package org.milyn.javabean.decoders;

import org.milyn.config.Configurable;
import org.milyn.cdr.SmooksConfigurationException;

import java.text.*;
import java.util.*;

/**
 * LocaleAwareDateDecoder is a decoder 'helper' that can be subclassed
 * by Date decoders to enable them to use locale specific date formats.
 * <pre>
 * Usage:
 * <resource-config selector="decoder:DecoderName">
 *      <resource>org.milyn.javabean.decoders.DateDecoder</resource>
 *      <param name="format">EEE MMM dd HH:mm:ss z yyyy</param>
 * </resource-config>
 * Optional parameters:
 *      <param name="locale-language">sv</param>
 *      <param name="locale-country">SE</param>
 *      <param name="verify-locale">false</param>
 * </pre>
 *
 * @author <a href="mailto:daniel.bevenius@gmail.com">daniel.bevenius@gmail.com</a>
 */
public abstract class LocaleAwareDateDecoder implements Configurable
{
    /**
     * Date format configuration key.
     */
    public static final String FORMAT = "format";

    /**
     * Default date format string
     */
    public static final String DEFAULT_DATE_FORMAT = "yyyy-MM-dd'T'HH:mm:ss";

    /**
     * ISO Language Code. Lower case two-letter code defined by ISO-639
     */
    public static final String LOCALE_LANGUAGE_CODE = "locale-language";

    /**
     * ISO Country Code. Upper case two-letter code defined by ISO-3166
     */
    public static final String LOCALE_COUNTRY_CODE = "locale-country";

    /**
     * True or false(default).
     * Whether or not a check should be performed to verify that
     * the specified locale is installed. This operation can take some
     * time and should be turned off in a production evironment
     */
    public static final String VERIFY_LOCALE = "verify-locale";

    private boolean verifyLocale;

    protected String format;

    /*
     * 	Need to initialize a default decoder as not calls can be make
     * 	directly to decode without calling setConfigurtion.
     */
    protected SimpleDateFormat decoder = new SimpleDateFormat( DEFAULT_DATE_FORMAT );

    public void setConfiguration(Properties resourceConfig) throws SmooksConfigurationException {
        format = resourceConfig.getProperty(FORMAT, DEFAULT_DATE_FORMAT);
        if (format == null) {
            throw new SmooksConfigurationException("Decoder must specify a 'format' parameter.");
        }

        final String languageCode = resourceConfig.getProperty(LOCALE_LANGUAGE_CODE);
        final String countryCode = resourceConfig.getProperty(LOCALE_COUNTRY_CODE);
        verifyLocale = Boolean.parseBoolean(resourceConfig.getProperty(VERIFY_LOCALE, "false"));

        decoder = new SimpleDateFormat(format.trim(), getLocale( languageCode, countryCode ));
    }

    /**
     * Returns a Locale matching the passed in languageCode, and countryCode
     *
     * @param languageCode	lowercase two-letter ISO-639 code.
     * @param countryCode	uppercase two-letter ISO-3166 code.
     * @return Locale		matching the passed in languageCode and optionally the
     * 						countryCode. If languageCode is null the default Locale
     * 						will be returned.
     * @throws SmooksConfigurationException
     * 						if the Locale is not installed on the system
     */
    protected Locale getLocale(final String languageCode, final String countryCode ) {
    	Locale locale = null;
    	if ( languageCode == null )
    		locale = Locale.getDefault();
    	else if ( countryCode == null  )
    		locale = new Locale( languageCode.trim() );
    	else
    		locale =  new Locale( languageCode.trim(), countryCode.trim() );
    	if ( verifyLocale )
    		if ( !isLocalInstalled( locale ) )
    			throw new SmooksConfigurationException( "Locale " + locale + " is not available on this system.");
    	return locale;
    }

    protected boolean isLocalInstalled(final Locale locale )
    {
    	return Arrays.asList( Locale.getAvailableLocales() ).contains( locale );
    }
}