/*
    * Licensed to the Apache Software Foundation (ASF) under one or more
    * contributor license agreements. See the NOTICE file distributed with
    * this work for additional information regarding copyright ownership.
    * The ASF licenses this file to You under the Apache license, Version 2.0
    * (the "License"); you may not use this file except in compliance with
    * the License. You may obtain a copy of the License at
    *
    *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the license for the specific language governing permissions and
   * limitations under the license.
   */
  package org.apache.logging.log4j.core.impl;
  
  import org.apache.logging.log4j.core.helpers.Loader;
  import org.apache.logging.log4j.status.StatusLogger;
  
  import java.io.PrintStream;
  import java.io.PrintWriter;
  import java.lang.reflect.Method;
  import java.lang.reflect.Modifier;
  import java.net.URL;
  import java.security.CodeSource;
  import java.util.HashMap;
  import java.util.Map;
  import java.util.Stack;
  
  /**
   * Wraps a Throwable to add packaging information about each stack trace element.
   */
  public class ThrowableProxy extends Throwable {
  
      private static final long serialVersionUID = -2752771578252251910L;
  
      private static Method getCallerClass;
  
      private static PrivateSecurityManager securityManager;
  
      private static final org.apache.logging.log4j.Logger LOGGER = StatusLogger.getLogger();
  
      private static Method getSuppressed;
  
      private final Throwable throwable;
      private final ThrowableProxy cause;
      private final ThrowableProxy[] suppressed;
      private int commonElementCount;
  
      private final StackTracePackageElement[] callerPackageData;
  
  
      static {
          setupCallerCheck();
          versionCheck();
      }
  
      /**
       * Construct the wrapper for the Throwable that includes packaging data.
       * @param throwable The Throwable to wrap.
       */
      public ThrowableProxy(Throwable throwable) {
          this.throwable = throwable;
          Map<String, CacheEntry> map = new HashMap<String, CacheEntry>();
          Stack<Class> stack = getCurrentStack();
          callerPackageData = resolvePackageData(stack, map, null, throwable.getStackTrace());
          this.cause = (throwable.getCause() == null) ? null :
              new ThrowableProxy(throwable, stack, map, throwable.getCause());
          suppressed = getSuppressed(throwable);
      }
  
      /**
       * Constructs the wrapper for a Throwable that is referenced as the cause by another
       * Throwable.
       * @param parent The Throwable referencing this Throwable.
       * @param stack The Class stack.
       * @param map The cache containing the packaging data.
       * @param cause The Throwable to wrap.
       */
      private ThrowableProxy(Throwable parent, Stack<Class> stack, Map<String, CacheEntry> map, Throwable cause) {
          this.throwable = cause;
          callerPackageData = resolvePackageData(stack, map, parent.getStackTrace(), cause.getStackTrace());
          this.cause = (throwable.getCause() == null) ? null :
              new ThrowableProxy(parent, stack, map, throwable.getCause());
          suppressed = getSuppressed(throwable);
      }
  
  
      @Override
      public void setStackTrace(StackTraceElement[] stackTraceElements) {
          throw new UnsupportedOperationException("Cannot set the stack trace on a ThrowableProxy");
      }
  
      @Override
      public String getMessage() {
          return throwable.getMessage();
      }
 
     @Override
     public String getLocalizedMessage() {
         return throwable.getLocalizedMessage();
     }
 
     @Override
     public Throwable getCause() {
         return cause;
     }
 
     /**
      * Added in Java 7.
      * @param exception A Throwable that was suppressed.
      */
     public void addSuppressed(Throwable exception) {
         throw new UnsupportedOperationException("Cannot add suppressed exceptions to a ThrowableProxy");
     }
 
     /**
      * Added in Java 7.
      * @return Any suppressed exceptions.
      */
     public Throwable[] getSuppressed() {
         return suppressed;
     }
 
     @Override
     public Throwable initCause(Throwable throwable) {
         throw new IllegalStateException("Cannot set the cause on a ThrowableProxy");
     }
 
