feat: add extension point for excerpt generation (#6348)

#### What type of PR is this?
/kind feature
/area core
/milestone 2.18.x

#### What this PR does / why we need it:
新增文章摘要生成扩展点用于扩展自动生成摘要的方式

#### Does this PR introduce a user-facing change?
```release-note
新增文章摘要生成扩展点用于扩展自动生成摘要的方式
```

api/src/main/java/run/halo/app/content/ExcerptGenerator.java

@@ -0,0 +1,32 @@
+package run.halo.app.content;
+
+import java.util.Set;
+import lombok.Data;
+import lombok.experimental.Accessors;
+import org.pf4j.ExtensionPoint;
+import reactor.core.publisher.Mono;
+
+public interface ExcerptGenerator extends ExtensionPoint {
+
+    Mono<String> generate(ExcerptGenerator.Context context);
+
+    @Data
+    @Accessors(chain = true)
+    class Context {
+        private String raw;
+        /**
+         * html content.
+         */
+        private String content;
+
+        private String rawType;
+        /**
+         * keywords in the content to help the excerpt generation more accurate.
+         */
+        private Set<String> keywords;
+        /**
+         * Max length of the generated excerpt.
+         */
+        private int maxLength;
+    }
+}

application/src/main/java/run/halo/app/core/extension/reconciler/PostReconciler.java

@@ -10,6 +10,7 @@ import static run.halo.app.extension.ExtensionUtil.removeFinalizers;
 import static run.halo.app.extension.MetadataUtil.nullSafeAnnotations;
 import static run.halo.app.extension.MetadataUtil.nullSafeLabels;
 import static run.halo.app.extension.index.query.QueryFactory.equal;
+import static run.halo.app.extension.index.query.QueryFactory.in;
 
 import com.google.common.hash.Hashing;
 import java.time.Duration;
@@ -20,7 +21,9 @@ import java.util.List;
 import java.util.Objects;
 import java.util.Optional;
 import java.util.Set;
+import java.util.stream.Collectors;
 import lombok.AllArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
 import org.apache.commons.lang3.BooleanUtils;
 import org.apache.commons.lang3.StringUtils;
 import org.jsoup.Jsoup;
@@ -28,8 +31,10 @@ import org.springframework.context.ApplicationEvent;
 import org.springframework.context.ApplicationEventPublisher;
 import org.springframework.data.domain.Sort;
 import org.springframework.stereotype.Component;
+import reactor.core.publisher.Mono;
 import run.halo.app.content.CategoryService;
 import run.halo.app.content.ContentWrapper;
+import run.halo.app.content.ExcerptGenerator;
 import run.halo.app.content.NotificationReasonConst;
 import run.halo.app.content.PostService;
 import run.halo.app.content.comment.CommentService;
@@ -39,6 +44,7 @@ import run.halo.app.core.extension.content.Post;
 import run.halo.app.core.extension.content.Post.PostPhase;
 import run.halo.app.core.extension.content.Post.VisibleEnum;
 import run.halo.app.core.extension.content.Snapshot;
+import run.halo.app.core.extension.content.Tag;
 import run.halo.app.core.extension.notification.Subscription;
 import run.halo.app.event.post.PostDeletedEvent;
 import run.halo.app.event.post.PostPublishedEvent;
@@ -62,6 +68,7 @@ import run.halo.app.infra.utils.HaloUtils;
 import run.halo.app.metrics.CounterService;
 import run.halo.app.metrics.MeterUtils;
 import run.halo.app.notification.NotificationCenter;
+import run.halo.app.plugin.extensionpoint.ExtensionGetter;
 
