/*

  * 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.commons.lang3.exception;

 import java.io.PrintStream;

 import java.io.PrintWriter;

 import java.io.StringWriter;

 import java.lang.reflect.InvocationTargetException;

 import java.lang.reflect.Method;

 import java.util.ArrayList;

 import java.util.List;

 import java.util.StringTokenizer;

 import org.apache.commons.lang3.ArrayUtils;

 import org.apache.commons.lang3.ClassUtils;

 import org.apache.commons.lang3.StringUtils;

 import org.apache.commons.lang3.SystemUtils;

 /**

  * <p>Provides utilities for manipulating and examining 

  * <code>Throwable</code> objects.</p>

  *

  * @since 1.0

  * @version $Id: ExceptionUtils.java 1436770 2013-01-22 07:09:45Z ggregory $

  */

 public class ExceptionUtils {

     /**

      * <p>Used when printing stack frames to denote the start of a

      * wrapped exception.</p>

      *

      * <p>Package private for accessibility by test suite.</p>

      */

     static final String WRAPPED_MARKER = " [wrapped] ";

     /**

      * <p>The names of methods commonly used to access a wrapped exception.</p>

      */

     // TODO: Remove in Lang 4.0

     private static final String[] CAUSE_METHOD_NAMES = {

         "getCause",

         "getNextException",

         "getTargetException",

         "getException",

         "getSourceException",

         "getRootCause",

         "getCausedByException",

         "getNested",

         "getLinkedException",

         "getNestedException",

         "getLinkedCause",

         "getThrowable",

     };

     /**

      * <p>

      * Public constructor allows an instance of <code>ExceptionUtils</code> to be created, although that is not

      * normally necessary.

      * </p>

      */

     public ExceptionUtils() {

         super();

     }

     //-----------------------------------------------------------------------

     /**

      * <p>Returns the default names used when searching for the cause of an exception.</p>

      *

      * <p>This may be modified and used in the overloaded getCause(Throwable, String[]) method.</p>

      *

      * @return cloned array of the default method names

      * @since 3.0

      * @deprecated This feature will be removed in Lang 4.0

      */

     @Deprecated

     public static String[] getDefaultCauseMethodNames() {

         return ArrayUtils.clone(CAUSE_METHOD_NAMES);

     }

     //-----------------------------------------------------------------------

     /**

      * <p>Introspects the <code>Throwable</code> to obtain the cause.</p>

      *

      * <p>The method searches for methods with specific names that return a 

      * <code>Throwable</code> object. This will pick up most wrapping exceptions,

      * including those from JDK 1.4.

      *

      * <p>The default list searched for are:</p>

      * <ul>

      *  <li><code>getCause()</code></li>

      *  <li><code>getNextException()</code></li>

      *  <li><code>getTargetException()</code></li>

      *  <li><code>getException()</code></li>

      *  <li><code>getSourceException()</code></li>

      *  <li><code>getRootCause()</code></li>

      *  <li><code>getCausedByException()</code></li>

      *  <li><code>getNested()</code></li>

      * </ul>

      * 

      * <p>If none of the above is found, returns <code>null</code>.</p>

      *

      * @param throwable  the throwable to introspect for a cause, may be null

      * @return the cause of the <code>Throwable</code>,

      *  <code>null</code> if none found or null throwable input

      * @since 1.0

      * @deprecated This feature will be removed in Lang 4.0

      */

     @Deprecated

     public static Throwable getCause(final Throwable throwable) {

         return getCause(throwable, CAUSE_METHOD_NAMES);

     }

     /**

      * <p>Introspects the <code>Throwable</code> to obtain the cause.</p>

      *

      * <p>A <code>null</code> set of method names means use the default set.

