/*
 * 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.log4j;

import java.io.IOException;
import java.io.File;
import java.io.InterruptedIOException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.Calendar;
import java.util.TimeZone;
import java.util.Locale;

import org.apache.log4j.helpers.LogLog;
import org.apache.log4j.spi.LoggingEvent;

/**
 * DailyRollingFileAppender extends {@link FileAppender} so that the underlying
 * file is rolled over at a user chosen frequency.
 * 
 * DailyRollingFileAppender has been observed to exhibit synchronization issues
 * and data loss. The log4j extras companion includes alternatives which should
 * be considered for new deployments and which are discussed in the
 * documentation for org.apache.log4j.rolling.RollingFileAppender.
 * 
 * <p>
 * The rolling schedule is specified by the <b>DatePattern</b> option. This
 * pattern should follow the {@link SimpleDateFormat} conventions. In
 * particular, you <em>must</em> escape literal text within a pair of single
 * quotes. A formatted version of the date pattern is used as the suffix for the
 * rolled file name.
 * 
 * <p>
 * For example, if the <b>File</b> option is set to <code>/foo/bar.log</code>
 * and the <b>DatePattern</b> set to <code>'.'yyyy-MM-dd</code>, on 2001-02-16
 * at midnight, the logging file <code>/foo/bar.log</code> will be copied to
 * <code>/foo/bar.log.2001-02-16</code> and logging for 2001-02-17 will continue
 * in <code>/foo/bar.log</code> until it rolls over the next day.
 * 
 * <p>
 * Is is possible to specify monthly, weekly, half-daily, daily, hourly, or
 * minutely rollover schedules.
 * 
 * <p>
 * <table border="1" cellpadding="2">
 * <tr>
 * <th>DatePattern</th>
 * <th>Rollover schedule</th>
 * <th>Example</th>
 * 
 * <tr>
 * <td><code>'.'yyyy-MM</code>
 * <td>Rollover at the beginning of each month</td>
 * 
 * <td>At midnight of May 31st, 2002 <code>/foo/bar.log</code> will be copied to
 * <code>/foo/bar.log.2002-05</code>. Logging for the month of June will be
 * output to <code>/foo/bar.log</code> until it is also rolled over the next
 * month.
 * 
 * <tr>
 * <td><code>'.'yyyy-ww</code>
 * 
 * <td>Rollover at the first day of each week. The first day of the week depends
 * on the locale.</td>
 * 
 * <td>Assuming the first day of the week is Sunday, on Saturday midnight, June
 * 9th 2002, the file <i>/foo/bar.log</i> will be copied to
 * <i>/foo/bar.log.2002-23</i>. Logging for the 24th week of 2002 will be output
 * to <code>/foo/bar.log</code> until it is rolled over the next week.
 * 
 * <tr>
 * <td><code>'.'yyyy-MM-dd</code>
 * 
 * <td>Rollover at midnight each day.</td>
 * 
 * <td>At midnight, on March 8th, 2002, <code>/foo/bar.log</code> will be copied
 * to <code>/foo/bar.log.2002-03-08</code>. Logging for the 9th day of March
 * will be output to <code>/foo/bar.log</code> until it is rolled over the next
 * day.
 * 
 * <tr>
 * <td><code>'.'yyyy-MM-dd-a</code>
 * 
 * <td>Rollover at midnight and midday of each day.</td>
 * 
 * <td>At noon, on March 9th, 2002, <code>/foo/bar.log</code> will be copied to
 * <code>/foo/bar.log.2002-03-09-AM</code>. Logging for the afternoon of the 9th
 * will be output to <code>/foo/bar.log</code> until it is rolled over at
 * midnight.
 * 
 * <tr>
 * <td><code>'.'yyyy-MM-dd-HH</code>
 * 
 * <td>Rollover at the top of every hour.</td>
 * 
 * <td>At approximately 11:00.000 o'clock on March 9th, 2002,
 * <code>/foo/bar.log</code> will be copied to
 * <code>/foo/bar.log.2002-03-09-10</code>. Logging for the 11th hour of the 9th
 * of March will be output to <code>/foo/bar.log</code> until it is rolled over
 * at the beginning of the next hour.
 * 
 * 
 * <tr>
 * <td><code>'.'yyyy-MM-dd-HH-mm</code>
 * 
 * <td>Rollover at the beginning of every minute.</td>
 * 
 * <td>At approximately 11:23,000, on March 9th, 2001, <code>/foo/bar.log</code>
 * will be copied to <code>/foo/bar.log.2001-03-09-10-22</code>. Logging for the
 * minute of 11:23 (9th of March) will be output to <code>/foo/bar.log</code>
 * until it is rolled over the next minute.
 * 
 * </table>
 * 
 * <p>
 * Do not use the colon ":" character in anywhere in the <b>DatePattern</b>
 * option. The text before the colon is interpeted as the protocol specificaion
 * of a URL which is probably not what you want.
 * 
 * 
 * @author Eirik Lygre
 * @author Ceki G&uuml;lc&uuml;
 */
public class DailyRollingFileAppender extends FileAppender {

