refactor: cascade delete snapshots and comments when post or page deleted (#2601)

#### What type of PR is this?
/kind bug
/area core
/milestone 2.0

#### What this PR does / why we need it:
当删除文章或自定义页面时级联删除内容快照和评论及计数器

see also #2602
#### Which issue(s) this PR fixes:

Fixes #2599

#### Special notes for your reviewer:
how to test it?
1. 新建一篇文章并创建一些评论（需要安装评论插件 [plugin-comment-widget](https://github.com/halo-sigs/plugin-comment-widget)）
2. 逻辑删除文章时评论不会被删除，真实删除则会
3. 新建一个文章,再删除它，然后查询 snaphost 模型看关联文章的数据有没有被删除
4. 自定义页面同上
5. 删除文章或自定义页面时会删除对应的 Counter 记录（`GET /apis/metrics.halo.run/v1alpha1/counters`）

/cc @halo-dev/sig-halo 
#### Does this PR introduce a user-facing change?

```release-note
修复删除文章或自定义页面时没有级联删除内容快照和评论的问题
```

src/main/java/run/halo/app/config/ExtensionConfiguration.java

@@ -55,6 +55,7 @@ import run.halo.app.extension.router.ExtensionCompositeRouterFunction;
 import run.halo.app.infra.ExternalUrlSupplier;
 import run.halo.app.infra.SystemConfigurableEnvironmentFetcher;
 import run.halo.app.infra.properties.HaloProperties;
+import run.halo.app.metrics.CounterService;
 import run.halo.app.plugin.ExtensionComponentsFinder;
 import run.halo.app.plugin.HaloPluginManager;
 import run.halo.app.plugin.resources.ReverseProxyRouterFunctionRegistry;
@@ -147,9 +148,10 @@ public class ExtensionConfiguration {
 
         @Bean
         Controller postController(ExtensionClient client, ContentService contentService,
-            PostPermalinkPolicy postPermalinkPolicy) {
+            PostPermalinkPolicy postPermalinkPolicy, CounterService counterService) {
             return new ControllerBuilder("post-controller", client)
-                .reconciler(new PostReconciler(client, contentService, postPermalinkPolicy))
+                .reconciler(new PostReconciler(client, contentService, postPermalinkPolicy,
+                    counterService))
                 .extension(new Post())
                 .build();
         }
@@ -195,10 +197,10 @@ public class ExtensionConfiguration {
 
         @Bean
         Controller singlePageController(ExtensionClient client, ContentService contentService,
-            ApplicationContext applicationContext) {
+            ApplicationContext applicationContext, CounterService counterService) {
             return new ControllerBuilder("single-page-controller", client)
                 .reconciler(new SinglePageReconciler(client, contentService,
-                    applicationContext)
+                    applicationContext, counterService)
                 )
                 .extension(new SinglePage())
                 .build();

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

@@ -12,13 +12,18 @@ import org.jsoup.Jsoup;
 import org.springframework.util.Assert;
 import run.halo.app.content.ContentService;
 import run.halo.app.content.permalinks.PostPermalinkPolicy;
+import run.halo.app.core.extension.Comment;
 import run.halo.app.core.extension.Post;
 import run.halo.app.core.extension.Snapshot;
 import run.halo.app.extension.ExtensionClient;
+import run.halo.app.extension.ExtensionOperator;
+import run.halo.app.extension.Ref;
 import run.halo.app.extension.controller.Reconciler;
 import run.halo.app.infra.Condition;
 import run.halo.app.infra.ConditionStatus;
 import run.halo.app.infra.utils.JsonUtils;
+import run.halo.app.metrics.CounterService;
+import run.halo.app.metrics.MeterUtils;
 
 /**
  * <p>Reconciler for {@link Post}.</p>
@@ -37,22 +42,29 @@ public class PostReconciler implements Reconciler<Reconciler.Request> {
     private final ExtensionClient client;
     private final ContentService contentService;
     private final PostPermalinkPolicy postPermalinkPolicy;
+    private final CounterService counterService;
 
     public PostReconciler(ExtensionClient client, ContentService contentService,
-        PostPermalinkPolicy postPermalinkPolicy) {
+        PostPermalinkPolicy postPermalinkPolicy, CounterService counterService) {
         this.client = client;
         this.contentService = contentService;
         this.postPermalinkPolicy = postPermalinkPolicy;
+        this.counterService = counterService;
     }
 
