refactor: snapshot attributes and post publish (#2709)

#### What type of PR is this?
/kind improvement
/area core
/milestone 2.0
 
#### What this PR does / why we need it:
1. 简化 Snapshot 的指责，去除 Snapshot 中关于 version，publishTime 等与发布相关的东西，Snapshot本身没有发布概念
2. 对应修改文章和自定义页面，将版本的概念转移到拥有 Snapshot 的模型上，如 Post 和 SinglePage

⚠️此 PR 为破坏性更新，对旧数据不兼容，可能导致旧数据文章内容无法显示问题

Console 端需要做出一些修改：
- 将文章发布前调用保存内容的 API 修改为 `/posts/{name}/content`
- 将自定义页面发布前调用保存内容的 API 修改为 `/singlepages/{name}/content`

发布接口提供了一个 `async` 参数，默认值为 `false`此时发布API需要等待发布成功后才返回结果，如果等待超时则提示`Publishing wait timeout.`, 如果传递 `async=true` 表示异步发布，更新完数据就成功，reconciler 在后台慢慢执行。

#### Special notes for your reviewer:
how to test it?
1. 新创建一篇文章，测试点击保存是否成功
2. 新创建一篇文章，测试编辑内容后直接发布是否成功
3. 测试发布过的文章的取消发布状态是否显示未发布状态
4. 对于 Snapshot，新建文章点保存会创建一个snapshot，点击发布则是更新之前点保存创建的一条，所以记录数不会多，发布之后进入编辑随便写点内容直接点发布后查询snapshot则会多一条记录。
5. 文章的 status 里的 conditions 最新添加的都在第一个即头插入，如果连续两次发布则不会在增加 condition，长度超过20条会把旧的 condition 删除掉
6. 自定义页面上同

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

```release-note
Action Required: 简化 Snapshot 模型的职责，去除版本相关属性
```

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

@@ -9,7 +9,6 @@
 import org.springframework.web.reactive.function.server.ServerResponse;
 import run.halo.app.content.ContentService;
 import run.halo.app.content.PostService;
-import run.halo.app.content.SinglePageService;
 import run.halo.app.content.permalinks.CategoryPermalinkPolicy;
 import run.halo.app.content.permalinks.PostPermalinkPolicy;
 import run.halo.app.content.permalinks.TagPermalinkPolicy;
@@ -151,11 +150,11 @@ Controller themeController(ExtensionClient client, HaloProperties haloProperties
         @Bean
         Controller postController(ExtensionClient client, ContentService contentService,
             PostPermalinkPolicy postPermalinkPolicy, CounterService counterService,
-            PostService postService) {
+            PostService postService, ApplicationContext applicationContext) {
             return new ControllerBuilder("post", client)
                 .reconciler(new PostReconciler(client, contentService, postService,
                     postPermalinkPolicy,
-                    counterService))
+                    counterService, applicationContext))
                 .extension(new Post())
                 // TODO Make it configurable
                 .workerCount(10)
@@ -204,10 +203,10 @@ Controller attachmentController(ExtensionClient client,
         @Bean
         Controller singlePageController(ExtensionClient client, ContentService contentService,
             ApplicationContext applicationContext, CounterService counterService,
-            SinglePageService singlePageService, ExternalUrlSupplier externalUrlSupplier) {
+            ExternalUrlSupplier externalUrlSupplier) {
             return new ControllerBuilder("single-page", client)
                 .reconciler(new SinglePageReconciler(client, contentService,
-                    applicationContext, singlePageService, counterService, externalUrlSupplier)
+                    applicationContext, counterService, externalUrlSupplier)
                 )
                 .extension(new SinglePage())
                 .build();

src/main/java/run/halo/app/content/ContentRequest.java

@@ -1,6 +1,7 @@
 package run.halo.app.content;
 
 import io.swagger.v3.oas.annotations.media.Schema;
+import java.util.HashMap;
 import org.apache.commons.lang3.StringUtils;
 import run.halo.app.core.extension.Snapshot;
 import run.halo.app.extension.Metadata;
@@ -17,31 +18,23 @@ public record ContentRequest(@Schema(required = true) Ref subjectRef,
                              @Schema(required = true) String rawType) {
 
     public Snapshot toSnapshot() {
-        Snapshot snapshot = new Snapshot();
+        final Snapshot snapshot = new Snapshot();
 