 /**
  * <p>Reconciler for {@link Post}.</p>
@@ -75,6 +82,7 @@ import run.halo.app.notification.NotificationCenter;
  * @author guqing
  * @since 2.0.0
  */
+@Slf4j
 @AllArgsConstructor
 @Component
 public class PostReconciler implements Reconciler<Reconciler.Request> {
@@ -85,6 +93,7 @@ public class PostReconciler implements Reconciler<Reconciler.Request> {
     private final CounterService counterService;
     private final CommentService commentService;
     private final CategoryService categoryService;
+    private final ExtensionGetter extensionGetter;
 
     private final ApplicationEventPublisher eventPublisher;
     private final NotificationCenter notificationCenter;
@@ -155,14 +164,7 @@ public class PostReconciler implements Reconciler<Reconciler.Request> {
                 }
                 var isAutoGenerate = defaultIfNull(excerpt.getAutoGenerate(), true);
                 if (isAutoGenerate) {
-                    Optional<ContentWrapper> contentWrapper =
+                    status.setExcerpt(getExcerpt(post));
-                        postService.getContent(post.getSpec().getReleaseSnapshot(),
-                                post.getSpec().getBaseSnapshot())
-                            .blockOptional();
-                    if (contentWrapper.isPresent()) {
-                        String contentRevised = contentWrapper.get().getContent();
-                        status.setExcerpt(getExcerpt(contentRevised));
-                    }
                 } else {
                     status.setExcerpt(excerpt.getRaw());
                 }
@@ -375,11 +377,57 @@ public class PostReconciler implements Reconciler<Reconciler.Request> {
             .block();
     }
 
-    private String getExcerpt(String htmlContent) {
+    private String getExcerpt(Post post) {
-        String shortHtmlContent = StringUtils.substring(htmlContent, 0, 500);
+        Optional<ContentWrapper> contentWrapper =
+            postService.getContent(post.getSpec().getReleaseSnapshot(),
+                    post.getSpec().getBaseSnapshot())
+                .blockOptional();
+        if (contentWrapper.isEmpty()) {
+            return StringUtils.EMPTY;
+        }
+        var content = contentWrapper.get();
+        var tags = listTagDisplayNames(post);
+
+        var keywords = new HashSet<>(tags);
+        keywords.add(post.getSpec().getTitle());
+
+        var context = new ExcerptGenerator.Context()
+            .setRaw(content.getRaw())
+            .setContent(content.getContent())
+            .setRawType(content.getRawType())
+            .setKeywords(keywords)
+            .setMaxLength(160);
+        return extensionGetter.getEnabledExtension(ExcerptGenerator.class)
+            .defaultIfEmpty(new DefaultExcerptGenerator())
+            .flatMap(generator -> generator.generate(context))
+            .onErrorResume(Throwable.class, e -> {
+                log.error("Failed to generate excerpt for post [{}]",
+                    post.getMetadata().getName(), e);
+                return Mono.empty();
+            })
+            .blockOptional()
+            .orElse(StringUtils.EMPTY);
+    }
+
+    private Set<String> listTagDisplayNames(Post post) {
+        return Optional.ofNullable(post.getSpec().getTags())
+            .map(tags -> client.listAll(Tag.class, ListOptions.builder()
+                .fieldQuery(in("metadata.name", tags))
+                .build(), Sort.unsorted())
+            )
+            .stream()
+            .flatMap(List::stream)
+            .map(tag -> tag.getSpec().getDisplayName())
+            .collect(Collectors.toSet());
+    }
+
+    static class DefaultExcerptGenerator implements ExcerptGenerator {
+        @Override
+        public Mono<String> generate(Context context) {
+            String shortHtmlContent = StringUtils.substring(context.getContent(), 0, 500);
             String text = Jsoup.parse(shortHtmlContent).text();
-        // TODO The default capture 150 words as excerpt
+            return Mono.just(StringUtils.substring(text, 0, 150));
-        return StringUtils.substring(text, 0, 150);
+        }
     }
 
     List<Snapshot> listSnapshots(Ref ref) {

application/src/main/java/run/halo/app/core/extension/reconciler/SinglePageReconciler.java