      * A <code>null</code> in the set of method names will be ignored.</p>

      *

      * @param throwable  the throwable to introspect for a cause, may be null

      * @param methodNames  the method names, null treated as default set

      * @return the cause of the <code>Throwable</code>,

      *  <code>null</code> if none found or null throwable input

      * @since 1.0

      * @deprecated This feature will be removed in Lang 4.0

      */

     @Deprecated

     public static Throwable getCause(final Throwable throwable, String[] methodNames) {

         if (throwable == null) {

             return null;

         }

         if (methodNames == null) {

             methodNames = CAUSE_METHOD_NAMES;

         }

         for (final String methodName : methodNames) {

             if (methodName != null) {

                 final Throwable cause = getCauseUsingMethodName(throwable, methodName);

                 if (cause != null) {

                     return cause;

                 }

             }

         }

         return null;

     }

     /**

      * <p>Introspects the <code>Throwable</code> to obtain the root cause.</p>

      *

      * <p>This method walks through the exception chain to the last element,

      * "root" of the tree, using {@link #getCause(Throwable)}, and

      * returns that exception.</p>

      *

      * <p>From version 2.2, this method handles recursive cause structures

      * that might otherwise cause infinite loops. If the throwable parameter

      * has a cause of itself, then null will be returned. If the throwable

      * parameter cause chain loops, the last element in the chain before the

      * loop is returned.</p>

      *

      * @param throwable  the throwable to get the root cause for, may be null

      * @return the root cause of the <code>Throwable</code>,

      *  <code>null</code> if none found or null throwable input

      */

     public static Throwable getRootCause(final Throwable throwable) {

         final List<Throwable> list = getThrowableList(throwable);

         return list.size() < 2 ? null : (Throwable)list.get(list.size() - 1);

     }

     /**

      * <p>Finds a <code>Throwable</code> by method name.</p>

      *

      * @param throwable  the exception to examine

      * @param methodName  the name of the method to find and invoke

      * @return the wrapped exception, or <code>null</code> if not found

      */

     // TODO: Remove in Lang 4.0

     private static Throwable getCauseUsingMethodName(final Throwable throwable, final String methodName) {

         Method method = null;

         try {

             method = throwable.getClass().getMethod(methodName);

         } catch (final NoSuchMethodException ignored) { // NOPMD

             // exception ignored

         } catch (final SecurityException ignored) { // NOPMD

             // exception ignored

         }

         if (method != null && Throwable.class.isAssignableFrom(method.getReturnType())) {

             try {

                 return (Throwable) method.invoke(throwable);

             } catch (final IllegalAccessException ignored) { // NOPMD

                 // exception ignored

             } catch (final IllegalArgumentException ignored) { // NOPMD

                 // exception ignored

             } catch (final InvocationTargetException ignored) { // NOPMD

                 // exception ignored

             }

         }

         return null;

     }

     //-----------------------------------------------------------------------

     /**

      * <p>Counts the number of <code>Throwable</code> objects in the

      * exception chain.</p>

      *

      * <p>A throwable without cause will return <code>1</code>.

      * A throwable with one cause will return <code>2</code> and so on.

      * A <code>null</code> throwable will return <code>0</code>.</p>

      *

      * <p>From version 2.2, this method handles recursive cause structures

      * that might otherwise cause infinite loops. The cause chain is

      * processed until the end is reached, or until the next item in the

      * chain is already in the result set.</p>

      *

      * @param throwable  the throwable to inspect, may be null

      * @return the count of throwables, zero if null input

      */

     public static int getThrowableCount(final Throwable throwable) {

         return getThrowableList(throwable).size();

     }

     /**

      * <p>Returns the list of <code>Throwable</code> objects in the

      * exception chain.</p>

      *

      * <p>A throwable without cause will return an array containing

      * one element - the input throwable.

      * A throwable with one cause will return an array containing

      * two elements. - the input throwable and the cause throwable.

      * A <code>null</code> throwable will return an array of size zero.</p>

      *

      * <p>From version 2.2, this method handles recursive cause structures

      * that might otherwise cause infinite loops. The cause chain is

      * processed until the end is reached, or until the next item in the

      * chain is already in the result set.</p>

      *

      * @see #getThrowableList(Throwable)

      * @param throwable  the throwable to inspect, may be null

      * @return the array of throwables, never null

      */

     public static Throwable[] getThrowables(final Throwable throwable) {

         final List<Throwable> list = getThrowableList(throwable);

         return list.toArray(new Throwable[list.size()]);

     }

     /**

      * <p>Returns the list of <code>Throwable</code> objects in the

      * exception chain.</p>

      *

      * <p>A throwable without cause will return a list containing

      * one element - the input throwable.

