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/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 * 
 * Copyright 2008 jOpenDocument, by ILM Informatique. All rights reserved.
 * 
 * The contents of this file are subject to the terms of the GNU
 * General Public License Version 3 only ("GPL").  
 * You may not use this file except in compliance with the License. 
 * You can obtain a copy of the License at http://www.gnu.org/licenses/gpl-3.0.html
 * See the License for the specific language governing permissions and limitations under the License.
 * 
 * When distributing the software, include this License Header Notice in each file.
 * 
 */

package org.jopendocument.util;

import java.io.IOException;
import java.util.Collections;
import java.util.Map;
import java.util.Properties;

/**
 * Useful for defining product wide values, like version, from a property file.
 * 
 * @author Sylvain
 */
public class ProductInfo {

    public static final String PROPERTIES_NAME = "/product.properties";
    public static final String NAME = "NAME";
    public static final String VERSION = "VERSION";

    private static ProductInfo INSTANCE;

    /**
     * If {@link #setInstance(ProductInfo)} was called with a non-null value, return that ;
     * otherwise use {@link #createDefault()}.
     * 
     * @return the current instance, can be null.
     */
    public synchronized static final ProductInfo getInstance() {
        if (INSTANCE == null) {
            try {
                INSTANCE = createDefault();
            } catch (IOException e) {
                throw new IllegalStateException("unable to load default product properties", e);
            }
        }
        return INSTANCE;
    }

    /**
     * Set the current instance.
     * 
     * @param i the new instance, can be null.
     */
    public synchronized static void setInstance(ProductInfo i) {
        INSTANCE = i;
    }

    /**
     * Create a product info from the default properties file, {@value #PROPERTIES_NAME}.
     * 
     * @return the default properties, or null if they couldn't be found.
     * @throws IOException if properties couldn't be loaded.
     */
    public static final ProductInfo createDefault() throws IOException {
        final Properties p = PropertiesUtils.createFromResource(ProductInfo.class, PROPERTIES_NAME);
        return p == null ? null : new ProductInfo(p);
    }

    private final Properties props;

    public ProductInfo(final String name) {
        this(Collections.singletonMap(NAME, name));
    }

    public ProductInfo(final Map map) {
        this(PropertiesUtils.createFromMap(map));
    }

    public ProductInfo(final Properties props) {
        if (props == null)
            throw new NullPointerException("Null properties");
        if (props.getProperty(NAME) == null)
            throw new IllegalArgumentException("Missing " + NAME);
        this.props = props;
    }

    /**
     * The properties.
     * 
     * @return the associated properties.
     */
    private final Properties getProps() {
        return this.props;
    }

    public final String getProperty(String name) {
        return this.getProps().getProperty(name);
    }

    public final String getProperty(String name, String def) {
        return this.getProps().getProperty(name, def);
    }

    public final String getName() {
        return this.getProperty(NAME, "unnamed product");
    }

    public final String getVersion() {
        return this.getProperty(VERSION);
    }
}