/*
    * 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;
  import org.apache.commons.lang3.SystemProperties;
  
  /**
   * This class represents a table of line numbers for debugging purposes. This attribute is used by the <em>Code</em>
   * attribute. It contains pairs of PCs and line numbers.
   *
   * @see Code
   * @see LineNumber
   */
  public final class LineNumberTable extends Attribute implements Iterable<LineNumber> {
  
      private static final int MAX_LINE_LENGTH = 72;
      private LineNumber[] lineNumberTable; // Table of line/numbers pairs
  
      /**
       * Constructs a new instance from a data input stream.
       *
       * @param nameIndex Index of name
       * @param length Content length in bytes
       * @param input Input stream
       * @param constantPool Array of constants
       * @throws IOException if an I/O Exception occurs in readUnsignedShort
       */
      LineNumberTable(final int nameIndex, final int length, final DataInput input, final ConstantPool constantPool) throws IOException {
          this(nameIndex, length, (LineNumber[]) null, constantPool);
          final int lineNumberTableLength = input.readUnsignedShort();
          lineNumberTable = new LineNumber[lineNumberTableLength];
          for (int i = 0; i < lineNumberTableLength; i++) {
              lineNumberTable[i] = new LineNumber(input);
          }
      }
  
      /**
       * Constructs a new instance.
       *
       * @param nameIndex Index of name
       * @param length Content length in bytes
       * @param lineNumberTable Table of line/numbers pairs
       * @param constantPool Array of constants
       */
      public LineNumberTable(final int nameIndex, final int length, final LineNumber[] lineNumberTable, final ConstantPool constantPool) {
          super(Const.ATTR_LINE_NUMBER_TABLE, nameIndex, length, constantPool);
          this.lineNumberTable = lineNumberTable != null ? lineNumberTable : LineNumber.EMPTY_ARRAY;
          Args.requireU2(this.lineNumberTable.length, "lineNumberTable.length");
      }
  
      /**
       * Constructs a new instance from another.
       * <p>
       * Note that both objects use the same references (shallow copy). Use copy() for a physical copy.
       * </p>
       */
      public LineNumberTable(final LineNumberTable c) {
          this(c.getNameIndex(), c.getLength(), c.getLineNumberTable(), 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.visitLineNumberTable(this);
      }
  
      /**
       * @return deep copy of this attribute
       */
     @Override
     public Attribute copy(final ConstantPool constantPool) {
         // TODO could use the lower level constructor and thereby allow
         // lineNumberTable to be made final
         final LineNumberTable c = (LineNumberTable) clone();
         c.lineNumberTable = new LineNumber[lineNumberTable.length];
         Arrays.setAll(c.lineNumberTable, i -> lineNumberTable[i].copy());
         c.setConstantPool(constantPool);
         return c;
     }
 
     /**
      * Dump line number table attribute to file stream in binary format.
      *
      * @param file Output file stream
      * @throws IOException if an I/O Exception occurs in writeShort
      */
     @Override
     public void dump(final DataOutputStream file) throws IOException {
         super.dump(file);
         file.writeShort(lineNumberTable.length);
         for (final LineNumber lineNumber : lineNumberTable) {
             lineNumber.dump(file);
         }
     }
 
     /**
      * @return Array of (pc offset, line number) pairs.
      */
     public LineNumber[] getLineNumberTable() {
         return lineNumberTable;
     }
 
     /**
      * Map byte code positions to source code lines.
      *
      * @param pos byte code offset
      * @return corresponding line in source code
      */
     public int getSourceLine(final int pos) {
         int l = 0;
         int r = lineNumberTable.length - 1;
         if (r < 0) {
             return -1;
         }
         int minIndex = -1;
         int min = -1;
         /*
          * Do a binary search since the array is ordered.
          */
         do {
             final int i = l + r >>> 1;
             final int j = lineNumberTable[i].getStartPC();
             if (j == pos) {
                 return lineNumberTable[i].getLineNumber();
             }
             if (pos < j) {
                 r = i - 1;
             } else {
                 l = i + 1;
             }
             /*
              * If exact match can't be found (which is the most common case) return the line number that corresponds to the greatest
              * index less than pos.
              */
             if (j < pos && j > min) {
                 min = j;
                 minIndex = i;
             }
         } while (l <= r);
         /*
          * It's possible that we did not find any valid entry for the bytecode offset we were looking for.
          */
         if (minIndex < 0) {
             return -1;
         }
         return lineNumberTable[minIndex].getLineNumber();
     }
 
     public int getTableLength() {
         return lineNumberTable.length;
     }
 
     @Override
     public Iterator<LineNumber> iterator() {
         return Stream.of(lineNumberTable).iterator();
     }
 
     /**
      * @param lineNumberTable the line number entries for this table
      */
     public void setLineNumberTable(final LineNumber[] lineNumberTable) {
         this.lineNumberTable = lineNumberTable != null ? lineNumberTable : LineNumber.EMPTY_ARRAY;
     }
 
     /**
      * @return String representation.
      */
     @Override
     public String toString() {
         final StringBuilder buf = new StringBuilder();
         final StringBuilder line = new StringBuilder();
         final String newLine = SystemProperties.getLineSeparator(() -> "\n");
         for (int i = 0; i < lineNumberTable.length; i++) {
             line.append(lineNumberTable[i].toString());
             if (i < lineNumberTable.length - 1) {
                 line.append(", ");
             }
             if (line.length() > MAX_LINE_LENGTH && i < lineNumberTable.length - 1) {
                 line.append(newLine);
                 buf.append(line);
                 line.setLength(0);
             }
         }
         buf.append(line);
         return buf.toString();
     }
 }