/*
 * 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.tomcat.util.log;

import org.apache.juli.logging.Log;

This helper class assists with the logging associated with invalid input
data. A developer may want all instances of invalid input data logged to
assist with debugging whereas in production it is likely to be desirable not
to log anything for invalid data. The following settings may be used:

NOTHING: Log nothing.
DEBUG_ALL: Log all problems at DEBUG log level.
INFO_THEN_DEBUG: Log first problem at INFO log level and any further
    issues in the following TBD (configurable) seconds at DEBUG level
INFO_ALL: Log all problems at INFO log level.

By default, INFO_THEN_DEBUG is used with a suppression time of 24 hours.
NOTE: This class is not completely thread-safe. When using INFO_THEN_DEBUG it
is possible that several INFO messages will be logged before dropping to
DEBUG.
/**
 * This helper class assists with the logging associated with invalid input
 * data. A developer may want all instances of invalid input data logged to
 * assist with debugging whereas in production it is likely to be desirable not
 * to log anything for invalid data. The following settings may be used:
 * <ul>
 * <li>NOTHING: Log nothing.</li>
 * <li>DEBUG_ALL: Log all problems at DEBUG log level.</li>
 * <li>INFO_THEN_DEBUG: Log first problem at INFO log level and any further
 *     issues in the following TBD (configurable) seconds at DEBUG level</li>
 * <li>INFO_ALL: Log all problems at INFO log level.</li>
 * </ul>
 * By default, INFO_THEN_DEBUG is used with a suppression time of 24 hours.
 *
 * NOTE: This class is not completely thread-safe. When using INFO_THEN_DEBUG it
 * is possible that several INFO messages will be logged before dropping to
 * DEBUG.
 */
public class UserDataHelper {

    private final Log log;

    private final Config config;

    // A value of 0 is equivalent to using INFO_ALL
    // A negative value will trigger infinite suppression
    // The value is milliseconds
    private final long suppressionTime;

    private volatile long lastInfoTime = 0;


    public UserDataHelper(Log log) {
        this.log = log;

        Config tempConfig;
        String configString = System.getProperty(
                "org.apache.juli.logging.UserDataHelper.CONFIG");
        if (configString == null) {
            tempConfig = Config.INFO_THEN_DEBUG;
        } else {
            try {
                tempConfig = Config.valueOf(configString);
            } catch (IllegalArgumentException iae) {
                // Ignore - use default
                tempConfig = Config.INFO_THEN_DEBUG;
            }
        }

        // Default suppression time of 1 day.
        suppressionTime = Integer.getInteger(
                "org.apache.juli.logging.UserDataHelper.SUPPRESSION_TIME",
                60 * 60 * 24).intValue() * 1000L;

        if (suppressionTime == 0) {
            tempConfig = Config.INFO_ALL;
        }

        config = tempConfig;
    }


    
Returns log mode for the next log message, or null if the
message should not be logged.

If INFO_THEN_DEBUG configuration option is enabled, this
method might change internal state of this object.
Returns:
Log mode, or null/**
     * Returns log mode for the next log message, or <code>null</code> if the
     * message should not be logged.
     *
     * <p>
     * If <code>INFO_THEN_DEBUG</code> configuration option is enabled, this
     * method might change internal state of this object.
     *
     * @return Log mode, or <code>null</code>
     */
    public Mode getNextMode() {
        if (Config.NONE == config) {
            return null;
        } else if (Config.DEBUG_ALL == config) {
            return log.isDebugEnabled() ? Mode.DEBUG : null;
        } else if (Config.INFO_THEN_DEBUG == config) {
            if (logAtInfo()) {
                return log.isInfoEnabled() ? Mode.INFO_THEN_DEBUG : null;
            } else {
                return log.isDebugEnabled() ? Mode.DEBUG : null;
            }
        } else if (Config.INFO_ALL == config) {
            return log.isInfoEnabled() ? Mode.INFO : null;
        }
        // Should never happen
        return null;
    }


    /*
     * Not completely thread-safe but good enough for this use case. I couldn't
     * see a simple enough way to make it completely thread-safe that was not
     * likely to compromise performance.
     */
    private boolean logAtInfo() {

        if (suppressionTime < 0 && lastInfoTime > 0) {
            return false;
        }

        long now = System.currentTimeMillis();

        if (lastInfoTime + suppressionTime > now) {
            return false;
        }

        lastInfoTime = now;
        return true;
    }


    private enum Config {
        NONE,
        DEBUG_ALL,
        INFO_THEN_DEBUG,
        INFO_ALL
    }

    
Log mode for the next log message.
/**
     * Log mode for the next log message.
     */
    public enum Mode {
        DEBUG,
        INFO_THEN_DEBUG,
        INFO
    }
}