/*
    * 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;
  
  /**
   * This class is derived from <em>Attribute</em> and represents the list of modules required, exported, opened or
   * provided by a module. There may be at most one Module attribute in a ClassFile structure.
   *
   * @see Attribute
   * @since 6.4.0
   */
  public final class Module extends Attribute {
  
      /**
       * The module file name extension.
       *
       * @since 6.7.0
       */
      public static final String EXTENSION = ".jmod";
  
      private static String getClassNameAtIndex(final ConstantPool cp, final int index, final boolean compactClassName) {
          final String className = cp.getConstantString(index, Const.CONSTANT_Class);
          if (compactClassName) {
              return Utility.compactClassName(className, false);
          }
          return className;
      }
      private final int moduleNameIndex;
      private final int moduleFlags;
  
      private final int moduleVersionIndex;
      private ModuleRequires[] requiresTable;
      private ModuleExports[] exportsTable;
      private ModuleOpens[] opensTable;
      private final int usesCount;
      private final int[] usesIndex;
  
      private ModuleProvides[] providesTable;
  
      /**
       * Constructs object from input stream.
       *
       * @param nameIndex Index in constant pool.
       * @param length Content length in bytes.
       * @param dataInput Input stream.
       * @param constantPool Array of constants.
       * @throws IOException if an I/O error occurs.
       */
      Module(final int nameIndex, final int length, final DataInput dataInput, final ConstantPool constantPool) throws IOException {
          super(Const.ATTR_MODULE, nameIndex, length, constantPool);
  
          moduleNameIndex = dataInput.readUnsignedShort();
          moduleFlags = dataInput.readUnsignedShort();
          moduleVersionIndex = dataInput.readUnsignedShort();
  
          final int requiresCount = dataInput.readUnsignedShort();
          requiresTable = new ModuleRequires[requiresCount];
          for (int i = 0; i < requiresCount; i++) {
              requiresTable[i] = new ModuleRequires(dataInput);
          }
  
          final int exportsCount = dataInput.readUnsignedShort();
          exportsTable = new ModuleExports[exportsCount];
          for (int i = 0; i < exportsCount; i++) {
              exportsTable[i] = new ModuleExports(dataInput);
          }
  
          final int opensCount = dataInput.readUnsignedShort();
          opensTable = new ModuleOpens[opensCount];
          for (int i = 0; i < opensCount; i++) {
              opensTable[i] = new ModuleOpens(dataInput);
          }
  
          usesIndex = ClassParser.readU2U2Table(dataInput);
          usesCount = usesIndex.length;
 
         final int providesCount = dataInput.readUnsignedShort();
         providesTable = new ModuleProvides[providesCount];
         for (int i = 0; i < providesCount; i++) {
             providesTable[i] = new ModuleProvides(dataInput);
         }
     }
 
     /**
      * 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.visitModule(this);
     }
 
     /**
      * @return deep copy of this attribute.
      */
     @Override
     public Attribute copy(final ConstantPool constantPool) {
         final Module c = (Module) clone();
 
         c.requiresTable = new ModuleRequires[requiresTable.length];
         Arrays.setAll(c.requiresTable, i -> requiresTable[i].copy());
 
         c.exportsTable = new ModuleExports[exportsTable.length];
         Arrays.setAll(c.exportsTable, i -> exportsTable[i].copy());
 
         c.opensTable = new ModuleOpens[opensTable.length];
         Arrays.setAll(c.opensTable, i -> opensTable[i].copy());
 
         c.providesTable = new ModuleProvides[providesTable.length];
         Arrays.setAll(c.providesTable, i -> providesTable[i].copy());
 
         c.setConstantPool(constantPool);
         return c;
     }
 
     /**
      * Dumps Module attribute to file stream in binary format.
      *
      * @param file Output file stream.
      * @throws IOException if an I/O error occurs.
      */
     @Override
     public void dump(final DataOutputStream file) throws IOException {
         super.dump(file);
 
         file.writeShort(moduleNameIndex);
         file.writeShort(moduleFlags);
         file.writeShort(moduleVersionIndex);
 
         file.writeShort(requiresTable.length);
         for (final ModuleRequires entry : requiresTable) {
             entry.dump(file);
         }
 
         file.writeShort(exportsTable.length);
         for (final ModuleExports entry : exportsTable) {
             entry.dump(file);
         }
 
         file.writeShort(opensTable.length);
         for (final ModuleOpens entry : opensTable) {
             entry.dump(file);
         }
 
         file.writeShort(usesIndex.length);
         for (final int entry : usesIndex) {
             file.writeShort(entry);
         }
 
         file.writeShort(providesTable.length);
         for (final ModuleProvides entry : providesTable) {
             entry.dump(file);
         }
     }
 
