/*
    * 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 java.util.Iterator;
  import java.util.stream.Stream;
  
  import org.apache.bcel.Const;
  import org.apache.bcel.util.Args;
  
  /**
   * This class represents colection of local variables in a method. This attribute is contained in the <em>Code</em>
   * attribute.
   *
   * @see Code
   * @see LocalVariable
   */
  public class LocalVariableTable extends Attribute implements Iterable<LocalVariable> {
  
      private static final LocalVariable[] EMPTY_ARRAY = {};
  
      private LocalVariable[] localVariableTable; // variables
  
      /**
       * Constructs object from input stream.
       *
       * @param nameIndex Index in constant pool.
       * @param length Content length in bytes.
       * @param input Input stream.
       * @param constantPool Array of constants.
       * @throws IOException Thrown if an I/O error occurs.
       */
      LocalVariableTable(final int nameIndex, final int length, final DataInput input, final ConstantPool constantPool) throws IOException {
          this(nameIndex, length, (LocalVariable[]) null, constantPool);
          final int localVariableTableLength = input.readUnsignedShort();
          localVariableTable = new LocalVariable[localVariableTableLength];
          for (int i = 0; i < localVariableTableLength; i++) {
              localVariableTable[i] = new LocalVariable(input, constantPool);
          }
      }
  
      /**
       * Constructs a new LocalVariableTable.
       *
       * @param nameIndex Index in constant pool to 'LocalVariableTable'.
       * @param length Content length in bytes.
       * @param localVariableTable Table of local variables.
       * @param constantPool Array of constants.
       */
      public LocalVariableTable(final int nameIndex, final int length, final LocalVariable[] localVariableTable, final ConstantPool constantPool) {
          super(Const.ATTR_LOCAL_VARIABLE_TABLE, nameIndex, length, constantPool);
          this.localVariableTable = localVariableTable != null ? localVariableTable : EMPTY_ARRAY;
          Args.requireU2(this.localVariableTable.length, "localVariableTable.length");
      }
  
      /**
       * Initialize from another object. Note that both objects use the same references (shallow copy). Use copy() for a
       * physical copy.
       *
       * @param c Source to copy.
       */
      public LocalVariableTable(final LocalVariableTable c) {
          this(c.getNameIndex(), c.getLength(), c.getLocalVariableTable(), c.getConstantPool());
      }
  
      /**
       * 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.visitLocalVariableTable(this);
      }
  
      /**
       * @return deep copy of this attribute.
       */
     @Override
     public Attribute copy(final ConstantPool constantPool) {
         final LocalVariableTable c = (LocalVariableTable) clone();
         c.localVariableTable = new LocalVariable[localVariableTable.length];
         Arrays.setAll(c.localVariableTable, i -> localVariableTable[i].copy());
         c.setConstantPool(constantPool);
         return c;
     }
 
     /**
      * Dumps local variable table attribute to file stream in binary format.
      *
      * @param file Output file stream.
      * @throws IOException Thrown if an I/O error occurs.
      */
     @Override
     public final void dump(final DataOutputStream file) throws IOException {
         super.dump(file);
         file.writeShort(Args.requireU2(localVariableTable.length, "localVariableTable.length"));
         for (final LocalVariable variable : localVariableTable) {
             variable.dump(file);
         }
     }
 
     /**
      * Gets the local variable for the given index.
      *
      * @param index The variable slot.
      * @return The first LocalVariable that matches the slot or null if not found.
      * @deprecated Since 5.2 because multiple variables can share the same slot, use getLocalVariable(int index, int pc) instead.
      */
     @java.lang.Deprecated
     public final LocalVariable getLocalVariable(final int index) {
         for (final LocalVariable variable : localVariableTable) {
             if (variable.getIndex() == index) {
                 return variable;
             }
         }
         return null;
     }
 
     /**
      * Gets the local variable for the given index and program counter.
      *
      * @param index The variable slot.
      * @param pc The current pc that this variable is alive.
      * @return The LocalVariable that matches or null if not found.
      */
     public final LocalVariable getLocalVariable(final int index, final int pc) {
         for (final LocalVariable variable : localVariableTable) {
             if (variable.getIndex() == index) {
                 final int startPc = variable.getStartPC();
                 final int endPc = startPc + variable.getLength();
                 if (pc >= startPc && pc < endPc) {
                     return variable;
                 }
             }
         }
         return null;
     }
 
     /**
      * Gets the local variable table.
      *
      * @return Array of local variables of method.
      */
     public final LocalVariable[] getLocalVariableTable() {
         return localVariableTable;
     }
 
     /**
      * Gets the table length.
      *
      * @return The table length.
      */
     public final int getTableLength() {
         return localVariableTable.length;
     }
 
     @Override
     public Iterator<LocalVariable> iterator() {
         return Stream.of(localVariableTable).iterator();
     }
 
     /**
      * Sets the local variable table.
      *
      * @param localVariableTable The local variable table to set.
      */
     public final void setLocalVariableTable(final LocalVariable[] localVariableTable) {
         this.localVariableTable = localVariableTable != null ? localVariableTable : EMPTY_ARRAY;
     }
 
     /**
      * @return String representation.
      */
     @Override
     public final String toString() {
         final StringBuilder buf = new StringBuilder();
         for (int i = 0; i < localVariableTable.length; i++) {
             buf.append(localVariableTable[i]);
             if (i < localVariableTable.length - 1) {
                 buf.append('\n');
             }
         }
         return buf.toString();
     }
 }