refactor: support chaining calls for flux and mono in javascript inline tag (#2715)

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

#### What this PR does / why we need it:
支持在 JavaScript 中对 Flux 或 Mono 的泛型类型属性链式调用
测试参考：
7e9bdec492/src/test/java/run/halo/app/theme/ReactiveFinderExpressionParserTests.java (L131-L147)
期望
7e9bdec492/src/test/java/run/halo/app/theme/ReactiveFinderExpressionParserTests.java (L64-L79)

#### Special notes for your reviewer:
/cc @halo-dev/sig-halo 
#### Does this PR introduce a user-facing change?

```release-note
支持在 JavaScript 中对 Flux 或 Mono 的泛型类型属性链式调用
```

src/main/java/run/halo/app/theme/ReactivePropertyAccessor.java

@@ -1,18 +1,16 @@
 package run.halo.app.theme;
 
-import com.fasterxml.jackson.databind.JsonNode;
-import java.util.ArrayList;
 import java.util.List;
 import org.springframework.expression.AccessException;
 import org.springframework.expression.EvaluationContext;
 import org.springframework.expression.PropertyAccessor;
 import org.springframework.expression.TypedValue;
+import org.springframework.expression.spel.ast.AstUtils;
 import org.springframework.integration.json.JsonPropertyAccessor;
 import org.springframework.lang.NonNull;
 import org.springframework.lang.Nullable;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
-import run.halo.app.infra.utils.JsonUtils;
 
 /**
  * A SpEL PropertyAccessor that knows how to read properties from {@link Mono} or {@link Flux}
@@ -24,25 +22,25 @@ import run.halo.app.infra.utils.JsonUtils;
  * @since 2.0.0
  */
 public class ReactivePropertyAccessor implements PropertyAccessor {
-    private static final Class<?>[] SUPPORTED_CLASSES = {
-        Mono.class,
-        Flux.class
-    };
-    private final JsonPropertyAccessor jsonPropertyAccessor = new JsonPropertyAccessor();
 
     @Override
     public Class<?>[] getSpecificTargetClasses() {
-        return SUPPORTED_CLASSES;
+        return null;
     }
 
     @Override
     public boolean canRead(@NonNull EvaluationContext context, Object target, @NonNull String name)
         throws AccessException {
-        if (target == null) {
+        if (isReactiveType(target)) {
-            return false;
+            return true;
         }
-        return Mono.class.isAssignableFrom(target.getClass())
+        List<PropertyAccessor> propertyAccessors = context.getPropertyAccessors();
-            || Flux.class.isAssignableFrom(target.getClass());
+        for (PropertyAccessor propertyAccessor : propertyAccessors) {
+            if (propertyAccessor.canRead(context, target, name)) {
+                return true;
+            }
+        }
+        return false;
     }
 
     @Override
@@ -52,29 +50,44 @@ public class ReactivePropertyAccessor implements PropertyAccessor {
         if (target == null) {
             return TypedValue.NULL;
         }
-        Class<?> clazz = target.getClass();
+        Object value = blockingGetForReactive(target);
-        Object value = null;
-        if (Mono.class.isAssignableFrom(clazz)) {
-            value = ((Mono<?>) target).block();
-        } else if (Flux.class.isAssignableFrom(clazz)) {
-            value = ((Flux<?>) target).toIterable();
-        }
-
-        if (value == null) {
-            return TypedValue.NULL;
-        }
 
