Remove String feature flags for LaunchDarkly (#33)

* Remove String feature flags for LaunchDarkly

* Apply suggestions from code review

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

* Apply suggestions from code review

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

---------

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

src/main/java/org/openrewrite/featureflags/RemoveBooleanFlag.java

@@ -72,7 +72,8 @@ public J visitMethodInvocation(J.MethodInvocation method, ExecutionContext ctx)
                     doAfterVisit(new SimplifyConstantIfBranchExecution().getVisitor());
                     doAfterVisit(new RemoveUnusedLocalVariables(null).getVisitor());
                     doAfterVisit(new RemoveUnusedPrivateFields().getVisitor());
-                    return new J.Literal(Tree.randomId(), Space.SINGLE_SPACE, Markers.EMPTY, replacementValue, String.valueOf(replacementValue), null, JavaType.Primitive.Boolean);
+                    J.Literal literal = new J.Literal(Tree.randomId(), Space.SINGLE_SPACE, Markers.EMPTY, replacementValue, String.valueOf(replacementValue), null, JavaType.Primitive.Boolean);
+                    return literal.withPrefix(mi.getPrefix());
                 }
                 return mi;
             }

src/main/java/org/openrewrite/featureflags/RemoveStringFlag.java

@@ -0,0 +1,90 @@
+/*
+ * Copyright 2023 the original author or authors.
+ * <p>
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * <p>
+ * https://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.openrewrite.featureflags;
+
+import lombok.EqualsAndHashCode;
+import lombok.Value;
+import org.openrewrite.*;
+import org.openrewrite.analysis.constantfold.ConstantFold;
+import org.openrewrite.analysis.util.CursorUtil;
+import org.openrewrite.java.JavaVisitor;
+import org.openrewrite.java.MethodMatcher;
+import org.openrewrite.java.search.UsesMethod;
+import org.openrewrite.java.tree.Expression;
+import org.openrewrite.java.tree.J;
+import org.openrewrite.java.tree.JavaType;
+import org.openrewrite.java.tree.Space;
+import org.openrewrite.marker.Markers;
+import org.openrewrite.staticanalysis.RemoveUnusedLocalVariables;
+import org.openrewrite.staticanalysis.RemoveUnusedPrivateFields;
+import org.openrewrite.staticanalysis.SimplifyConstantIfBranchExecution;
+
+@Value
+@EqualsAndHashCode(callSuper = false)
+public class RemoveStringFlag extends Recipe {
+
+    @Override
+    public String getDisplayName() {
+        return "Remove a boolean feature flag for feature key";
+    }
+
+    @Override
+    public String getDescription() {
+        return "Replace method invocations for feature key with value, and simplify constant if branch execution.";
+    }
+
+    @Option(displayName = "Method pattern",
+            description = "A method pattern to match against. The first argument must be the feature key as `String`.",
+            example = "dev.openfeature.sdk.Client getBooleanValue(String, Boolean)")
+    String methodPattern;
+
+    @Option(displayName = "Feature flag key",
+            description = "The key of the feature flag to remove.",
+            example = "flag-key-123abc")
+    String featureKey;
+
+    @Option(displayName = "Replacement value",
+            description = "The value to replace the feature flag check with.",
+            example = "topic-456")
+    String replacementValue;
+
+    @Override
+    public TreeVisitor<?, ExecutionContext> getVisitor() {
+        final MethodMatcher methodMatcher = new MethodMatcher(methodPattern, true);
+        JavaVisitor<ExecutionContext> visitor = new JavaVisitor<ExecutionContext>() {
+            @Override
+            public J visitMethodInvocation(J.MethodInvocation method, ExecutionContext ctx) {
+                J.MethodInvocation mi = (J.MethodInvocation) super.visitMethodInvocation(method, ctx);
+                if (methodMatcher.matches(mi) && isFeatureKey(mi.getArguments().get(0))) {
+                    doAfterVisit(new SimplifyConstantIfBranchExecution().getVisitor());
+                    doAfterVisit(new RemoveUnusedLocalVariables(null).getVisitor());
+                    doAfterVisit(new RemoveUnusedPrivateFields().getVisitor());
+                    J.Literal literal = new J.Literal(Tree.randomId(), Space.SINGLE_SPACE, Markers.EMPTY, replacementValue, '"' + replacementValue + '"', null, JavaType.Primitive.String);
+                    return literal.withPrefix(mi.getPrefix());
+                }
+                return mi;
+            }
+
+            private boolean isFeatureKey(Expression firstArgument) {
+                return CursorUtil.findCursorForTree(getCursor(), firstArgument)
+                               .bind(c -> ConstantFold.findConstantLiteralValue(c, String.class))
+                               .map(featureKey::equals)
+                               .orSome(false);
+            }
+        };
+        return Preconditions.check(new UsesMethod<>(methodMatcher), visitor);
+    }
+}