      * A throwable with one cause will return a list containing

      * two elements. - the input throwable and the cause throwable.

      * A <code>null</code> throwable will return a list of size zero.</p>

      *

      * <p>This method handles recursive cause structures that might

      * otherwise cause infinite loops. The cause chain is processed until

      * the end is reached, or until the next item in the chain is already

      * in the result set.</p>

      *

      * @param throwable  the throwable to inspect, may be null

      * @return the list of throwables, never null

      * @since Commons Lang 2.2

      */

     public static List<Throwable> getThrowableList(Throwable throwable) {

         final List<Throwable> list = new ArrayList<Throwable>();

         while (throwable != null && list.contains(throwable) == false) {

             list.add(throwable);

             throwable = ExceptionUtils.getCause(throwable);

         }

         return list;

     }

     //-----------------------------------------------------------------------

     /**

      * <p>Returns the (zero based) index of the first <code>Throwable</code>

      * that matches the specified class (exactly) in the exception chain.

      * Subclasses of the specified class do not match - see

      * {@link #indexOfType(Throwable, Class)} for the opposite.</p>

      *

      * <p>A <code>null</code> throwable returns <code>-1</code>.

      * A <code>null</code> type returns <code>-1</code>.

      * No match in the chain returns <code>-1</code>.</p>

      *

      * @param throwable  the throwable to inspect, may be null

      * @param clazz  the class to search for, subclasses do not match, null returns -1

      * @return the index into the throwable chain, -1 if no match or null input

      */

     public static int indexOfThrowable(final Throwable throwable, final Class<?> clazz) {

         return indexOf(throwable, clazz, 0, false);

     }

     /**

      * <p>Returns the (zero based) index of the first <code>Throwable</code>

      * that matches the specified type in the exception chain from

      * a specified index.

      * Subclasses of the specified class do not match - see

      * {@link #indexOfType(Throwable, Class, int)} for the opposite.</p>

      *

      * <p>A <code>null</code> throwable returns <code>-1</code>.

      * A <code>null</code> type returns <code>-1</code>.

      * No match in the chain returns <code>-1</code>.

      * A negative start index is treated as zero.

      * A start index greater than the number of throwables returns <code>-1</code>.</p>

      *

      * @param throwable  the throwable to inspect, may be null

      * @param clazz  the class to search for, subclasses do not match, null returns -1

      * @param fromIndex  the (zero based) index of the starting position,

      *  negative treated as zero, larger than chain size returns -1

      * @return the index into the throwable chain, -1 if no match or null input

      */

     public static int indexOfThrowable(final Throwable throwable, final Class<?> clazz, final int fromIndex) {

         return indexOf(throwable, clazz, fromIndex, false);

     }

     //-----------------------------------------------------------------------

     /**

      * <p>Returns the (zero based) index of the first <code>Throwable</code>

      * that matches the specified class or subclass in the exception chain.

      * Subclasses of the specified class do match - see

      * {@link #indexOfThrowable(Throwable, Class)} for the opposite.</p>

      *

      * <p>A <code>null</code> throwable returns <code>-1</code>.

      * A <code>null</code> type returns <code>-1</code>.

      * No match in the chain returns <code>-1</code>.</p>

      *

      * @param throwable  the throwable to inspect, may be null

      * @param type  the type to search for, subclasses match, null returns -1

      * @return the index into the throwable chain, -1 if no match or null input

      * @since 2.1

      */

     public static int indexOfType(final Throwable throwable, final Class<?> type) {

         return indexOf(throwable, type, 0, true);

     }

     /**

      * <p>Returns the (zero based) index of the first <code>Throwable</code>

      * that matches the specified type in the exception chain from

      * a specified index.

      * Subclasses of the specified class do match - see

      * {@link #indexOfThrowable(Throwable, Class)} for the opposite.</p>

      *

      * <p>A <code>null</code> throwable returns <code>-1</code>.

      * A <code>null</code> type returns <code>-1</code>.

      * No match in the chain returns <code>-1</code>.

