refactor: content page meta tags now override global injected

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

@@ -8,6 +8,9 @@
 
 /**
  * Theme template <code>head</code> tag snippet injection processor.
+ * <p>Head processor is processed order by {@link org.springframework.core.annotation.Order}
+ * annotation, Higher order will be processed first and so that low-priority processor can be
+ * overwritten head tag written by high-priority processor.</p>
  *
  * @author guqing
  * @since 2.0.0

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

@@ -9,6 +9,7 @@
 import java.util.Map;
 import lombok.AllArgsConstructor;
 import org.apache.commons.lang3.StringUtils;
+import org.springframework.core.annotation.Order;
 import org.springframework.stereotype.Component;
 import org.springframework.web.util.HtmlUtils;
 import org.thymeleaf.context.ITemplateContext;
@@ -29,6 +30,7 @@
  * @since 2.0.0
  */
 @Component
+@Order(1)
 @AllArgsConstructor
 public class ContentTemplateHeadProcessor implements TemplateHeadProcessor {
     private static final String POST_NAME_VARIABLE = "name";

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

@@ -0,0 +1,78 @@
+package run.halo.app.theme.dialect;
+
+import java.util.ArrayList;
+import java.util.Comparator;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+import lombok.AllArgsConstructor;
+import org.apache.commons.lang3.StringUtils;
+import org.springframework.core.annotation.Order;
+import org.springframework.stereotype.Component;
+import org.thymeleaf.context.ITemplateContext;
+import org.thymeleaf.model.IModel;
+import org.thymeleaf.model.ITemplateEvent;
+import org.thymeleaf.model.IText;
+import org.thymeleaf.processor.element.IElementModelStructureHandler;
+import reactor.core.publisher.Mono;
+
+/**
+ * <p>This processor will remove the duplicate meta tag with the same name in head tag and only
+ * keep the last one.</p>
+ * <p>This processor will be executed last.</p>
+ *
+ * @author guqing
+ * @since 2.0.0
+ */
+@Order
+@Component
+@AllArgsConstructor
+public class DuplicateMetaTagProcessor implements TemplateHeadProcessor {
+    static final Pattern META_PATTERN = Pattern.compile("<meta\\s+name=\"(\\w+)\"(.*?)>");
+
+    @Override
+    public Mono<Void> process(ITemplateContext context, IModel model,
+        IElementModelStructureHandler structureHandler) {
+        IModel newModel = context.getModelFactory().createModel();
+
+        Map<String, IndexedModel> uniqueMetaTags = new LinkedHashMap<>();
+        List<IndexedModel> otherModel = new ArrayList<>();
+        for (int i = 0; i < model.size(); i++) {
+            ITemplateEvent templateEvent = model.get(i);
+            // If the current node is a text node, it is processed separately.
+            // Because the text node may contain multiple meta tags.
+            if (templateEvent instanceof IText textNode) {
+                String text = textNode.getText();
+                Matcher matcher = META_PATTERN.matcher(text);
+                while (matcher.find()) {
+                    String tagLine = matcher.group(0);
+                    String nameAttribute = matcher.group(1);
+                    IText metaTagNode = context.getModelFactory().createText(tagLine);
+                    uniqueMetaTags.put(nameAttribute, new IndexedModel(i, metaTagNode));
+                    text = text.replace(tagLine, "");
+                }
+                if (StringUtils.isNotBlank(text)) {
+                    IText otherText = context.getModelFactory()
+                        .createText(text);
+                    otherModel.add(new IndexedModel(i, otherText));
+                }
+            } else {
+                otherModel.add(new IndexedModel(i, templateEvent));
+            }
+        }
+
+        otherModel.addAll(uniqueMetaTags.values());
+        otherModel.stream().sorted(Comparator.comparing(IndexedModel::index))
+            .map(IndexedModel::templateEvent)
+            .forEach(newModel::add);
+
+        model.reset();
+        model.addModel(newModel);
+        return Mono.empty();
+    }
+
+    record IndexedModel(int index, ITemplateEvent templateEvent) {
+    }
+}