src/main/java/org/openrewrite/featureflags/launchdarkly/RemoveStringVariation.java

@@ -0,0 +1,58 @@
+/*
+ * Copyright 2024 the original author or authors.
+ * <p>
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * <p>
+ * https://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.openrewrite.featureflags.launchdarkly;
+
+import lombok.EqualsAndHashCode;
+import lombok.Value;
+import org.openrewrite.Option;
+import org.openrewrite.Recipe;
+import org.openrewrite.featureflags.RemoveBooleanFlag;
+import org.openrewrite.featureflags.RemoveStringFlag;
+
+import java.util.Collections;
+import java.util.List;
+
+@Value
+@EqualsAndHashCode(callSuper = false)
+public class RemoveStringVariation extends Recipe {
+
+    @Override
+    public String getDisplayName() {
+        return "Remove LaunchDarkly's `boolVariation` for feature key";
+    }
+
+    @Override
+    public String getDescription() {
+        return "Replace `boolVariation` invocations for feature key with value, and simplify constant if branch execution.";
+    }
+
+    @Option(displayName = "Feature flag key",
+            description = "The key of the feature flag to remove.",
+            example = "flag-key-123abc")
+    String featureKey;
+
+    @Option(displayName = "Replacement value",
+            description = "The value to replace the feature flag check with.",
+            example = "topic-456")
+    String replacementValue;
+
+    @Override
+    public List<Recipe> getRecipeList() {
+        return Collections.singletonList(new RemoveStringFlag(
+                "com.launchdarkly.sdk.server.LDClient stringVariation(String, com.launchdarkly.sdk.*, String)",
+                featureKey, replacementValue));
+    }
+}

src/test/java/org/openrewrite/featureflags/RemoveBooleanFlagTest.java

@@ -16,6 +16,7 @@
 package org.openrewrite.featureflags;
 
 import org.junit.jupiter.api.Test;
+import org.openrewrite.DocumentExample;
 import org.openrewrite.Issue;
 import org.openrewrite.test.RewriteTest;
 import org.openrewrite.test.SourceSpec;
@@ -25,6 +26,7 @@
 class RemoveBooleanFlagTest implements RewriteTest {
 
     @Test
+    @DocumentExample
     void customMethodPatternForWrapper() {
         rewriteRun(
           spec -> spec.recipe(new RemoveBooleanFlag("com.acme.bank.CustomLaunchDarklyWrapper featureFlagEnabled(String, boolean)", "flag-key-123abc", true)),

