feat: implement as decorator

Author: alexandraoberaigner

src/main/java/dev/openfeature/sdk/HookContext.java

@@ -5,7 +5,6 @@
 import lombok.NonNull;
 import lombok.Value;
 import lombok.With;
-import lombok.experimental.NonFinal;
 
 /**
  * A data class to hold immutable context that {@link Hook} instances use.
@@ -27,8 +26,6 @@ public class HookContext<T> {
     ClientMetadata clientMetadata;
     Metadata providerMetadata;
 
-    HookData hookData;
-
     /**
      * Builds {@link HookContext} instances from request data.
      *
@@ -57,4 +54,8 @@ public static <T> HookContext<T> from(
                 .defaultValue(defaultValue)
                 .build();
     }
+
+    HookData getHookData() {
+        return null;
+    }
 }

src/main/java/dev/openfeature/sdk/HookContextDecorator.java

@@ -0,0 +1,23 @@
+package dev.openfeature.sdk;
+
+/**
+ * A base decorator class for {@link HookContext} that enables dynamic enhancement of its functionality.
+ * This class wraps an existing {@code HookContext<T>} instance and delegates method calls to it.
+ *
+ * @param <T> the type for the flag being evaluated
+ */
+class HookContextDecorator<T> extends HookContext<T> {
+
+    HookContext<T> decorated;
+
+    protected HookContextDecorator(HookContext<T> context) {
+        super(context.getFlagKey(), context.getType(), context.getDefaultValue(), context.getCtx(), context.getClientMetadata(),
+                context.getProviderMetadata());
+        this.decorated = context;
+    }
+
+    @Override
+    public HookData getHookData() {
+        return decorated.getHookData();
+    }
+}

src/main/java/dev/openfeature/sdk/HookContextWithData.java

@@ -1,14 +1,21 @@
 package dev.openfeature.sdk;
 
-public class HookContextWithData<T> extends HookContext<T> {
+/**
+ * A concrete decorator for {@link HookContext} that adds {@link HookData} to the existing functionality.
+ *
+ * @param <T> the type for the flag being evaluated
+ */
+public class HookContextWithData<T> extends HookContextDecorator<T> {
 
-    private HookContextWithData(String flagKey, FlagValueType type, T defaultValue,
-            EvaluationContext ctx, ClientMetadata clientMetadata, Metadata providerMetadata, HookData data) {
-        super(flagKey, type, defaultValue, ctx, clientMetadata, providerMetadata, data);
+    private final HookData hookData;
+
+    public HookContextWithData(HookContext<T> context, HookData data) {
+        super(context);
+        this.hookData = data;
     }
 
-    public static <T> HookContextWithData<T> of(HookContext<T> context, HookData data) {
-        return new HookContextWithData<>(context.getFlagKey(), context.getType(), context.getDefaultValue(), context.getCtx(), context.getClientMetadata(),
-                context.getProviderMetadata(), data);
+    @Override
+    public HookData getHookData() {
+        return hookData;
     }
 }

src/main/java/dev/openfeature/sdk/HookSupport.java

@@ -88,7 +88,7 @@ private <T> void executeChecked(
             BiConsumer<Hook<T>, HookContext> hookCode,
             String hookMethod) {
         try {
-            var hookCtxWithData = HookContextWithData.of(hookContext, hookData);
+            var hookCtxWithData = new HookContextWithData(hookContext, hookData);
             hookCode.accept(hook, hookCtxWithData);
         } catch (Exception exception) {
             log.error(
@@ -109,7 +109,7 @@ private <T> void executeHooksUnchecked(
             for (Pair<Hook, HookData> hookDataPair : hookDataPairs) {
                 Hook hook = hookDataPair.getLeft();
                 HookData hookData = hookDataPair.getRight();
-                var hookCtxWithData = HookContextWithData.of(hookContext, hookData);
+                var hookCtxWithData = new HookContextWithData(hookContext, hookData);
                 hookCode.accept(hook, hookCtxWithData);
             }
         }
@@ -130,7 +130,7 @@ private EvaluationContext callBeforeHooks(
             HookData hookData = hookDataPair.getRight();
 
             // Create a new context with this hook's data
-            HookContext contextWithHookData = HookContextWithData.of(hookCtx, hookData);
+            HookContext contextWithHookData = new HookContextWithData(hookCtx, hookData);
             Optional<EvaluationContext> optional =
                     Optional.ofNullable(hook.before(contextWithHookData, hints)).orElse(Optional.empty());
             if (optional.isPresent()) {

src/test/java/dev/openfeature/sdk/HookContextTest.java

@@ -41,7 +41,7 @@ void shouldCreateHookContextWithHookData() {
         HookData hookData = HookData.create();
         hookData.set("test", "value");
 
-        HookContextWithData contextWithData = HookContextWithData.of(context, hookData);
+        HookContextWithData contextWithData = new HookContextWithData(context, hookData);
 
         assertNotNull(contextWithData.getHookData());
         assertEquals("value", contextWithData.getHookData().get("test"));
@@ -71,7 +71,7 @@ void shouldCreateHookContextWithHookDataUsingWith() {
         HookData hookData = HookData.create();
         hookData.set("timing", System.currentTimeMillis());
 
-        HookContext<String> contextWithHookData = HookContextWithData.of(originalContext, hookData);
+        HookContext<String> contextWithHookData = new HookContextWithData(originalContext, hookData);
 
         assertNull(originalContext.getHookData());
         assertNotNull(contextWithHookData.getHookData());