/*
 * Copyright 2002-2017 the original author or authors.
 *
 * Licensed 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.springframework.aop.interceptor;

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

import org.aopalliance.intercept.MethodInvocation;
import org.apache.commons.logging.Log;

import org.springframework.core.Constants;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;
import org.springframework.util.StopWatch;
import org.springframework.util.StringUtils;

MethodInterceptor implementation that allows for highly customizable method-level tracing, using placeholders. 
Trace messages are written on method entry, and if the method invocation succeeds
on method exit. If an invocation results in an exception, then an exception message
is written. The contents of these trace messages is fully customizable and special
placeholders are available to allow you to include runtime information in your log
messages. The placeholders available are:

$[methodName] - replaced with the name of the method being invoked
$[targetClassName] - replaced with the name of the class that is the target of the invocation
$[targetClassShortName] - replaced with the short name of the class that is the target of the invocation
$[returnValue] - replaced with the value returned by the invocation
$[argumentTypes] - replaced with a comma-separated list of the short class names of the method arguments
$[arguments] - replaced with a comma-separated list of the String representation of the method arguments
$[exception] - replaced with the String representation of any Throwable raised during the invocation
$[invocationTime] - replaced with the time, in milliseconds, taken by the method invocation

There are restrictions on which placeholders can be used in which messages:
see the individual message properties for details on the valid placeholders.
Author:
Rob Harrop, Juergen Hoeller
See Also:
setEnterMessage
setExitMessage
setExceptionMessage
SimpleTraceInterceptor
Since:
1.2/**
 * {@code MethodInterceptor} implementation that allows for highly customizable
 * method-level tracing, using placeholders.
 *
 * <p>Trace messages are written on method entry, and if the method invocation succeeds
 * on method exit. If an invocation results in an exception, then an exception message
 * is written. The contents of these trace messages is fully customizable and special
 * placeholders are available to allow you to include runtime information in your log
 * messages. The placeholders available are:
 *
 * <p><ul>
 * <li>{@code $[methodName]} - replaced with the name of the method being invoked</li>
 * <li>{@code $[targetClassName]} - replaced with the name of the class that is
 * the target of the invocation</li>
 * <li>{@code $[targetClassShortName]} - replaced with the short name of the class
 * that is the target of the invocation</li>
 * <li>{@code $[returnValue]} - replaced with the value returned by the invocation</li>
 * <li>{@code $[argumentTypes]} - replaced with a comma-separated list of the
 * short class names of the method arguments</li>
 * <li>{@code $[arguments]} - replaced with a comma-separated list of the
 * {@code String} representation of the method arguments</li>
 * <li>{@code $[exception]} - replaced with the {@code String} representation
 * of any {@code Throwable} raised during the invocation</li>
 * <li>{@code $[invocationTime]} - replaced with the time, in milliseconds,
 * taken by the method invocation</li>
 * </ul>
 *
 * <p>There are restrictions on which placeholders can be used in which messages:
 * see the individual message properties for details on the valid placeholders.
 *
 * @author Rob Harrop
 * @author Juergen Hoeller
 * @since 1.2
 * @see #setEnterMessage
 * @see #setExitMessage
 * @see #setExceptionMessage
 * @see SimpleTraceInterceptor
 */
@SuppressWarnings("serial")
public class CustomizableTraceInterceptor extends AbstractTraceInterceptor {

	
The $[methodName] placeholder. Replaced with the name of the method being invoked. /**
	 * The {@code $[methodName]} placeholder.
	 * Replaced with the name of the method being invoked.
	 */
	public static final String PLACEHOLDER_METHOD_NAME = "$[methodName]";

	
The $[targetClassName] placeholder. Replaced with the fully-qualified name of the Class of the method invocation target. /**
	 * The {@code $[targetClassName]} placeholder.
	 * Replaced with the fully-qualified name of the {@code Class}
	 * of the method invocation target.
	 */
	public static final String PLACEHOLDER_TARGET_CLASS_NAME = "$[targetClassName]";