@@ -17,6 +17,9 @@ import org.jsoup.Jsoup;
 import org.springframework.data.domain.Sort;
 import org.springframework.stereotype.Component;
 import org.springframework.util.Assert;
+import reactor.core.publisher.Mono;
+import run.halo.app.content.ContentWrapper;
+import run.halo.app.content.ExcerptGenerator;
 import run.halo.app.content.NotificationReasonConst;
 import run.halo.app.content.SinglePageService;
 import run.halo.app.content.comment.CommentService;
@@ -43,6 +46,7 @@ import run.halo.app.infra.utils.JsonUtils;
 import run.halo.app.metrics.CounterService;
 import run.halo.app.metrics.MeterUtils;
 import run.halo.app.notification.NotificationCenter;
+import run.halo.app.plugin.extensionpoint.ExtensionGetter;
 
 /**
  * <p>Reconciler for {@link SinglePage}.</p>
@@ -65,6 +69,7 @@ public class SinglePageReconciler implements Reconciler<Reconciler.Request> {
     private final SinglePageService singlePageService;
     private final CounterService counterService;
     private final CommentService commentService;
+    private final ExtensionGetter extensionGetter;
 
     private final ExternalUrlSupplier externalUrlSupplier;
 
@@ -318,12 +323,7 @@ public class SinglePageReconciler implements Reconciler<Reconciler.Request> {
             }
 
             if (excerpt.getAutoGenerate()) {
-                singlePageService.getContent(spec.getHeadSnapshot(), spec.getBaseSnapshot())
+                status.setExcerpt(getExcerpt(singlePage));
-                    .blockOptional()
-                    .ifPresent(content -> {
-                        String contentRevised = content.getContent();
-                        status.setExcerpt(getExcerpt(contentRevised));
-                    });
             } else {
                 status.setExcerpt(excerpt.getRaw());
             }
@@ -363,11 +363,40 @@ public class SinglePageReconciler implements Reconciler<Reconciler.Request> {
         });
     }
 
-    private String getExcerpt(String htmlContent) {
+    private String getExcerpt(SinglePage singlePage) {
-        String shortHtmlContent = StringUtils.substring(htmlContent, 0, 500);
+        Optional<ContentWrapper> contentWrapper =
+            singlePageService.getContent(singlePage.getSpec().getReleaseSnapshot(),
+                    singlePage.getSpec().getBaseSnapshot())
+                .blockOptional();
+        if (contentWrapper.isEmpty()) {
+            return StringUtils.EMPTY;
+        }
+        var content = contentWrapper.get();
+        var context = new ExcerptGenerator.Context()
+            .setRaw(content.getRaw())
+            .setContent(content.getContent())
+            .setRaw(content.getRawType())
+            .setKeywords(Set.of())
+            .setMaxLength(160);
+        return extensionGetter.getEnabledExtension(ExcerptGenerator.class)
+            .defaultIfEmpty(new DefaultExcerptGenerator())
+            .flatMap(generator -> generator.generate(context))
+            .onErrorResume(Throwable.class, e -> {
+                log.error("Failed to generate excerpt for single page [{}]",
+                    singlePage.getMetadata().getName(), e);
+                return Mono.empty();
+            })
+            .blockOptional()
+            .orElse(StringUtils.EMPTY);
+    }
+
+    static class DefaultExcerptGenerator implements ExcerptGenerator {
+        @Override
+        public Mono<String> generate(Context context) {
+            String shortHtmlContent = StringUtils.substring(context.getContent(), 0, 500);
             String text = Jsoup.parse(shortHtmlContent).text();
-        // TODO The default capture 150 words as excerpt
+            return Mono.just(StringUtils.substring(text, 0, 150));
-        return StringUtils.substring(text, 0, 150);
+        }
     }
 
     private boolean isDeleted(SinglePage singlePage) {

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

@@ -87,4 +87,13 @@ spec:
   displayName: 页脚标签内容处理器
   type: MULTI_INSTANCE
   description: "提供用于扩展 <halo:footer/> 标签内容的扩展方式。"
-  
+---
+apiVersion: plugin.halo.run/v1alpha1
+kind: ExtensionPointDefinition
+metadata:
+  name: excerpt-generator
+spec:
+  className: run.halo.app.content.ExcerptGenerator
+  displayName: 摘要生成器
+  type: SINGLETON
+  description: "提供自动生成摘要的方式扩展，如使用算法提取或使用 AI 生成。"

application/src/test/java/run/halo/app/core/extension/reconciler/PostReconcilerTest.java

