/*
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you 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.apache.maven.shared.dependency.analyzer.asm;
  
  import org.objectweb.asm.AnnotationVisitor;
  import org.objectweb.asm.Label;
  import org.objectweb.asm.MethodVisitor;
  import org.objectweb.asm.Opcodes;
  import org.objectweb.asm.Type;
  import org.objectweb.asm.TypePath;
  import org.objectweb.asm.signature.SignatureReader;
  import org.objectweb.asm.signature.SignatureVisitor;
  
  /**
   * Computes the set of classes referenced by visited code.
   * Inspired by <code>org.objectweb.asm.depend.DependencyVisitor</code> in the ASM dependencies example.
   *
   * @author <a href="mailto:markhobson@gmail.com">Mark Hobson</a>
   */
  public class DefaultMethodVisitor extends MethodVisitor {
      private final AnnotationVisitor annotationVisitor;
  
      private final SignatureVisitor signatureVisitor;
  
      private final ResultCollector resultCollector;
  
      /**
       * <p>Constructor for DefaultMethodVisitor.</p>
       *
       * @param annotationVisitor a {@link org.objectweb.asm.AnnotationVisitor} object.
       * @param signatureVisitor a {@link org.objectweb.asm.signature.SignatureVisitor} object.
       * @param resultCollector a {@link org.apache.maven.shared.dependency.analyzer.asm.ResultCollector} object.
       */
      public DefaultMethodVisitor(
              AnnotationVisitor annotationVisitor, SignatureVisitor signatureVisitor, ResultCollector resultCollector) {
          super(Opcodes.ASM9);
          this.annotationVisitor = annotationVisitor;
          this.signatureVisitor = signatureVisitor;
          this.resultCollector = resultCollector;
      }
  
      /** {@inheritDoc} */
      public AnnotationVisitor visitAnnotation(final String desc, final boolean visible) {
          resultCollector.addDesc(desc);
  
          return annotationVisitor;
      }
  
      /** {@inheritDoc} */
      @Override
      public AnnotationVisitor visitTypeAnnotation(int typeRef, TypePath typePath, String desc, boolean visible) {
          resultCollector.addDesc(desc);
  
          return annotationVisitor;
      }
  
      /** {@inheritDoc} */
      public AnnotationVisitor visitParameterAnnotation(final int parameter, final String desc, final boolean visible) {
          resultCollector.addDesc(desc);
  
          return annotationVisitor;
      }
  
      /** {@inheritDoc} */
      @Override
      public AnnotationVisitor visitLocalVariableAnnotation(
              int typeRef, TypePath typePath, Label[] start, Label[] end, int[] index, String desc, boolean visible) {
          resultCollector.addDesc(desc);
  
          return annotationVisitor;
      }
  
      /** {@inheritDoc} */
      public void visitTypeInsn(final int opcode, final String desc) {
          if (desc.charAt(0) == '[') {
              resultCollector.addDesc(desc);
          } else {
              resultCollector.addName(desc);
          }
      }
  
      /** {@inheritDoc} */
      public void visitFieldInsn(final int opcode, final String owner, final String name, final String desc) {
         resultCollector.addName(owner);
         /*
          * NOTE: Merely accessing a field does not impose a direct dependency on its type. For example, the code line
          * <code>java.lang.Object var = bean.field;</code> does not directly depend on the type of the field. A direct
          * dependency is only introduced when the code explicitly references the field's type by means of a variable
          * declaration or a type check/cast. Those cases are handled by other visitor callbacks.
          */
     }
 
     /** {@inheritDoc} */
     @Override
     public void visitMethodInsn(int opcode, String owner, String name, String desc, boolean itf) {
         resultCollector.addName(owner);
     }
 
     /** {@inheritDoc} */
     public void visitLdcInsn(final Object cst) {
         if (cst instanceof Type) {
             resultCollector.addType((Type) cst);
         }
     }
 
     /** {@inheritDoc} */
     public void visitMultiANewArrayInsn(final String desc, final int dims) {
         resultCollector.addDesc(desc);
     }
 
     /** {@inheritDoc} */
     public void visitTryCatchBlock(final Label start, final Label end, final Label handler, final String type) {
         resultCollector.addName(type);
     }
 
     /** {@inheritDoc} */
     public void visitLocalVariable(
             final String name,
             final String desc,
             final String signature,
             final Label start,
             final Label end,
             final int index) {
         if (signature == null) {
             resultCollector.addDesc(desc);
         } else {
             addTypeSignature(signature);
         }
     }
 
     private void addTypeSignature(final String signature) {
         if (signature != null) {
             new SignatureReader(signature).acceptType(signatureVisitor);
         }
     }
 }