     @Override
     public String toString() {
         return throwable.toString();
     }
 
     @Override
     public void printStackTrace() {
         throwable.printStackTrace();
     }
 
     @Override
     public void printStackTrace(PrintStream printStream) {
         throwable.printStackTrace(printStream);
     }
 
     @Override
     public void printStackTrace(PrintWriter printWriter) {
         throwable.printStackTrace(printWriter);
     }
 
     @Override
     public Throwable fillInStackTrace() {
         return this;
     }
 
     @Override
     public StackTraceElement[] getStackTrace() {
         return throwable.getStackTrace();
     }
 
     /**
      * Format the Throwable that is the cause of this Throwable.
      * @return The formatted Throwable that caused this Throwable.
      */
     public String getRootCauseStackTrace() {
         StringBuilder sb = new StringBuilder();
         if (cause != null) {
             formatWrapper(sb, cause);
             sb.append("Wrapped by: ");
         }
         sb.append(throwable.toString());
         sb.append("\n");
         formatElements(sb, 0, throwable.getStackTrace(), callerPackageData);
         return sb.toString();
     }
 
     /**
      * Formats the specified Throwable.
      * @param sb StringBuilder to contain the formatted Throwable.
      * @param cause The Throwable to format.
      */
     public void formatWrapper(StringBuilder sb, ThrowableProxy cause) {
         Throwable caused = cause.getCause();
         if (caused != null) {
             formatWrapper(sb, cause.cause);
             sb.append("Wrapped by: ");
         }
         sb.append(cause).append("\n");
         formatElements(sb, cause.commonElementCount, cause.getStackTrace(), cause.callerPackageData);
     }
 
     /**
      * Format the stack trace including packaging information.
      * @return The formatted stack trace including packaging information.
      */
     public String getExtendedStackTrace() {
         StringBuilder sb = new StringBuilder(throwable.toString());
         sb.append("\n");
         formatElements(sb, 0, throwable.getStackTrace(), callerPackageData);
         if (cause != null) {
             formatCause(sb, cause);
         }
         return sb.toString();
     }
 
     /**
      * Format the suppressed Throwables.
      * @return The formatted suppressed Throwables.
      */
     public String getSuppressedStackTrace() {
         if (suppressed == null || suppressed.length == 0) {
             return "";
         }
         StringBuilder sb = new StringBuilder("Suppressed Stack Trace Elements:\n");
         for (ThrowableProxy proxy : suppressed) {
             sb.append(proxy.getExtendedStackTrace());
         }
         return sb.toString();
     }
 
     private void formatCause(StringBuilder sb, ThrowableProxy cause) {
         sb.append("Caused by: ").append(cause).append("\n");
         formatElements(sb, cause.commonElementCount, cause.getStackTrace(), cause.callerPackageData);
         if (cause.getCause() != null) {
             formatCause(sb, cause.cause);
         }
     }
 
     private void formatElements(StringBuilder sb, int commonCount, StackTraceElement[] causedTrace,
                                 StackTracePackageElement[] packageData) {
         for (int i = 0; i < packageData.length; ++i) {
             sb.append("\tat ");
             sb.append(causedTrace[i]);
             sb.append(" ");
             sb.append(packageData[i]);
             sb.append("\n");
         }
         if (commonCount != 0) {
             sb.append("\t... ").append(commonCount).append(" more").append("\n");
         }
     }
 
     /**
      * Initialize the cache by resolving everything in the current stack trace via Reflection.getCallerClass
      * or via the SecurityManager if either are available. These are the only Classes that can be trusted
      * to be accurate.
      * @return A Deque containing the current stack of Class objects.
      */
     private Stack<Class> getCurrentStack() {
         if (getCallerClass != null) {
             Stack<Class> classes = new Stack<Class>();
             int index = 2;
             Class clazz = getCallerClass(index);
             while (clazz != null) {
                 classes.push(clazz);
                 clazz = getCallerClass(++index);
             }
             return classes;
         } else if (securityManager != null) {
             Class[] array = securityManager.getClasses();
             Stack<Class> classes = new Stack<Class>();
             for (Class clazz : array) {
                 classes.push(clazz);
             }
             return classes;
         }
         return new Stack<Class>();
     }
 
