FileBuilder

/**
 * Portions of this software was developed by employees of the National Institute
 * of Standards and Technology (NIST), an agency of the Federal Government and is
 * being made available as a public service. Pursuant to title 17 United States
 * Code Section 105, works of NIST employees are not subject to copyright
 * protection in the United States. This software may be subject to foreign
 * copyright. Permission in the United States and in foreign countries, to the
 * extent that NIST may hold copyright, to use, copy, modify, create derivative
 * works, and distribute this software and its documentation without fee is hereby
 * granted on a non-exclusive basis, provided that this notice and disclaimer
 * of warranty appears in all copies.
 *
 * THE SOFTWARE IS PROVIDED 'AS IS' WITHOUT ANY WARRANTY OF ANY KIND, EITHER
 * EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING, BUT NOT LIMITED TO, ANY WARRANTY
 * THAT THE SOFTWARE WILL CONFORM TO SPECIFICATIONS, ANY IMPLIED WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, AND FREEDOM FROM
 * INFRINGEMENT, AND ANY WARRANTY THAT THE DOCUMENTATION WILL CONFORM TO THE
 * SOFTWARE, OR ANY WARRANTY THAT THE SOFTWARE WILL BE ERROR FREE.  IN NO EVENT
 * SHALL NIST BE LIABLE FOR ANY DAMAGES, INCLUDING, BUT NOT LIMITED TO, DIRECT,
 * INDIRECT, SPECIAL OR CONSEQUENTIAL DAMAGES, ARISING OUT OF, RESULTING FROM,
 * OR IN ANY WAY CONNECTED WITH THIS SOFTWARE, WHETHER OR NOT BASED UPON WARRANTY,
 * CONTRACT, TORT, OR OTHERWISE, WHETHER OR NOT INJURY WAS SUSTAINED BY PERSONS OR
 * PROPERTY OR OTHERWISE, AND WHETHER OR NOT LOSS WAS SUSTAINED FROM, OR AROSE OUT
 * OF THE RESULTS OF, OR USE OF, THE SOFTWARE OR SERVICES PROVIDED HEREUNDER.
 */

package gov.nist.secauto.swid.builder.resource.file;

import static gov.nist.secauto.swid.builder.util.Util.requireNonEmpty;

import gov.nist.secauto.swid.builder.resource.HashAlgorithm;
import gov.nist.secauto.swid.builder.resource.HashUtils;
import gov.nist.secauto.swid.builder.resource.ResourceCollectionEntryGenerator;

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.security.NoSuchAlgorithmException;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Objects;

public class FileBuilder extends AbstractFileSystemItemBuilder<FileBuilder> {
  private Long size;
  private String version;
  private Map<HashAlgorithm, byte[]> hashAlgorithmToValueMap = new LinkedHashMap<>();

  protected FileBuilder() {
    super();
  }

  @Override
  public void reset() {
    super.reset();
    this.size = null;
    this.version = null;
    this.hashAlgorithmToValueMap = new LinkedHashMap<>();
  }

  public static FileBuilder create() {
    return new FileBuilder();
  }

  @Override
  public <T> void accept(T parentContext, ResourceCollectionEntryGenerator<T> creator) {
    creator.generate(parentContext, this);
  }

  public Long getSize() {
    return size;
  }

  public String getVersion() {
    return version;
  }

  public Map<HashAlgorithm, byte[]> getHashAlgorithmToValueMap() {
    return hashAlgorithmToValueMap;
  }

  /**
   * Sets the to-be-built file's size to the provided value.
   *
   * @param size
   *          a non-zero integer indicating the file's size in bytes
   * @return the same builder instance
   */
  public FileBuilder size(long size) {
    if (size < 0) {
      throw new IllegalArgumentException("the size value must be a positive number");
    }
    this.size = size;
    return this;
  }

  /**
   * Sets the to-be-built file's hash value, for the provided algorithm, to the provided value. An
   * {@link InputStream} is used to retrieve the files contents to calculate the hash value. The
   * caller is resposnible for closing the stream used by this method.
   *
   * @param algorithm
   *          the algorithm to establish a hash value for
   * @param file
   *          the file to hash
   * @return the same builder instance
   * @throws NoSuchAlgorithmException
   *           if the hash algorithm is not supported
   * @throws IOException
   *           if an error occurs while reading the stream
   */
  public FileBuilder hash(HashAlgorithm algorithm, File file) throws NoSuchAlgorithmException, IOException {
    InputStream is = new BufferedInputStream(new FileInputStream(file));
    return hash(algorithm, is);
  }

  /**
   * Sets the file's hash value, for the provided algorithm, to the provided value. An
   * {@link InputStream} is used to retrieve the files contents to calculate the hash value. The
   * caller is responsible for closing the stream used by this method.
   *
   * @param algorithm
   *          the algorithm to establish a hash value for
   * @param is
   *          an {@link InputStream} that can be used to read the file
   * @return the same builder instance
   * @throws NoSuchAlgorithmException
   *           if the hash algorithm is not supported
   * @throws IOException
   *           if an error occurs while reading the stream
   */
  public FileBuilder hash(HashAlgorithm algorithm, InputStream is) throws NoSuchAlgorithmException, IOException {
    byte[] digest = HashUtils.hash(algorithm, is);
    return hash(algorithm, digest);
  }

  /**
   * Sets the file's hash value, for the provided algorithm, to the provided value.
   *
   * @param algorithm
   *          the algorithm to establish a hash value for
   * @param hashBytes
   *          the digest value as a byte array.
   * @return the same builder instance
   */
  public FileBuilder hash(HashAlgorithm algorithm, byte[] hashBytes) {
    Objects.requireNonNull(algorithm, "algorithm");
    Objects.requireNonNull(hashBytes, "hashBytes");
    hashAlgorithmToValueMap.put(algorithm, hashBytes);
    return this;
  }

  /**
   * Sets the file's hash value, for the provided algorithm, to the provided value.
   *
   * @param algorithm
   *          the algorithm to establish a hash value for
   * @param hashHexBytes
   *          the digest value as a hex string.
   * @return the same builder instance
   */
  public FileBuilder hash(HashAlgorithm algorithm, String hashHexBytes) {
    Objects.requireNonNull(algorithm, "algorithm");
    Objects.requireNonNull(hashHexBytes, "hashBytes");
    hashAlgorithmToValueMap.put(algorithm, HashUtils.toBytes(hashHexBytes));
    return this;
  }

  /**
   * Sets the to-be-built file's version to the provided value.
   *
   * @param version
   *          the version value to use
   * @return the same builder instance
   */
  public FileBuilder version(String version) {
    requireNonEmpty(version, "version");
    this.version = version;
    return this;
  }

}