         List<PropertyAccessor> propertyAccessorsToTry =
             getPropertyAccessorsToTry(value, context.getPropertyAccessors());
         for (PropertyAccessor propertyAccessor : propertyAccessorsToTry) {
             try {
-                return propertyAccessor.read(context, target, name);
+                TypedValue result = propertyAccessor.read(context, value, name);
+                return new TypedValue(blockingGetForReactive(result.getValue()));
             } catch (AccessException e) {
-                // ignore
+                // ignore this
             }
         }
-        JsonNode jsonNode = JsonUtils.DEFAULT_JSON_MAPPER.convertValue(value, JsonNode.class);
+
-        return jsonPropertyAccessor.read(context, jsonNode, name);
+        throw new AccessException("Cannot read property '" + name + "' from [" + value + "]");
+    }
+
+    @Nullable
+    private static Object blockingGetForReactive(@Nullable Object target) {
+        if (target == null) {
+            return null;
+        }
+        Class<?> clazz = target.getClass();
+        Object value = target;
+        if (Mono.class.isAssignableFrom(clazz)) {
+            value = ((Mono<?>) target).block();
+        } else if (Flux.class.isAssignableFrom(clazz)) {
+            value = ((Flux<?>) target).collectList().block();
+        }
+        return value;
+    }
+
+    private boolean isReactiveType(Object target) {
+        if (target == null) {
+            return false;
+        }
+        Class<?> clazz = target.getClass();
+        return Mono.class.isAssignableFrom(clazz)
+            || Flux.class.isAssignableFrom(clazz);
     }
 
     private List<PropertyAccessor> getPropertyAccessorsToTry(
@@ -82,27 +95,10 @@ public class ReactivePropertyAccessor implements PropertyAccessor {
 
         Class<?> targetType = (contextObject != null ? contextObject.getClass() : null);
 
-        List<PropertyAccessor> specificAccessors = new ArrayList<>();
+        List<PropertyAccessor> resolvers =
-        List<PropertyAccessor> generalAccessors = new ArrayList<>();
+            AstUtils.getPropertyAccessorsToTry(targetType, propertyAccessors);
-        for (PropertyAccessor resolver : propertyAccessors) {
+        // remove this resolver to avoid infinite loop
-            Class<?>[] targets = resolver.getSpecificTargetClasses();
+        resolvers.remove(this);
-            if (targets == null) {
-                // generic resolver that says it can be used for any type
-                generalAccessors.add(resolver);
-            } else if (targetType != null) {
-                for (Class<?> clazz : targets) {
-                    if (clazz == targetType) {
-                        specificAccessors.add(resolver);
-                        break;
-                    } else if (clazz.isAssignableFrom(targetType)) {
-                        generalAccessors.add(resolver);
-                    }
-                }
-            }
-        }
-        List<PropertyAccessor> resolvers = new ArrayList<>(specificAccessors);
-        generalAccessors.removeAll(specificAccessors);
-        resolvers.addAll(generalAccessors);
         return resolvers;
     }
 

src/main/java/run/halo/app/theme/ReactiveSpelVariableExpressionEvaluator.java

@@ -37,7 +37,7 @@ public class ReactiveSpelVariableExpressionEvaluator
             return ((Mono<?>) returnValue).block();
         }
         if (Flux.class.isAssignableFrom(clazz)) {
-            return ((Flux<?>) returnValue).toIterable();
+            return ((Flux<?>) returnValue).collectList().block();
         }
         return returnValue;
     }

