refactor: optimize the usage of comment widget extension point (#4249)

#### What type of PR is this?
/kind improvement
/area core
/milestone 2.8.x

#### What this PR does / why we need it:
优化评论扩展点的使用方式

how to test it?
测试评论插件是否正常可用

#### Does this PR introduce a user-facing change?
```release-note
优化评论扩展点的使用方式
```

application/src/main/java/run/halo/app/plugin/extensionpoint/DefaultExtensionGetter.java

@@ -1,11 +1,14 @@
 package run.halo.app.plugin.extensionpoint;
 
 import java.util.Comparator;
+import java.util.List;
 import java.util.Set;
 import java.util.stream.Stream;
 import lombok.RequiredArgsConstructor;
 import org.pf4j.ExtensionPoint;
 import org.springframework.context.ApplicationContext;
+import org.springframework.core.annotation.AnnotationAwareOrderComparator;
+import org.springframework.lang.NonNull;
 import org.springframework.stereotype.Component;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
@@ -32,14 +35,17 @@ public class DefaultExtensionGetter implements ExtensionGetter {
             .switchIfEmpty(Mono.just(ExtensionPointEnabled.EMPTY))
             .mapNotNull(enabled -> {
                 var implClassNames = enabled.getOrDefault(extensionPoint.getName(), Set.of());
-                return pluginManager.getExtensions(extensionPoint)
+                List<T> allExtensions = getAllExtensions(extensionPoint);
+                if (allExtensions.isEmpty()) {
+                    return null;
+                }
+                return allExtensions
                     .stream()
                     .filter(impl -> implClassNames.contains(impl.getClass().getName()))
                     .findFirst()
                     // Fallback to local implementation of the extension point.
                     // This will happen when no proper configuration is found.
-                    .orElseGet(() ->
+                    .orElseGet(() -> allExtensions.get(0));
-                        applicationContext.getBeanProvider(extensionPoint).getIfAvailable());
             });
     }
 
@@ -74,14 +80,21 @@ public class DefaultExtensionGetter implements ExtensionGetter {
                 if (type == ExtensionPointDefinition.ExtensionPointType.SINGLETON) {
                     return getEnabledExtension(extensionPoint).flux();
                 }
+
+                // TODO If the type is sortable, may need to process the returned order.
+                return Flux.fromIterable(getAllExtensions(extensionPoint));
+            });
+    }
+
+    @NonNull
+    <T extends ExtensionPoint> List<T> getAllExtensions(Class<T> extensionPoint) {
         Stream<T> pluginExtsStream = pluginManager.getExtensions(extensionPoint)
             .stream();
         Stream<T> systemExtsStream = applicationContext.getBeanProvider(extensionPoint)
             .orderedStream();
-                // TODO If the type is sortable, may need to process the returned order.
+        return Stream.concat(systemExtsStream, pluginExtsStream)
-                return Flux.just(pluginExtsStream, systemExtsStream)
+            .sorted(new AnnotationAwareOrderComparator())
-                    .flatMap(Flux::fromStream);
+            .toList();
-            });
     }
 
     Mono<ExtensionPointDefinition> fetchExtensionPointDefinition(

application/src/main/java/run/halo/app/theme/dialect/CommentElementTagProcessor.java

@@ -1,6 +1,5 @@
 package run.halo.app.theme.dialect;
 
-import java.util.List;
 import org.springframework.context.ApplicationContext;
 import org.thymeleaf.context.ITemplateContext;
 import org.thymeleaf.model.IProcessableElementTag;
@@ -8,7 +7,7 @@ import org.thymeleaf.processor.element.AbstractElementTagProcessor;
 import org.thymeleaf.processor.element.IElementTagStructureHandler;
 import org.thymeleaf.spring6.context.SpringContextUtils;
 import org.thymeleaf.templatemode.TemplateMode;
-import run.halo.app.plugin.ExtensionComponentsFinder;
+import run.halo.app.plugin.extensionpoint.ExtensionGetter;
 
