From a35aa5ecd4990556f7651401288b1e25dbd91a5b Mon Sep 17 00:00:00 2001
From: Martin Kouba <mkouba@redhat.com>
Date: Mon, 11 Sep 2023 11:37:20 +0200
Subject: [PATCH] Qute: introduce InjectableFragment

- type-safe fragments should honor the selected variant
- fixes https://github.com/quarkiverse/quarkus-renarde/issues/165
---
 .../fragment/CheckedTemplateFragmentTest.java | 16 +++-
 .../CheckedTemplateFragmentVariantTest.java   | 54 +++++++++++
 .../qute/runtime/TemplateProducer.java        | 93 +++++++++++++++++--
 .../main/java/io/quarkus/qute/Template.java   |  4 +
 4 files changed, 157 insertions(+), 10 deletions(-)
 create mode 100644 extensions/qute/deployment/src/test/java/io/quarkus/qute/deployment/typesafe/fragment/CheckedTemplateFragmentVariantTest.java

diff --git a/extensions/qute/deployment/src/test/java/io/quarkus/qute/deployment/typesafe/fragment/CheckedTemplateFragmentTest.java b/extensions/qute/deployment/src/test/java/io/quarkus/qute/deployment/typesafe/fragment/CheckedTemplateFragmentTest.java
index c5a7cb3502be3..4b143f2c73ff7 100644
--- a/extensions/qute/deployment/src/test/java/io/quarkus/qute/deployment/typesafe/fragment/CheckedTemplateFragmentTest.java
+++ b/extensions/qute/deployment/src/test/java/io/quarkus/qute/deployment/typesafe/fragment/CheckedTemplateFragmentTest.java
@@ -11,6 +11,7 @@
 import io.quarkus.qute.CheckedTemplate;
 import io.quarkus.qute.TemplateGlobal;
 import io.quarkus.qute.TemplateInstance;
+import io.quarkus.qute.Variant;
 import io.quarkus.test.QuarkusUnitTest;
 
 public class CheckedTemplateFragmentTest {
@@ -26,10 +27,21 @@ public class CheckedTemplateFragmentTest {
                             "{#fragment id=foo}{#for i in bar}{i_count}. <{i}>{#if i_hasNext}, {/if}{/for}{/fragment}"),
                             "templates/CheckedTemplateFragmentTest/foos.html"));
 
