refactor: content page meta tags now override global injected (#4069)

#### What type of PR is this?
/kind improvement
/area core
/milestone 2.7.x

#### What this PR does / why we need it:
修复文章页 HTML Meta 标签重复问题

see #4049 for more details.

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

Fixes #4049

#### Does this PR introduce a user-facing change?

```release-note
修复文章页 Meta Description 标签重复问题
```

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

@@ -8,6 +8,9 @@ import reactor.core.publisher.Mono;
 
 /**
  * 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.List;
 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 @@ import run.halo.app.theme.router.ModelConst;
  * @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 @@ package run.halo.app.theme.dialect;
 
 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 @@ public class GlobalHeadInjectionProcessor extends AbstractElementModelProcessor
         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 @@ public class GlobalHeadInjectionProcessor extends AbstractElementModelProcessor
                 .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 @@ package run.halo.app.theme.dialect;
 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 @@ import run.halo.app.infra.SystemSetting;
  * @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 @@ import run.halo.app.theme.router.ModelConst;
 
 /**
  * <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 {
 

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

@@ -0,0 +1,196 @@
+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.when;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import org.jsoup.Jsoup;
+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 org.springframework.context.ApplicationContext;
+import org.thymeleaf.IEngineConfiguration;
+import org.thymeleaf.TemplateEngine;
+import org.thymeleaf.context.Context;
+import org.thymeleaf.spring6.dialect.SpringStandardDialect;
+import org.thymeleaf.spring6.expression.ThymeleafEvaluationContext;
+import org.thymeleaf.templateresolver.StringTemplateResolver;
+import org.thymeleaf.templateresource.ITemplateResource;
+import org.thymeleaf.templateresource.StringTemplateResource;
+import reactor.core.publisher.Mono;
+import run.halo.app.core.extension.content.Post;
+import run.halo.app.extension.Metadata;
+import run.halo.app.infra.SystemConfigurableEnvironmentFetcher;
+import run.halo.app.infra.SystemSetting;
+import run.halo.app.plugin.ExtensionComponentsFinder;
+import run.halo.app.theme.DefaultTemplateEnum;
+import run.halo.app.theme.finders.PostFinder;
+import run.halo.app.theme.finders.SinglePageFinder;
+import run.halo.app.theme.finders.vo.PostVo;
+import run.halo.app.theme.router.ModelConst;
+
+/**
+ * Integration tests for {@link ContentTemplateHeadProcessor}.
+ *
+ * @author guqing
+ * @see HaloProcessorDialect
+ * @see GlobalHeadInjectionProcessor
+ * @see ContentTemplateHeadProcessor
+ * @see TemplateHeadProcessor
+ * @see TemplateGlobalHeadProcessor
+ * @see TemplateFooterElementTagProcessor
+ * @since 2.7.0
+ */
+@ExtendWith(MockitoExtension.class)
+class ContentTemplateHeadProcessorIntegrationTest {
+    @Mock
+    private ApplicationContext applicationContext;
+
+    @Mock
+    private PostFinder postFinder;
+
+    @Mock
+    private SinglePageFinder singlePageFinder;
+
+    @Mock
+    private SystemConfigurableEnvironmentFetcher fetcher;
+
+    @Mock
+    private ExtensionComponentsFinder extensionComponentsFinder;
+
+    private TemplateEngine templateEngine;
+
+    @BeforeEach
+    void setUp() {
+        HaloProcessorDialect haloProcessorDialect = new HaloProcessorDialect();
+        templateEngine = new TemplateEngine();
+        templateEngine.setDialects(Set.of(haloProcessorDialect, new SpringStandardDialect()));
+        templateEngine.addTemplateResolver(new TestTemplateResolver());
+
+        Map<String, TemplateHeadProcessor> map = new HashMap<>();
+        map.put("postTemplateHeadProcessor",
+            new ContentTemplateHeadProcessor(postFinder, singlePageFinder));
+        map.put("templateGlobalHeadProcessor", new TemplateGlobalHeadProcessor(fetcher));
+        map.put("seoProcessor", new GlobalSeoProcessor(fetcher));
+        map.put("duplicateMetaTagProcessor", new DuplicateMetaTagProcessor());
+        lenient().when(applicationContext.getBeansOfType(eq(TemplateHeadProcessor.class)))
+            .thenReturn(map);
+
+        SystemSetting.Seo seo = new SystemSetting.Seo();
+        seo.setKeywords("global keywords");
+        seo.setDescription("global description");