     /**
      * Resolve all the stack entries in this stack trace that are not common with the parent.
      * @param stack The callers Class stack.
      * @param map The cache of CacheEntry objects.
      * @param rootTrace The first stack trace resolve or null.
      * @param stackTrace The stack trace being resolved.
      * @return The StackTracePackageElement array.
      */
     private StackTracePackageElement[] resolvePackageData(Stack<Class> stack, Map<String, CacheEntry> map,
                                                           StackTraceElement[] rootTrace,
                                                           StackTraceElement[] stackTrace) {
         int stackLength;
         if (rootTrace != null) {
             int rootIndex = rootTrace.length - 1;
             int stackIndex = stackTrace.length - 1;
             while (rootIndex >= 0 && stackIndex >= 0 && rootTrace[rootIndex].equals(stackTrace[stackIndex])) {
                 --rootIndex;
                 --stackIndex;
             }
             commonElementCount = stackTrace.length - 1 - stackIndex;
             stackLength = stackIndex + 1;
         } else {
             commonElementCount = 0;
             stackLength = stackTrace.length;
         }
         StackTracePackageElement[] packageArray = new StackTracePackageElement[stackLength];
         Class clazz = stack.peek();
         ClassLoader lastLoader = null;
         for (int i = stackLength - 1; i >= 0; --i) {
             String className = stackTrace[i].getClassName();
             // The stack returned from getCurrentStack will be missing entries for  java.lang.reflect.Method.invoke()
             // and its implementation. The Throwable might also contain stack entries that are no longer
             // present as those methods have returned.
             if (className.equals(clazz.getName())) {
                 CacheEntry entry = resolvePackageElement(clazz, true);
                 packageArray[i] = entry.element;
                 lastLoader = entry.loader;
                 stack.pop();
                 clazz = stack.peek();
             } else {
                 if (map.containsKey(className)) {
                     CacheEntry entry = map.get(className);
                     packageArray[i] = entry.element;
                     if (entry.loader != null) {
                         lastLoader = entry.loader;
                     }
                 } else {
                     CacheEntry entry = resolvePackageElement(loadClass(lastLoader, className), false);
                     packageArray[i] = entry.element;
                     map.put(className, entry);
                     if (entry.loader != null) {
                         lastLoader = entry.loader;
                     }
                 }
             }
         }
         return packageArray;
     }
 
 
     /**
      * Construct the CacheEntry from the Class's information.
      * @param callerClass The Class.
      * @param exact True if the class was obtained via Reflection.getCallerClass.
      * @return The CacheEntry.
      */
     private CacheEntry resolvePackageElement(Class callerClass, boolean exact) {
         String location = "?";
         String version = "?";
         ClassLoader lastLoader = null;
         if (callerClass != null) {
             try {
                 CodeSource source = callerClass.getProtectionDomain().getCodeSource();
                 if (source != null) {
                     URL locationURL = source.getLocation();
                     if (locationURL != null) {
                         String str = locationURL.toString().replace('\\', '/');
                         int index = str.lastIndexOf("/");
                         if (index >= 0 && index == str.length() - 1) {
                             index = str.lastIndexOf("/", index - 1);
                             location = str.substring(index + 1);
                         } else {
                             location = str.substring(index + 1);
                         }
                     }
                 }
             } catch (Exception ex) {
                 // Ignore the exception.
             }
             Package pkg = callerClass.getPackage();
             if (pkg != null) {
                 String ver = pkg.getImplementationVersion();
                 if (ver != null) {
                     version = ver;
                 }
             }
             lastLoader = callerClass.getClassLoader();
         }
         return new CacheEntry(new StackTracePackageElement(location, version, exact), lastLoader);
     }
 