	
The $[targetClassShortName] placeholder. Replaced with the short name of the Class of the method invocation target. /**
	 * The {@code $[targetClassShortName]} placeholder.
	 * Replaced with the short name of the {@code Class} of the
	 * method invocation target.
	 */
	public static final String PLACEHOLDER_TARGET_CLASS_SHORT_NAME = "$[targetClassShortName]";

	
The $[returnValue] placeholder. Replaced with the String representation of the value returned by the method invocation. /**
	 * The {@code $[returnValue]} placeholder.
	 * Replaced with the {@code String} representation of the value
	 * returned by the method invocation.
	 */
	public static final String PLACEHOLDER_RETURN_VALUE = "$[returnValue]";

	
The $[argumentTypes] placeholder. Replaced with a comma-separated list of the argument types for the method invocation. Argument types are written as short class names. /**
	 * The {@code $[argumentTypes]} placeholder.
	 * Replaced with a comma-separated list of the argument types for the
	 * method invocation. Argument types are written as short class names.
	 */
	public static final String PLACEHOLDER_ARGUMENT_TYPES = "$[argumentTypes]";

	
The $[arguments] placeholder. Replaced with a comma separated list of the argument values for the method invocation. Relies on the toString() method of each argument type. /**
	 * The {@code $[arguments]} placeholder.
	 * Replaced with a comma separated list of the argument values for the
	 * method invocation. Relies on the {@code toString()} method of
	 * each argument type.
	 */
	public static final String PLACEHOLDER_ARGUMENTS = "$[arguments]";

	
The $[exception] placeholder. Replaced with the String representation of any Throwable raised during method invocation. /**
	 * The {@code $[exception]} placeholder.
	 * Replaced with the {@code String} representation of any
	 * {@code Throwable} raised during method invocation.
	 */
	public static final String PLACEHOLDER_EXCEPTION = "$[exception]";

	
The $[invocationTime] placeholder. Replaced with the time taken by the invocation (in milliseconds). /**
	 * The {@code $[invocationTime]} placeholder.
	 * Replaced with the time taken by the invocation (in milliseconds).
	 */
	public static final String PLACEHOLDER_INVOCATION_TIME = "$[invocationTime]";

	
The default message used for writing method entry messages.
/**
	 * The default message used for writing method entry messages.
	 */
	private static final String DEFAULT_ENTER_MESSAGE = "Entering method '" +
			PLACEHOLDER_METHOD_NAME + "' of class [" + PLACEHOLDER_TARGET_CLASS_NAME + "]";

	
The default message used for writing method exit messages.
/**
	 * The default message used for writing method exit messages.
	 */
	private static final String DEFAULT_EXIT_MESSAGE = "Exiting method '" +
			PLACEHOLDER_METHOD_NAME + "' of class [" + PLACEHOLDER_TARGET_CLASS_NAME + "]";

	
The default message used for writing exception messages.
/**
	 * The default message used for writing exception messages.
	 */
	private static final String DEFAULT_EXCEPTION_MESSAGE = "Exception thrown in method '" +
			PLACEHOLDER_METHOD_NAME + "' of class [" + PLACEHOLDER_TARGET_CLASS_NAME + "]";

	
The Pattern used to match placeholders. /**
	 * The {@code Pattern} used to match placeholders.
	 */
	private static final Pattern PATTERN = Pattern.compile("\\$\\[\\p{Alpha}+\\]");

	
The Set of allowed placeholders. /**
	 * The {@code Set} of allowed placeholders.
	 */
	private static final Set<Object> ALLOWED_PLACEHOLDERS =
			new Constants(CustomizableTraceInterceptor.class).getValues("PLACEHOLDER_");


	
The message for method entry.
/**
	 * The message for method entry.
	 */
	private String enterMessage = DEFAULT_ENTER_MESSAGE;

	
The message for method exit.
/**
	 * The message for method exit.
	 */
	private String exitMessage = DEFAULT_EXIT_MESSAGE;

	
The message for exceptions during method execution.
/**
	 * The message for exceptions during method execution.
	 */
	private String exceptionMessage = DEFAULT_EXCEPTION_MESSAGE;