     @Override
     public Result reconcile(Request request) {
         client.fetch(Post.class, request.name())
             .ifPresent(post -> {
-                if (isDeleted(post)) {
+                if (ExtensionOperator.isDeleted(post)) {
                     cleanUpResourcesAndRemoveFinalizer(request.name());
                     return;
                 }
+                if (Objects.equals(true, post.getSpec().getDeleted())) {
+                    // remove permalink from permalink indexer
+                    postPermalinkPolicy.onPermalinkDelete(post);
+                    return;
+                }
                 addFinalizerIfNecessary(post);
 
                 reconcileMetadata(request.name());
@@ -198,6 +210,23 @@ public class PostReconciler implements Reconciler<Reconciler.Request> {
     private void cleanUpResources(Post post) {
         // remove permalink from permalink indexer
         postPermalinkPolicy.onPermalinkDelete(post);
+
+        // clean up snapshots
+        Snapshot.SubjectRef subjectRef =
+            Snapshot.SubjectRef.of(Post.KIND, post.getMetadata().getName());
+        client.list(Snapshot.class,
+                snapshot -> subjectRef.equals(snapshot.getSpec().getSubjectRef()), null)
+            .forEach(client::delete);
+
+        // clean up comments
+        Ref ref = Ref.of(post);
+        client.list(Comment.class, comment -> comment.getSpec().getSubjectRef().equals(ref),
+                null)
+            .forEach(client::delete);
+
+        // delete counter
+        counterService.deleteByName(MeterUtils.nameOf(Post.class, post.getMetadata().getName()))
+            .block();
     }
 
     private Map<String, String> getLabelsOrDefault(Post post) {
@@ -224,9 +253,4 @@ public class PostReconciler implements Reconciler<Reconciler.Request> {
     private boolean isPublished(Post post) {
         return Objects.equals(true, post.getSpec().getPublished());
     }
-
-    private boolean isDeleted(Post post) {
-        return Objects.equals(true, post.getSpec().getDeleted())
-            || post.getMetadata().getDeletionTimestamp() != null;
-    }
 }

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

@@ -16,16 +16,21 @@ import org.springframework.context.ApplicationContext;
 import org.springframework.util.Assert;
 import run.halo.app.content.ContentService;
 import run.halo.app.content.permalinks.ExtensionLocator;
+import run.halo.app.core.extension.Comment;
 import run.halo.app.core.extension.Post;
 import run.halo.app.core.extension.SinglePage;
 import run.halo.app.core.extension.Snapshot;
 import run.halo.app.extension.ExtensionClient;
+import run.halo.app.extension.ExtensionOperator;
 import run.halo.app.extension.GroupVersionKind;
+import run.halo.app.extension.Ref;
 import run.halo.app.extension.controller.Reconciler;
 import run.halo.app.infra.Condition;
 import run.halo.app.infra.ConditionStatus;
 import run.halo.app.infra.utils.JsonUtils;
 import run.halo.app.infra.utils.PathUtils;
+import run.halo.app.metrics.CounterService;
+import run.halo.app.metrics.MeterUtils;
 import run.halo.app.theme.router.PermalinkIndexAddCommand;
 import run.halo.app.theme.router.PermalinkIndexDeleteCommand;
 
@@ -47,12 +52,14 @@ public class SinglePageReconciler implements Reconciler<Reconciler.Request> {
     private final ExtensionClient client;
     private final ContentService contentService;
     private final ApplicationContext applicationContext;
+    private final CounterService counterService;
 
     public SinglePageReconciler(ExtensionClient client, ContentService contentService,
-        ApplicationContext applicationContext) {
+        ApplicationContext applicationContext, CounterService counterService) {
         this.client = client;
         this.contentService = contentService;
         this.applicationContext = applicationContext;
+        this.counterService = counterService;
     }
 
     @Override
@@ -60,10 +67,16 @@ public class SinglePageReconciler implements Reconciler<Reconciler.Request> {
         client.fetch(SinglePage.class, request.name())
             .ifPresent(singlePage -> {
                 SinglePage oldPage = JsonUtils.deepCopy(singlePage);
-                if (isDeleted(oldPage)) {
+                if (ExtensionOperator.isDeleted(singlePage)) {
                     cleanUpResourcesAndRemoveFinalizer(request.name());
                     return;
                 }
+
+                if (Objects.equals(true, singlePage.getSpec().getDeleted())) {
+                    // remove permalink from permalink indexer
+                    permalinkOnDelete(singlePage);
+                    return;
+                }
                 addFinalizerIfNecessary(oldPage);
 
