legado/book/src/main/java/me/ag2s/epublib/domain/Identifier.java

package me.ag2s.epublib.domain;

import java.io.Serializable;
import java.util.List;
import java.util.UUID;

import me.ag2s.epublib.util.StringUtil;

/**
 * A Book's identifier.
 *
 * Defaults to a random UUID and scheme "UUID"
 *
 * @author paul
 */
public class Identifier implements Serializable {

  private static final long serialVersionUID = 955949951416391810L;
  @SuppressWarnings("unused")
  public interface Scheme {

    String UUID = "UUID";
    String ISBN = "ISBN";
    String URL = "URL";
    String URI = "URI";
  }

  private boolean bookId = false;
  private String scheme;
  private String value;

  /**
   * Creates an Identifier with as value a random UUID and scheme "UUID"
   */
  public Identifier() {
    this(Scheme.UUID, UUID.randomUUID().toString());
  }


  public Identifier(String scheme, String value) {
    this.scheme = scheme;
    this.value = value;
  }

  /**
   * The first identifier for which the bookId is true is made the
   * bookId identifier.
   *
   * If no identifier has bookId == true then the first bookId identifier
   * is written as the primary.
   *
   * @param identifiers i
   * @return The first identifier for which the bookId is true is made
   * 		the bookId identifier.
   */
  public static Identifier getBookIdIdentifier(List<Identifier> identifiers) {
    if (identifiers == null || identifiers.isEmpty()) {
      return null;
    }

    Identifier result = null;
    for (Identifier identifier : identifiers) {
      if (identifier.isBookId()) {
        result = identifier;
        break;
      }
    }

    if (result == null) {
      result = identifiers.get(0);
    }

    return result;
  }

  public String getScheme() {
    return scheme;
  }

  public void setScheme(String scheme) {
    this.scheme = scheme;
  }

  public String getValue() {
    return value;
  }

  public void setValue(String value) {
    this.value = value;
  }


  public void setBookId(boolean bookId) {
    this.bookId = bookId;
  }


  /**
   * This bookId property allows the book creator to add multiple ids and
   * tell the epubwriter which one to write out as the bookId.
   *
   * The Dublin Core metadata spec allows multiple identifiers for a Book.
   * The epub spec requires exactly one identifier to be marked as the book id.
   *
   * @return whether this is the unique book id.
   */
  public boolean isBookId() {
    return bookId;
  }

  public int hashCode() {
    return StringUtil.defaultIfNull(scheme).hashCode() ^ StringUtil
        .defaultIfNull(value).hashCode();
  }

  public boolean equals(Object otherIdentifier) {
    if (!(otherIdentifier instanceof Identifier)) {
      return false;
    }
    return StringUtil.equals(scheme, ((Identifier) otherIdentifier).scheme)
        && StringUtil.equals(value, ((Identifier) otherIdentifier).value);
  }
  @SuppressWarnings("NullableProblems")
  @Override
  public String toString() {
    if (StringUtil.isBlank(scheme)) {
      return "" + value;
    }
    return "" + scheme + ":" + value;
  }
}