/*
    * 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.data;
  
  /*
   * This file is a modified copy of org.apache.bcel.classfile.ConstantPool.java.
   * It was chosen as it generates both tableswitch and lookupswitch byte codes.
   * It has been modified to compile stand alone within the BCEL test environment.
   * The code is not executed but the classfile is used as input to a BCEL test case.
   */
  
  import java.io.DataOutputStream;
  import java.io.IOException;
  
  import org.apache.bcel.Const;
  import org.apache.bcel.classfile.ClassFormatException;
  import org.apache.bcel.classfile.Constant;
  import org.apache.bcel.classfile.ConstantCP;
  import org.apache.bcel.classfile.ConstantClass;
  import org.apache.bcel.classfile.ConstantDouble;
  import org.apache.bcel.classfile.ConstantFloat;
  import org.apache.bcel.classfile.ConstantInteger;
  import org.apache.bcel.classfile.ConstantInvokeDynamic;
  import org.apache.bcel.classfile.ConstantLong;
  import org.apache.bcel.classfile.ConstantMethodHandle;
  import org.apache.bcel.classfile.ConstantMethodType;
  import org.apache.bcel.classfile.ConstantModule;
  import org.apache.bcel.classfile.ConstantNameAndType;
  import org.apache.bcel.classfile.ConstantPackage;
  import org.apache.bcel.classfile.ConstantString;
  import org.apache.bcel.classfile.ConstantUtf8;
  import org.apache.bcel.classfile.Node;
  import org.apache.bcel.classfile.Utility;
  
  /**
   * This class represents the constant pool, that is, a table of constants, of a parsed classfile. It may contain null
   * references, due to the JVM specification that skips an entry after an 8-byte constant (double, long) entry. Those
   * interested in generating constant pools programatically should see <a href="../generic/ConstantPoolGen.html">
   * ConstantPoolGen</a>.
   *
   * @see Constant
   * @see org.apache.bcel.generic.ConstantPoolGen
   */
  public abstract class ConstantPoolX implements Cloneable, Node {
  
      private static String escape(final String str) {
          final int len = str.length();
          final StringBuilder buf = new StringBuilder(len + 5);
          final char[] ch = str.toCharArray();
          for (int i = 0; i < len; i++) {
              switch (ch[i]) {
              case '\n':
                  buf.append("\\n");
                  break;
              case '\r':
                  buf.append("\\r");
                  break;
              case '\t':
                  buf.append("\\t");
                  break;
              case '\b':
                  buf.append("\\b");
                  break;
              case '"':
                  buf.append("\\\"");
                  break;
              default:
                  buf.append(ch[i]);
              }
          }
          return buf.toString();
      }
  
      private Constant[] constantPool;
  
      /**
       * Resolves constant to a string representation.
       *
       * @param c Constant to be printed.
       * @return String representation.
       */
      public String constantToString(Constant c) throws ClassFormatException {
          final String str;
         final int i;
         final byte tag = c.getTag();
         switch (tag) {
         case Const.CONSTANT_Class:
             i = ((ConstantClass) c).getNameIndex();
             c = getConstant(i, Const.CONSTANT_Utf8);
             str = Utility.compactClassName(((ConstantUtf8) c).getBytes(), false);
             break;
         case Const.CONSTANT_String:
             i = ((ConstantString) c).getStringIndex();
             c = getConstant(i, Const.CONSTANT_Utf8);
             str = "\"" + escape(((ConstantUtf8) c).getBytes()) + "\"";
             break;
         case Const.CONSTANT_Utf8:
             str = ((ConstantUtf8) c).getBytes();
             break;
         case Const.CONSTANT_Double:
             str = String.valueOf(((ConstantDouble) c).getBytes());
             break;
         case Const.CONSTANT_Float:
             str = String.valueOf(((ConstantFloat) c).getBytes());
             break;
         case Const.CONSTANT_Long:
             str = String.valueOf(((ConstantLong) c).getBytes());
             break;
         case Const.CONSTANT_Integer:
             str = String.valueOf(((ConstantInteger) c).getBytes());
             break;
         case Const.CONSTANT_NameAndType:
             str = constantToString(((ConstantNameAndType) c).getNameIndex(), Const.CONSTANT_Utf8) + " "
                 + constantToString(((ConstantNameAndType) c).getSignatureIndex(), Const.CONSTANT_Utf8);
             break;
         case Const.CONSTANT_InterfaceMethodref:
         case Const.CONSTANT_Methodref:
         case Const.CONSTANT_Fieldref:
             str = constantToString(((ConstantCP) c).getClassIndex(), Const.CONSTANT_Class) + "."
                 + constantToString(((ConstantCP) c).getNameAndTypeIndex(), Const.CONSTANT_NameAndType);
             break;
         case Const.CONSTANT_MethodHandle:
             // Note that the ReferenceIndex may point to a Fieldref, Methodref or
             // InterfaceMethodref - so we need to peek ahead to get the actual type.
             final ConstantMethodHandle cmh = (ConstantMethodHandle) c;
             str = Const.getMethodHandleName(cmh.getReferenceKind()) + " "
                 + constantToString(cmh.getReferenceIndex(), getConstant(cmh.getReferenceIndex()).getTag());
             break;
         case Const.CONSTANT_MethodType:
             final ConstantMethodType cmt = (ConstantMethodType) c;
             str = constantToString(cmt.getDescriptorIndex(), Const.CONSTANT_Utf8);
             break;
         case Const.CONSTANT_InvokeDynamic:
             final ConstantInvokeDynamic cid = (ConstantInvokeDynamic) c;
             str = cid.getBootstrapMethodAttrIndex() + ":" + constantToString(cid.getNameAndTypeIndex(), Const.CONSTANT_NameAndType);
             break;
         case Const.CONSTANT_Module:
             i = ((ConstantModule) c).getNameIndex();
             c = getConstant(i, Const.CONSTANT_Utf8);
             str = Utility.compactClassName(((ConstantUtf8) c).getBytes(), false);
             break;
         case Const.CONSTANT_Package:
             i = ((ConstantPackage) c).getNameIndex();
             c = getConstant(i, Const.CONSTANT_Utf8);
             str = Utility.compactClassName(((ConstantUtf8) c).getBytes(), false);
             break;
         default: // Never reached
             throw new IllegalArgumentException("Unknown constant type " + tag);
         }
         return str;
     }
 