                 reconcileStatus(request.name());
@@ -92,6 +105,24 @@ public class SinglePageReconciler implements Reconciler<Reconciler.Request> {
     private void cleanUpResources(SinglePage singlePage) {
         // remove permalink from permalink indexer
         permalinkOnDelete(singlePage);
+
+        // clean up snapshot
+        Snapshot.SubjectRef subjectRef =
+            Snapshot.SubjectRef.of(SinglePage.KIND, singlePage.getMetadata().getName());
+        client.list(Snapshot.class,
+                snapshot -> subjectRef.equals(snapshot.getSpec().getSubjectRef()), null)
+            .forEach(client::delete);
+
+        // clean up comments
+        Ref ref = Ref.of(singlePage);
+        client.list(Comment.class, comment -> comment.getSpec().getSubjectRef().equals(ref),
+                null)
+            .forEach(client::delete);
+
+        // delete counter for single page
+        counterService.deleteByName(
+                MeterUtils.nameOf(SinglePage.class, singlePage.getMetadata().getName()))
+            .block();
     }
 
     private void cleanUpResourcesAndRemoveFinalizer(String pageName) {

src/main/java/run/halo/app/extension/ExtensionOperator.java

@@ -95,4 +95,9 @@ public interface ExtensionOperator {
     static <T extends ExtensionOperator> Predicate<T> isNotDeleted() {
         return ext -> ext.getMetadata().getDeletionTimestamp() == null;
     }
+
+    static boolean isDeleted(ExtensionOperator extension) {
+        return extension.getMetadata() != null
+            && extension.getMetadata().getDeletionTimestamp() != null;
+    }
 }

src/main/java/run/halo/app/metrics/CounterService.java

@@ -1,5 +1,6 @@
 package run.halo.app.metrics;
 
+import reactor.core.publisher.Mono;
 import run.halo.app.core.extension.Counter;
 
 /**
@@ -9,4 +10,6 @@ import run.halo.app.core.extension.Counter;
 public interface CounterService {
 
     Counter getByName(String counterName);
+
+    Mono<Counter> deleteByName(String counterName);
 }

src/main/java/run/halo/app/metrics/CounterServiceImpl.java

@@ -4,8 +4,10 @@ import io.micrometer.core.instrument.MeterRegistry;
 import io.micrometer.core.instrument.Tag;
 import java.util.Collection;
 import org.springframework.stereotype.Service;
+import reactor.core.publisher.Mono;
 import run.halo.app.core.extension.Counter;
 import run.halo.app.extension.Metadata;
+import run.halo.app.extension.ReactiveExtensionClient;
 
 /**
  * Counter service implementation.
@@ -17,24 +19,39 @@ import run.halo.app.extension.Metadata;
 public class CounterServiceImpl implements CounterService {
 
     private final MeterRegistry meterRegistry;
+    private final ReactiveExtensionClient client;
 
-    public CounterServiceImpl(MeterRegistry meterRegistry) {
+    public CounterServiceImpl(MeterRegistry meterRegistry, ReactiveExtensionClient client) {
         this.meterRegistry = meterRegistry;
+        this.client = client;
     }
 
     @Override
     public Counter getByName(String counterName) {
-        Tag commonTag = MeterUtils.METRICS_COMMON_TAG;
+        Collection<io.micrometer.core.instrument.Counter> counters =
-        Collection<io.micrometer.core.instrument.Counter> counters = meterRegistry.find(counterName)
+            findCounters(counterName);
-            .tag(commonTag.getKey(),
-                valueMatch -> commonTag.getValue().equals(valueMatch))
-            .counters();
 
         Counter counter = emptyCounter(counterName);
         counter.populateFrom(counters);
         return counter;
     }
 
+    private Collection<io.micrometer.core.instrument.Counter> findCounters(String counterName) {
+        Tag commonTag = MeterUtils.METRICS_COMMON_TAG;
+        return meterRegistry.find(counterName)
+            .tag(commonTag.getKey(),
+                valueMatch -> commonTag.getValue().equals(valueMatch))
+            .counters();
+    }
+
+    @Override
+    public Mono<Counter> deleteByName(String counterName) {
+        return client.fetch(Counter.class, counterName)
+            .flatMap(counter -> client.delete(counter)
+                .doOnNext(deleted -> findCounters(counterName).forEach(meterRegistry::remove))
+                .thenReturn(counter));
+    }
+
     private Counter emptyCounter(String name) {
         Counter counter = new Counter();
         counter.setMetadata(new Metadata());

