/*
 * Licensed 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.
 *
 * Copyright 2012-2018 the original author or authors.
 */
package org.assertj.core.util.diff;

import static org.assertj.core.util.Preconditions.checkState;

import java.util.List;

/**
 * Copy from https://code.google.com/p/java-diff-utils/.
 * <p>
 * Holds the information about the part of text involved in the diff process
 * 
 * <p>
 * Text is represented as <code>Object[]</code> because the diff engine is
 * capable of handling more than plain ascci. In fact, arrays or lists of any
 * type that implements {@link Object#hashCode hashCode()} and
 * {@link Object#equals equals()} correctly can be subject to
 * differencing using this library.
 * </p>
 * 
 * @author Dmitry Naumenko
 * @param <T> The type of the compared elements in the 'lines'.
 */
public class Chunk<T> {

  private final int position;
  private List<T> lines;

  /**
   * Creates a chunk and saves a copy of affected lines
   * 
   * @param position
   *            the start position
   * @param lines
   *            the affected lines
   */
  public Chunk(int position, List<T> lines) {
    this.position = position;
    this.lines = lines;
  }

  /**
   * Verifies that this chunk's saved text matches the corresponding text in
   * the given sequence.
   * 
   * @param target
   *            the sequence to verify against.
   */
  public void verify(List<T> target) throws IllegalStateException {
    checkState(last() <= target.size(), "Incorrect Chunk: the position of chunk > target size");
    for (int i = 0; i < size(); i++) {
      checkState(target.get(position + i).equals(lines.get(i)),
                 "Incorrect Chunk: the chunk content doesn't match the target");
    }
  }

  /**
   * @return the start position of chunk in the text
   */
  public int getPosition() {
    return position;
  }

  /**
   * @return the affected lines
   */
  public List<T> getLines() {
    return lines;
  }

  /**
   * Return the chunk size
   * @return the chunk size
   */
  public int size() {
    return lines.size();
  }

  /**
   * Returns the index of the last line of the chunk.
   * @return the index of the last line of the chunk.
   */
  public int last() {
    return getPosition() + size() - 1;
  }

  @Override
  public int hashCode() {
    final int prime = 31;
    int result = 1;
    result = prime * result + ((lines == null) ? 0 : lines.hashCode());
    result = prime * result + position;
    result = prime * result + size();
    return result;
  }

  @Override
  public boolean equals(Object obj) {
    if (this == obj)
      return true;
    if (obj == null)
      return false;
    if (getClass() != obj.getClass())
      return false;
    @SuppressWarnings("rawtypes")
    Chunk other = (Chunk) obj;
    if (lines == null) {
      if (other.lines != null)
        return false;
    } else if (!lines.equals(other.lines))
      return false;
    return position == other.position;
  }

  @Override
  public String toString() {
    return "[position: " + position + ", size: " + size() + ", lines: " + lines + "]";
  }

}