      * A negative start index is treated as zero.

      * A start index greater than the number of throwables returns <code>-1</code>.</p>

      *

      * @param throwable  the throwable to inspect, may be null

      * @param type  the type to search for, subclasses match, null returns -1

      * @param fromIndex  the (zero based) index of the starting position,

      *  negative treated as zero, larger than chain size returns -1

      * @return the index into the throwable chain, -1 if no match or null input

      * @since 2.1

      */

     public static int indexOfType(final Throwable throwable, final Class<?> type, final int fromIndex) {

         return indexOf(throwable, type, fromIndex, true);

     }

     /**

      * <p>Worker method for the <code>indexOfType</code> methods.</p>

      *

      * @param throwable  the throwable to inspect, may be null

      * @param type  the type to search for, subclasses match, null returns -1

      * @param fromIndex  the (zero based) index of the starting position,

      *  negative treated as zero, larger than chain size returns -1

      * @param subclass if <code>true</code>, compares with {@link Class#isAssignableFrom(Class)}, otherwise compares

      * using references

      * @return index of the <code>type</code> within throwables nested within the specified <code>throwable</code>

      */

     private static int indexOf(final Throwable throwable, final Class<?> type, int fromIndex, final boolean subclass) {

         if (throwable == null || type == null) {

             return -1;

         }

         if (fromIndex < 0) {

             fromIndex = 0;

         }

         final Throwable[] throwables = ExceptionUtils.getThrowables(throwable);

         if (fromIndex >= throwables.length) {

             return -1;

         }

         if (subclass) {

             for (int i = fromIndex; i < throwables.length; i++) {

                 if (type.isAssignableFrom(throwables[i].getClass())) {

                     return i;

                 }

             }

         } else {

             for (int i = fromIndex; i < throwables.length; i++) {

                 if (type.equals(throwables[i].getClass())) {

                     return i;

                 }

             }

         }

         return -1;

     }

     //-----------------------------------------------------------------------

     /**

      * <p>Prints a compact stack trace for the root cause of a throwable

      * to <code>System.err</code>.</p>

      *

      * <p>The compact stack trace starts with the root cause and prints

      * stack frames up to the place where it was caught and wrapped.

      * Then it prints the wrapped exception and continues with stack frames

      * until the wrapper exception is caught and wrapped again, etc.</p>

      *

      * <p>The output of this method is consistent across JDK versions.

      * Note that this is the opposite order to the JDK1.4 display.</p>

      *

      * <p>The method is equivalent to <code>printStackTrace</code> for throwables

      * that don't have nested causes.</p>

      *

      * @param throwable  the throwable to output

      * @since 2.0

      */

     public static void printRootCauseStackTrace(final Throwable throwable) {

         printRootCauseStackTrace(throwable, System.err);

     }

     /**

      * <p>Prints a compact stack trace for the root cause of a throwable.</p>

      *

      * <p>The compact stack trace starts with the root cause and prints

      * stack frames up to the place where it was caught and wrapped.

      * Then it prints the wrapped exception and continues with stack frames

      * until the wrapper exception is caught and wrapped again, etc.</p>

      *

      * <p>The output of this method is consistent across JDK versions.

      * Note that this is the opposite order to the JDK1.4 display.</p>

      *

      * <p>The method is equivalent to <code>printStackTrace</code> for throwables

      * that don't have nested causes.</p>

      *

      * @param throwable  the throwable to output, may be null

      * @param stream  the stream to output to, may not be null

      * @throws IllegalArgumentException if the stream is <code>null</code>

      * @since 2.0

      */

     public static void printRootCauseStackTrace(final Throwable throwable, final PrintStream stream) {

         if (throwable == null) {

             return;

         }

         if (stream == null) {

             throw new IllegalArgumentException("The PrintStream must not be null");

         }

         final String trace[] = getRootCauseStackTrace(throwable);

         for (final String element : trace) {

             stream.println(element);

         }

         stream.flush();

     }

     /**

      * <p>Prints a compact stack trace for the root cause of a throwable.</p>

      *

      * <p>The compact stack trace starts with the root cause and prints

      * stack frames up to the place where it was caught and wrapped.

