/*
    * 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
    *
    *      http://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 exports table of the Module attribute. Each entry describes a package which may
   * open the parent module.
   *
   * @see Module
   * @since 6.4.0
   */
  public final class ModuleExports implements Cloneable, Node {
  
      private static String getToModuleNameAtIndex(final ConstantPool constantPool, final int index) {
          return constantPool.getConstantString(index, Const.CONSTANT_Module);
      }
      private final int exportsIndex; // points to CONSTANT_Package_info
      private final int exportsFlags;
      private final int exportsToCount;
  
      private final int[] exportsToIndex; // points to CONSTANT_Module_info
  
      /**
       * Constructs object from file stream.
       *
       * @param file Input stream
       * @throws IOException if an I/O Exception occurs in readUnsignedShort
       */
      ModuleExports(final DataInput file) throws IOException {
          exportsIndex = file.readUnsignedShort();
          exportsFlags = file.readUnsignedShort();
          exportsToCount = file.readUnsignedShort();
          exportsToIndex = new int[exportsToCount];
          for (int i = 0; i < exportsToCount; i++) {
              exportsToIndex[i] = file.readUnsignedShort();
          }
      }
  
      /**
       * 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.visitModuleExports(this);
      }
  
      /**
       * @return deep copy of this object
       */
      public ModuleExports copy() {
          try {
              return (ModuleExports) clone();
          } catch (final CloneNotSupportedException e) {
              // TODO should this throw?
          }
          return null;
      }
  
      /**
       * Dump table entry to file stream in binary format.
       *
       * @param file Output file stream
       * @throws IOException if an I/O Exception occurs in writeShort
       */
      public void dump(final DataOutputStream file) throws IOException {
          file.writeShort(exportsIndex);
          file.writeShort(exportsFlags);
          file.writeShort(exportsToCount);
          for (final int entry : exportsToIndex) {
              file.writeShort(entry);
          }
      }
  
      /**
       * Gets the flags for this ModuleExports.
      * @return the exportsFlags
      * @since 6.10.0
      */
     public int getExportsFlags() {
         return exportsFlags;
     }
 
     /**
      * Gets the exported package name.
      * @param constantPool the constant pool from the ClassFile
      * @return the exported package name
      * @since 6.10.0
      */
     public String getPackageName(final ConstantPool constantPool) {
         return constantPool.constantToString(exportsIndex, Const.CONSTANT_Package);
     }
 
     /**
      * Gets an array of module names for this ModuleExports.
      * @param constantPool Array of constants usually obtained from the ClassFile object
      * @return array of module names following 'exports to'
      * @since 6.10.0
      */
     public String[] getToModuleNames(final ConstantPool constantPool) {
         final String[] toModuleNames = new String[exportsToCount];
         for (int i = 0; i < exportsToCount; i++) {
             toModuleNames[i] = getToModuleNameAtIndex(constantPool, exportsToIndex[i]);
         }
         return toModuleNames;
     }
 
     /**
      * @return String representation
      */
     @Override
     public String toString() {
         return "exports(" + exportsIndex + ", " + exportsFlags + ", " + exportsToCount + ", ...)";
     }
 
     /**
      * @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", exportsFlags));
         buf.append(", to(").append(exportsToCount).append("):\n");
         for (final int index : exportsToIndex) {
             final String moduleName = getToModuleNameAtIndex(constantPool, index);
             buf.append("      ").append(moduleName).append("\n");
         }
         return buf.substring(0, buf.length() - 1); // remove the last newline
     }
 }