         Metadata metadata = new Metadata();
-        metadata.setName(defaultName(subjectRef));
+        metadata.setAnnotations(new HashMap<>());
         snapshot.setMetadata(metadata);
 
         Snapshot.SnapShotSpec snapShotSpec = new Snapshot.SnapShotSpec();
         snapShotSpec.setSubjectRef(subjectRef);
-        snapShotSpec.setVersion(1);
+
         snapShotSpec.setRawType(rawType);
         snapShotSpec.setRawPatch(StringUtils.defaultString(raw()));
         snapShotSpec.setContentPatch(StringUtils.defaultString(content()));
-        String displayVersion = Snapshot.displayVersionFrom(snapShotSpec.getVersion());
-        snapShotSpec.setDisplayVersion(displayVersion);
 
         snapshot.setSpec(snapShotSpec);
         return snapshot;
     }
 
-    private String defaultName(Ref subjectRef) {
-        // example: Post-apost-v1-snapshot
-        return String.join("-", subjectRef.getKind(),
-            subjectRef.getName(), "v1", "snapshot");
-    }
-
     public String rawPatchFrom(String originalRaw) {
         // originalRaw content from v1
         return PatchUtils.diffToJsonPatch(originalRaw, this.raw);

src/main/java/run/halo/app/content/ContentService.java

@@ -17,15 +17,13 @@ public interface ContentService {
 
     Mono<ContentWrapper> draftContent(ContentRequest content);
 
-    Mono<ContentWrapper> updateContent(ContentRequest content);
+    Mono<ContentWrapper> draftContent(ContentRequest content, String parentName);
 
-    Mono<ContentWrapper> publish(String headSnapshotName, Ref subjectRef);
+    Mono<ContentWrapper> updateContent(ContentRequest content);
 
     Mono<Snapshot> getBaseSnapshot(Ref subjectRef);
 
     Mono<Snapshot> latestSnapshotVersion(Ref subjectRef);
 
-    Mono<Snapshot> latestPublishedSnapshot(Ref subjectRef);
-
     Flux<Snapshot> listSnapshots(Ref subjectRef);
 }

src/main/java/run/halo/app/content/ContentWrapper.java

@@ -11,7 +11,6 @@
 @Builder
 public class ContentWrapper {
     private String snapshotName;
-    private Integer version;
     private String raw;
     private String content;
     private String rawType;

src/main/java/run/halo/app/content/PostService.java

@@ -17,6 +17,4 @@ public interface PostService {
     Mono<Post> draftPost(PostRequest postRequest);
 
     Mono<Post> updatePost(PostRequest postRequest);
-
-    Mono<Post> publishPost(String postName);
 }

src/main/java/run/halo/app/content/SinglePageService.java

@@ -17,6 +17,4 @@ public interface SinglePageService {
     Mono<SinglePage> draft(SinglePageRequest pageRequest);
 
     Mono<SinglePage> update(SinglePageRequest pageRequest);
-
-    Mono<SinglePage> publish(String name);
 }

src/main/java/run/halo/app/content/impl/ContentServiceImpl.java

@@ -3,13 +3,13 @@
 import java.security.Principal;
 import java.time.Instant;
 import java.util.Comparator;
-import java.util.Map;
 import java.util.UUID;
-import org.apache.commons.lang3.StringUtils;
+import java.util.function.Function;
 import org.springframework.security.core.context.ReactiveSecurityContextHolder;
 import org.springframework.security.core.context.SecurityContext;
 import org.springframework.stereotype.Component;
 import org.springframework.util.Assert;
+import org.thymeleaf.util.StringUtils;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
 import run.halo.app.content.ContentRequest;
@@ -28,10 +28,6 @@
  */
 @Component
 public class ContentServiceImpl implements ContentService {
-    private static final Comparator<Snapshot> SNAPSHOT_COMPARATOR =
-        Comparator.comparing(snapshot -> snapshot.getSpec().getVersion());
-    public static Comparator<Snapshot> LATEST_SNAPSHOT_COMPARATOR = SNAPSHOT_COMPARATOR.reversed();
-
     private final ReactiveExtensionClient client;
 
     public ContentServiceImpl(ReactiveExtensionClient client) {
@@ -46,61 +42,56 @@ public Mono<ContentWrapper> getContent(String name) {
     }
 
