/*
    * 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.DataOutputStream;
  import java.io.IOException;
  import java.util.Arrays;
  
  import org.apache.bcel.Const;
  import org.apache.bcel.util.Args;
  import org.apache.commons.lang3.ArrayUtils;
  
  /**
   * This class represents the table of exceptions that are thrown by a method. This attribute may be used once per
   * method. The name of this class is <em>ExceptionTable</em> for historical reasons; The Java Virtual Machine
   * Specification, Second Edition defines this attribute using the name <em>Exceptions</em> (which is inconsistent with
   * the other classes).
   *
   * <pre>
   * Exceptions_attribute {
   *   u2 attribute_name_index;
   *   u4 attribute_length;
   *   u2 number_of_exceptions;
   *   u2 exception_index_table[number_of_exceptions];
   * }
   * </pre>
   *
   * @see Code
   */
  public final class ExceptionTable extends Attribute {
  
      private int[] exceptionIndexTable; // constant pool
  
      /**
       * Initialize from another object. Note that both objects use the same references (shallow copy). Use copy() for a
       * physical copy.
       *
       * @param c Source to copy.
       */
      public ExceptionTable(final ExceptionTable c) {
          this(c.getNameIndex(), c.getLength(), c.getExceptionIndexTable(), c.getConstantPool());
      }
  
      /**
       * Constructs object from input stream.
       *
       * @param nameIndex Index in constant pool.
       * @param length Content length in bytes.
       * @param input Input stream.
       * @param constantPool Array of constants.
       * @throws IOException if an I/O error occurs.
       */
      ExceptionTable(final int nameIndex, final int length, final DataInput input, final ConstantPool constantPool) throws IOException {
          this(nameIndex, length, (int[]) null, constantPool);
          exceptionIndexTable = ClassParser.readU2U2Table(input);
      }
  
      /**
       * Constructs an ExceptionTable.
       *
       * @param nameIndex Index in constant pool.
       * @param length Content length in bytes.
       * @param exceptionIndexTable Table of indices in constant pool.
       * @param constantPool Array of constants.
       */
      public ExceptionTable(final int nameIndex, final int length, final int[] exceptionIndexTable, final ConstantPool constantPool) {
          super(Const.ATTR_EXCEPTIONS, nameIndex, length, constantPool);
          this.exceptionIndexTable = ArrayUtils.nullToEmpty(exceptionIndexTable);
          Args.requireU2(this.exceptionIndexTable.length, "exceptionIndexTable.length");
      }
  
      /**
       * Called by objects that are traversing the nodes of the tree implicitly defined by the contents of a Java class.
       * That is, the hierarchy of methods, fields, attributes, and so on spawns a tree of objects.
       *
       * @param v Visitor object.
       */
      @Override
      public void accept(final Visitor v) {
          v.visitExceptionTable(this);
      }
 
     /**
      * Creates a deep copy of this attribute.
      *
      * @return deep copy of this attribute.
      */
     @Override
     public Attribute copy(final ConstantPool constantPool) {
         final ExceptionTable c = (ExceptionTable) clone();
         if (exceptionIndexTable != null) {
             c.exceptionIndexTable = exceptionIndexTable.clone();
         }
         c.setConstantPool(constantPool);
         return c;
     }
 
     /**
      * Dumps exceptions attribute to file stream in binary format.
      *
      * @param file Output file stream.
      * @throws IOException if an I/O error occurs.
      */
     @Override
     public void dump(final DataOutputStream file) throws IOException {
         super.dump(file);
         file.writeShort(exceptionIndexTable.length);
         for (final int index : exceptionIndexTable) {
             file.writeShort(index);
         }
     }
 
     /**
      * Gets the array of indices into constant pool of thrown exceptions.
      *
      * @return Array of indices into constant pool of thrown exceptions.
      */
     public int[] getExceptionIndexTable() {
         return exceptionIndexTable;
     }
 
     /**
      * Gets the class names of thrown exceptions.
      *
      * @return class names of thrown exceptions.
      */
     public String[] getExceptionNames() {
         final String[] names = new String[exceptionIndexTable.length];
         Arrays.setAll(names, i -> Utility.pathToPackage(super.getConstantPool().getConstantString(exceptionIndexTable[i], Const.CONSTANT_Class)));
         return names;
     }
 
     /**
      * Gets the length of exception table.
      *
      * @return Length of exception table.
      */
     public int getNumberOfExceptions() {
         return exceptionIndexTable == null ? 0 : exceptionIndexTable.length;
     }
 
     /**
      * Sets the exception index table.
      *
      * @param exceptionIndexTable the list of exception indexes Also redefines number_of_exceptions according to table
      *        length.
      */
     public void setExceptionIndexTable(final int[] exceptionIndexTable) {
         this.exceptionIndexTable = ArrayUtils.nullToEmpty(exceptionIndexTable);
     }
 
     /**
      * @return String representation, that is, a list of thrown exceptions.
      */
     @Override
     public String toString() {
         final StringBuilder buf = new StringBuilder();
         String str;
         buf.append("Exceptions: ");
         for (int i = 0; i < exceptionIndexTable.length; i++) {
             str = super.getConstantPool().getConstantString(exceptionIndexTable[i], Const.CONSTANT_Class);
             buf.append(Utility.compactClassName(str, false));
             if (i < exceptionIndexTable.length - 1) {
                 buf.append(", ");
             }
         }
         return buf.toString();
     }
 }