package org.keycloak.util;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * @author <a href="mailto:bill@burkecentral.com">Bill Burke</a>
 * @version $Revision: 1 $
 */
public class EnvUtil {
    private static final Pattern p = Pattern.compile("[$][{]([^}]+)[}]");

    /**
     * Replaces any ${} strings with their corresponding environent variable.
     *
     * @param val
     * @return
     */
    public static String replace(String val) {
        Matcher matcher = p.matcher(val);
        StringBuffer buf = new StringBuffer();
        while (matcher.find()) {
            String envVar = matcher.group(1);
            String envVal = System.getProperty(envVar);
            if (envVal == null) envVal = "NOT-SPECIFIED";
            matcher.appendReplacement(buf, envVal.replace("\\", "\\\\"));
        }
        matcher.appendTail(buf);
        return buf.toString();
    }
}