+    @SuppressWarnings("unchecked")
     @Test
     public void testFragment() {
-        assertEquals("Foo", Templates.items(null).getFragment("item").data("it", new Item("Foo")).render());
-        assertEquals("Foo", Templates.items$item(new Item("Foo")).render());
+        TemplateInstance items = Templates.items(null);
+        List<Variant> variants = (List<Variant>) items.getAttribute(TemplateInstance.VARIANTS);
+        assertEquals(1, variants.size());
+        assertEquals("text/html", variants.get(0).getContentType());
+        assertEquals("Foo", items.getFragment("item").data("it", new Item("Foo")).render());
+
+        TemplateInstance fragment = Templates.items$item(new Item("Foo"));
+        variants = (List<Variant>) fragment.getAttribute(TemplateInstance.VARIANTS);
+        assertEquals(1, variants.size());
+        assertEquals("text/html", variants.get(0).getContentType());
+        assertEquals("Foo", fragment.render());
+
         assertEquals("FooAndBar is a long name", Templates.items$item(new Item("FooAndBar")).render());
         assertEquals("1. <1>, 2. <2>, 3. <3>, 4. <4>, 5. <5>", Templates.foos$foo().render());
     }
diff --git a/extensions/qute/deployment/src/test/java/io/quarkus/qute/deployment/typesafe/fragment/CheckedTemplateFragmentVariantTest.java b/extensions/qute/deployment/src/test/java/io/quarkus/qute/deployment/typesafe/fragment/CheckedTemplateFragmentVariantTest.java
new file mode 100644
index 0000000000000..62461b07bbd1d
--- /dev/null
+++ b/extensions/qute/deployment/src/test/java/io/quarkus/qute/deployment/typesafe/fragment/CheckedTemplateFragmentVariantTest.java
@@ -0,0 +1,54 @@
+package io.quarkus.qute.deployment.typesafe.fragment;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.util.List;
+
+import org.jboss.shrinkwrap.api.asset.StringAsset;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.RegisterExtension;
+
+import io.quarkus.qute.CheckedTemplate;
+import io.quarkus.qute.TemplateInstance;
+import io.quarkus.qute.Variant;
+import io.quarkus.test.QuarkusUnitTest;
+
+public class CheckedTemplateFragmentVariantTest {
+
+    @RegisterExtension
+    static final QuarkusUnitTest config = new QuarkusUnitTest()
+            .withApplicationRoot(root -> root
+                    .addClasses(Templates.class, Item.class)
+                    .addAsResource(new StringAsset(
+                            "{#each items}{#fragment id='item'}<p>{it.name}</p>{/fragment}{/each}"),
+                            "templates/CheckedTemplateFragmentVariantTest/items.html")
+                    .addAsResource(new StringAsset(
+                            "{#each items}{#fragment id='item'}{it.name}{/fragment}{/each}"),
+                            "templates/CheckedTemplateFragmentVariantTest/items.txt"));
+
+    @SuppressWarnings("unchecked")
+    @Test
+    public void testFragment() {
+        TemplateInstance fragment = Templates.items$item(new Item("Foo"));
+        List<Variant> variants = (List<Variant>) fragment.getAttribute(TemplateInstance.VARIANTS);
+        assertEquals(2, variants.size());
+
+        assertEquals("<p>Foo</p>",
+                fragment.setAttribute(TemplateInstance.SELECTED_VARIANT, Variant.forContentType("text/html")).render());
+        assertEquals("Foo",
+                fragment.setAttribute(TemplateInstance.SELECTED_VARIANT, Variant.forContentType("text/plain")).render());
+        // A variant for application/json does not exist, use the default - html wins
+        assertEquals("<p>Foo</p>",
+                fragment.setAttribute(TemplateInstance.SELECTED_VARIANT, Variant.forContentType("application/json")).render());
+    }
+
+    @CheckedTemplate
+    public static class Templates {
+
+        static native TemplateInstance items(List<Item> items);
+
+        static native TemplateInstance items$item(Item it);
+
+    }
+
+}
diff --git a/extensions/qute/runtime/src/main/java/io/quarkus/qute/runtime/TemplateProducer.java b/extensions/qute/runtime/src/main/java/io/quarkus/qute/runtime/TemplateProducer.java
index 10b9900f0272f..b35a7e5efc999 100644
--- a/extensions/qute/runtime/src/main/java/io/quarkus/qute/runtime/TemplateProducer.java
+++ b/extensions/qute/runtime/src/main/java/io/quarkus/qute/runtime/TemplateProducer.java
@@ -87,9 +87,6 @@ Template getTemplate(InjectionPoint injectionPoint) {
         if (path == null || path.isEmpty()) {
             throw new IllegalStateException("No template location specified");
         }
-        // We inject a delegating template in order to:
-        // 1. Be able to select an appropriate variant if needed
-        // 2. Be able to reload the template when needed, i.e. when the cache is cleared
         return new InjectableTemplate(path, templateVariants, engine);
     }
 
@@ -100,11 +97,18 @@ public Template getInjectableTemplate(String path) {
         return new InjectableTemplate(path, templateVariants, engine);
     }
 
+    /**
+     * We inject a delegating template in order to:
+     *
+     * 1. Be able to select an appropriate variant if needed
+     * 2. Be able to reload the template when needed, i.e. when the cache is cleared
+     */
     static class InjectableTemplate implements Template {
 
         private final String path;
         private final TemplateVariants variants;
         private final Engine engine;
+        // Some methods may only work if a single template variant is found
         private final LazyValue<Template> unambiguousTemplate;
 
         public InjectableTemplate(String path, Map<String, TemplateVariants> templateVariants, Engine engine) {
@@ -179,10 +183,7 @@ public String getId() {
 
