package org.cyclopsgroup.jmxterm;
   
   import org.apache.commons.beanutils.ConvertUtils;
   import org.apache.commons.io.output.NullOutputStream;
   import org.apache.commons.lang3.ClassUtils;
   import org.apache.commons.lang3.StringUtils;
   import org.apache.commons.lang3.math.NumberUtils;
   import org.cyclopsgroup.jmxterm.utils.ValueFormat;
   
  import javax.management.remote.JMXServiceURL;
  import java.io.IOException;
  import java.io.PrintStream;
  import java.util.regex.Pattern;
  
  /**
   * Utility class for syntax checking
   *
   * @author <a href="mailto:jiaqi.guo@gmail.com">Jiaqi Guo</a>
   */
  public final class SyntaxUtils {
    /**
     * NULL string identifier
     */
    public static final String NULL = ValueFormat.NULL;
  
    /**
     * Null print stream to redirect std streams
     */
    public static final PrintStream NULL_PRINT_STREAM = new PrintStream(new NullOutputStream(), true);
  
    private static final Pattern PATTERN_HOST_PORT = Pattern.compile("^(\\w|\\.|\\-)+\\:\\d+$");
  
    /**
     * @param url String expression of MBean server URL or abbreviation like localhost:9991
     * @param jpm Java process manager to get process URL
     * @return Parsed JMXServerURL
     * @throws IOException IO error
     */
    public static JMXServiceURL getUrl(String url, JavaProcessManager jpm) throws IOException {
      if (StringUtils.isEmpty(url)) {
        throw new IllegalArgumentException("Empty URL is not allowed");
      } else if (NumberUtils.isDigits(url) && jpm != null) {
        Integer pid = Integer.parseInt(url);
        JavaProcess p;
  
        p = jpm.get(pid);
        if (p == null) {
          throw new NullPointerException("No such PID " + pid);
        }
        if (!p.isManageable()) {
          p.startManagementAgent();
          if (!p.isManageable()) {
            throw new IllegalStateException("Managed agent for PID " + pid + " couldn't start. PID "
                + pid + " is not manageable");
          }
        }
        return new JMXServiceURL(p.toUrl());
  
      } else if (PATTERN_HOST_PORT.matcher(url).find()) {
        return new JMXServiceURL("service:jmx:rmi:///jndi/rmi://" + url + "/jmxrmi");
      } else {
        return new JMXServiceURL(url);
      }
    }
  
    /**
     * Check if string value is <code>null</code>
     *
     * @param s String value
     * @return True if value is <code>null</code>
     */
    public static boolean isNull(String s) {
      return StringUtils.equalsIgnoreCase(NULL, s) || StringUtils.equals("*", s);
    }
  
    /**
     * Parse given string expression to expected type of value
     *
     * @param expression String expression
     * @param type Target type
     * @return Object of value
     */
    public static Object parse(String expression, String type) {
      if (expression == null || StringUtils.equalsIgnoreCase(NULL, expression)) {
        return null;
      }
      Class<?> c;
      try {
        c = ClassUtils.getClass(type);
      } catch (ClassNotFoundException e) {
        throw new IllegalArgumentException("Type " + type + " isn't valid", e);
      }
      if (c == String.class) {
        return expression;
      }
      if (StringUtils.isEmpty(expression)) {
        return null;
      }
      return ConvertUtils.convert(expression, c);
   }
 
   private SyntaxUtils() {}
 }