	
Set the template used for method entry log messages.
This template can contain any of the following placeholders:

$[targetClassName]
$[targetClassShortName]
$[argumentTypes]
$[arguments]

/**
	 * Set the template used for method entry log messages.
	 * This template can contain any of the following placeholders:
	 * <ul>
	 * <li>{@code $[targetClassName]}</li>
	 * <li>{@code $[targetClassShortName]}</li>
	 * <li>{@code $[argumentTypes]}</li>
	 * <li>{@code $[arguments]}</li>
	 * </ul>
	 */
	public void setEnterMessage(String enterMessage) throws IllegalArgumentException {
		Assert.hasText(enterMessage, "enterMessage must not be empty");
		checkForInvalidPlaceholders(enterMessage);
		Assert.doesNotContain(enterMessage, PLACEHOLDER_RETURN_VALUE,
				"enterMessage cannot contain placeholder " + PLACEHOLDER_RETURN_VALUE);
		Assert.doesNotContain(enterMessage, PLACEHOLDER_EXCEPTION,
				"enterMessage cannot contain placeholder " + PLACEHOLDER_EXCEPTION);
		Assert.doesNotContain(enterMessage, PLACEHOLDER_INVOCATION_TIME,
				"enterMessage cannot contain placeholder " + PLACEHOLDER_INVOCATION_TIME);
		this.enterMessage = enterMessage;
	}

	
Set the template used for method exit log messages.
This template can contain any of the following placeholders:

$[targetClassName]
$[targetClassShortName]
$[argumentTypes]
$[arguments]
$[returnValue]
$[invocationTime]

/**
	 * Set the template used for method exit log messages.
	 * This template can contain any of the following placeholders:
	 * <ul>
	 * <li>{@code $[targetClassName]}</li>
	 * <li>{@code $[targetClassShortName]}</li>
	 * <li>{@code $[argumentTypes]}</li>
	 * <li>{@code $[arguments]}</li>
	 * <li>{@code $[returnValue]}</li>
	 * <li>{@code $[invocationTime]}</li>
	 * </ul>
	 */
	public void setExitMessage(String exitMessage) {
		Assert.hasText(exitMessage, "exitMessage must not be empty");
		checkForInvalidPlaceholders(exitMessage);
		Assert.doesNotContain(exitMessage, PLACEHOLDER_EXCEPTION,
				"exitMessage cannot contain placeholder" + PLACEHOLDER_EXCEPTION);
		this.exitMessage = exitMessage;
	}

	
Set the template used for method exception log messages.
This template can contain any of the following placeholders:

$[targetClassName]
$[targetClassShortName]
$[argumentTypes]
$[arguments]
$[exception]

/**
	 * Set the template used for method exception log messages.
	 * This template can contain any of the following placeholders:
	 * <ul>
	 * <li>{@code $[targetClassName]}</li>
	 * <li>{@code $[targetClassShortName]}</li>
	 * <li>{@code $[argumentTypes]}</li>
	 * <li>{@code $[arguments]}</li>
	 * <li>{@code $[exception]}</li>
	 * </ul>
	 */
	public void setExceptionMessage(String exceptionMessage) {
		Assert.hasText(exceptionMessage, "exceptionMessage must not be empty");
		checkForInvalidPlaceholders(exceptionMessage);
		Assert.doesNotContain(exceptionMessage, PLACEHOLDER_RETURN_VALUE,
				"exceptionMessage cannot contain placeholder " + PLACEHOLDER_RETURN_VALUE);
		this.exceptionMessage = exceptionMessage;
	}