      * Then it prints the wrapped exception and continues with stack frames

      * until the wrapper exception is caught and wrapped again, etc.</p>

      *

      * <p>The output of this method is consistent across JDK versions.

      * Note that this is the opposite order to the JDK1.4 display.</p>

      *

      * <p>The method is equivalent to <code>printStackTrace</code> for throwables

      * that don't have nested causes.</p>

      *

      * @param throwable  the throwable to output, may be null

      * @param writer  the writer to output to, may not be null

      * @throws IllegalArgumentException if the writer is <code>null</code>

      * @since 2.0

      */

     public static void printRootCauseStackTrace(final Throwable throwable, final PrintWriter writer) {

         if (throwable == null) {

             return;

         }

         if (writer == null) {

             throw new IllegalArgumentException("The PrintWriter must not be null");

         }

         final String trace[] = getRootCauseStackTrace(throwable);

         for (final String element : trace) {

             writer.println(element);

         }

         writer.flush();

     }

     //-----------------------------------------------------------------------

     /**

      * <p>Creates a compact stack trace for the root cause of the supplied

      * <code>Throwable</code>.</p>

      *

      * <p>The output of this method is consistent across JDK versions.

      * It consists of the root exception followed by each of its wrapping

      * exceptions separated by '[wrapped]'. Note that this is the opposite

      * order to the JDK1.4 display.</p>

      *

      * @param throwable  the throwable to examine, may be null

      * @return an array of stack trace frames, never null

      * @since 2.0

      */

     public static String[] getRootCauseStackTrace(final Throwable throwable) {

         if (throwable == null) {

             return ArrayUtils.EMPTY_STRING_ARRAY;

         }

         final Throwable throwables[] = getThrowables(throwable);

         final int count = throwables.length;

         final List<String> frames = new ArrayList<String>();

         List<String> nextTrace = getStackFrameList(throwables[count - 1]);

         for (int i = count; --i >= 0;) {

             final List<String> trace = nextTrace;

             if (i != 0) {

                 nextTrace = getStackFrameList(throwables[i - 1]);

                 removeCommonFrames(trace, nextTrace);

             }

             if (i == count - 1) {

                 frames.add(throwables[i].toString());

             } else {

                 frames.add(WRAPPED_MARKER + throwables[i].toString());

             }

             for (int j = 0; j < trace.size(); j++) {

                 frames.add(trace.get(j));

             }

         }

         return frames.toArray(new String[frames.size()]);

     }

     /**

      * <p>Removes common frames from the cause trace given the two stack traces.</p>

      *

      * @param causeFrames  stack trace of a cause throwable

      * @param wrapperFrames  stack trace of a wrapper throwable

      * @throws IllegalArgumentException if either argument is null

      * @since 2.0

      */

     public static void removeCommonFrames(final List<String> causeFrames, final List<String> wrapperFrames) {

         if (causeFrames == null || wrapperFrames == null) {

             throw new IllegalArgumentException("The List must not be null");

         }

         int causeFrameIndex = causeFrames.size() - 1;

         int wrapperFrameIndex = wrapperFrames.size() - 1;

         while (causeFrameIndex >= 0 && wrapperFrameIndex >= 0) {

             // Remove the frame from the cause trace if it is the same

             // as in the wrapper trace

             final String causeFrame = causeFrames.get(causeFrameIndex);

             final String wrapperFrame = wrapperFrames.get(wrapperFrameIndex);

             if (causeFrame.equals(wrapperFrame)) {

                 causeFrames.remove(causeFrameIndex);

             }

             causeFrameIndex--;

             wrapperFrameIndex--;

         }

     }

     //-----------------------------------------------------------------------

     /**

      * <p>Gets the stack trace from a Throwable as a String.</p>

      *

      * <p>The result of this method vary by JDK version as this method

      * uses {@link Throwable#printStackTrace(java.io.PrintWriter)}.

