/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.cocoon.woody.datatype.convertor;

import java.util.Locale;
import java.util.Date;
import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;

/**
 * A Convertor for {@link java.util.Date Date} objects backed by the
 * {@link java.text.SimpleDateFormat SimpleDateFormat} class.
 *
 * <p>It can be configured to use one of three <strong>variants</strong>: date,
 * time or datetime and one of four <strong>styles</strong>: long, full, medium or short.
 *
 * <p>Alternatively, a <strong>formatting pattern</strong> can be used. This can either be a locale-dependent
 * or locale-independent formatting pattern. When looking up a formatting pattern, a mechansim
 * similar to resource bundle lookup is used. Suppose the locale is nl-BE, then first a formatting
 * pattern for nl-BE will be sought, then one for nl, and if that is not
 * found, finally the locale-independent formatting pattern will be used.
 *
 * <p><strong>NOTE:</strong> the earlier statement about the fact that this class uses java.text.SimpleDateFormat
 * is not entirely correct. In fact, it uses a small wrapper class that will either delegate to
 * java.text.SimpleDateFormat or com.ibm.icu.text.SimpleDateFormat. The com.ibm version will automatically
 * be used if it is present on the classpath, otherwise the java.text version will be used.
 *
 * @version CVS $Id$
 */
public class FormattingDateConvertor implements Convertor {
    /** See {@link #setStyle}. */
    private int style;
    /** See {@link #setVariant}. */
    private int variant;
    /** Locale-specific formatting patterns. */
    private LocaleMap localizedPatterns;
    /** Non-locale specific formatting pattern. */
    private String nonLocalizedPattern;

    public static final int DATE = 1;
    public static final int TIME = 2;
    public static final int DATE_TIME = 3;

    public FormattingDateConvertor() {
        this.style = java.text.DateFormat.SHORT;
        this.variant = DATE;
        this.localizedPatterns = new LocaleMap();
    }

    public Object convertFromString(String value, Locale locale, Convertor.FormatCache formatCache) {
        DateFormat dateFormat = getDateFormat(locale, formatCache);
        try {
            return dateFormat.parse(value);
        } catch (ParseException e) {
            return null;
        }
    }

    public String convertToString(Object value, Locale locale, Convertor.FormatCache formatCache) {
        DateFormat dateFormat = getDateFormat(locale, formatCache);
        return dateFormat.format((Date)value);
    }

    private final DateFormat getDateFormat(Locale locale, Convertor.FormatCache formatCache) {
        DateFormat dateFormat = null;
        if (formatCache != null)
            dateFormat = (DateFormat)formatCache.get();
        if (dateFormat == null) {
            dateFormat = getDateFormat(locale);
            if (formatCache != null)
                formatCache.store(dateFormat);
        }
        return dateFormat;
    }

    protected DateFormat getDateFormat(Locale locale) {
        SimpleDateFormat dateFormat = null;

        switch (variant) {
            case DATE:
                dateFormat = (SimpleDateFormat)DateFormat.getDateInstance(style, locale);
                break;
            case TIME:
                dateFormat = (SimpleDateFormat)DateFormat.getTimeInstance(style, locale);
                break;
            case DATE_TIME:
                dateFormat = (SimpleDateFormat)DateFormat.getDateTimeInstance(style, style, locale);
                break;
        }

        String pattern = (String)localizedPatterns.get(locale);

        if (pattern != null)
            // Note: this was previously using applyLocalizedPattern() which allows to use
            // a locale-specific pattern syntax, e.g. in french "j" (jour) for "d" and
            // "a" (annee) for "y". But the localized pattern syntax is very little known and thus
            // led to some weird pattern syntax error messages.
            dateFormat.applyPattern(pattern);
        else if (nonLocalizedPattern != null)
            dateFormat.applyPattern(nonLocalizedPattern);

        return dateFormat;
    }

    public Class getTypeClass() {
        return Date.class;
    }

    /**
     *
     * @param style one of the constants FULL, LONG, MEDIUM or SHORT defined in the {@link Date} class.
     */
    public void setStyle(int style) {
        this.style = style;
    }

    public void setVariant(int variant) {
        if (variant != DATE && variant != TIME && variant != DATE_TIME)
            throw new IllegalArgumentException("Invalid value for variant parameter.");
        this.variant = variant;
    }

    public void addFormattingPattern(Locale locale, String pattern) {
        localizedPatterns.put(locale, pattern);
    }

    public void setNonLocalizedPattern(String pattern) {
        this.nonLocalizedPattern = pattern;
    }
}