// Path: java/core/src/main/java/eu/mais_h/mathsync/digest/Digester.java
// public interface Digester {
// 
//   /**
//    * Digests an item serialized as an array of bytes.
//    *
//    * <p>Any byte array value must be accepted and have a non <code>null</code> return value: for any <code>a</code>,
//    * <code>digest(a) != null</code>.</p>
//    *
//    * <p>All valid inputs should produce in output an array of the same size:for any <code>a1</code> and
//    * <code>a2</code>, <code>digest(a1).length == digest(a2).length</code>.</p>
//    *
//    * <p>The output must be consistent, an identical output should be returned if called twice on the same array: for
//    * any <code>a1</code> and <code>a2</code>, <code>Arrays.equals(a1, a2)</code> implies
//    * <code>Arrays.equals(digest(a1), digest(a2))</code>.</p>
//    *
//    * <p>In addition to those constrains, it is recommended that it has the properties of a
//    * <a href="http://en.wikipedia.org/wiki/Cryptographic_hash_function">cryptographic hash function</a>.</p>
//    *
//    * @param source the item serialized as an array of bytes.
//    * @return the message digest of the item.
//    * @throws IllegalArgumentException if the input array is <code>null</code>.
//    */
//   byte[] digest(byte[] source);
// }
// 
// Path: java/core/src/main/java/eu/mais_h/mathsync/digest/Sha1Digester.java
// public class Sha1Digester implements Digester {
// 
//   private static final String DIGEST_ALGORITHM = "SHA-1";
//   private static final Sha1Digester INSTANCE = new Sha1Digester();
// 
//   private Sha1Digester() {
//   }
// 
//   /**
//    * Digests according to SHA-1 specification.
//    */
//   @Override
//   public byte[] digest(byte[] source) {
//     if (source == null) {
//       throw new IllegalArgumentException("Cannot digest null source");
//     }
// 
//     MessageDigest md;
//     try {
//       md = MessageDigest.getInstance(DIGEST_ALGORITHM);
//     } catch (NoSuchAlgorithmException e) {
//       throw new AssertionError("JVM does not support " + DIGEST_ALGORITHM + " algorithm", e);
//     }
//     md.update(source);
//     return md.digest();
//   }
// 
//   @Override
//   public String toString() {
//     return DIGEST_ALGORITHM;
//   }
// 
//   /**
//    * Retrieves an instance of this digester kind.
//    *
//    * @return an instance of this digester kind.
//    */
//   public static Sha1Digester get() {
//     return INSTANCE;
//   }
// }
// 
// Path: java/core/src/main/java/eu/mais_h/mathsync/serialize/Serializer.java
// public interface Serializer<T> {
// 
//   /**
//    * Serializes an object to an array of byte.
//    *
//    * <p>Any instance of <code>T</code> must be accepted and have a non <code>null</code> return value:
//    * for any <code>o</code>, <code>o instanceof T</code> implies <code>serialize(o) != null</code>.</p>
//    *
//    * <p>The output must be consistent, an identical output should be returned if called twice on the equal
//    * objects: for any <code>o1</code> and <code>o2</code>, <code>o1.equals(o2)</code> implies
//    * <code>Arrays.equals(serialize(o1), serialize(o2))</code>.</p>
//    *
//    * @param item the object to serialize.
//    * @return the array of bytes representing the input object on the wire.
//    */
//   byte[] serialize(T item);
// }


import java.util.Iterator;
import java.util.Set;
import eu.mais_h.mathsync.digest.Digester;
import eu.mais_h.mathsync.digest.Sha1Digester;
import eu.mais_h.mathsync.serialize.Serializer;
package eu.mais_h.mathsync;



/**
 * Summarizer which iterates on items in the current state to build summaries.
 */
public class SummarizerFromItems implements Summarizer {

  private final SerializedItems items;
  private final Digester digester;
  private final BucketSelector selector;

  SummarizerFromItems(SerializedItems items, Digester digester, BucketSelector selector) {
    this.items = items;
    this.digester = digester;
    this.selector = selector;
  }

  /**
   * {@inheritDoc}
   *
   * <p>Summaries produced have a size of <code>O(2^level)</code>.</p>
   */
  @Override
  public Summary summarize(int level) {
    int size = Defaults.ibfSizeFromLevel(level);
    Summary empty;
    if (size > items.size()) {
      empty = FullContent.EMPTY;
    } else {
      empty = new Ibf(size, digester, selector);
    }
    Summary filled = empty.plus(items.iterator());
    return filled;
  }

  /**
   * Builds a simple summarizer.
   *
   * @param items the set of containing all items in the current state.
   * @param serializer the serializer to use to serialize items.
   * @return a summarizer with {@link Sha1Digester SHA-1 digester} and default spread.
   */
  public static <T> Summarizer simple(Set<? extends T> items, Serializer<? super T> serializer) {
    return custom(items, serializer, Sha1Digester.get(), Defaults.defaultSelector());
  }