src/test/java/org/openrewrite/featureflags/RemoveStringFlagTest.java

@@ -0,0 +1,104 @@
+/*
+ * Copyright 2024 the original author or authors.
+ * <p>
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * <p>
+ * https://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.openrewrite.featureflags;
+
+import org.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.Test;
+import org.openrewrite.DocumentExample;
+import org.openrewrite.java.JavaParser;
+import org.openrewrite.test.RecipeSpec;
+import org.openrewrite.test.RewriteTest;
+
+import static org.openrewrite.java.Assertions.java;
+
+class RemoveStringFlagTest implements RewriteTest {
+
+    @Override
+    public void defaults(RecipeSpec spec) {
+        spec.recipe(new RemoveStringFlag("com.acme.bank.InHouseFF getStringFeatureFlagValue(String, String)", "flag-key-123abc", "topic-456"))
+          // language=java
+          .parser(JavaParser.fromJavaVersion().dependsOn(
+            """
+              package com.acme.bank;
+              public class InHouseFF {
+                  public String getStringFeatureFlagValue(String key, String fallback) {
+                      return fallback;
+                  }
+              }
+              """
+          ));
+    }
+
+    @DocumentExample
+    @Test
+    void removeStringFeatureFlag() {
+        rewriteRun(
+          spec -> spec.recipe(new RemoveStringFlag("com.acme.bank.InHouseFF getStringFeatureFlagValue(String, String)", "flag-key-123abc", "topic-456")),
+          // language=java
+          java(
+            """
+              import com.acme.bank.InHouseFF;
+              class Foo {
+                  private InHouseFF inHouseFF = new InHouseFF();
+                  void bar() {
+                      String topic = inHouseFF.getStringFeatureFlagValue("flag-key-123abc", "topic-123");
+                      System.out.println("Publishing to topic: " + topic);
+                  }
+              }
+              """,
+            """
+              class Foo {
+                  void bar() {
+                      String topic = "topic-456";
+                      System.out.println("Publishing to topic: " + topic);
+                  }
+              }
+              """
+          )
+        );
+    }
+
+    @Disabled("This test is disabled because it is not yet implemented.")
+    @Test
+    void removeEqualsComparison() {
+        rewriteRun(
+          spec -> spec.recipe(new RemoveStringFlag("com.acme.bank.InHouseFF getStringFeatureFlagValue(String, String)", "flag-key-123abc", "topic-456")),
+          // language=java
+          java(
+            """
+              import com.acme.bank.InHouseFF;
+              class Foo {
+                  private InHouseFF inHouseFF = new InHouseFF();
+                  void bar() {
+                      if ("topic-456".equals(inHouseFF.getStringFeatureFlagValue("flag-key-123abc", "topic-123"))) {
+                          // Application code to show the feature
+                          System.out.println("Feature is on");
+                      }
+                  }
+              }
+              """,
+            """
+              class Foo {
+                  void bar() {
+                      // Application code to show the feature
+                      System.out.println("Feature is on");
+                  }
+              }
+              """
+          )
+        );
+    }
+}

src/test/java/org/openrewrite/featureflags/launchdarkly/RemoveStringVariationTest.java

@@ -0,0 +1,65 @@
+/*
+ * Copyright 2024 the original author or authors.
+ * <p>
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * <p>
+ * https://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.openrewrite.featureflags.launchdarkly;
+
+import org.junit.jupiter.api.Test;
+import org.openrewrite.DocumentExample;
+import org.openrewrite.InMemoryExecutionContext;
+import org.openrewrite.java.JavaParser;
+import org.openrewrite.test.RecipeSpec;
+import org.openrewrite.test.RewriteTest;
+
+import static org.openrewrite.java.Assertions.java;
+
+class RemoveStringVariationTest implements RewriteTest {
+
+    @Override
+    public void defaults(RecipeSpec spec) {
+        spec.recipe(new RemoveStringVariation("flag-key-123abc", "topic-456"))
+          .parser(JavaParser.fromJavaVersion()
+            .classpathFromResources(new InMemoryExecutionContext(), "launchdarkly-java-server-sdk-6"));
+    }
+
+    @Test
+    @DocumentExample
+    void replaceStringVariation() {
+        rewriteRun(
+          // language=java
+          java(
+            """
+              import com.launchdarkly.sdk.LDContext;
+              import com.launchdarkly.sdk.server.LDClient;
+              class Foo {
+                  private LDClient client = new LDClient("sdk-key-123abc");
+                  void bar() {
+                      LDContext context = null;
+                      String topic = client.stringVariation("flag-key-123abc", context, "topic-123");
+                      System.out.println("Publishing to topic: " + topic);
+                  }
+              }
+              """,
+            """
+              class Foo {
+                  void bar() {
+                      String topic = "topic-456";
+                      System.out.println("Publishing to topic: " + topic);
+                  }
+              }
+              """
+          )
+        );
+    }
+}