src/test/java/run/halo/app/theme/ReactiveFinderExpressionParserTests.java

@@ -0,0 +1,151 @@
+package run.halo.app.theme;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.node.ArrayNode;
+import com.fasterxml.jackson.databind.node.ObjectNode;
+import java.util.Map;
+import java.util.Set;
+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.standard.expression.IStandardVariableExpressionEvaluator;
+import org.thymeleaf.templateresolver.StringTemplateResolver;
+import org.thymeleaf.templateresource.ITemplateResource;
+import org.thymeleaf.templateresource.StringTemplateResource;
+import reactor.core.publisher.Flux;
+import reactor.core.publisher.Mono;
+import run.halo.app.infra.utils.JsonUtils;
+import run.halo.app.theme.dialect.HaloProcessorDialect;
+
+/**
+ * Tests expression parser for reactive return value.
+ *
+ * @author guqing
+ * @see ReactivePropertyAccessor
+ * @see ReactiveSpelVariableExpressionEvaluator
+ * @since 2.0.0
+ */
+@ExtendWith(MockitoExtension.class)
+public class ReactiveFinderExpressionParserTests {
+    @Mock
+    private ApplicationContext applicationContext;
+
+    private TemplateEngine templateEngine;
+
+    @BeforeEach
+    void setUp() {
+        HaloProcessorDialect haloProcessorDialect = new HaloProcessorDialect();
+        templateEngine = new TemplateEngine();
+        templateEngine.setDialects(Set.of(haloProcessorDialect, new SpringStandardDialect() {
+            @Override
+            public IStandardVariableExpressionEvaluator getVariableExpressionEvaluator() {
+                return new ReactiveSpelVariableExpressionEvaluator();
+            }
+        }));
+        templateEngine.addTemplateResolver(new TestTemplateResolver());
+    }
+
+    @Test
+    void javascriptInlineParser() {
+        Context context = getContext();
+        context.setVariable("target", new TestReactiveFinder());
+        context.setVariable("genericMap", Map.of("key", "value"));
+        String result = templateEngine.process("javascriptInline", context);
+        assertThat(result).isEqualTo("""
+            <p>value</p>
+            <p>ruibaby</p>
+            <p>guqing</p>
+            <p>bar</p>
+            <script>
+                var genericValue = "value";
+                var name = "guqing";
+                var names = ["guqing","johnniang","ruibaby"];
+                var users = [{"name":"guqing"},{"name":"ruibaby"},{"name":"johnniang"}];
+                var userListItem = "guqing";
+                var objectJsonNodeFlux = [{"name":"guqing"}];
+                var objectJsonNodeFluxChain = "guqing";
+                var mapMono = "bar";
+                var arrayNodeMono = "bar";
+            </script>
+            """);
+    }
+
+    static class TestReactiveFinder {
+        public Mono<String> getName() {
+            return Mono.just("guqing");
+        }
+
+        public Flux<String> names() {
+            return Flux.just("guqing", "johnniang", "ruibaby");
+        }
+
+        public Flux<TestUser> users() {
+            return Flux.just(
+                new TestUser("guqing"), new TestUser("ruibaby"), new TestUser("johnniang")
+            );
+        }
+
+        public Flux<JsonNode> objectJsonNodeFlux() {
+            ObjectNode objectNode = JsonUtils.DEFAULT_JSON_MAPPER.createObjectNode();
+            objectNode.put("name", "guqing");
+            return Flux.just(objectNode);
+        }
+
+        public Mono<Map<String, Object>> mapMono() {
+            return Mono.just(Map.of("foo", "bar"));
+        }
+
+        public Mono<JsonNode> arrayNodeMono() {
+            ArrayNode arrayNode = JsonUtils.DEFAULT_JSON_MAPPER.createArrayNode();
+            arrayNode.add(arrayNode.objectNode().put("foo", "bar"));
+            return Mono.just(arrayNode);
+        }
+    }
+
+    record TestUser(String name) {
+    }
+
+    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) {
+            return new StringTemplateResource("""
+                <p th:text="${genericMap.key}"></p>
+                <p th:text="${target.users[1].name}"></p>
+                <p th:text="${target.objectJsonNodeFlux[0].name}"></p>
+                <p th:text="${target.arrayNodeMono.get(0).foo}"></p>
+                <script th:inline="javascript">
+                    var genericValue = /*[[${genericMap.key}]]*/;
+                    var name = /*[[${target.getName()}]]*/;
+                    var names = /*[[${target.names()}]]*/;
+                    var users = /*[[${target.users()}]]*/;
+                    var userListItem = /*[[${target.users[0].name}]]*/;
+                    var objectJsonNodeFlux = /*[[${target.objectJsonNodeFlux()}]]*/;
+                    var objectJsonNodeFluxChain = /*[[${target.objectJsonNodeFlux[0].name}]]*/;
+                    var mapMono = /*[[${target.mapMono.foo}]]*/;
+                    var arrayNodeMono = /*[[${target.arrayNodeMono.get(0).foo}]]*/;
+                </script>
+                 """);
+        }
+
+    }
+}