     /**
      * @return table of exported interfaces.
      * @see ModuleExports
      */
     public ModuleExports[] getExportsTable() {
         return exportsTable;
     }
 
     /**
      * Gets flags for this module.
      *
      * @return module flags.
      * @since 6.10.0
      */
     public int getModuleFlags() {
         return moduleFlags;
     }
 
     /**
      * Gets module name.
      *
      * @param cp Array of constants.
      * @return module name.
      * @since 6.10.0
      */
     public String getModuleName(final ConstantPool cp) {
         return cp.getConstantString(moduleNameIndex, Const.CONSTANT_Module);
     }
 
     /**
      * @return table of provided interfaces.
      * @see ModuleOpens
      */
     public ModuleOpens[] getOpensTable() {
         return opensTable;
     }
 
     /**
      * @return table of provided interfaces.
      * @see ModuleProvides
      */
     public ModuleProvides[] getProvidesTable() {
         return providesTable;
     }
 
     /**
      * @return table of required modules.
      * @see ModuleRequires
      */
     public ModuleRequires[] getRequiresTable() {
         return requiresTable;
     }
 
     /**
      * Gets the array of class names for this module's uses.
      *
      * @param constantPool Array of constants usually obtained from the ClassFile object.
      * @param compactClassName false for original constant pool value, true to replace '/' with '.'.
      * @return array of used class names.
      * @since 6.10.0
      */
     public String[] getUsedClassNames(final ConstantPool constantPool, final boolean compactClassName) {
         final String[] usedClassNames = new String[usesCount];
         for (int i = 0; i < usesCount; i++) {
             usedClassNames[i] = getClassNameAtIndex(constantPool, usesIndex[i], compactClassName);
         }
         return usedClassNames;
     }
 
     /**
      * Gets version for this module.
      *
      * @param cp Array of constants.
      * @return version from constant pool, "0" if version index is 0.
      * @since 6.10.0
      */
     public String getVersion(final ConstantPool cp) {
         return moduleVersionIndex == 0 ? "0" : cp.getConstantString(moduleVersionIndex, Const.CONSTANT_Utf8);
     }
 
     /**
      * @return String representation, that is, a list of packages.
      */
     @Override
     public String toString() {
         final ConstantPool cp = super.getConstantPool();
         final StringBuilder buf = new StringBuilder();
         buf.append("Module:\n");
         buf.append("  name:    ").append(Utility.pathToPackage(getModuleName(cp))).append("\n");
         buf.append("  flags:   ").append(String.format("%04x", moduleFlags)).append("\n");
         final String version = getVersion(cp);
         buf.append("  version: ").append(version).append("\n");
 
         buf.append("  requires(").append(requiresTable.length).append("):\n");
         for (final ModuleRequires module : requiresTable) {
             buf.append("    ").append(module.toString(cp)).append("\n");
         }
 
         buf.append("  exports(").append(exportsTable.length).append("):\n");
         for (final ModuleExports module : exportsTable) {
             buf.append("    ").append(module.toString(cp)).append("\n");
         }
 
         buf.append("  opens(").append(opensTable.length).append("):\n");
         for (final ModuleOpens module : opensTable) {
             buf.append("    ").append(module.toString(cp)).append("\n");
         }
 
         buf.append("  uses(").append(usesIndex.length).append("):\n");
         for (final int index : usesIndex) {
             final String className = getClassNameAtIndex(cp, index, true);
             buf.append("    ").append(className).append("\n");
         }
 
         buf.append("  provides(").append(providesTable.length).append("):\n");
         for (final ModuleProvides module : providesTable) {
             buf.append("    ").append(module.toString(cp)).append("\n");
         }
 
         return buf.substring(0, buf.length() - 1); // remove the last newline
     }
 }