	
Writes a log message before the invocation based on the value of enterMessage. If the invocation succeeds, then a log message is written on exit based on the value exitMessage. If an exception occurs during invocation, then a message is written based on the value of exceptionMessage. 
See Also:
setEnterMessage
setExitMessage
setExceptionMessage/**
	 * Writes a log message before the invocation based on the value of {@code enterMessage}.
	 * If the invocation succeeds, then a log message is written on exit based on the value
	 * {@code exitMessage}. If an exception occurs during invocation, then a message is
	 * written based on the value of {@code exceptionMessage}.
	 * @see #setEnterMessage
	 * @see #setExitMessage
	 * @see #setExceptionMessage
	 */
	@Override
	protected Object invokeUnderTrace(MethodInvocation invocation, Log logger) throws Throwable {
		String name = ClassUtils.getQualifiedMethodName(invocation.getMethod());
		StopWatch stopWatch = new StopWatch(name);
		Object returnValue = null;
		boolean exitThroughException = false;
		try {
			stopWatch.start(name);
			writeToLog(logger,
					replacePlaceholders(this.enterMessage, invocation, null, null, -1));
			returnValue = invocation.proceed();
			return returnValue;
		}
		catch (Throwable ex) {
			if (stopWatch.isRunning()) {
				stopWatch.stop();
			}
			exitThroughException = true;
			writeToLog(logger, replacePlaceholders(
					this.exceptionMessage, invocation, null, ex, stopWatch.getTotalTimeMillis()), ex);
			throw ex;
		}
		finally {
			if (!exitThroughException) {
				if (stopWatch.isRunning()) {
					stopWatch.stop();
				}
				writeToLog(logger, replacePlaceholders(
						this.exitMessage, invocation, returnValue, null, stopWatch.getTotalTimeMillis()));
			}
		}
	}

	
Replace the placeholders in the given message with the supplied values,
or values derived from those supplied.
Params:
message – the message template containing the placeholders to be replaced
methodInvocation – the MethodInvocation being logged. Used to derive values for all placeholders except $[exception] and $[returnValue].
returnValue – any value returned by the invocation. Used to replace the $[returnValue] placeholder. May be null.
throwable – any Throwable raised during the invocation. The value of Throwable.toString() is replaced for the $[exception] placeholder. May be null.
invocationTime – the value to write in place of the $[invocationTime] placeholder
Returns:
the formatted output to write to the log/**
	 * Replace the placeholders in the given message with the supplied values,
	 * or values derived from those supplied.
	 * @param message the message template containing the placeholders to be replaced
	 * @param methodInvocation the {@code MethodInvocation} being logged.
	 * Used to derive values for all placeholders except {@code $[exception]}
	 * and {@code $[returnValue]}.
	 * @param returnValue any value returned by the invocation.
	 * Used to replace the {@code $[returnValue]} placeholder. May be {@code null}.
	 * @param throwable any {@code Throwable} raised during the invocation.
	 * The value of {@code Throwable.toString()} is replaced for the
	 * {@code $[exception]} placeholder. May be {@code null}.
	 * @param invocationTime the value to write in place of the
	 * {@code $[invocationTime]} placeholder
	 * @return the formatted output to write to the log
	 */
	protected String replacePlaceholders(String message, MethodInvocation methodInvocation,
			@Nullable Object returnValue, @Nullable Throwable throwable, long invocationTime) {

		Matcher matcher = PATTERN.matcher(message);

		StringBuffer output = new StringBuffer();
		while (matcher.find()) {
			String match = matcher.group();
			if (PLACEHOLDER_METHOD_NAME.equals(match)) {
				matcher.appendReplacement(output, Matcher.quoteReplacement(methodInvocation.getMethod().getName()));
			}
			else if (PLACEHOLDER_TARGET_CLASS_NAME.equals(match)) {
				String className = getClassForLogging(methodInvocation.getThis()).getName();
				matcher.appendReplacement(output, Matcher.quoteReplacement(className));
			}
			else if (PLACEHOLDER_TARGET_CLASS_SHORT_NAME.equals(match)) {
				String shortName = ClassUtils.getShortName(getClassForLogging(methodInvocation.getThis()));
				matcher.appendReplacement(output, Matcher.quoteReplacement(shortName));
			}
			else if (PLACEHOLDER_ARGUMENTS.equals(match)) {
				matcher.appendReplacement(output,
						Matcher.quoteReplacement(StringUtils.arrayToCommaDelimitedString(methodInvocation.getArguments())));
			}
			else if (PLACEHOLDER_ARGUMENT_TYPES.equals(match)) {
				appendArgumentTypes(methodInvocation, matcher, output);
			}
			else if (PLACEHOLDER_RETURN_VALUE.equals(match)) {
				appendReturnValue(methodInvocation, matcher, output, returnValue);
			}
			else if (throwable != null && PLACEHOLDER_EXCEPTION.equals(match)) {
				matcher.appendReplacement(output, Matcher.quoteReplacement(throwable.toString()));
			}
			else if (PLACEHOLDER_INVOCATION_TIME.equals(match)) {
				matcher.appendReplacement(output, Long.toString(invocationTime));
			}
			else {
				// Should not happen since placeholders are checked earlier.
				throw new IllegalArgumentException("Unknown placeholder [" + match + "]");
			}
		}
		matcher.appendTail(output);