+        lenient().when(fetcher.fetch(eq(SystemSetting.Seo.GROUP), eq(SystemSetting.Seo.class)))
+            .thenReturn(Mono.just(seo));
+
+        SystemSetting.CodeInjection codeInjection = new SystemSetting.CodeInjection();
+        codeInjection.setGlobalHead(
+            "<meta name=\"description\" content=\"global-head-description\"/>");
+        codeInjection.setContentHead(
+            "<meta name=\"description\" content=\"content-head-description\"/>");
+        lenient().when(fetcher.fetch(eq(SystemSetting.CodeInjection.GROUP),
+            eq(SystemSetting.CodeInjection.class))).thenReturn(Mono.just(codeInjection));
+
+        lenient().when(applicationContext.getBean(eq(SystemConfigurableEnvironmentFetcher.class)))
+            .thenReturn(fetcher);
+        lenient().when(fetcher.fetch(eq(SystemSetting.Seo.GROUP), eq(SystemSetting.Seo.class)))
+            .thenReturn(Mono.empty());
+
+        lenient().when(applicationContext.getBean(eq(ExtensionComponentsFinder.class)))
+            .thenReturn(extensionComponentsFinder);
+
+        lenient().when(extensionComponentsFinder.getExtensions(eq(TemplateHeadProcessor.class)))
+            .thenReturn(new ArrayList<>(map.values()));
+    }
+
+
+    @Test
+    void overrideGlobalMetaTest() {
+        Context context = getContext();
+        context.setVariable("name", "fake-post");
+        // template id flag is used by TemplateGlobalHeadProcessor
+        context.setVariable(ModelConst.TEMPLATE_ID, DefaultTemplateEnum.POST.getValue());
+
+        List<Map<String, String>> htmlMetas = new ArrayList<>();
+        htmlMetas.add(mutableMetaMap("keyword", "postK1,postK2"));
+        htmlMetas.add(mutableMetaMap("description", "post-description"));
+        htmlMetas.add(mutableMetaMap("other", "post-other-meta"));
+        Post.PostSpec postSpec = new Post.PostSpec();
+        postSpec.setHtmlMetas(htmlMetas);
+        Metadata metadata = new Metadata();
+        metadata.setName("fake-post");
+        PostVo postVo = PostVo.builder().spec(postSpec).metadata(metadata).build();
+        when(postFinder.getByName(eq("fake-post"))).thenReturn(Mono.just(postVo));
+
+        String result = templateEngine.process("post", context);
+        /*
+          this test case shows:
+            1. global seo meta keywords and description is overridden by content head meta
+            2. global head meta is overridden by content head meta
+            3. but global head meta is not overridden by global seo meta
+         */
+        assertThat(Jsoup.parse(result).html()).isEqualTo("""
+           <!doctype html>
+           <html lang="en">
+            <head>
+             <meta charset="UTF-8">
+             <title>Post detail</title>
+             <meta name="description" content="post-description">
+             <meta name="keyword" content="postK1,postK2">
+             <meta name="other" content="post-other-meta">
+            </head>
+            <body>
+             this is body
+            </body>
+           </html>""");
+    }
+
+    Map<String, String> mutableMetaMap(String nameValue, String contentValue) {
+        Map<String, String> map = new HashMap<>();
+        map.put("name", nameValue);
+        map.put("content", contentValue);
+        return map;
+    }
+
+    private Context getContext() {
+        Context context = new Context();
+        context.setVariable(
+            ThymeleafEvaluationContext.THYMELEAF_EVALUATION_CONTEXT_CONTEXT_VARIABLE_NAME,
+            new ThymeleafEvaluationContext(applicationContext, null));
+        return context;
+    }
+
+    static class TestTemplateResolver extends StringTemplateResolver {
+        @Override
+        protected ITemplateResource computeTemplateResource(IEngineConfiguration configuration,
+            String ownerTemplate, String template,
+            Map<String, Object> templateResolutionAttributes) {
+            if (template.equals("post")) {
+                return new StringTemplateResource(postTemplate());
+            }
+            return null;
+        }
+
+        private String postTemplate() {
+            return """
+                <!DOCTYPE html>
+                <html lang="en" xmlns:th="http://www.thymeleaf.org">
+                  <head>
+                    <meta charset="UTF-8" />
+                    <title>Post detail</title>
+                  </head>
+                  <body>
+                    this is body
+                  </body>
+                </html>
+                """;
+        }
+    }
+}