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

@@ -2,9 +2,10 @@
 
 import java.util.Collection;
 import org.springframework.context.ApplicationContext;
+import org.springframework.core.annotation.AnnotationAwareOrderComparator;
 import org.thymeleaf.context.ITemplateContext;
 import org.thymeleaf.model.IModel;
-import org.thymeleaf.model.IModelFactory;
+import org.thymeleaf.model.ITemplateEvent;
 import org.thymeleaf.processor.element.AbstractElementModelProcessor;
 import org.thymeleaf.processor.element.IElementModelStructureHandler;
 import org.thymeleaf.spring6.context.SpringContextUtils;
@@ -51,14 +52,23 @@ protected void doProcess(ITemplateContext context, IModel model,
         structureHandler.setLocalVariable(PROCESS_FLAG, true);
 
         // handle <head> tag
+        if (model.size() < 2) {
+            return;
+        }
 
         /*
          * Create the DOM structure that will be substituting our custom tag.
          * The headline will be shown inside a '<div>' tag, and so this must
          * be created first and then a Text node must be added to it.
          */
-        final IModelFactory modelFactory = context.getModelFactory();
-        IModel modelToInsert = modelFactory.createModel();
+        IModel modelToInsert = model.cloneModel();
+        // close </head> tag
+        final ITemplateEvent closeHeadTag = modelToInsert.get(modelToInsert.size() - 1);
+        modelToInsert.remove(modelToInsert.size() - 1);
+
+        // open <head> tag
+        final ITemplateEvent openHeadTag = modelToInsert.get(0);
+        modelToInsert.remove(0);
 
         // apply processors to modelToInsert
         Collection<TemplateHeadProcessor> templateHeadProcessors =
@@ -69,14 +79,20 @@ protected void doProcess(ITemplateContext context, IModel model,
                 .block();
         }
 
-        // add to target model
-        model.insertModel(model.size() - 1, modelToInsert);
+        // reset model to insert
+        model.reset();
+        model.add(openHeadTag);
+        model.addModel(modelToInsert);
+        model.add(closeHeadTag);
     }
 
     private Collection<TemplateHeadProcessor> getTemplateHeadProcessors(ITemplateContext context) {
         ApplicationContext appCtx = SpringContextUtils.getApplicationContext(context);
         ExtensionComponentsFinder componentsFinder =
             appCtx.getBean(ExtensionComponentsFinder.class);
-        return componentsFinder.getExtensions(TemplateHeadProcessor.class);
+        return componentsFinder.getExtensions(TemplateHeadProcessor.class)
+            .stream()
+            .sorted(AnnotationAwareOrderComparator.INSTANCE)
+            .toList();
     }
 }

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

@@ -3,6 +3,7 @@
 import lombok.AllArgsConstructor;
 import org.apache.commons.lang3.BooleanUtils;
 import org.apache.commons.lang3.StringUtils;
+import org.springframework.core.Ordered;
 import org.springframework.core.annotation.Order;
 import org.springframework.stereotype.Component;
 import org.thymeleaf.context.ITemplateContext;
@@ -20,7 +21,7 @@
  * @see SystemSetting.Seo
  * @since 2.0.0
  */
-@Order
+@Order(Ordered.HIGHEST_PRECEDENCE + 1)
 @Component
 @AllArgsConstructor
 public class GlobalSeoProcessor implements TemplateHeadProcessor {

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

@@ -1,6 +1,8 @@
 package run.halo.app.theme.dialect;
 
 import org.apache.commons.lang3.StringUtils;
+import org.springframework.core.Ordered;
+import org.springframework.core.annotation.Order;
 import org.springframework.stereotype.Component;
 import org.thymeleaf.context.ITemplateContext;
 import org.thymeleaf.model.IModel;
@@ -14,10 +16,12 @@
 
 /**
  * <p>Global custom head snippet injection for theme global setting.</p>
+ * <p>Globally injected head snippet can be overridden by content template.</p>
  *
  * @author guqing
  * @since 2.0.0
  */
+@Order(Ordered.HIGHEST_PRECEDENCE + 2)
 @Component
 public class TemplateGlobalHeadProcessor implements TemplateHeadProcessor {