

bundles/org.openhab.core.automation.module.script/src/main/java/org/openhab/core/automation/module/script/internal/provider/ScriptModuleTypeProvider.java

@@ -14,13 +14,11 @@
 
 import java.util.ArrayList;
 import java.util.Collection;
+import java.util.LinkedList;
 import java.util.List;
 import java.util.Locale;
 import java.util.Map;
-import java.util.Optional;
 import java.util.TreeMap;
-import java.util.stream.Collectors;
-import java.util.stream.Stream;
 
 import javax.script.ScriptEngine;
 
@@ -42,6 +40,7 @@
 import org.openhab.core.config.core.ConfigDescriptionParameterBuilder;
 import org.openhab.core.config.core.ParameterOption;
 import org.osgi.service.component.annotations.Component;
+import org.osgi.service.component.annotations.Deactivate;
 import org.osgi.service.component.annotations.Reference;
 import org.osgi.service.component.annotations.ReferenceCardinality;
 import org.osgi.service.component.annotations.ReferencePolicy;
@@ -59,12 +58,20 @@
 public class ScriptModuleTypeProvider implements ModuleTypeProvider {
 
     private final Logger logger = LoggerFactory.getLogger(ScriptModuleTypeProvider.class);
+    private final List<ProviderChangeListener<ModuleType>> listeners = new LinkedList<>();
     private final Map<String, String> parameterOptions = new TreeMap<>();
 
+    @Deactivate
+    public void deactivate() {
+        listeners.clear();
+    }
+
     @SuppressWarnings("unchecked")
     @Override
     public @Nullable ModuleType getModuleType(String UID, @Nullable Locale locale) {
-        if (ScriptActionHandler.TYPE_ID.equals(UID)) {
+        if (parameterOptions.isEmpty()) {
+            return null;
+        } else if (ScriptActionHandler.TYPE_ID.equals(UID)) {
             return getScriptActionType(locale);
         } else if (ScriptConditionHandler.TYPE_ID.equals(UID)) {
             return getScriptConditionType(locale);
@@ -73,26 +80,22 @@ public class ScriptModuleTypeProvider implements ModuleTypeProvider {
         }
     }
 
-    private @Nullable ModuleType getScriptActionType(@Nullable Locale locale) {
-        if (parameterOptions.isEmpty()) {
-            return null;
-        } else {
-            List<Output> outputs = new ArrayList<>();
-            Output result = new Output("result", "java.lang.Object", "result", "the script result", null, null, null);
-            outputs.add(result);
-            return new ActionType(ScriptActionHandler.TYPE_ID, getConfigDescriptions(locale), "execute a given script",
-                    "Allows the execution of a user-defined script.", null, Visibility.VISIBLE, null, outputs);
-        }
+    private ModuleType getScriptActionType(@Nullable Locale locale) {
+        List<Output> outputs = new ArrayList<>();
+        Output result = new Output("result", "java.lang.Object", "result", "the script result", null, null, null);
+        outputs.add(result);
+        return new ActionType(ScriptActionHandler.TYPE_ID, getConfigDescriptions(locale), "execute a given script",
+                "Allows the execution of a user-defined script.", null, Visibility.VISIBLE, null, outputs);
     }
 
-    private @Nullable ModuleType getScriptConditionType(@Nullable Locale locale) {
-        if (parameterOptions.isEmpty()) {
-            return null;
-        } else {
-            return new ConditionType(ScriptConditionHandler.TYPE_ID, getConfigDescriptions(locale),
-                    "a given script evaluates to true", "Allows the definition of a condition through a script.", null,
-                    Visibility.VISIBLE, null);
-        }
+    private ModuleType getScriptConditionType(@Nullable Locale locale) {
+        return new ConditionType(ScriptConditionHandler.TYPE_ID, getConfigDescriptions(locale),
+                "a given script evaluates to true", "Allows the definition of a condition through a script.", null,
+                Visibility.VISIBLE, null);
+    }
+
+    private List<ModuleType> getModuleTypesUnconditionally(@Nullable Locale locale) {
+        return List.of(getScriptActionType(locale), getScriptConditionType(locale));
     }
 
     /**
@@ -118,10 +121,7 @@ private List<ConfigDescriptionParameter> getConfigDescriptions(@Nullable Locale
 
     @Override
     public Collection<ModuleType> getModuleTypes(@Nullable Locale locale) {
-        return Stream
-                .of(Optional.ofNullable(getScriptActionType(locale)),
-                        Optional.ofNullable(getScriptConditionType(locale)))
-                .filter(Optional::isPresent).map(Optional::get).collect(Collectors.toUnmodifiableList());
+        return parameterOptions.isEmpty() ? List.of() : getModuleTypesUnconditionally(locale);
     }
 
     @Override
@@ -131,12 +131,40 @@ public Collection<ModuleType> getAll() {
 
     @Override
     public void addProviderChangeListener(ProviderChangeListener<ModuleType> listener) {
-        // does nothing because this provider does not change
+        synchronized (listeners) {
+            listeners.add(listener);
+        }
     }
 
     @Override
     public void removeProviderChangeListener(ProviderChangeListener<ModuleType> listener) {
-        // does nothing because this provider does not change
+        synchronized (listeners) {
+            listeners.remove(listener);
+        }
+    }
+
+    private void notifyModuleTypesAdded() {
+        List<ProviderChangeListener<ModuleType>> snapshot = null;
+        synchronized (listeners) {
+            snapshot = new LinkedList<>(listeners);
+        }
+        for (ModuleType moduleType : getModuleTypesUnconditionally(null)) {
+            for (ProviderChangeListener<ModuleType> listener : snapshot) {
+                listener.added(this, moduleType);
+            }
+        }
+    }
+
+    private void notifyModuleTypesRemoved() {
+        List<ProviderChangeListener<ModuleType>> snapshot = null;
+        synchronized (listeners) {
+            snapshot = new LinkedList<>(listeners);
+        }
+        for (ModuleType moduleType : getModuleTypesUnconditionally(null)) {
+            for (ProviderChangeListener<ModuleType> listener : snapshot) {
+                listener.removed(this, moduleType);
+            }
+        }
     }
 
     /**
@@ -149,8 +177,12 @@ public void setScriptEngineFactory(ScriptEngineFactory engineFactory) {
         if (!scriptTypes.isEmpty()) {
             ScriptEngine scriptEngine = engineFactory.createScriptEngine(scriptTypes.get(0));
             if (scriptEngine != null) {
+                boolean notifyListeners = parameterOptions.isEmpty();
                 parameterOptions.put(getPreferredMimeType(engineFactory), getLanguageName(scriptEngine.getFactory()));
                 logger.trace("ParameterOptions: {}", parameterOptions);
+                if (notifyListeners) {
+                    notifyModuleTypesAdded();
+                }
             } else {
                 logger.trace("setScriptEngineFactory: engine was null");
             }
@@ -166,6 +198,9 @@ public void unsetScriptEngineFactory(ScriptEngineFactory engineFactory) {
             if (scriptEngine != null) {
                 parameterOptions.remove(getPreferredMimeType(engineFactory));
                 logger.trace("ParameterOptions: {}", parameterOptions);
+                if (parameterOptions.isEmpty()) {
+                    notifyModuleTypesRemoved();
+                }
             } else {
                 logger.trace("unsetScriptEngineFactory: engine was null");
             }