/*
    * 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 org.apache.bcel.Const;
  
  /**
   * This class represents an entry in the opens table of the Module attribute. Each entry describes a package which the
   * parent module opens.
   *
   * @see Module
   * @since 6.4.0
   */
  public final class ModuleOpens implements Cloneable, Node {
  
      private static String getToModuleNameAtIndex(final ConstantPool constantPool, final int index) {
          return constantPool.getConstantString(index, Const.CONSTANT_Module);
      }
      private final int opensIndex; // points to CONSTANT_Package_info
      private final int opensFlags;
      private final int opensToCount;
  
      private final int[] opensToIndex; // points to CONSTANT_Module_info
  
      /**
       * Constructs object from file stream.
       *
       * @param dataInput Input stream.
       * @throws IOException Thrown if an I/O Exception occurs in readUnsignedShort.
       */
      ModuleOpens(final DataInput dataInput) throws IOException {
          opensIndex = dataInput.readUnsignedShort();
          opensFlags = dataInput.readUnsignedShort();
          opensToIndex = ClassParser.readU2U2Table(dataInput);
          opensToCount = opensToIndex.length;
      }
  
      /**
       * 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.visitModuleOpens(this);
      }
  
      /**
       * Creates a deep copy of this object.
       *
       * @return deep copy of this object.
       */
      public ModuleOpens copy() {
          try {
              return (ModuleOpens) clone();
          } catch (final CloneNotSupportedException e) {
              // TODO should this throw?
          }
          return null;
      }
  
      /**
       * Dumps table entry to file stream in binary format.
       *
       * @param file Output file stream.
       * @throws IOException Thrown if an I/O Exception occurs in writeShort.
       */
      public void dump(final DataOutputStream file) throws IOException {
          file.writeShort(opensIndex);
          file.writeShort(opensFlags);
          file.writeShort(opensToCount);
          for (final int entry : opensToIndex) {
              file.writeShort(entry);
          }
      }
  
      /**
      * Gets the flags for this ModuleOpens.
      *
      * @return The opensFlags.
      * @since 6.10.0
      */
     public int getOpensFlags() {
         return opensFlags;
     }
 
     /**
      * Gets the opened package name.
      *
      * @param constantPool The constant pool from the ClassFile.
      * @return The opened package name.
      * @since 6.10.0
      */
     public String getPackageName(final ConstantPool constantPool) {
         return constantPool.constantToString(opensIndex, Const.CONSTANT_Package);
     }
 
     /**
      * Gets an array of module names for this ModuleOpens.
      *
      * @param constantPool Array of constants usually obtained from the ClassFile object.
      * @return array of module names following 'opens to'.
      * @since 6.10.0
      */
     public String[] getToModuleNames(final ConstantPool constantPool) {
         final String[] toModuleNames = new String[opensToCount];
         for (int i = 0; i < opensToCount; i++) {
             toModuleNames[i] = getToModuleNameAtIndex(constantPool, opensToIndex[i]);
         }
         return toModuleNames;
     }
 
     /**
      * @return String representation.
      */
     @Override
     public String toString() {
         return "opens(" + opensIndex + ", " + opensFlags + ", " + opensToCount + ", ...)";
     }
 
     /**
      * Gets the resolved string representation.
      *
      * @param constantPool The constant pool.
      * @return Resolved string representation.
      */
     public String toString(final ConstantPool constantPool) {
         final StringBuilder buf = new StringBuilder();
         final String packageName = getPackageName(constantPool);
         buf.append(packageName);
         buf.append(", ").append(String.format("%04x", opensFlags));
         buf.append(", to(").append(opensToCount).append("):\n");
         for (final int index : opensToIndex) {
             final String moduleName = getToModuleNameAtIndex(constantPool, index);
             buf.append("      ").append(moduleName).append("\n");
         }
         return buf.substring(0, buf.length() - 1); // remove the last newline
     }
 }