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

@@ -167,11 +167,11 @@ class HaloProcessorDialectTest {
               <head>
                 <meta charset="UTF-8" />
                 <title>Post</title>
-              <meta content="post-meta-V1" name="post-meta-V1" />
+              <meta name="global-head-test" content="test" />
+            <meta name="content-head-test" content="test" />
+            <meta content="post-meta-V1" name="post-meta-V1" />
             <meta content="post-meta-V2" name="post-meta-V2" />
             <meta name="description" content="" />
-            <meta name="global-head-test" content="test" />
-            <meta name="content-head-test" content="test" />
             </head>
               <body>
                 <p>post</p>
@@ -203,9 +203,9 @@ class HaloProcessorDialectTest {
               <head>
                 <meta charset="UTF-8" />
                 <title>Seo Test</title>
-              <meta name="global-head-test" content="test" />
+              <meta name="robots" content="noindex" />
+            <meta name="global-head-test" content="test" />
             <link rel="icon" href="favicon.ico" />
-            <meta name="robots" content="noindex" />
             </head>
               <body>
                 seo setting test.
@@ -234,10 +234,10 @@ class HaloProcessorDialectTest {
               <head>
                 <meta charset="UTF-8" />
                 <title>Seo Test</title>
-              <meta name="global-head-test" content="test" />
-            <link rel="icon" href="favicon.ico" />
-            <meta name="keywords" content="K1, K2, K3" />
+              <meta name="keywords" content="K1, K2, K3" />
             <meta name="description" content="This is a description." />
+            <meta name="global-head-test" content="test" />
+            <link rel="icon" href="favicon.ico" />
             </head>
               <body>
                 seo setting test.

application/src/test/java/run/halo/app/theme/message/ThemeMessageResolverIntegrationTest.java

@@ -72,10 +72,7 @@ public class ThemeMessageResolverIntegrationTest {
             .isEqualTo("""
                 <!DOCTYPE html>
                 <html lang="en">
-                <head>
-                    <meta charset="UTF-8">
-                    <title>Title</title>
-                </head>
+                <head><meta charset="UTF-8"><title>Title</title></head>
                 <body>
                 index
                 <div>zh</div>
@@ -96,10 +93,7 @@ public class ThemeMessageResolverIntegrationTest {
             .isEqualTo("""
                 <!DOCTYPE html>
                 <html lang="en">
-                <head>
-                    <meta charset="UTF-8">
-                    <title>Title</title>
-                </head>
+                <head><meta charset="UTF-8"><title>Title</title></head>
                 <body>
                 index
                 <div>en</div>
@@ -120,10 +114,7 @@ public class ThemeMessageResolverIntegrationTest {
             .isEqualTo("""
                 <!DOCTYPE html>
                 <html lang="en">
-                <head>
-                    <meta charset="UTF-8">
-                    <title>Title</title>
-                </head>
+                <head><meta charset="UTF-8"><title>Title</title></head>
                 <body>
                 index
                 <div>foo</div>
@@ -144,10 +135,7 @@ public class ThemeMessageResolverIntegrationTest {
             .isEqualTo("""
                 <!DOCTYPE html>
                 <html lang="en">
-                <head>
-                    <meta charset="UTF-8">
-                    <title>Title</title>
-                </head>
+                <head><meta charset="UTF-8"><title>Title</title></head>
                 <body>
                 index
                 <div>zh</div>
@@ -166,10 +154,7 @@ public class ThemeMessageResolverIntegrationTest {
             .isEqualTo("""
                 <!DOCTYPE html>
                 <html lang="en">
-                <head>
-                    <meta charset="UTF-8">
-                    <title>Other theme title</title>
-                </head>
+                <head><meta charset="UTF-8"><title>Other theme title</title></head>
                 <body>
                 <p>Other 首页</p>
                 </body>
@@ -182,10 +167,7 @@ public class ThemeMessageResolverIntegrationTest {
             .isEqualTo("""
                 <!DOCTYPE html>
                 <html lang="en">
-                <head>
-                    <meta charset="UTF-8">
-                    <title>Other theme title</title>
-                </head>
+                <head><meta charset="UTF-8"><title>Other theme title</title></head>
                 <body>
                 <p>other index</p>
                 </body>