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

@@ -30,6 +30,7 @@ import run.halo.app.core.extension.Snapshot;
 import run.halo.app.extension.ExtensionClient;
 import run.halo.app.extension.Metadata;
 import run.halo.app.extension.controller.Reconciler;
+import run.halo.app.metrics.CounterService;
 import run.halo.app.theme.router.PermalinkIndexAddCommand;
 import run.halo.app.theme.router.PermalinkIndexDeleteCommand;
 import run.halo.app.theme.router.PermalinkIndexUpdateCommand;
@@ -50,11 +51,15 @@ class SinglePageReconcilerTest {
     @Mock
     private ApplicationContext applicationContext;
 
+    @Mock
+    private CounterService counterService;
+
     private SinglePageReconciler singlePageReconciler;
 
     @BeforeEach
     void setUp() {
-        singlePageReconciler = new SinglePageReconciler(client, contentService, applicationContext);
+        singlePageReconciler = new SinglePageReconciler(client, contentService, applicationContext,
+            counterService);
     }
 
     @Test

src/test/java/run/halo/app/extension/ExtensionOperatorTest.java

@@ -22,4 +22,20 @@ class ExtensionOperatorTest {
         when(metadata.getDeletionTimestamp()).thenReturn(Instant.now());
         assertFalse(ExtensionOperator.isNotDeleted().test(ext));
     }
+
+    @Test
+    void testIsDeleted() {
+        var ext = mock(ExtensionOperator.class);
+
+        when(ext.getMetadata()).thenReturn(null);
+        assertFalse(ExtensionOperator.isDeleted(ext));
+
+        var metadata = mock(Metadata.class);
+        when(ext.getMetadata()).thenReturn(metadata);
+        when(metadata.getDeletionTimestamp()).thenReturn(null);
+        assertFalse(ExtensionOperator.isDeleted(ext));
+
+        when(metadata.getDeletionTimestamp()).thenReturn(Instant.now());
+        assertTrue(ExtensionOperator.isDeleted(ext));
+    }
 }

src/test/java/run/halo/app/metrics/CounterServiceImplTest.java

@@ -1,11 +1,24 @@
 package run.halo.app.metrics;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.Mockito.lenient;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
 
 import io.micrometer.core.instrument.simple.SimpleMeterRegistry;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.Mock;
+import org.mockito.junit.jupiter.MockitoExtension;
+import reactor.core.publisher.Mono;
+import reactor.test.StepVerifier;
+import run.halo.app.core.extension.Counter;
 import run.halo.app.core.extension.Post;
+import run.halo.app.extension.Metadata;
+import run.halo.app.extension.ReactiveExtensionClient;
 
 /**
  * Tests for {@link CounterServiceImpl}.
@@ -13,20 +26,32 @@ import run.halo.app.core.extension.Post;
  * @author guqing
  * @since 2.0.0
  */
+@ExtendWith(MockitoExtension.class)
 class CounterServiceImplTest {
 
+    @Mock
+    private ReactiveExtensionClient client;
     private CounterServiceImpl counterService;
 
     @BeforeEach
     void setUp() {
         SimpleMeterRegistry simpleMeterRegistry = new SimpleMeterRegistry();
-        counterService = new CounterServiceImpl(simpleMeterRegistry);
+        counterService = new CounterServiceImpl(simpleMeterRegistry, client);
         String counterName = MeterUtils.nameOf(Post.class, "fake-post");
         MeterUtils.visitCounter(simpleMeterRegistry,
             counterName).increment();
 
         MeterUtils.approvedCommentCounter(simpleMeterRegistry, counterName)
             .increment(2);
+
+        Counter counter = new Counter();
+        counter.setMetadata(new Metadata());
+        counter.getMetadata().setName(counterName);
+        counter.setVisit(2);
+
+        lenient().when(client.delete(any())).thenReturn(Mono.just(counter));
+        lenient().when(client.fetch(eq(Counter.class), eq(counterName)))
+            .thenReturn(Mono.just(counter));
     }
 
     @Test
@@ -38,4 +63,16 @@ class CounterServiceImplTest {
         assertThat(counter.getTotalComment()).isEqualTo(0);
         assertThat(counter.getApprovedComment()).isEqualTo(2);
     }
+
+    @Test
+    void deleteByName() {
+        String counterName = MeterUtils.nameOf(Post.class, "fake-post");
+        counterService.deleteByName(counterName)
+            .as(StepVerifier::create)
+            .consumeNextWith(counter -> {
+                verify(client, times(1)).delete(any(Counter.class));
+                assertThat(counterService.getByName(counterName).getVisit()).isEqualTo(0);
+            })
+            .verifyComplete();
+    }
 }