         @Override
         public Fragment getFragment(String identifier) {
-            if (unambiguousTemplate != null) {
-                return unambiguousTemplate.get().getFragment(identifier);
-            }
-            throw ambiguousTemplates("getFragment()");
+            return new InjectableFragment(identifier);
         }
 
         @Override
@@ -202,6 +203,66 @@ public String toString() {
             return "Injectable template [path=" + path + "]";
         }
 
+        class InjectableFragment implements Fragment {
+
+            private final String identifier;
+
+            InjectableFragment(String identifier) {
+                this.identifier = identifier;
+            }
+
+            @Override
+            public List<Expression> getExpressions() {
+                return InjectableTemplate.this.getExpressions();
+            }
+
+            @Override
+            public Expression findExpression(Predicate<Expression> predicate) {
+                return InjectableTemplate.this.findExpression(predicate);
+            }
+
+            @Override
+            public String getGeneratedId() {
+                return InjectableTemplate.this.getGeneratedId();
+            }
+
+            @Override
+            public Optional<Variant> getVariant() {
+                return InjectableTemplate.this.getVariant();
+            }
+
+            @Override
+            public List<ParameterDeclaration> getParameterDeclarations() {
+                return InjectableTemplate.this.getParameterDeclarations();
+            }
+
+            @Override
+            public String getId() {
+                return identifier;
+            }
+
+            @Override
+            public Template getOriginalTemplate() {
+                return InjectableTemplate.this;
+            }
+
+            @Override
+            public Fragment getFragment(String id) {
+                return InjectableTemplate.this.getFragment(id);
+            }
+
+            @Override
+            public Set<String> getFragmentIds() {
+                return InjectableTemplate.this.getFragmentIds();
+            }
+
+            @Override
+            public TemplateInstance instance() {
+                return new InjectableFragmentTemplateInstanceImpl(identifier);
+            }
+
+        }
+
         class InjectableTemplateInstanceImpl extends TemplateInstanceBase {
 
             InjectableTemplateInstanceImpl() {
@@ -261,7 +322,7 @@ private TemplateInstance templateInstance() {
                 return instance;
             }
 
-            private Template template() {
+            protected Template template() {
                 if (unambiguousTemplate != null) {
                     return unambiguousTemplate.get();
                 }
@@ -280,6 +341,22 @@ private Template template() {
             }
 
         }
+
+        class InjectableFragmentTemplateInstanceImpl extends InjectableTemplateInstanceImpl {
+
+            private final String identifier;
+
+            private InjectableFragmentTemplateInstanceImpl(String identifier) {
+                this.identifier = identifier;
+            }
+
+            @Override
+            protected Template template() {
+                return super.template().getFragment(identifier);
+            }
+
+        }
+
     }
 
     static class TemplateVariants {
diff --git a/independent-projects/qute/core/src/main/java/io/quarkus/qute/Template.java b/independent-projects/qute/core/src/main/java/io/quarkus/qute/Template.java
index 76d778db7fd30..3f9008fa2f998 100644
--- a/independent-projects/qute/core/src/main/java/io/quarkus/qute/Template.java
+++ b/independent-projects/qute/core/src/main/java/io/quarkus/qute/Template.java
@@ -117,12 +117,14 @@ default String render() {
     }
 
     /**
+     * If invoked upon a fragment instance then delegate to the defining template.
      *
      * @return an immutable list of expressions used in the template
      */
     List<Expression> getExpressions();
 
     /**
+     * If invoked upon a fragment instance then delegate to the defining template.
      *
      * @param predicate
      * @return the first expression matching the given predicate or {@code null} if no such expression is used in the template
@@ -146,12 +148,14 @@ default String render() {
     String getId();
 
     /**
+     * If invoked upon a fragment instance then delegate to the defining template.
      *
      * @return the template variant
      */
     Optional<Variant> getVariant();
 
     /**
+     * If invoked upon a fragment instance then delegate to the defining template.
      *
      * @return an immutable list of all parameter declarations defined in the template
      */