/*
    * 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.generic;
  
  import java.io.DataOutputStream;
  import java.io.IOException;
  
  import org.apache.bcel.ExceptionConst;
  import org.apache.bcel.util.ByteSequence;
  
  /**
   * LDC - Push item from constant pool.
   *
   * <pre>
   * Stack: ... -&gt; ..., item
   * </pre>
   */
  public class LDC extends CPInstruction implements PushInstruction, ExceptionThrower {
  
      /**
       * Empty constructor needed for Instruction.readInstruction. Not to be used otherwise.
       */
      LDC() {
      }
  
      /**
       * Constructs an LDC instruction.
       *
       * @param index index into constant pool.
       */
      public LDC(final int index) {
          super(org.apache.bcel.Const.LDC_W, index);
          setSize();
      }
  
      /**
       * Call corresponding visitor method(s). The order is: Call visitor methods of implemented interfaces first, then call
       * methods according to the class hierarchy in descending order, that is, the most specific visitXXX() call comes last.
       *
       * @param v Visitor object.
       */
      @Override
      public void accept(final Visitor v) {
          v.visitStackProducer(this);
          v.visitPushInstruction(this);
          v.visitExceptionThrower(this);
          v.visitTypedInstruction(this);
          v.visitCPInstruction(this);
          v.visitLDC(this);
      }
  
      /**
       * Dumps instruction as byte code to stream out.
       *
       * @param out Output stream.
       */
      @Override
      public void dump(final DataOutputStream out) throws IOException {
          out.writeByte(super.getOpcode());
          if (super.getLength() == 2) { // TODO useless check?
              out.writeByte(super.getIndex());
          } else {
              out.writeShort(super.getIndex());
          }
      }
  
      @Override
      public Class<?>[] getExceptions() {
          return ExceptionConst.createExceptions(ExceptionConst.EXCS.EXCS_STRING_RESOLUTION);
      }
  
      @Override
      public Type getType(final ConstantPoolGen cpg) {
          switch (cpg.getConstantPool().getConstant(super.getIndex()).getTag()) {
          case org.apache.bcel.Const.CONSTANT_String:
              return Type.STRING;
          case org.apache.bcel.Const.CONSTANT_Float:
              return Type.FLOAT;
          case org.apache.bcel.Const.CONSTANT_Integer:
              return Type.INT;
          case org.apache.bcel.Const.CONSTANT_Class:
              return Type.CLASS;
          case org.apache.bcel.Const.CONSTANT_Dynamic:
             return Type.OBJECT;
         default: // Never reached
             throw new IllegalArgumentException("Unknown or invalid constant type at " + super.getIndex());
         }
     }
 
     /**
      * Gets the constant value from the constant pool.
      *
      * @param cpg constant pool generator.
      * @return The constant value.
      */
     public Object getValue(final ConstantPoolGen cpg) {
         org.apache.bcel.classfile.Constant c = cpg.getConstantPool().getConstant(super.getIndex());
         switch (c.getTag()) {
         case org.apache.bcel.Const.CONSTANT_String:
             final int i = ((org.apache.bcel.classfile.ConstantString) c).getStringIndex();
             c = cpg.getConstantPool().getConstant(i);
             return ((org.apache.bcel.classfile.ConstantUtf8) c).getBytes();
         case org.apache.bcel.Const.CONSTANT_Float:
             return Float.valueOf(((org.apache.bcel.classfile.ConstantFloat) c).getBytes());
         case org.apache.bcel.Const.CONSTANT_Integer:
             return Integer.valueOf(((org.apache.bcel.classfile.ConstantInteger) c).getBytes());
         case org.apache.bcel.Const.CONSTANT_Class:
             final int nameIndex = ((org.apache.bcel.classfile.ConstantClass) c).getNameIndex();
             c = cpg.getConstantPool().getConstant(nameIndex);
             return Type.getType(Type.internalTypeNameToSignature(((org.apache.bcel.classfile.ConstantUtf8) c).getBytes()));
         case org.apache.bcel.Const.CONSTANT_Dynamic:
             // Really not sure what to return here, maybe a BootstrapMethod instance but how do we get it?
             return c;
         default: // Never reached
             throw new IllegalArgumentException("Unknown or invalid constant type at " + super.getIndex());
         }
     }
 
     /**
      * Reads needed data (for example index) from file.
      */
     @Override
     protected void initFromFile(final ByteSequence bytes, final boolean wide) throws IOException {
         super.setLength(2);
         super.setIndex(bytes.readUnsignedByte());
     }
 
     /**
      * Sets the index to constant pool and adjust size.
      */
     @Override
     public final void setIndex(final int index) {
         super.setIndex(index);
         setSize();
     }
 
     /**
      * Adjusts to proper size.
      */
     protected final void setSize() {
         if (super.getIndex() <= org.apache.bcel.Const.MAX_BYTE) { // Fits in one byte?
             super.setOpcode(org.apache.bcel.Const.LDC);
             super.setLength(2);
         } else {
             super.setOpcode(org.apache.bcel.Const.LDC_W);
             super.setLength(3);
         }
     }
 }