refactor: conditionally render comment for theme (#4271)

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

#### What this PR does / why we need it:
按条件渲染评论组件以简化主题端对评论组件是否显示的条件控制

使用了评论标签的模板页面都能直接使用 `${haloCommentEnabled}` 取值能得到评论组件是否可见的结果为`true/false` 用于在需要级联条件渲染的组件上使用，如：

```html
<!-- 评论组件不可见时不渲染标题 -->
<p th:if="${haloCommentEnabled}">评论</p>
<halo:comment />
```

how to test it?
在主题端未加渲染条件时：
1. 测试全局评论组件是否开启的设置是否有效
2. 测试文章和自定义页面是否开启评论的设置是否有效
3. 测试评论组件启用和停止时评论组件的渲染是否正确
4. 测试 `${haloCommentEnabled}` 结果是否正确

#### Which issue(s) this PR fixes:
Fixes #4137

#### Does this PR introduce a user-facing change?
```release-note
按条件渲染评论组件以简化主题端对评论组件是否显示的条件控制
```

api/src/main/java/run/halo/app/theme/dialect/CommentWidget.java

@@ -13,6 +13,8 @@ import org.thymeleaf.processor.element.IElementTagStructureHandler;
  */
 public interface CommentWidget extends ExtensionPoint {
 
+    String ENABLE_COMMENT_ATTRIBUTE = CommentWidget.class.getName() + ".ENABLE";
+
     void render(ITemplateContext context, IProcessableElementTag tag,
         IElementTagStructureHandler structureHandler);
 }

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

@@ -1,12 +1,20 @@
 package run.halo.app.theme.dialect;
 
+import static org.apache.commons.lang3.BooleanUtils.isFalse;
+import static org.apache.commons.lang3.BooleanUtils.isTrue;
+
+import java.util.Optional;
 import org.springframework.context.ApplicationContext;
+import org.springframework.core.convert.support.DefaultConversionService;
+import org.thymeleaf.context.Contexts;
 import org.thymeleaf.context.ITemplateContext;
+import org.thymeleaf.context.IWebContext;
 import org.thymeleaf.model.IProcessableElementTag;
 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.infra.SystemConfigurableEnvironmentFetcher;
 import run.halo.app.plugin.extensionpoint.ExtensionGetter;
 
 
@@ -19,6 +27,7 @@ import run.halo.app.plugin.extensionpoint.ExtensionGetter;
  */
 public class CommentElementTagProcessor extends AbstractElementTagProcessor {
 
+    public static final String COMMENT_ENABLED_MODEL_ATTRIBUTE = "haloCommentEnabled";
     private static final String TAG_NAME = "comment";
 
     private static final int PRECEDENCE = 1000;
@@ -42,16 +51,49 @@ public class CommentElementTagProcessor extends AbstractElementTagProcessor {
     @Override
     protected void doProcess(ITemplateContext context, IProcessableElementTag tag,
         IElementTagStructureHandler structureHandler) {
-        final ApplicationContext appCtx = SpringContextUtils.getApplicationContext(context);
+        getCommentWidget(context).ifPresentOrElse(commentWidget -> {
-        ExtensionGetter extensionGetter = appCtx.getBean(ExtensionGetter.class);
+            populateAllowCommentAttribute(context, true);
-        CommentWidget commentWidget =
+            commentWidget.render(context, tag, structureHandler);
-            extensionGetter.getEnabledExtensionByDefinition(CommentWidget.class)
+        }, () -> {
-                .next()
+            populateAllowCommentAttribute(context, false);
-                .block();
-        if (commentWidget == null) {
             structureHandler.replaceWith("", false);
-            return;
+        });
+    }
+
+    static void populateAllowCommentAttribute(ITemplateContext context, boolean allowComment) {
+        if (Contexts.isWebContext(context)) {
+            IWebContext webContext = Contexts.asWebContext(context);
+            webContext.getExchange()
+                .setAttributeValue(COMMENT_ENABLED_MODEL_ATTRIBUTE, allowComment);
         }
-        commentWidget.render(context, tag, structureHandler);
+    }
+
+    static Optional<CommentWidget> getCommentWidget(ITemplateContext context) {
+        final ApplicationContext appCtx = SpringContextUtils.getApplicationContext(context);
+        SystemConfigurableEnvironmentFetcher environmentFetcher =
+            appCtx.getBean(SystemConfigurableEnvironmentFetcher.class);
+        var commentSetting = environmentFetcher.fetchComment()
+            .blockOptional()
+            .orElseThrow();
+        var globalEnabled = isTrue(commentSetting.getEnable());
+        if (!globalEnabled) {
+            return Optional.empty();
+        }
+
+        if (Contexts.isWebContext(context)) {
+            IWebContext webContext = Contexts.asWebContext(context);
+            Object attributeValue = webContext.getExchange()
+                .getAttributeValue(CommentWidget.ENABLE_COMMENT_ATTRIBUTE);
+            Boolean enabled = DefaultConversionService.getSharedInstance()
+                .convert(attributeValue, Boolean.class);
+            if (isFalse(enabled)) {
+                return Optional.empty();
+            }
+        }
+
+        ExtensionGetter extensionGetter = appCtx.getBean(ExtensionGetter.class);
+        return extensionGetter.getEnabledExtensionByDefinition(CommentWidget.class)
+            .next()
+            .blockOptional();
     }
 }

