/*
 * 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.filter;

import org.pentaho.reporting.engine.classic.core.ReportElement;
import org.pentaho.reporting.engine.classic.core.function.ExpressionRuntime;

import java.text.DateFormatSymbols;
import java.text.Format;
import java.text.SimpleDateFormat;
import java.util.Locale;

/**
 * Parses a String into a java.util.Date. The string is read from the given datasource and then parsed by the dateformat
 * contained in this FormatParser.
 * <p/>
 * <p/>
 * If the object read from the datasource is no string, the value is converted to string using String.valueOf (Object)
 * <p/>
 * This implementation uses a SimpleDateFormat and grants more control over the parsing results.
 *
 * @author Thomas Morgner
 * @see java.text.SimpleDateFormat
 */
public class SimpleDateFormatParser extends DateFormatParser {
  /**
   * The last locale used to convert numbers.
   */
  private Locale lastLocale;
  /**
   * A flag indicating whether this filter should try to detect locales changes.
   */
  private boolean keepState;

  /**
   * DefaultConstructor.
   */
  public SimpleDateFormatParser() {
    setFormatter( new SimpleDateFormat() );
  }

  /**
   * Returns the SimpleDateFormat object used in this parser.
   *
   * @return The date format object.
   */
  public SimpleDateFormat getSimpleDateFormat() {
    return (SimpleDateFormat) getFormatter();
  }

  /**
   * Sets the date format for the parser.
   *
   * @param format
   *          The format.
   * @throws NullPointerException
   *           if the format given is null
   */
  public void setSimpleDateFormat( final SimpleDateFormat format ) {
    super.setFormatter( format );
  }

  /**
   * Sets the date format for the filter. This narrows the allows formats down to SimpleDateFormat.
   *
   * @param format
   *          The format.
   * @throws NullPointerException
   *           if the format given is null
   * @throws ClassCastException
   *           if the format given is no DateFormat
   */
  public void setFormatter( final Format format ) {
    final SimpleDateFormat sdfmt = (SimpleDateFormat) format;
    super.setFormatter( sdfmt );
  }

  /**
   * Returns the formatString for this SimpleDateFormat. For a more detailed explaination of SimpleDateFormat
   * formatstrings see java.text.SimpleDateFormat.
   *
   * @return the formatstring used for this DateFormat.
   * @see java.text.SimpleDateFormat
   */
  public String getFormatString() {
    return getSimpleDateFormat().toPattern();
  }

  /**
   * defines the formatString for this SimpleDateFormat.
   *
   * @param format
   *          the formatString
   * @throws IllegalArgumentException
   *           if the string is invalid
   */
  public void setFormatString( final String format ) {
    getSimpleDateFormat().applyPattern( format );
  }

  /**
   * Returns a localized formatString for this SimpleDateFormat. For a more detailed explaination of SimpleDateFormat
   * formatstrings see java.text.SimpleDateFormat.
   *
   * @return the localized format string.
   * @see java.text.SimpleDateFormat
   */
  public String getLocalizedFormatString() {
    return getSimpleDateFormat().toLocalizedPattern();
  }

  /**
   * defines the localized formatString for this SimpleDateFormat.
   *
   * @param format
   *          the formatString
   * @throws IllegalArgumentException
   *           if the string is invalid
   */
  public void setLocalizedFormatString( final String format ) {
    getSimpleDateFormat().applyLocalizedPattern( format );
  }

  /**
   * Defines, whether the filter should keep its state, if a locale change is detected. This will effectivly disable the
   * locale update.
   *
   * @return true, if the locale should not update the DateSymbols, false otherwise.
   */
  public boolean isKeepState() {
    return keepState;
  }

  /**
   * Defines, whether the filter should keep its state, if a locale change is detected. This will effectivly disable the
   * locale update.
   *
   * @param keepState
   *          set to true, if the locale should not update the DateSymbols, false otherwise.
   */
  public void setKeepState( final boolean keepState ) {
    this.keepState = keepState;
  }

  /**
   * Returns the formatted string. The value is read using the data source given and formated using the formatter of
   * this object. The formating is guaranteed to completly form the object to an string or to return the defined
   * NullValue.
   * <p/>
   * If format, datasource or object are null, the NullValue is returned.
   *
   * @param runtime
   *          the expression runtime that is used to evaluate formulas and expressions when computing the value of this
   *          filter.
   * @param element
   * @return The formatted value.
   */
  public Object getValue( final ExpressionRuntime runtime, final ReportElement element ) {
    if ( keepState == false && runtime != null ) {
      final Locale locale = runtime.getResourceBundleFactory().getLocale();
      if ( locale != null && locale.equals( lastLocale ) == false ) {
        lastLocale = locale;
        getSimpleDateFormat().setDateFormatSymbols( new DateFormatSymbols( locale ) );
      }
    }
    return super.getValue( runtime, element );
  }
}