		return output.toString();
	}

	
Adds the String representation of the method return value to the supplied StringBuffer. Correctly handles null and void results. 
Params:
methodInvocation – the MethodInvocation that returned the value
matcher – the Matcher containing the matched placeholder
output – the StringBuffer to write output to
returnValue – the value returned by the method invocation./**
	 * Adds the {@code String} representation of the method return value
	 * to the supplied {@code StringBuffer}. Correctly handles
	 * {@code null} and {@code void} results.
	 * @param methodInvocation the {@code MethodInvocation} that returned the value
	 * @param matcher the {@code Matcher} containing the matched placeholder
	 * @param output the {@code StringBuffer} to write output to
	 * @param returnValue the value returned by the method invocation.
	 */
	private void appendReturnValue(
			MethodInvocation methodInvocation, Matcher matcher, StringBuffer output, @Nullable Object returnValue) {

		if (methodInvocation.getMethod().getReturnType() == void.class) {
			matcher.appendReplacement(output, "void");
		}
		else if (returnValue == null) {
			matcher.appendReplacement(output, "null");
		}
		else {
			matcher.appendReplacement(output, Matcher.quoteReplacement(returnValue.toString()));
		}
	}

	
Adds a comma-separated list of the short Class names of the method argument types to the output. For example, if a method has signature put(java.lang.String, java.lang.Object) then the value returned will be String, Object. 
Params:
methodInvocation – the MethodInvocation being logged. Arguments will be retrieved from the corresponding Method.
matcher – the Matcher containing the state of the output
output – the StringBuffer containing the output/**
	 * Adds a comma-separated list of the short {@code Class} names of the
	 * method argument types to the output. For example, if a method has signature
	 * {@code put(java.lang.String, java.lang.Object)} then the value returned
	 * will be {@code String, Object}.
	 * @param methodInvocation the {@code MethodInvocation} being logged.
	 * Arguments will be retrieved from the corresponding {@code Method}.
	 * @param matcher the {@code Matcher} containing the state of the output
	 * @param output the {@code StringBuffer} containing the output
	 */
	private void appendArgumentTypes(MethodInvocation methodInvocation, Matcher matcher, StringBuffer output) {
		Class<?>[] argumentTypes = methodInvocation.getMethod().getParameterTypes();
		String[] argumentTypeShortNames = new String[argumentTypes.length];
		for (int i = 0; i < argumentTypeShortNames.length; i++) {
			argumentTypeShortNames[i] = ClassUtils.getShortName(argumentTypes[i]);
		}
		matcher.appendReplacement(output,
				Matcher.quoteReplacement(StringUtils.arrayToCommaDelimitedString(argumentTypeShortNames)));
	}

	
Checks to see if the supplied String has any placeholders that are not specified as constants on this class and throws an IllegalArgumentException if so. /**
	 * Checks to see if the supplied {@code String} has any placeholders
	 * that are not specified as constants on this class and throws an
	 * {@code IllegalArgumentException} if so.
	 */
	private void checkForInvalidPlaceholders(String message) throws IllegalArgumentException {
		Matcher matcher = PATTERN.matcher(message);
		while (matcher.find()) {
			String match = matcher.group();
			if (!ALLOWED_PLACEHOLDERS.contains(match)) {
				throw new IllegalArgumentException("Placeholder [" + match + "] is not valid");
			}
		}
	}

}