     @Override
-    public Mono<ContentWrapper> draftContent(ContentRequest contentRequest) {
-        return getContextUsername()
-            .flatMap(username -> {
-                // create snapshot
-                Snapshot snapshot = contentRequest.toSnapshot();
-                snapshot.addContributor(username);
-                return client.create(snapshot)
-                    .flatMap(this::restoredContent);
-            });
+    public Mono<ContentWrapper> draftContent(ContentRequest content) {
+        return this.draftContent(content, content.headSnapshotName());
+    }
+
+    @Override
+    public Mono<ContentWrapper> draftContent(ContentRequest contentRequest, String parentName) {
+        return Mono.defer(
+                () -> {
+                    Snapshot snapshot = contentRequest.toSnapshot();
+                    snapshot.getMetadata().setName(UUID.randomUUID().toString());
+                    snapshot.getSpec().setParentSnapshotName(parentName);
+                    return getBaseSnapshot(contentRequest.subjectRef())
+                        .defaultIfEmpty(snapshot)
+                        .map(baseSnapshot -> determineRawAndContentPatch(snapshot, baseSnapshot,
+                            contentRequest))
+                        .flatMap(source -> getContextUsername()
+                            .map(username -> {
+                                Snapshot.addContributor(source, username);
+                                source.getSpec().setOwner(username);
+                                return source;
+                            })
+                            .defaultIfEmpty(source)
+                        );
+                })
+            .flatMap(snapshot -> client.create(snapshot)
+                .flatMap(this::restoredContent));
     }
 
     @Override
     public Mono<ContentWrapper> updateContent(ContentRequest contentRequest) {
         Assert.notNull(contentRequest, "The contentRequest must not be null");
         Assert.notNull(contentRequest.headSnapshotName(), "The headSnapshotName must not be null");
-        return Mono.zip(getContextUsername(),
-                client.fetch(Snapshot.class, contentRequest.headSnapshotName()))
-            .flatMap(tuple -> {
-                String username = tuple.getT1();
-                Snapshot headSnapShot = tuple.getT2();
-                return handleSnapshot(headSnapShot, contentRequest, username);
-            })
+        Ref subjectRef = contentRequest.subjectRef();
+        return client.fetch(Snapshot.class, contentRequest.headSnapshotName())
+            .flatMap(headSnapshot -> getBaseSnapshot(subjectRef)
+                .map(baseSnapshot -> determineRawAndContentPatch(headSnapshot, baseSnapshot,
+                    contentRequest)
+                )
+            )
+            .flatMap(headSnapshot -> getContextUsername()
+                .map(username -> {
+                    Snapshot.addContributor(headSnapshot, username);
+                    return headSnapshot;
+                })
+                .defaultIfEmpty(headSnapshot)
+            )
+            .flatMap(client::update)
             .flatMap(this::restoredContent);
     }
 