     /**
      * Invoke Reflection.getCallerClass via reflection. This is slightly slower than calling the method
      * directly but removes any dependency on Sun's JDK being present at compile time. The difference
      * can be measured by running the ReflectionComparison test.
      * @param index The index into the stack trace.
      * @return The Class at the specified stack entry.
      */
     private Class getCallerClass(int index) {
         if (getCallerClass != null) {
             try {
                 Object[] params = new Object[]{index};
                 return (Class) getCallerClass.invoke(null, params);
             } catch (Exception ex) {
                 // logger.debug("Unable to determine caller class via Sun Reflection", ex);
             }
         }
         return null;
     }
 
     /**
      * Loads classes not located via Reflection.getCallerClass.
      * @param lastLoader The ClassLoader that loaded the Class that called this Class.
      * @param className The name of the Class.
      * @return The Class object for the Class or null if it could not be located.
      */
     private Class loadClass(ClassLoader lastLoader, String className) {
         Class clazz;
         if (lastLoader != null) {
             try {
                 clazz = lastLoader.loadClass(className);
                 if (clazz != null) {
                     return clazz;
                 }
             } catch (Exception ex) {
                 // Ignore exception.
             }
         }
         try {
             clazz = Thread.currentThread().getContextClassLoader().loadClass(className);
         } catch (ClassNotFoundException e) {
             try {
                 clazz = Class.forName(className);
             } catch (ClassNotFoundException e1) {
                 try {
                     clazz = getClass().getClassLoader().loadClass(className);
                 } catch (ClassNotFoundException e2) {
                     return null;
                 }
             }
         }
         return clazz;
     }
 
     private static void versionCheck() {
         Method[] methods = Throwable.class.getMethods();
         for (Method method : methods) {
             if (method.getName().equals("getSuppressed")) {
                 getSuppressed = method;
             }
         }
     }
 
     /**
      * Determine if Reflection.getCallerClass is available.
      */
     private static void setupCallerCheck() {
         try {
             ClassLoader loader = Loader.getClassLoader();
             Class clazz = loader.loadClass("sun.reflect.Reflection");
             Method[] methods = clazz.getMethods();
             for (Method method : methods) {
                 int modifier = method.getModifiers();
                 if (method.getName().equals("getCallerClass") && Modifier.isStatic(modifier)) {
                     getCallerClass = method;
                     return;
                 }
             }
         } catch (ClassNotFoundException cnfe) {
             LOGGER.debug("sun.reflect.Reflection is not installed");
         }
 
         try {
             PrivateSecurityManager mgr = new PrivateSecurityManager();
             if (mgr.getClasses() != null) {
                 securityManager = mgr;
             } else {
                 // This shouldn't happen.
                 LOGGER.error("Unable to obtain call stack from security manager");
             }
         } catch (Exception ex) {
             LOGGER.debug("Unable to install security manager", ex);
         }
     }
 
     private ThrowableProxy[] getSuppressed(Throwable throwable) {
         ThrowableProxy[] supp = null;
         if (getSuppressed != null) {
             try {
                 Throwable[] array = (Throwable[]) getSuppressed.invoke(throwable, null);
                 supp = new ThrowableProxy[array.length];
                 int i = 0;
                 for (Throwable t : array) {
                     supp[i] = new ThrowableProxy(t);
                     ++i;
                 }
             } catch (Exception ex) {
                 //
             }
         }
         return supp;
     }
 
     /**
      * Cached StackTracePackageElement and the ClassLoader.
      */
     private class CacheEntry {
         private StackTracePackageElement element;
         private ClassLoader loader;
 
         public CacheEntry(StackTracePackageElement element, ClassLoader loader) {
             this.element = element;
             this.loader = loader;
         }
     }
 
     /**
      * Security Manager for accessing the call stack.
      */
     private static class PrivateSecurityManager extends SecurityManager {
         public Class[] getClasses() {
             return getClassContext();
         }
     }
 }