/*
    * 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 a bootstrap method attribute, that is, the bootstrap method ref, the number of bootstrap arguments
   * and an array of the bootstrap arguments.
   *
   * @see <a href="https://docs.oracle.com/javase/specs/jvms/se8/html/jvms-4.html#jvms-4.7.23"> The class File Format :
   *      The BootstrapMethods Attribute</a>
   * @since 6.0
   */
  public class BootstrapMethod implements Cloneable {
  
      static final BootstrapMethod[] EMPTY_ARRAY = {};
  
      /** Index of the CONSTANT_MethodHandle_info structure in the constant_pool table */
      private int bootstrapMethodRef;
  
      /** Array of references to the constant_pool table */
      private int[] bootstrapArguments;
  
      /**
       * Initialize from another object.
       *
       * @param c Source to copy.
       */
      public BootstrapMethod(final BootstrapMethod c) {
          this(c.getBootstrapMethodRef(), c.getBootstrapArguments().clone());
      }
  
      /**
       * Constructs object from input stream.
       *
       * @param input Input stream.
       * @throws IOException Thrown if an I/O error occurs.
       */
      BootstrapMethod(final DataInput input) throws IOException {
          this(input.readUnsignedShort(), input.readUnsignedShort());
  
          for (int i = 0; i < bootstrapArguments.length; i++) {
              bootstrapArguments[i] = input.readUnsignedShort();
          }
      }
  
      // helper method
      private BootstrapMethod(final int bootstrapMethodRef, final int numBootstrapArguments) {
          this(bootstrapMethodRef, new int[numBootstrapArguments]);
      }
  
      /**
       * Constructs a BootstrapMethod.
       *
       * @param bootstrapMethodRef int index into constant_pool of CONSTANT_MethodHandle.
       * @param bootstrapArguments int[] indices into constant_pool of CONSTANT_[type]_info.
       */
      public BootstrapMethod(final int bootstrapMethodRef, final int[] bootstrapArguments) {
          this.bootstrapMethodRef = bootstrapMethodRef;
          setBootstrapArguments(bootstrapArguments);
      }
  
      /**
       * Creates a deep copy of this object.
       *
       * @return deep copy of this object.
       */
      public BootstrapMethod copy() {
          try {
              final BootstrapMethod c = (BootstrapMethod) clone();
              c.bootstrapArguments = bootstrapArguments.clone();
              return c;
          } catch (final CloneNotSupportedException ignore) {
              // TODO should this throw?
         }
         return null;
     }
 
     /**
      * Dumps object to file stream in binary format.
      *
      * @param file Output file stream.
      * @throws IOException Thrown if an I/O error occurs.
      */
     public final void dump(final DataOutputStream file) throws IOException {
         file.writeShort(bootstrapMethodRef);
         file.writeShort(Args.requireU2(bootstrapArguments.length, "bootstrapArguments.length"));
         for (final int bootstrapArgument : bootstrapArguments) {
             file.writeShort(bootstrapArgument);
         }
     }
 
     /**
      * Gets the bootstrap arguments.
      *
      * @return int[] of bootstrap_method indices into constant_pool of CONSTANT_[type]_info.
      */
     public int[] getBootstrapArguments() {
         return bootstrapArguments;
     }
 
     /**
      * Gets the bootstrap method reference.
      *
      * @return index into constant_pool of bootstrap_method.
      */
     public int getBootstrapMethodRef() {
         return bootstrapMethodRef;
     }
 
     /**
      * Gets the count of number of bootstrap arguments.
      *
      * @return count of number of bootstrap arguments.
      */
     public int getNumBootstrapArguments() {
         return bootstrapArguments.length;
     }
 
     /**
      * Sets the bootstrap arguments.
      *
      * @param bootstrapArguments int[] indices into constant_pool of CONSTANT_[type]_info.
      */
     public void setBootstrapArguments(final int[] bootstrapArguments) {
         this.bootstrapArguments = ArrayUtils.nullToEmpty(bootstrapArguments);
     }
 
     /**
      * Sets the bootstrap method reference.
      *
      * @param bootstrapMethodRef int index into constant_pool of CONSTANT_MethodHandle.
      */
     public void setBootstrapMethodRef(final int bootstrapMethodRef) {
         this.bootstrapMethodRef = bootstrapMethodRef;
     }
 
     /**
      * Gets a string representation.
      *
      * @return String representation.
      */
     @Override
     public final String toString() {
         return "BootstrapMethod(" + bootstrapMethodRef + ", " + bootstrapArguments.length + ", " + Arrays.toString(bootstrapArguments) + ")";
     }
 
     /**
      * Gets a resolved string representation.
      *
      * @param constantPool The constant pool.
      * @return Resolved string representation.
      */
     public final String toString(final ConstantPool constantPool) {
         final StringBuilder buf = new StringBuilder();
         final String bootstrapMethodName = constantPool.constantToString(bootstrapMethodRef, Const.CONSTANT_MethodHandle);
         buf.append(Utility.compactClassName(bootstrapMethodName, false));
         final int bootstrapArgumentsLen = bootstrapArguments.length;
         if (bootstrapArgumentsLen > 0) {
             buf.append("\nMethod Arguments:");
             for (int i = 0; i < bootstrapArgumentsLen; i++) {
                 buf.append("\n  ").append(i).append(": ");
                 buf.append(constantPool.constantToString(constantPool.getConstant(bootstrapArguments[i])));
             }
         }
         return buf.toString();
     }
 }