  /**
   * Builds a custom summarizer.
   *
   * @param items the set of containing all items in the current state.
   * @param serializer the serializer to use to serialize items.
   * @param digester the custom digester to use.
   * @param selector the strategy to choose buckets to store items in.
   * @return a summarizer corresponding to the input.
   */
// Path: java/core/src/main/java/eu/mais_h/mathsync/digest/Digester.java
// public interface Digester {
// 
//   /**
//    * Digests an item serialized as an array of bytes.
//    *
//    * <p>Any byte array value must be accepted and have a non <code>null</code> return value: for any <code>a</code>,
//    * <code>digest(a) != null</code>.</p>
//    *
//    * <p>All valid inputs should produce in output an array of the same size:for any <code>a1</code> and
//    * <code>a2</code>, <code>digest(a1).length == digest(a2).length</code>.</p>
//    *
//    * <p>The output must be consistent, an identical output should be returned if called twice on the same array: for
//    * any <code>a1</code> and <code>a2</code>, <code>Arrays.equals(a1, a2)</code> implies
//    * <code>Arrays.equals(digest(a1), digest(a2))</code>.</p>
//    *
//    * <p>In addition to those constrains, it is recommended that it has the properties of a
//    * <a href="http://en.wikipedia.org/wiki/Cryptographic_hash_function">cryptographic hash function</a>.</p>
//    *
//    * @param source the item serialized as an array of bytes.
//    * @return the message digest of the item.
//    * @throws IllegalArgumentException if the input array is <code>null</code>.
//    */
//   byte[] digest(byte[] source);
// }
// 
// Path: java/core/src/main/java/eu/mais_h/mathsync/digest/Sha1Digester.java
// public class Sha1Digester implements Digester {
// 
//   private static final String DIGEST_ALGORITHM = "SHA-1";
//   private static final Sha1Digester INSTANCE = new Sha1Digester();
// 
//   private Sha1Digester() {
//   }
// 
//   /**
//    * Digests according to SHA-1 specification.
//    */
//   @Override
//   public byte[] digest(byte[] source) {
//     if (source == null) {
//       throw new IllegalArgumentException("Cannot digest null source");
//     }
// 
//     MessageDigest md;
//     try {
//       md = MessageDigest.getInstance(DIGEST_ALGORITHM);
//     } catch (NoSuchAlgorithmException e) {
//       throw new AssertionError("JVM does not support " + DIGEST_ALGORITHM + " algorithm", e);
//     }
//     md.update(source);
//     return md.digest();
//   }
// 
//   @Override
//   public String toString() {
//     return DIGEST_ALGORITHM;
//   }
// 
//   /**
//    * Retrieves an instance of this digester kind.
//    *
//    * @return an instance of this digester kind.
//    */
//   public static Sha1Digester get() {
//     return INSTANCE;
//   }
// }
// 
// Path: java/core/src/main/java/eu/mais_h/mathsync/serialize/Serializer.java
// public interface Serializer<T> {
// 
//   /**
//    * Serializes an object to an array of byte.
//    *
//    * <p>Any instance of <code>T</code> must be accepted and have a non <code>null</code> return value:
//    * for any <code>o</code>, <code>o instanceof T</code> implies <code>serialize(o) != null</code>.</p>
//    *
//    * <p>The output must be consistent, an identical output should be returned if called twice on the equal
//    * objects: for any <code>o1</code> and <code>o2</code>, <code>o1.equals(o2)</code> implies
//    * <code>Arrays.equals(serialize(o1), serialize(o2))</code>.</p>
//    *
//    * @param item the object to serialize.
//    * @return the array of bytes representing the input object on the wire.
//    */
//   byte[] serialize(T item);
// }


// Path: java/core/src/main/java/eu/mais_h/mathsync/SummarizerFromItems.java
import java.util.Iterator;
import java.util.Set;
import eu.mais_h.mathsync.digest.Digester;
import eu.mais_h.mathsync.digest.Sha1Digester;
import eu.mais_h.mathsync.serialize.Serializer;

package eu.mais_h.mathsync;



/**
 * Summarizer which iterates on items in the current state to build summaries.
 */
public class SummarizerFromItems implements Summarizer {

  private final SerializedItems items;
  private final Digester digester;
  private final BucketSelector selector;

  SummarizerFromItems(SerializedItems items, Digester digester, BucketSelector selector) {
    this.items = items;
    this.digester = digester;
    this.selector = selector;
  }

  /**
   * {@inheritDoc}
   *
   * <p>Summaries produced have a size of <code>O(2^level)</code>.</p>
   */
  @Override
  public Summary summarize(int level) {
    int size = Defaults.ibfSizeFromLevel(level);
    Summary empty;
    if (size > items.size()) {
      empty = FullContent.EMPTY;
    } else {
      empty = new Ibf(size, digester, selector);
    }
    Summary filled = empty.plus(items.iterator());
    return filled;
  }

  /**
   * Builds a simple summarizer.
   *
   * @param items the set of containing all items in the current state.
   * @param serializer the serializer to use to serialize items.
   * @return a summarizer with {@link Sha1Digester SHA-1 digester} and default spread.
   */
  public static <T> Summarizer simple(Set<? extends T> items, Serializer<? super T> serializer) {
    return custom(items, serializer, Sha1Digester.get(), Defaults.defaultSelector());
  }

  /**
   * Builds a custom summarizer.
   *
   * @param items the set of containing all items in the current state.
   * @param serializer the serializer to use to serialize items.
   * @param digester the custom digester to use.
   * @param selector the strategy to choose buckets to store items in.
   * @return a summarizer corresponding to the input.
   */
  public static <T> Summarizer custom(Set<? extends T> items, Serializer<? super T> serializer, Digester digester, BucketSelector selector) {