      * On JDK1.3 and earlier, the cause exception will not be shown

      * unless the specified throwable alters printStackTrace.</p>

      *

      * @param throwable  the <code>Throwable</code> to be examined

      * @return the stack trace as generated by the exception's

      *  <code>printStackTrace(PrintWriter)</code> method

      */

     public static String getStackTrace(final Throwable throwable) {

         final StringWriter sw = new StringWriter();

         final PrintWriter pw = new PrintWriter(sw, true);

         throwable.printStackTrace(pw);

         return sw.getBuffer().toString();

     }

     /**

      * <p>Captures the stack trace associated with the specified

      * <code>Throwable</code> object, decomposing it into a list of

      * stack frames.</p>

      *

      * <p>The result of this method vary by JDK version as this method

      * uses {@link Throwable#printStackTrace(java.io.PrintWriter)}.

      * On JDK1.3 and earlier, the cause exception will not be shown

      * unless the specified throwable alters printStackTrace.</p>

      *

      * @param throwable  the <code>Throwable</code> to examine, may be null

      * @return an array of strings describing each stack frame, never null

      */

     public static String[] getStackFrames(final Throwable throwable) {

         if (throwable == null) {

             return ArrayUtils.EMPTY_STRING_ARRAY;

         }

         return getStackFrames(getStackTrace(throwable));

     }

     //-----------------------------------------------------------------------

     /**

      * <p>Returns an array where each element is a line from the argument.</p>

      *

      * <p>The end of line is determined by the value of {@link SystemUtils#LINE_SEPARATOR}.</p>

      *

      * @param stackTrace  a stack trace String

      * @return an array where each element is a line from the argument

      */

     static String[] getStackFrames(final String stackTrace) {

         final String linebreak = SystemUtils.LINE_SEPARATOR;

         final StringTokenizer frames = new StringTokenizer(stackTrace, linebreak);

         final List<String> list = new ArrayList<String>();

         while (frames.hasMoreTokens()) {

             list.add(frames.nextToken());

         }

         return list.toArray(new String[list.size()]);

     }

     /**

      * <p>Produces a <code>List</code> of stack frames - the message

      * is not included. Only the trace of the specified exception is

      * returned, any caused by trace is stripped.</p>

      *

      * <p>This works in most cases - it will only fail if the exception

      * message contains a line that starts with:

      * <code>&quot;&nbsp;&nbsp;&nbsp;at&quot;.</code></p>

      * 

      * @param t is any throwable

      * @return List of stack frames

      */

     static List<String> getStackFrameList(final Throwable t) {

         final String stackTrace = getStackTrace(t);

         final String linebreak = SystemUtils.LINE_SEPARATOR;

         final StringTokenizer frames = new StringTokenizer(stackTrace, linebreak);

         final List<String> list = new ArrayList<String>();

         boolean traceStarted = false;

         while (frames.hasMoreTokens()) {

             final String token = frames.nextToken();

             // Determine if the line starts with <whitespace>at

             final int at = token.indexOf("at");

             if (at != -1 && token.substring(0, at).trim().isEmpty()) {

                 traceStarted = true;

                 list.add(token);

             } else if (traceStarted) {

                 break;

             }

         }

         return list;

     }

     //-----------------------------------------------------------------------

     /**

      * Gets a short message summarising the exception.

      * <p>

      * The message returned is of the form

      * {ClassNameWithoutPackage}: {ThrowableMessage}

      *

      * @param th  the throwable to get a message for, null returns empty string

      * @return the message, non-null

      * @since Commons Lang 2.2

      */

     public static String getMessage(final Throwable th) {

         if (th == null) {

             return "";

         }

         final String clsName = ClassUtils.getShortClassName(th, null);

         final String msg = th.getMessage();

         return clsName + ": " + StringUtils.defaultString(msg);

     }

     //-----------------------------------------------------------------------

     /**

      * Gets a short message summarising the root cause exception.

      * <p>

      * The message returned is of the form

      * {ClassNameWithoutPackage}: {ThrowableMessage}

      *

      * @param th  the throwable to get a message for, null returns empty string

      * @return the message, non-null

      * @since Commons Lang 2.2

      */

     public static String getRootCauseMessage(final Throwable th) {

         Throwable root = ExceptionUtils.getRootCause(th);

         root = root == null ? th : root;

         return getMessage(root);

     }

 }