     /**
      * Retrieves constant at 'index' from constant pool and resolve it to a string representation.
      *
      * @param index of constant in constant pool.
      * @param tag expected type.
      * @return String representation.
      */
     public String constantToString(final int index, final byte tag) throws ClassFormatException {
         final Constant c = getConstant(index, tag);
         return constantToString(c);
     }
 
     /**
      * Dumps constant pool to file stream in binary format.
      *
      * @param file Output file stream.
      * @throws IOException if an I/O error occurs.
      */
     public void dump(final DataOutputStream file) throws IOException {
         file.writeShort(constantPool.length);
         for (int i = 1; i < constantPool.length; i++) {
             if (constantPool[i] != null) {
                 constantPool[i].dump(file);
             }
         }
     }
 
     /**
      * Gets constant from constant pool.
      *
      * @param index Index in constant pool.
      * @return Constant value.
      * @see Constant
      */
     public Constant getConstant(final int index) {
         if (index >= constantPool.length || index < 0) {
             throw new ClassFormatException("Invalid constant pool reference: " + index + ". Constant pool size is: " + constantPool.length);
         }
         return constantPool[index];
     }
 
     /**
      * Gets constant from constant pool and check whether it has the expected type.
      *
      * @param index Index in constant pool.
      * @param tag Tag of expected constant, that is, its type.
      * @return Constant value.
      * @see Constant
      * @throws ClassFormatException
      */
     public Constant getConstant(final int index, final byte tag) throws ClassFormatException {
         final Constant c = getConstant(index);
         if (c == null) {
             throw new ClassFormatException("Constant pool at index " + index + " is null.");
         }
         if (c.getTag() != tag) {
             throw new ClassFormatException("Expected class '" + Const.getConstantName(tag) + "' at index " + index + " and got " + c);
         }
         return c;
     }
 
     /**
      * @return Array of constants.
      * @see Constant
      */
     public Constant[] getConstantPool() {
         return constantPool;
     }
 
     /**
      * Gets string from constant pool and bypass the indirection of 'ConstantClass' and 'ConstantString' objects. I.e. these
      * classes have an index field that points to another entry of the constant pool of type 'ConstantUtf8' which contains
      * the real data.
      *
      * @param index Index in constant pool.
      * @param tag Tag of expected constant, either ConstantClass or ConstantString.
      * @return Contents of string reference.
      * @see ConstantClass
      * @see ConstantString
      * @throws ClassFormatException
      */
     public String getConstantString(final int index, final byte tag) throws ClassFormatException {
         final int i;
         Constant c = getConstant(index, tag);
         /*
          * This switch() is not that elegant, since the four classes have the same contents, they just differ in the name of the
          * index field variable. But we want to stick to the JVM naming conventions closely though we could have solved these
          * more elegantly by using the same variable name or by subclassing.
          */
         switch (tag) {
         case Const.CONSTANT_Class:
             i = ((ConstantClass) c).getNameIndex();
             break;
         case Const.CONSTANT_String:
             i = ((ConstantString) c).getStringIndex();
             break;
         case Const.CONSTANT_Module:
             i = ((ConstantModule) c).getNameIndex();
             break;
         case Const.CONSTANT_Package:
             i = ((ConstantPackage) c).getNameIndex();
             break;
         default:
             throw new IllegalArgumentException("getConstantString called with illegal tag " + tag);
         }
         // Finally get the string from the constant pool
         c = getConstant(i, Const.CONSTANT_Utf8);
         return ((ConstantUtf8) c).getBytes();
     }
 
     /**
      * @return Length of constant pool.
      */
     public int getLength() {
         return constantPool == null ? 0 : constantPool.length;
     }
 
     /**
      * @param constant Constant to set.
      */
     public void setConstant(final int index, final Constant constant) {
         constantPool[index] = constant;
     }
 
     /**
      * @param constantPool.
      */
     public void setConstantPool(final Constant[] constantPool) {
         this.constantPool = constantPool;
     }
 
     /**
      * @return String representation.
      */
     @Override
     public String toString() {
         final StringBuilder buf = new StringBuilder();
         for (int i = 1; i < constantPool.length; i++) {
             buf.append(i).append(")").append(constantPool[i]).append("\n");
         }
         return buf.toString();
     }
 
 }