/*
 * Copyright 2015 Urs Metz
 *
 * 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
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * 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.pitest.mutationtest.engine.gregor.mutators;

import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.Opcodes;
import org.objectweb.asm.Type;
import org.pitest.mutationtest.engine.MutationIdentifier;
import org.pitest.mutationtest.engine.gregor.MethodInfo;
import org.pitest.mutationtest.engine.gregor.MethodMutatorFactory;
import org.pitest.mutationtest.engine.gregor.MutationContext;

/**
 * Mutator for non-void methods whos return type matches
 * the receiver's type that replaces the method call with the receiver.
 * E. g. the method call
 * <p/>
 * <pre>
 *   public int originalMethod() {
 *     String someString = "pit";
 *     return someString.toUpperCase();
 *   }
 * </pre>
 * <p/>
 * is mutated to
 * <p/>
 * <pre>
 *   public int mutatedMethod() {
 *     String someString = "pit";
 *     return someString;
 *   }
 * </pre>
 */
public enum NakedReceiverMutator implements MethodMutatorFactory {

  NAKED_RECEIVER;

  public MethodVisitor create(final MutationContext context,
      final MethodInfo methodInfo, final MethodVisitor methodVisitor) {
    return new ReplaceMethodCallWithObjectVisitor(context, methodVisitor, this);
  }

  public String getGloballyUniqueId() {
    return this.getClass().getName();
  }

  public String getName() {
    return name();
  }

  static class ReplaceMethodCallWithObjectVisitor extends MethodVisitor {

    private final MethodMutatorFactory factory;
    private final MutationContext      context;

    public ReplaceMethodCallWithObjectVisitor(final MutationContext context,
        final MethodVisitor writer, final MethodMutatorFactory factory) {
      super(Opcodes.ASM5, writer);
      this.factory = factory;
      this.context = context;
    }

    @Override
    public void visitMethodInsn(final int opcode, final String owner,
        final String name, final String desc, final boolean itf) {
      if (hasReturnTypeMatchingReceiverType(desc, owner)) {
        final MutationIdentifier newId = this.context
            .registerMutation(this.factory,
                "replaced call to " + owner + "::" + name + " with receiver");
      } else {
        this.mv.visitMethodInsn(opcode, owner, name, desc, itf);
      }
    }

    private boolean hasReturnTypeMatchingReceiverType(final String desc,
        String owner) {
      return Type.getObjectType(owner).equals(Type.getReturnType(desc));
    }

  }
}

@@ -1144,24 +1144,16 @@
 od call%0A
- * %3Cp/%3E%0A
  * %3Cpre%3E
@@ -1279,24 +1279,16 @@
  %3C/pre%3E%0A
- * %3Cp/%3E%0A
  * is mu
@@ -1300,16 +1300,8 @@
  to%0A
- * %3Cp/%3E%0A
  * %3C

Fix JavaDoc issues that make JDK8 build fail