/*
    * 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
    *
   *   https://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.bcel.classfile;
  
  import java.io.DataInput;
  import java.io.IOException;
  import java.util.Objects;
  
  import org.apache.bcel.generic.Type;
  import org.apache.bcel.util.BCELComparator;
  
  /**
   * This class represents the method info structure, that is, the representation for a method in the class. See JVM
   * specification for details. A method has access flags, a name, a signature and a number of attributes.
   */
  public final class Method extends FieldOrMethod {
  
      /**
       * Empty array constant.
       *
       * @since 6.6.0
       */
      public static final Method[] EMPTY_ARRAY = {};
  
      private static BCELComparator<Method> bcelComparator = new BCELComparator<Method>() {
  
          @Override
          public boolean equals(final Method a, final Method b) {
              return a == b || a != null && b != null && Objects.equals(a.getName(), b.getName()) && Objects.equals(a.getSignature(), b.getSignature());
          }
  
          @Override
          public int hashCode(final Method o) {
              return o != null ? Objects.hash(o.getSignature(), o.getName()) : 0;
          }
      };
  
      /**
       * Gets the comparison strategy object.
       *
       * @return Comparison strategy object.
       */
      public static BCELComparator<Method> getComparator() {
          return bcelComparator;
      }
  
      /**
       * Sets the comparison strategy object.
       *
       * @param comparator Comparison strategy object.
       */
      public static void setComparator(final BCELComparator<Method> comparator) {
          bcelComparator = comparator;
      }
  
      /** Annotations defined on the parameters of a method. */
      private ParameterAnnotationEntry[] parameterAnnotationEntries;
  
      /**
       * Empty constructor, all attributes have to be defined via 'setXXX' methods. Use at your own risk.
       */
      public Method() {
      }
  
      /**
       * Constructs object from file stream.
       *
       * @param file Input stream.
       * @throws IOException if an I/O error occurs.
       * @throws ClassFormatException if a class is malformed or cannot be interpreted as a class file.
       */
      Method(final DataInput file, final ConstantPool constantPool) throws IOException, ClassFormatException {
          super(file, constantPool);
      }
  
      /**
       * Constructs a Method.
       *
       * @param accessFlags Access rights of method.
       * @param nameIndex Points to field name in constant pool.
       * @param signatureIndex Points to encoded signature.
       * @param attributes Collection of attributes.
       * @param constantPool Array of constants.
      */
     public Method(final int accessFlags, final int nameIndex, final int signatureIndex, final Attribute[] attributes, final ConstantPool constantPool) {
         super(accessFlags, nameIndex, signatureIndex, attributes, constantPool);
     }
 
     /**
      * Initialize from another object. Note that both objects use the same references (shallow copy). Use clone() for a
      * physical copy.
      *
      * @param c Source to copy.
      */
     public Method(final Method c) {
         super(c);
     }
 
     /**
      * Called by objects that are traversing the nodes of the tree implicitly defined by the contents of a Java class.
      * I.e., the hierarchy of methods, fields, attributes, etc. spawns a tree of objects.
      *
      * @param v Visitor object.
      */
     @Override
     public void accept(final Visitor v) {
         v.visitMethod(this);
     }
 
     /**
      * Creates a deep copy of this method.
      *
      * @param constantPool the constant pool.
      * @return deep copy of this method.
      */
     public Method copy(final ConstantPool constantPool) {
         return (Method) copy_(constantPool);
     }
 
     /**
      * Return value as defined by given BCELComparator strategy. By default two method objects are said to be equal when
      * their names and signatures are equal.
      *
      * @see Object#equals(Object)
      */
     @Override
     public boolean equals(final Object obj) {
         return obj instanceof Method && bcelComparator.equals(this, (Method) obj);
     }
 
     /**
      * Gets array of method argument types.
      *
      * @return array of method argument types.
      */
     public Type[] getArgumentTypes() {
         return Type.getArgumentTypes(getSignature());
     }
 
