/*
 *
 * Copyright (c) 2013 - 2017 Lijun Liao
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License version 3
 * as published by the Free Software Foundation with the addition of the
 * following permission added to Section 15 as permitted in Section 7(a):
 *
 * FOR ANY PART OF THE COVERED WORK IN WHICH THE COPYRIGHT IS OWNED BY
 * THE AUTHOR LIJUN LIAO. LIJUN LIAO DISCLAIMS THE WARRANTY OF NON INFRINGEMENT
 * OF THIRD PARTY RIGHTS.
 *
 * 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 Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 *
 * The interactive user interfaces in modified source and object code versions
 * of this program must display Appropriate Legal Notices, as required under
 * Section 5 of the GNU Affero General Public License.
 *
 * You can be released from the requirements of the license by purchasing
 * a commercial license. Buying such a license is mandatory as soon as you
 * develop commercial activities involving the XiPKI software without
 * disclosing the source code of your own applications.
 *
 * For more information, please contact Lijun Liao at this
 * address: lijun.liao@gmail.com
 */

package org.xipki.commons.console.karaf.intern;

import java.io.File;
import java.nio.charset.Charset;

/**
 * Provides access to configuration values.
 *
 * @author Lijun Liao
 * @since 2.0.0
 */

public class Configuration {

    private Configuration() {
    }

    public static String getLineSeparator() {
        return System.getProperty("line.separator");
    }

    public static File getUserHome() {
        return new File(System.getProperty("user.home"));
    }

    public static String getOsName() {
        return System.getProperty("os.name").toLowerCase();
    }

    public static boolean isWindows() {
        return getOsName().startsWith("windows");
    }

    public static String getFileEncoding() {
        return System.getProperty("file.encoding");
    }

    /**
     * Get the default encoding. Will first look at the LC_CTYPE environment variable, then the
     * input.encoding system property, then the default charset according to the JVM.
     *
     * @return The default encoding to use when none is specified.
     */
    public static String getEncoding() {
        // LC_CTYPE is usually in the form en_US.UTF-8
        String envEncoding = extractEncodingFromCtype(System.getenv("LC_CTYPE"));
        if (envEncoding != null) {
            return envEncoding;
        }
        return System.getProperty("input.encoding", Charset.defaultCharset().name());
    }

    /**
     * Parses the LC_CTYPE value to extract the encoding according to the POSIX standard, which
     * says that the LC_CTYPE environment variable may be of the format
     * <code>[language[_territory][.codeset][@modifier]]</code>
     *
     * @param ctype The ctype to parse, may be null
     * @return The encoding, if one was present, otherwise null
     */
    static String extractEncodingFromCtype(final String ctype) {
        if (ctype != null && ctype.indexOf('.') > 0) {
            String encodingAndModifier = ctype.substring(ctype.indexOf('.') + 1);
            return (encodingAndModifier.indexOf('@') > 0)
                ? encodingAndModifier.substring(0, encodingAndModifier.indexOf('@'))
                : encodingAndModifier;
        }
        return null;
    }

}