package de.lmu.ifi.dbs.elki.database.ids.integer;
/*
This file is part of ELKI:
Environment for Developing KDD-Applications Supported by Index-Structures

Copyright (C) 2011
Ludwig-Maximilians-Universität München
Lehr- und Forschungseinheit für Datenbanksysteme
ELKI Development Team

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU Affero General Public License for more details.

You should have received a copy of the GNU Affero General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

import java.util.concurrent.atomic.AtomicInteger;

import de.lmu.ifi.dbs.elki.database.ids.ArrayModifiableDBIDs;
import de.lmu.ifi.dbs.elki.database.ids.DBID;
import de.lmu.ifi.dbs.elki.database.ids.DBIDFactory;
import de.lmu.ifi.dbs.elki.database.ids.DBIDPair;
import de.lmu.ifi.dbs.elki.database.ids.DBIDs;
import de.lmu.ifi.dbs.elki.database.ids.HashSetModifiableDBIDs;
import de.lmu.ifi.dbs.elki.database.ids.DBIDRange;
import de.lmu.ifi.dbs.elki.database.ids.TreeSetModifiableDBIDs;
import de.lmu.ifi.dbs.elki.database.ids.generic.GenericArrayModifiableDBIDs;
import de.lmu.ifi.dbs.elki.database.ids.generic.GenericHashSetModifiableDBIDs;
import de.lmu.ifi.dbs.elki.database.ids.generic.GenericTreeSetModifiableDBIDs;
import de.lmu.ifi.dbs.elki.persistent.ByteBufferSerializer;
import de.lmu.ifi.dbs.elki.persistent.FixedSizeByteBufferSerializer;
import de.lmu.ifi.dbs.elki.utilities.exceptions.AbortException;

/**
 * Trivial DBID management, that never reuses IDs and just gives them out in sequence.
 * Statically allocated DBID ranges are given positive values,
 * Dynamically allocated DBIDs are given negative values.
 * 
 * @author Erich Schubert
 * 
 * @apiviz.landmark
 * @apiviz.stereotype factory
 * @apiviz.uses IntegerDBID oneway - - «create»
 * @apiviz.uses IntegerDBIDPair oneway - - «create»
 * @apiviz.uses IntegerDBIDRange oneway - - «create»
 * @apiviz.uses GenericArrayModifiableDBIDs oneway - - «create»
 * @apiviz.uses GenericHashSetModifiableDBIDs oneway - - «create»
 * @apiviz.uses GenericTreeSetModifiableDBIDs oneway - - «create»
 */
public class TrivialDBIDFactory implements DBIDFactory {
  /**
   * Keep track of the smallest dynamic DBID offset not used
   */
  AtomicInteger next = new AtomicInteger(1);
  
  /**
   * Constructor
   */
  public TrivialDBIDFactory() {
    super();
  }

  @Override
  public DBID generateSingleDBID() {
    final int id = next.getAndIncrement();
    if (id == Integer.MAX_VALUE) {
      throw new AbortException("DBID allocation error - too many objects allocated!");
    }
    DBID ret = new IntegerDBID(id);
    return ret;
  }

  @Override
  public void deallocateSingleDBID(@SuppressWarnings("unused") DBID id) {
    // ignore.
  }

  @Override
  public DBIDRange generateStaticDBIDRange(int size) {
    final int start = next.getAndAdd(size);
    if (start > next.get()) {
      throw new AbortException("DBID range allocation error - too many objects allocated!");
    }
    DBIDRange alloc = new IntegerDBIDRange(start, size);
    return alloc;
  }

  @Override
  public void deallocateDBIDRange(@SuppressWarnings("unused") DBIDRange range) {
    // ignore.
  }

  @Override
  public DBID importInteger(int id) {
    return new IntegerDBID(id);
  }

  @Override
  public ArrayModifiableDBIDs newArray() {
    return new GenericArrayModifiableDBIDs();
  }

  @Override
  public HashSetModifiableDBIDs newHashSet() {
    return new GenericHashSetModifiableDBIDs();
  }

  @Override
  public TreeSetModifiableDBIDs newTreeSet() {
    return new GenericTreeSetModifiableDBIDs();
  }

  @Override
  public ArrayModifiableDBIDs newArray(int size) {
    return new GenericArrayModifiableDBIDs(size);
  }

  @Override
  public HashSetModifiableDBIDs newHashSet(int size) {
    return new GenericHashSetModifiableDBIDs(size);
  }

  @Override
  public TreeSetModifiableDBIDs newTreeSet(int size) {
    return new GenericTreeSetModifiableDBIDs(size);
  }

  @Override
  public ArrayModifiableDBIDs newArray(DBIDs existing) {
    return new GenericArrayModifiableDBIDs(existing);
  }

  @Override
  public HashSetModifiableDBIDs newHashSet(DBIDs existing) {
    return new GenericHashSetModifiableDBIDs(existing);
  }

  @Override
  public TreeSetModifiableDBIDs newTreeSet(DBIDs existing) {
    return new GenericTreeSetModifiableDBIDs(existing);
  }

  @Override
  public DBIDPair makePair(DBID first, DBID second) {
    return new IntegerDBIDPair(first.getIntegerID(), second.getIntegerID());
  }

  @Override
  public ByteBufferSerializer<DBID> getDBIDSerializer() {
    return IntegerDBID.dynamicSerializer;
  }

  @Override
  public FixedSizeByteBufferSerializer<DBID> getDBIDSerializerStatic() {
    return IntegerDBID.staticSerializer;
  }

  @Override
  public Class<? extends DBID> getTypeRestriction() {
    return IntegerDBID.class;
  }
}