application/src/main/java/run/halo/app/theme/router/ModelMapUtils.java

@@ -6,6 +6,7 @@ import run.halo.app.core.extension.content.Post;
 import run.halo.app.core.extension.content.SinglePage;
 import run.halo.app.extension.Scheme;
 import run.halo.app.theme.DefaultTemplateEnum;
+import run.halo.app.theme.dialect.CommentWidget;
 import run.halo.app.theme.finders.vo.PostVo;
 import run.halo.app.theme.finders.vo.SinglePageVo;
 
@@ -32,6 +33,7 @@ public abstract class ModelMapUtils {
         model.put("groupVersionKind", POST_SCHEME.groupVersionKind());
         model.put("plural", POST_SCHEME.plural());
         model.put("post", postVo);
+        model.put(CommentWidget.ENABLE_COMMENT_ATTRIBUTE, postVo.getSpec().getAllowComment());
         return model;
     }
 
@@ -48,6 +50,7 @@ public abstract class ModelMapUtils {
         model.put("plural", SINGLE_PAGE_SCHEME.plural());
         model.put(ModelConst.TEMPLATE_ID, DefaultTemplateEnum.SINGLE_PAGE.getValue());
         model.put("singlePage", pageVo);
+        model.put(CommentWidget.ENABLE_COMMENT_ATTRIBUTE, pageVo.getSpec().getAllowComment());
         return model;
     }
 }

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

@@ -2,6 +2,9 @@ package run.halo.app.theme.dialect;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.Mockito.lenient;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
 
 import java.util.Map;
@@ -16,6 +19,7 @@ import org.thymeleaf.IEngineConfiguration;
 import org.thymeleaf.TemplateEngine;
 import org.thymeleaf.context.Context;
 import org.thymeleaf.context.ITemplateContext;
+import org.thymeleaf.context.WebEngineContext;
 import org.thymeleaf.model.IProcessableElementTag;
 import org.thymeleaf.processor.element.IElementTagStructureHandler;
 import org.thymeleaf.spring6.dialect.SpringStandardDialect;
@@ -23,7 +27,11 @@ import org.thymeleaf.spring6.expression.ThymeleafEvaluationContext;
 import org.thymeleaf.templateresolver.StringTemplateResolver;
 import org.thymeleaf.templateresource.ITemplateResource;
 import org.thymeleaf.templateresource.StringTemplateResource;
+import org.thymeleaf.web.IWebExchange;
 import reactor.core.publisher.Flux;
+import reactor.core.publisher.Mono;
+import run.halo.app.infra.SystemConfigurableEnvironmentFetcher;
+import run.halo.app.infra.SystemSetting;
 import run.halo.app.plugin.ExtensionComponentsFinder;
 import run.halo.app.plugin.extensionpoint.ExtensionGetter;
 
@@ -44,6 +52,9 @@ class CommentElementTagProcessorTest {
     @Mock
     private ExtensionGetter extensionGetter;
 
+    @Mock
+    private SystemConfigurableEnvironmentFetcher environmentFetcher;
+
     private TemplateEngine templateEngine;
 
     @BeforeEach
@@ -52,7 +63,7 @@ class CommentElementTagProcessorTest {
         templateEngine = new TemplateEngine();
         templateEngine.setDialects(Set.of(haloProcessorDialect, new SpringStandardDialect()));
         templateEngine.addTemplateResolver(new TestTemplateResolver());
-        when(applicationContext.getBean(eq(ExtensionGetter.class)))
+        lenient().when(applicationContext.getBean(eq(ExtensionGetter.class)))
             .thenReturn(extensionGetter);
     }
 
@@ -60,6 +71,13 @@ class CommentElementTagProcessorTest {
     void doProcess() {
         Context context = getContext();
 