@@ -25,6 +25,7 @@ import org.mockito.junit.jupiter.MockitoExtension;
 import org.springframework.context.ApplicationEventPublisher;
 import reactor.core.publisher.Mono;
 import run.halo.app.content.ContentWrapper;
+import run.halo.app.content.ExcerptGenerator;
 import run.halo.app.content.NotificationReasonConst;
 import run.halo.app.content.PostService;
 import run.halo.app.content.TestPost;
@@ -36,6 +37,7 @@ import run.halo.app.event.post.PostPublishedEvent;
 import run.halo.app.extension.ExtensionClient;
 import run.halo.app.extension.controller.Reconciler;
 import run.halo.app.notification.NotificationCenter;
+import run.halo.app.plugin.extensionpoint.ExtensionGetter;
 
 /**
  * Tests for {@link PostReconciler}.
@@ -61,6 +63,9 @@ class PostReconcilerTest {
     @Mock
     private NotificationCenter notificationCenter;
 
+    @Mock
+    private ExtensionGetter extensionGetter;
+
     @InjectMocks
     private PostReconciler postReconciler;
 
@@ -96,7 +101,7 @@ class PostReconcilerTest {
         verify(postPermalinkPolicy, times(1)).permalink(any());
 
         Post value = captor.getValue();
-        assertThat(value.getStatus().getExcerpt()).isNull();
+        assertThat(value.getStatus().getExcerpt()).isEmpty();
         assertThat(value.getStatus().getContributors()).isEqualTo(List.of("guqing", "zhangsan"));
     }
 
@@ -126,6 +131,9 @@ class PostReconcilerTest {
         Snapshot snapshotV1 = TestPost.snapshotV1();
         snapshotV1.getSpec().setContributors(Set.of("guqing"));
 
+        when(extensionGetter.getEnabledExtension(eq(ExcerptGenerator.class)))
+            .thenReturn(Mono.empty());
+
         when(client.listAll(eq(Snapshot.class), any(), any()))
             .thenReturn(List.of(snapshotV1, snapshotV2));
 
@@ -162,6 +170,9 @@ class PostReconcilerTest {
             when(client.fetch(eq(Snapshot.class), eq(post.getSpec().getReleaseSnapshot())))
                 .thenReturn(Optional.of(snapshotV2));
 
+            when(extensionGetter.getEnabledExtension(eq(ExcerptGenerator.class)))
+                .thenReturn(Mono.empty());
+
             when(client.listAll(eq(Snapshot.class), any(), any()))
                 .thenReturn(List.of());
 
@@ -191,6 +202,9 @@ class PostReconcilerTest {
                     .rawType("markdown")
                     .build()));
 
+            when(extensionGetter.getEnabledExtension(eq(ExcerptGenerator.class)))
+                .thenReturn(Mono.empty());
+
             when(client.listAll(eq(Snapshot.class), any(), any()))
                 .thenReturn(List.of());
 

application/src/test/java/run/halo/app/core/extension/reconciler/SinglePageReconcilerTest.java

@@ -26,6 +26,7 @@ import org.mockito.junit.jupiter.MockitoExtension;
 import org.springframework.context.ApplicationContext;
 import reactor.core.publisher.Mono;
 import run.halo.app.content.ContentWrapper;
+import run.halo.app.content.ExcerptGenerator;
 import run.halo.app.content.NotificationReasonConst;
 import run.halo.app.content.SinglePageService;
 import run.halo.app.content.TestPost;
@@ -39,6 +40,7 @@ import run.halo.app.extension.controller.Reconciler;
 import run.halo.app.infra.ExternalUrlSupplier;
 import run.halo.app.metrics.CounterService;
 import run.halo.app.notification.NotificationCenter;
+import run.halo.app.plugin.extensionpoint.ExtensionGetter;
 
