/*
 * ====================================================================
 * Copyright (c) 2005-2012 sventon project. All rights reserved.
 *
 * This software is licensed as described in the file LICENSE, which
 * you should have received as part of this distribution. The terms
 * are also available at http://www.sventon.org.
 * If newer versions of this license are posted there, you may use a
 * newer version instead, at your option.
 * ====================================================================
 */
package org.sventon.diff;

import de.regnis.q.sequence.line.diff.QDiffGenerator;
import de.regnis.q.sequence.line.diff.QDiffManager;
import de.regnis.q.sequence.line.diff.QDiffNormalGenerator;
import de.regnis.q.sequence.line.diff.QDiffUniGenerator;

import java.io.*;
import java.util.HashMap;
import java.util.Map;

/**
 * Class for producing normal or unified diff results.
 *
 * @author jesper@sventon.org
 */
public final class DiffProducer {

  /**
   * Left (old) input.
   */
  private final InputStream left;

  /**
   * Right (new) input.
   */
  private final InputStream right;

  /**
   * Character encoding.
   */
  private final String encoding;

  private final Map generatorProperties = new HashMap();

  static {
    QDiffNormalGenerator.setup();
    QDiffUniGenerator.setup();
  }

  /**
   * Constructor.
   *
   * @param left     The left (old) InputStream.
   * @param right    The right (new) InputStream.
   * @param encoding Encoding to use.
   */
  public DiffProducer(final InputStream left, final InputStream right, final String encoding) {
    this(left, right, encoding, null);
  }

  /**
   * Constructor.
   *
   * @param left                The left (old) InputStream.
   * @param right               The right (new) InputStream.
   * @param encoding            Encoding to use.
   * @param generatorProperties Generator properties, see {@link de.regnis.q.sequence.line.diff.QDiffGeneratorFactory}.
   */
  public DiffProducer(final InputStream left, final InputStream right, final String encoding, final Map generatorProperties) {
    this.left = left;
    this.right = right;
    this.encoding = encoding;
    if (generatorProperties != null) {
      //noinspection unchecked
      this.generatorProperties.putAll(generatorProperties);
    }
  }

  /**
   * Performs a normal diff of given left and right.
   *
   * @param output Result output
   * @throws IOException if IO error occurs.
   */
  public void doNormalDiff(final OutputStream output) throws IOException {
    doDiff(output, QDiffNormalGenerator.TYPE);
  }

  /**
   * Performs a unified diff of given left and right.
   *
   * @param output Result output
   * @throws IOException if IO error occurs.
   */
  public void doUnifiedDiff(final OutputStream output) throws IOException {
    doDiff(output, QDiffUniGenerator.TYPE);
  }

  /**
   * Performs a diff of given left, right and type.
   *
   * @param output        Result output
   * @param generatorType {@link QDiffNormalGenerator#TYPE} or {@link QDiffUniGenerator#TYPE}
   * @throws IOException if IO error occurs.
   */
  private void doDiff(final OutputStream output, final String generatorType) throws IOException {
    final QDiffGenerator generator = QDiffManager.getDiffGenerator(generatorType, generatorProperties);
    final Writer writer = new OutputStreamWriter(output);
    QDiffManager.generateTextDiff(left, right, encoding, writer, generator);
    writer.flush();
    writer.close();
  }
}