+        when(applicationContext.getBean(eq(SystemConfigurableEnvironmentFetcher.class)))
+            .thenReturn(environmentFetcher);
+        var commentSetting = mock(SystemSetting.Comment.class);
+        when(environmentFetcher.fetchComment())
+            .thenReturn(Mono.just(commentSetting));
+        when(commentSetting.getEnable()).thenReturn(true);
+
         when(extensionGetter.getEnabledExtensionByDefinition(eq(CommentWidget.class)))
             .thenReturn(Flux.empty());
         String result = templateEngine.process("commentWidget", context);
@@ -87,6 +105,74 @@ class CommentElementTagProcessorTest {
             """);
     }
 
+    @Test
+    void getCommentWidget() {
+        when(applicationContext.getBean(eq(SystemConfigurableEnvironmentFetcher.class)))
+            .thenReturn(environmentFetcher);
+        SystemSetting.Comment commentSetting = mock(SystemSetting.Comment.class);
+        when(environmentFetcher.fetchComment())
+            .thenReturn(Mono.just(commentSetting));
+
+        CommentWidget commentWidget = mock(CommentWidget.class);
+        when(extensionGetter.getEnabledExtensionByDefinition(CommentWidget.class))
+            .thenReturn(Flux.just(commentWidget));
+        WebEngineContext webContext = mock(WebEngineContext.class);
+        var evaluationContext = mock(ThymeleafEvaluationContext.class);
+        when(webContext.getVariable(
+            eq(ThymeleafEvaluationContext.THYMELEAF_EVALUATION_CONTEXT_CONTEXT_VARIABLE_NAME)))
+            .thenReturn(evaluationContext);
+        when(evaluationContext.getApplicationContext()).thenReturn(applicationContext);
+        IWebExchange webExchange = mock(IWebExchange.class);
+        when(webContext.getExchange()).thenReturn(webExchange);
+
+        // comment disabled
+        when(commentSetting.getEnable()).thenReturn(true);
+        assertThat(CommentElementTagProcessor.getCommentWidget(webContext).isPresent()).isTrue();
+
+        // comment enabled
+        when(commentSetting.getEnable()).thenReturn(false);
+        assertThat(CommentElementTagProcessor.getCommentWidget(webContext).isPresent()).isFalse();
+
+        // comment enabled and ENABLE_COMMENT_ATTRIBUTE is true
+        when(commentSetting.getEnable()).thenReturn(true);
+        when(webExchange.getAttributeValue(CommentWidget.ENABLE_COMMENT_ATTRIBUTE))
+            .thenReturn(true);
+        assertThat(CommentElementTagProcessor.getCommentWidget(webContext).isPresent()).isTrue();
+
+        // comment enabled and ENABLE_COMMENT_ATTRIBUTE is false
+        when(commentSetting.getEnable()).thenReturn(true);
+        when(webExchange.getAttributeValue(CommentWidget.ENABLE_COMMENT_ATTRIBUTE))
+            .thenReturn(false);
+        assertThat(CommentElementTagProcessor.getCommentWidget(webContext).isPresent()).isFalse();
+
+        // comment enabled and ENABLE_COMMENT_ATTRIBUTE is null
+        when(commentSetting.getEnable()).thenReturn(true);
+        when(webExchange.getAttributeValue(CommentWidget.ENABLE_COMMENT_ATTRIBUTE))
+            .thenReturn(null);
+        assertThat(CommentElementTagProcessor.getCommentWidget(webContext).isPresent()).isTrue();
+
+        // comment enabled and ENABLE_COMMENT_ATTRIBUTE is 'false'
+        when(commentSetting.getEnable()).thenReturn(true);
+        when(webExchange.getAttributeValue(CommentWidget.ENABLE_COMMENT_ATTRIBUTE))
+            .thenReturn("false");
+        assertThat(CommentElementTagProcessor.getCommentWidget(webContext).isPresent()).isFalse();
+    }
+
+    @Test
+    void populateAllowCommentAttribute() {
+        WebEngineContext webContext = mock(WebEngineContext.class);
+        IWebExchange webExchange = mock(IWebExchange.class);
+        when(webContext.getExchange()).thenReturn(webExchange);
+
+        CommentElementTagProcessor.populateAllowCommentAttribute(webContext, true);
+        verify(webExchange).setAttributeValue(
+            eq(CommentElementTagProcessor.COMMENT_ENABLED_MODEL_ATTRIBUTE), eq(true));
+
+        CommentElementTagProcessor.populateAllowCommentAttribute(webContext, false);
+        verify(webExchange).setAttributeValue(
+            eq(CommentElementTagProcessor.COMMENT_ENABLED_MODEL_ATTRIBUTE), eq(false));
+    }
+
     static class DefaultCommentWidget implements CommentWidget {
 
         @Override