-    @Override
-    public Mono<ContentWrapper> publish(String headSnapshotName, Ref subjectRef) {
-        Assert.notNull(headSnapshotName, "The headSnapshotName must not be null");
-        return client.fetch(Snapshot.class, headSnapshotName)
-            .flatMap(snapshot -> {
-                if (snapshot.isPublished()) {
-                    // there is nothing to publish
-                    return restoredContent(snapshot.getMetadata().getName(),
-                        subjectRef);
-                }
-                Map<String, String> labels = ExtensionUtil.nullSafeLabels(snapshot);
-                Snapshot.putPublishedLabel(labels);
-                Snapshot.SnapShotSpec snapshotSpec = snapshot.getSpec();
-                snapshotSpec.setPublishTime(Instant.now());
-                snapshotSpec.setDisplayVersion(
-                    Snapshot.displayVersionFrom(snapshotSpec.getVersion()));
-                return client.update(snapshot)
-                    .then(Mono.defer(
-                        () -> restoredContent(snapshot.getMetadata().getName(), subjectRef))
-                    );
-            });
-    }
-
-    private Mono<ContentWrapper> restoredContent(String snapshotName,
-        Ref subjectRef) {
-        return getBaseSnapshot(subjectRef)
-            .flatMap(baseSnapshot -> client.fetch(Snapshot.class, snapshotName)
-                .map(snapshot -> snapshot.applyPatch(baseSnapshot)));
-    }
-
     private Mono<ContentWrapper> restoredContent(Snapshot headSnapshot) {
         return getBaseSnapshot(headSnapshot.getSpec().getSubjectRef())
             .map(headSnapshot::applyPatch);
@@ -109,78 +100,17 @@ private Mono<ContentWrapper> restoredContent(Snapshot headSnapshot) {
     @Override
     public Mono<Snapshot> getBaseSnapshot(Ref subjectRef) {
         return listSnapshots(subjectRef)
-            .filter(snapshot -> snapshot.getSpec().getVersion() == 1)
+            .sort(createTimeReversedComparator().reversed())
+            .filter(p -> StringUtils.equals(Boolean.TRUE.toString(),
+                ExtensionUtil.nullSafeAnnotations(p).get(Snapshot.KEEP_RAW_ANNO)))
             .next();
     }
 
-    private Mono<Snapshot> handleSnapshot(Snapshot headSnapshot, ContentRequest contentRequest,
-        String username) {
-        Ref subjectRef = contentRequest.subjectRef();
-        return getBaseSnapshot(subjectRef).flatMap(baseSnapshot -> {
-            String baseSnapshotName = baseSnapshot.getMetadata().getName();
-            return latestPublishedSnapshot(subjectRef)
-                .flatMap(latestReleasedSnapshot -> {
-                    Snapshot newSnapshot = contentRequest.toSnapshot();
-                    newSnapshot.getSpec().setSubjectRef(subjectRef);
-                    newSnapshot.addContributor(username);
-                    // has released snapshot, there are 3 assumptions:
-                    // if headPtr != releasePtr && head is not published, then update its content
-                    // directly
-                    // if headPtr != releasePtr && head is published, then create a new snapshot
-                    // if headPtr == releasePtr, then create a new snapshot too
-                    return latestSnapshotVersion(subjectRef)
-                        .flatMap(latestSnapshot -> {
-                            String headSnapshotName = contentRequest.headSnapshotName();
-                            newSnapshot.getSpec()
-                                .setVersion(latestSnapshot.getSpec().getVersion() + 1);
-                            newSnapshot.getSpec().setDisplayVersion(
-                                Snapshot.displayVersionFrom(newSnapshot.getSpec().getVersion()));
-                            newSnapshot.getSpec()
-                                .setParentSnapshotName(headSnapshotName);
-                            // head is published or headPtr == releasePtr
-                            String releasedSnapshotName =
-                                latestReleasedSnapshot.getMetadata().getName();
-                            if (headSnapshot.isPublished() || StringUtils.equals(headSnapshotName,
-                                releasedSnapshotName)) {
-                                String latestSnapshotName = latestSnapshot.getMetadata().getName();
-                                if (!headSnapshotName.equals(latestSnapshotName)
-                                    && !latestSnapshot.isPublished()) {
-                                    // publish it then create new one
-                                    return publish(latestSnapshotName, subjectRef)
-                                        .then(createNewSnapshot(newSnapshot, baseSnapshotName,
-                                            contentRequest));
-                                }
-                                // create a new snapshot,done
-                                return createNewSnapshot(newSnapshot, baseSnapshotName,
-                                    contentRequest);
-                            }
-
-                            // otherwise update its content directly
-                            return updateRawAndContentToHeadSnapshot(headSnapshot, baseSnapshotName,
-                                contentRequest);
-                        });
-                })
-                // no released snapshot, indicating v1 now, just update the content directly
-                .switchIfEmpty(Mono.defer(
-                    () -> updateRawAndContentToHeadSnapshot(headSnapshot, baseSnapshotName,
-                        contentRequest)));
-        });
-    }
-
     @Override
     public Mono<Snapshot> latestSnapshotVersion(Ref subjectRef) {
         Assert.notNull(subjectRef, "The subjectRef must not be null.");
         return listSnapshots(subjectRef)
-            .sort(LATEST_SNAPSHOT_COMPARATOR)
-            .next();
-    }
-
-    @Override
-    public Mono<Snapshot> latestPublishedSnapshot(Ref subjectRef) {
-        Assert.notNull(subjectRef, "The subjectRef must not be null.");
-        return listSnapshots(subjectRef)
-            .filter(Snapshot::isPublished)
-            .sort(LATEST_SNAPSHOT_COMPARATOR)
+            .sort(createTimeReversedComparator())
             .next();
     }
 