 /**
  * Tests for {@link SinglePageReconciler}.
@@ -66,6 +68,9 @@ class SinglePageReconcilerTest {
     @Mock
     NotificationCenter notificationCenter;
 
+    @Mock
+    ExtensionGetter extensionGetter;
+
     @InjectMocks
     private SinglePageReconciler singlePageReconciler;
 
@@ -79,9 +84,10 @@ class SinglePageReconcilerTest {
         String name = "page-A";
         SinglePage page = pageV1();
         page.getSpec().setHeadSnapshot("page-A-head-snapshot");
+        page.getSpec().setReleaseSnapshot(page.getSpec().getHeadSnapshot());
         when(client.fetch(eq(SinglePage.class), eq(name)))
             .thenReturn(Optional.of(page));
-        when(singlePageService.getContent(eq(page.getSpec().getHeadSnapshot()),
+        when(singlePageService.getContent(eq(page.getSpec().getReleaseSnapshot()),
             eq(page.getSpec().getBaseSnapshot())))
             .thenReturn(Mono.just(ContentWrapper.builder()
                 .snapshotName(page.getSpec().getHeadSnapshot())
@@ -99,6 +105,9 @@ class SinglePageReconcilerTest {
             .thenReturn(List.of(snapshotV1, snapshotV2));
         when(externalUrlSupplier.get()).thenReturn(URI.create(""));
 
+        when(extensionGetter.getEnabledExtension(eq(ExcerptGenerator.class)))
+            .thenReturn(Mono.empty());
+
         ArgumentCaptor<SinglePage> captor = ArgumentCaptor.forClass(SinglePage.class);
         singlePageReconciler.reconcile(new Reconciler.Request(name));
 
@@ -141,7 +150,7 @@ class SinglePageReconcilerTest {
             page.getSpec().setReleaseSnapshot("page-fake-released-snapshot");
             when(client.fetch(eq(SinglePage.class), eq(name)))
                 .thenReturn(Optional.of(page));
-            when(singlePageService.getContent(eq(page.getSpec().getHeadSnapshot()),
+            when(singlePageService.getContent(eq(page.getSpec().getReleaseSnapshot()),
                 eq(page.getSpec().getBaseSnapshot())))
                 .thenReturn(Mono.just(ContentWrapper.builder()
                     .snapshotName(page.getSpec().getHeadSnapshot())
@@ -156,6 +165,9 @@ class SinglePageReconcilerTest {
             when(client.fetch(eq(Snapshot.class), eq(page.getSpec().getReleaseSnapshot())))
                 .thenReturn(Optional.of(snapshotV2));
 
+            when(extensionGetter.getEnabledExtension(eq(ExcerptGenerator.class)))
+                .thenReturn(Mono.empty());
+
             when(client.listAll(eq(Snapshot.class), any(), any()))
                 .thenReturn(List.of());
 
@@ -176,7 +188,7 @@ class SinglePageReconcilerTest {
             page.getSpec().setPublish(false);
             when(client.fetch(eq(SinglePage.class), eq(name)))
                 .thenReturn(Optional.of(page));
-            when(singlePageService.getContent(eq(page.getSpec().getHeadSnapshot()),
+            when(singlePageService.getContent(eq(page.getSpec().getReleaseSnapshot()),
                 eq(page.getSpec().getBaseSnapshot())))
                 .thenReturn(Mono.just(ContentWrapper.builder()
                     .snapshotName(page.getSpec().getHeadSnapshot())
@@ -186,6 +198,9 @@ class SinglePageReconcilerTest {
                     .build())
                 );
 
+            when(extensionGetter.getEnabledExtension(eq(ExcerptGenerator.class)))
+                .thenReturn(Mono.empty());
+
             when(client.listAll(eq(Snapshot.class), any(), any()))
                 .thenReturn(List.of());