/**
    * Copyright (c) 2004-2011 QOS.ch
    * All rights reserved.
    *
    * Permission is hereby granted, free  of charge, to any person obtaining
    * a  copy  of this  software  and  associated  documentation files  (the
    * "Software"), to  deal in  the Software without  restriction, including
    * without limitation  the rights to  use, copy, modify,  merge, publish,
    * distribute,  sublicense, and/or sell  copies of  the Software,  and to
   * permit persons to whom the Software  is furnished to do so, subject to
   * the following conditions:
   *
   * The  above  copyright  notice  and  this permission  notice  shall  be
   * included in all copies or substantial portions of the Software.
   *
   * THE  SOFTWARE IS  PROVIDED  "AS  IS", WITHOUT  WARRANTY  OF ANY  KIND,
   * EXPRESS OR  IMPLIED, INCLUDING  BUT NOT LIMITED  TO THE  WARRANTIES OF
   * MERCHANTABILITY,    FITNESS    FOR    A   PARTICULAR    PURPOSE    AND
   * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
   * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
   * OF CONTRACT, TORT OR OTHERWISE,  ARISING FROM, OUT OF OR IN CONNECTION
   * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
   *
   */
  package org.slf4j.helpers;
  
  /**
   * An internal utility class.
   *
   * @author Alexander Dorokhine
   * @author Ceki Gülcü
   */
  public final class Util {
  
      private Util() {
      }
  
      public static String safeGetSystemProperty(String key) {
          if (key == null)
              throw new IllegalArgumentException("null input");
  
          String result = null;
          try {
              result = System.getProperty(key);
          } catch (java.lang.SecurityException sm) {
              ; // ignore
          }
          return result;
      }
  
      public static boolean safeGetBooleanSystemProperty(String key) {
          String value = safeGetSystemProperty(key);
          if (value == null)
              return false;
          else
              return value.equalsIgnoreCase("true");
      }
  
      /**
       * In order to call {@link SecurityManager#getClassContext()}, which is a
       * protected method, we add this wrapper which allows the method to be visible
       * inside this package.
       */
      private static final class ClassContextSecurityManager extends SecurityManager {
          protected Class<?>[] getClassContext() {
              return super.getClassContext();
          }
      }
  
      private static ClassContextSecurityManager SECURITY_MANAGER;
      private static boolean SECURITY_MANAGER_CREATION_ALREADY_ATTEMPTED = false;
  
      private static ClassContextSecurityManager getSecurityManager() {
          if (SECURITY_MANAGER != null)
              return SECURITY_MANAGER;
          else if (SECURITY_MANAGER_CREATION_ALREADY_ATTEMPTED)
              return null;
          else {
              SECURITY_MANAGER = safeCreateSecurityManager();
              SECURITY_MANAGER_CREATION_ALREADY_ATTEMPTED = true;
              return SECURITY_MANAGER;
          }
      }
  
      private static ClassContextSecurityManager safeCreateSecurityManager() {
          try {
              return new ClassContextSecurityManager();
          } catch (java.lang.SecurityException sm) {
              return null;
          }
      }
  
      /**
       * Returns the name of the class which called the invoking method.
       *
       * @return the name of the class which called the invoking method.
       */
      public static Class<?> getCallingClass() {
          ClassContextSecurityManager securityManager = getSecurityManager();
         if (securityManager == null)
             return null;
         Class<?>[] trace = securityManager.getClassContext();
         String thisClassName = Util.class.getName();
 
         // Advance until Util is found
         int i;
         for (i = 0; i < trace.length; i++) {
             if (thisClassName.equals(trace[i].getName()))
                 break;
         }
 
         // trace[i] = Util; trace[i+1] = caller; trace[i+2] = caller's caller
         if (i >= trace.length || i + 2 >= trace.length) {
             throw new IllegalStateException("Failed to find org.slf4j.helpers.Util or its caller in the stack; " + "this should not happen");
         }
 
         return trace[i + 2];
     }
 
     static final public void report(String msg, Throwable t) {
         System.err.println(msg);
         System.err.println("Reported exception:");
         t.printStackTrace();
     }
 
     static final public void report(String msg) {
         System.err.println("SLF4J: " + msg);
     }
 
 }