@@ -197,47 +127,38 @@ private Mono<String> getContextUsername() {
             .map(Principal::getName);
     }
 
-    private Mono<Snapshot> updateRawAndContentToHeadSnapshot(Snapshot snapshotToUpdate,
-        String baseSnapshotName,
-        ContentRequest contentRequest) {
-        return client.fetch(Snapshot.class, baseSnapshotName)
-            .flatMap(baseSnapshot -> {
-                determineRawAndContentPatch(snapshotToUpdate,
-                    baseSnapshot, contentRequest);
-                return client.update(snapshotToUpdate)
-                    .thenReturn(snapshotToUpdate);
-            });
-    }
-
-    private Mono<Snapshot> createNewSnapshot(Snapshot snapshotToCreate,
-        String baseSnapshotName,
-        ContentRequest contentRequest) {
-        return client.fetch(Snapshot.class, baseSnapshotName)
-            .flatMap(baseSnapshot -> {
-                determineRawAndContentPatch(snapshotToCreate,
-                    baseSnapshot, contentRequest);
-                snapshotToCreate.getMetadata().setName(UUID.randomUUID().toString());
-                snapshotToCreate.getSpec().setSubjectRef(contentRequest.subjectRef());
-                return client.create(snapshotToCreate)
-                    .thenReturn(snapshotToCreate);
-            });
-    }
-
-    private void determineRawAndContentPatch(Snapshot snapshotToUse, Snapshot baseSnapshot,
+    private Snapshot determineRawAndContentPatch(Snapshot snapshotToUse, Snapshot baseSnapshot,
         ContentRequest contentRequest) {
+        Assert.notNull(baseSnapshot, "The baseSnapshot must not be null.");
+        Assert.notNull(contentRequest, "The contentRequest must not be null.");
+        Assert.notNull(snapshotToUse, "The snapshotToUse not be null.");
         String originalRaw = baseSnapshot.getSpec().getRawPatch();
         String originalContent = baseSnapshot.getSpec().getContentPatch();
+        String baseSnapshotName = baseSnapshot.getMetadata().getName();
 
+        snapshotToUse.getSpec().setLastModifyTime(Instant.now());
         // it is the v1 snapshot, set the content directly
-        if (snapshotToUse.getSpec().getVersion() == 1) {
+        if (StringUtils.equals(baseSnapshotName, snapshotToUse.getMetadata().getName())) {
             snapshotToUse.getSpec().setRawPatch(contentRequest.raw());
             snapshotToUse.getSpec().setContentPatch(contentRequest.content());
+            ExtensionUtil.nullSafeAnnotations(snapshotToUse)
+                .put(Snapshot.KEEP_RAW_ANNO, Boolean.TRUE.toString());
         } else {
             // otherwise diff a patch based on the v1 snapshot
             String revisedRaw = contentRequest.rawPatchFrom(originalRaw);
             String revisedContent = contentRequest.contentPatchFrom(originalContent);
             snapshotToUse.getSpec().setRawPatch(revisedRaw);
             snapshotToUse.getSpec().setContentPatch(revisedContent);
         }
+        return snapshotToUse;
+    }
+
+    Comparator<Snapshot> createTimeReversedComparator() {
+        Function<Snapshot, String> name = snapshot -> snapshot.getMetadata().getName();
+        Function<Snapshot, Instant> createTime = snapshot -> snapshot.getMetadata()
+            .getCreationTimestamp();
+        return Comparator.comparing(createTime)
+            .thenComparing(name)
+            .reversed();
     }
 }