 
 /**
@@ -44,15 +43,15 @@ public class CommentElementTagProcessor extends AbstractElementTagProcessor {
     protected void doProcess(ITemplateContext context, IProcessableElementTag tag,
         IElementTagStructureHandler structureHandler) {
         final ApplicationContext appCtx = SpringContextUtils.getApplicationContext(context);
-        ExtensionComponentsFinder componentsFinder =
+        ExtensionGetter extensionGetter = appCtx.getBean(ExtensionGetter.class);
-            appCtx.getBean(ExtensionComponentsFinder.class);
+        CommentWidget commentWidget =
-        List<CommentWidget> commentWidgets = componentsFinder.getExtensions(CommentWidget.class);
+            extensionGetter.getEnabledExtensionByDefinition(CommentWidget.class)
-        if (commentWidgets.isEmpty()) {
+                .next()
+                .block();
+        if (commentWidget == null) {
             structureHandler.replaceWith("", false);
             return;
         }
-        // TODO if find more than one comment widget, query CommentWidget setting to decide which
+        commentWidget.render(context, tag, structureHandler);
-        //  one to use.
-        commentWidgets.get(0).render(context, tag, structureHandler);
     }
 }

application/src/main/resources/extensions/extensionpoint-definitions.yaml

@@ -18,7 +18,7 @@ spec:
   className: run.halo.app.theme.ReactivePostContentHandler
   displayName: ReactivePostContentHandler
   type: MULTI_INSTANCE
-  description: "Provides a way to extend the post content to be displayed in the theme-side."
+  description: "Provides a way to extend the post content to be displayed on the theme-side."
 
 ---
 apiVersion: plugin.halo.run/v1alpha1
@@ -29,4 +29,15 @@ spec:
   className: run.halo.app.theme.ReactiveSinglePageContentHandler
   displayName: ReactiveSinglePageContentHandler
   type: MULTI_INSTANCE
-  description: "Provides a way to extend the single page content to be displayed in the theme-side."
+  description: "Provides a way to extend the single page content to be displayed on the theme-side."
+
+---
+apiVersion: plugin.halo.run/v1alpha1
+kind: ExtensionPointDefinition
+metadata:
+  name: comment-widget
+spec:
+  className: run.halo.app.theme.dialect.CommentWidget
+  displayName: CommentWidget
+  type: SINGLETON
+  description: "Provides an extension point for the comment widget on the theme-side."

application/src/test/java/run/halo/app/theme/dialect/CommentElementTagProcessorTest.java

@@ -4,7 +4,6 @@ import static org.assertj.core.api.Assertions.assertThat;
 import static org.mockito.ArgumentMatchers.eq;
 import static org.mockito.Mockito.when;
 
-import java.util.List;
 import java.util.Map;
 import java.util.Set;
 import org.junit.jupiter.api.BeforeEach;
@@ -24,7 +23,9 @@ import org.thymeleaf.spring6.expression.ThymeleafEvaluationContext;
 import org.thymeleaf.templateresolver.StringTemplateResolver;
 import org.thymeleaf.templateresource.ITemplateResource;
 import org.thymeleaf.templateresource.StringTemplateResource;
+import reactor.core.publisher.Flux;
 import run.halo.app.plugin.ExtensionComponentsFinder;
+import run.halo.app.plugin.extensionpoint.ExtensionGetter;
 
 /**
  * Tests for {@link CommentElementTagProcessor}.
@@ -41,7 +42,7 @@ class CommentElementTagProcessorTest {
     private ApplicationContext applicationContext;
 
     @Mock
-    private ExtensionComponentsFinder componentsFinder;
+    private ExtensionGetter extensionGetter;
 
     private TemplateEngine templateEngine;
 
@@ -51,14 +52,16 @@ class CommentElementTagProcessorTest {
         templateEngine = new TemplateEngine();
         templateEngine.setDialects(Set.of(haloProcessorDialect, new SpringStandardDialect()));
         templateEngine.addTemplateResolver(new TestTemplateResolver());
-        when(applicationContext.getBean(eq(ExtensionComponentsFinder.class)))
+        when(applicationContext.getBean(eq(ExtensionGetter.class)))
-            .thenReturn(componentsFinder);
+            .thenReturn(extensionGetter);
     }
 
     @Test
     void doProcess() {
         Context context = getContext();
 
+        when(extensionGetter.getEnabledExtensionByDefinition(eq(CommentWidget.class)))
+            .thenReturn(Flux.empty());
         String result = templateEngine.process("commentWidget", context);
         assertThat(result).isEqualTo("""
             <!DOCTYPE html>
@@ -70,8 +73,8 @@ class CommentElementTagProcessorTest {
             </html>
             """);
 
-        when(componentsFinder.getExtensions(CommentWidget.class))
+        when(extensionGetter.getEnabledExtensionByDefinition(eq(CommentWidget.class)))
-            .thenReturn(List.of(new DefaultCommentWidget()));
+            .thenReturn(Flux.just(new DefaultCommentWidget()));
         result = templateEngine.process("commentWidget", context);
         assertThat(result).isEqualTo("""
             <!DOCTYPE html>