     /**
      * Gets Code attribute of method, if any.
      *
      * @return Code attribute of method, if any.
      */
     public Code getCode() {
         for (final Attribute attribute : super.getAttributes()) {
             if (attribute instanceof Code) {
                 return (Code) attribute;
             }
         }
         return null;
     }
 
     /**
      * Gets ExceptionTable attribute of method, if any.
      *
      * @return ExceptionTable attribute of method, if any, that is, list all exceptions the method may throw not exception handlers.
      */
     public ExceptionTable getExceptionTable() {
         for (final Attribute attribute : super.getAttributes()) {
             if (attribute instanceof ExceptionTable) {
                 return (ExceptionTable) attribute;
             }
         }
         return null;
     }
 
     /**
      * Gets LineNumberTable of code attribute if any.
      *
      * @return LineNumberTable of code attribute if any, for example the call is forwarded to the Code attribute.
      */
     public LineNumberTable getLineNumberTable() {
         final Code code = getCode();
         if (code == null) {
             return null;
         }
         return code.getLineNumberTable();
     }
 
     /**
      * Gets LocalVariableTable of code attribute if any.
      *
      * @return LocalVariableTable of code attribute if any, for example the call is forwarded to the Code attribute.
      */
     public LocalVariableTable getLocalVariableTable() {
         final Code code = getCode();
         if (code == null) {
             return null;
         }
         return code.getLocalVariableTable();
     }
 
     /**
      * Gets the local variable type table attribute {@link LocalVariableTypeTable}.
      *
      * @return LocalVariableTypeTable of code attribute if any, for example the call is forwarded to the Code attribute.
      * @since 6.10.0
      */
     public LocalVariableTypeTable getLocalVariableTypeTable() {
         final Code code = getCode();
         if (code == null) {
             return null;
         }
         return code.getLocalVariableTypeTable();
     }
 
     /**
      * Gets Annotations on the parameters of a method.
      *
      * @return Annotations on the parameters of a method.
      * @since 6.0
      */
     public ParameterAnnotationEntry[] getParameterAnnotationEntries() {
         if (parameterAnnotationEntries == null) {
             parameterAnnotationEntries = ParameterAnnotationEntry.createParameterAnnotationEntries(getAttributes());
         }
         return parameterAnnotationEntries;
     }
 
     /**
      * Gets return type of method.
      *
      * @return return type of method.
      */
     public Type getReturnType() {
         return Type.getReturnType(getSignature());
     }
 
     /**
      * Return value as defined by given BCELComparator strategy. By default return the hash code of the method's name XOR
      * signature.
      *
      * @see Object#hashCode()
      */
     @Override
     public int hashCode() {
         return bcelComparator.hashCode(this);
     }
 
     /**
      * Return string representation close to declaration format, 'public static void main(String[] args) throws
      * IOException', for example.
      *
      * @return String representation of the method.
      */
     @Override
     public String toString() {
         final String access = Utility.accessToString(super.getAccessFlags());
         // Get name and signature from constant pool
         ConstantUtf8 c = super.getConstantPool().getConstantUtf8(super.getSignatureIndex());
         String signature = c.getBytes();
         c = super.getConstantPool().getConstantUtf8(super.getNameIndex());
         final String name = c.getBytes();
         signature = Utility.methodSignatureToString(signature, name, access, true, getLocalVariableTable());
         final StringBuilder buf = new StringBuilder(signature);
         for (final Attribute attribute : super.getAttributes()) {
             if (!(attribute instanceof Code || attribute instanceof ExceptionTable)) {
                 buf.append(" [").append(attribute).append("]");
             }
         }
         final ExceptionTable e = getExceptionTable();
         if (e != null) {
             final String str = e.toString();
             if (!str.isEmpty()) {
                 buf.append("\n\t\tthrows ").append(str);
             }
         }
         return buf.toString();
     }
 }