package org.litesoft.GWT.client.util.externalization;

import org.litesoft.commonfoundation.base.*;
import org.litesoft.core.util.*;

import com.google.gwt.i18n.client.Dictionary;

import java.util.*;

public class ExternalizedText implements TemplateSource {
    private static ExternalizedText instance;

    private final Dictionary dictionary;
    private final Set<String> keys;

    public static ExternalizedText getInstance() {
        if ( instance == null ) {
            instance = new ExternalizedText( Dictionary.getDictionary( "ExternalTemplateText" ) );
        }
        return instance;
    }

    private ExternalizedText( Dictionary dictionary ) {
        this.dictionary = dictionary;
        this.keys = dictionary.keySet();
    }

    private String safeGet( String key ) {
        return keys.contains( key ) ? dictionary.get( key ) : null;
    }

    /**
     * Get the Template value associated with the key
     *
     * @param key Leading and trailing spaces are ignored
     *
     * @return null or the Template value associated with the key
     */
    @Override
    public String get( String key ) {
        key = ConstrainTo.significantOrNull( key );
        return (key != null) ? ConstrainTo.significantOrNull( safeGet( key ) ) : null;
    }

    /**
     * Get the Template value associated with the key or the defaultValue if the
     * key was not found or its value was empty
     *
     * @param key Leading and trailing spaces are ignored
     *
     * @return The Template value associated with the key or the defaultValue if
     * the key was not found or its value was empty
     */
    @Override
    public String get( String key, String defaultValue ) {
        return ConstrainTo.firstNonNull( get( key ), defaultValue );
    }
}