/*
 * This program is free software; you can redistribute it and/or modify it under the
 * terms of the GNU Lesser General Public License, version 2.1 as published by the Free Software
 * Foundation.
 *
 * You should have received a copy of the GNU Lesser General Public License along with this
 * program; if not, you can obtain a copy at http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html
 * or from the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * 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 Lesser General Public License for more details.
 *
 * Copyright (c) 2001 - 2013 Object Refinery Ltd, Pentaho Corporation and Contributors..  All rights reserved.
 */

package org.pentaho.reporting.engine.classic.core.function;

import org.pentaho.reporting.engine.classic.core.event.ReportEvent;
import org.pentaho.reporting.engine.classic.core.states.ReportStateKey;
import org.pentaho.reporting.engine.classic.core.util.IntegerCache;

import java.io.IOException;
import java.io.ObjectInputStream;
import java.util.HashMap;

/**
 * A report function that counts the total of groups in a report. If a null-groupname is given, all groups are counted.
 * <p/>
 * A group can be defined using the property "group". If the group property is not set, all group starts get counted.
 *
 * @author Thomas Morgner
 */
public class TotalGroupCountFunction extends GroupCountFunction {
  /**
   * A map of results, keyed by the process-key.
   */
  private transient HashMap<ReportStateKey, Integer> results;
  /**
   * The currently computed result.
   */
  private transient Integer result;
  /**
   * The global state key is used to store the result for the whole report.
   */
  private transient ReportStateKey globalStateKey;
  /**
   * The current group key is used to store the result for the current group.
   */
  private transient ReportStateKey groupStateKey;

  /**
   * Default constructor.
   */
  public TotalGroupCountFunction() {
    results = new HashMap<ReportStateKey, Integer>();
  }

  /**
   * Receives notification that the report has started.
   *
   * @param event
   *          the event.
   */
  public void reportInitialized( final ReportEvent event ) {
    super.reportInitialized( event );
    globalStateKey = event.getState().getProcessKey();
    if ( FunctionUtilities.isDefinedPrepareRunLevel( this, event ) ) {
      results.clear();
      result = IntegerCache.getInteger( getCount() );
      results.put( globalStateKey, result );
    } else {
      result = results.get( globalStateKey );
    }
  }

  /**
   * Receives notification that a group has started.
   *
   * @param event
   *          the event.
   */
  public void groupStarted( final ReportEvent event ) {
    super.groupStarted( event );

    if ( FunctionUtilities.isDefinedGroup( getParentGroup(), event ) ) {
      groupStateKey = event.getState().getProcessKey();
      if ( FunctionUtilities.isDefinedPrepareRunLevel( this, event ) ) {
        result = IntegerCache.getInteger( getCount() );
        results.put( globalStateKey, result );
        results.put( groupStateKey, result );
        return;
      } else {
        // Activate the current group, which was filled in the prepare run.
        result = results.get( groupStateKey );
      }
    }

    final String definedGroupName = getGroup();
    if ( definedGroupName == null || FunctionUtilities.isDefinedGroup( definedGroupName, event ) ) {
      // count all groups...
      if ( FunctionUtilities.isDefinedPrepareRunLevel( this, event ) ) {
        result = IntegerCache.getInteger( getCount() );
        results.put( globalStateKey, result );
        results.put( groupStateKey, result );
      }
    }
  }

  /**
   * Returns the computed value.
   *
   * @return the computed value.
   */
  public Object getValue() {
    return result;
  }

  /**
   * Return a completly separated copy of this function. The copy does no longer share any changeable objects with the
   * original function.
   *
   * @return a copy of this function.
   */
  public Expression getInstance() {
    final TotalGroupCountFunction fn = (TotalGroupCountFunction) super.getInstance();
    fn.results = new HashMap<ReportStateKey, Integer>();
    return fn;
  }

  /**
   * Helper function for the serialization.
   *
   * @param in
   *          the input stream.
   * @throws IOException
   *           if an IO error occured.
   * @throws ClassNotFoundException
   *           if a required class could not be found.
   */
  private void readObject( final ObjectInputStream in ) throws IOException, ClassNotFoundException {
    in.defaultReadObject();
    this.results = new HashMap<ReportStateKey, Integer>();
  }

}