    // The code assumes that the following constants are in a increasing
    // sequence.
    static final int TOP_OF_TROUBLE = -1;
    static final int TOP_OF_MINUTE = 0;
    static final int TOP_OF_HOUR = 1;
    static final int HALF_DAY = 2;
    static final int TOP_OF_DAY = 3;
    static final int TOP_OF_WEEK = 4;
    static final int TOP_OF_MONTH = 5;

    /**
     * The date pattern. By default, the pattern is set to "'.'yyyy-MM-dd" meaning
     * daily rollover.
     */
    private String datePattern = "'.'yyyy-MM-dd";

    /**
     * The log file will be renamed to the value of the scheduledFilename variable
     * when the next interval is entered. For example, if the rollover period is one
     * hour, the log file will be renamed to the value of "scheduledFilename" at the
     * beginning of the next hour.
     * 
     * The precise time when a rollover occurs depends on logging activity.
     */
    private String scheduledFilename;

    /**
     * The next time we estimate a rollover should occur.
     */
    private long nextCheck = System.currentTimeMillis() - 1;

    Date now = new Date();

    SimpleDateFormat sdf;

    RollingCalendar rc = new RollingCalendar();

    int checkPeriod = TOP_OF_TROUBLE;

    // The gmtTimeZone is used only in computeCheckPeriod() method.
    static final TimeZone gmtTimeZone = TimeZone.getTimeZone("GMT");

    /**
     * The default constructor does nothing.
     */
    public DailyRollingFileAppender() {
    }

    /**
     * Instantiate a <code>DailyRollingFileAppender</code> and open the file
     * designated by <code>filename</code>. The opened filename will become the
     * ouput destination for this appender.
     * 
     */
    public DailyRollingFileAppender(Layout layout, String filename, String datePattern) throws IOException {
	super(layout, filename, true);
	this.datePattern = datePattern;
	activateOptions();
    }

    /**
     * The <b>DatePattern</b> takes a string in the same format as expected by
     * {@link SimpleDateFormat}. This options determines the rollover schedule.
     */
    public void setDatePattern(String pattern) {
	datePattern = pattern;
    }

    /** Returns the value of the <b>DatePattern</b> option. */
    public String getDatePattern() {
	return datePattern;
    }

    public void activateOptions() {
	super.activateOptions();
	if (datePattern != null && fileName != null) {
	    now.setTime(System.currentTimeMillis());
	    sdf = new SimpleDateFormat(datePattern);
	    int type = computeCheckPeriod();
	    printPeriodicity(type);
	    rc.setType(type);
	    File file = new File(fileName);
	    scheduledFilename = fileName + sdf.format(new Date(file.lastModified()));

	} else {
	    LogLog.error("Either File or DatePattern options are not set for appender [" + name + "].");
	}
    }

    void printPeriodicity(int type) {
	switch (type) {
	case TOP_OF_MINUTE:
	    LogLog.debug("Appender [" + name + "] to be rolled every minute.");
	    break;
	case TOP_OF_HOUR:
	    LogLog.debug("Appender [" + name + "] to be rolled on top of every hour.");
	    break;
	case HALF_DAY:
	    LogLog.debug("Appender [" + name + "] to be rolled at midday and midnight.");
	    break;
	case TOP_OF_DAY:
	    LogLog.debug("Appender [" + name + "] to be rolled at midnight.");
	    break;
	case TOP_OF_WEEK:
	    LogLog.debug("Appender [" + name + "] to be rolled at start of week.");
	    break;
	case TOP_OF_MONTH:
	    LogLog.debug("Appender [" + name + "] to be rolled at start of every month.");
	    break;
	default:
	    LogLog.warn("Unknown periodicity for appender [" + name + "].");
	}
    }

    // This method computes the roll over period by looping over the
    // periods, starting with the shortest, and stopping when the r0 is
    // different from from r1, where r0 is the epoch formatted according
    // the datePattern (supplied by the user) and r1 is the
    // epoch+nextMillis(i) formatted according to datePattern. All date
    // formatting is done in GMT and not local format because the test
    // logic is based on comparisons relative to 1970-01-01 00:00:00
    // GMT (the epoch).

    int computeCheckPeriod() {
	RollingCalendar rollingCalendar = new RollingCalendar(gmtTimeZone, Locale.getDefault());
	// set sate to 1970-01-01 00:00:00 GMT
	Date epoch = new Date(0);
	if (datePattern != null) {
	    for (int i = TOP_OF_MINUTE; i <= TOP_OF_MONTH; i++) {
		SimpleDateFormat simpleDateFormat = new SimpleDateFormat(datePattern);
		simpleDateFormat.setTimeZone(gmtTimeZone); // do all date formatting in GMT
		String r0 = simpleDateFormat.format(epoch);
		rollingCalendar.setType(i);
		Date next = new Date(rollingCalendar.getNextCheckMillis(epoch));
		String r1 = simpleDateFormat.format(next);
		// System.out.println("Type = "+i+", r0 = "+r0+", r1 = "+r1);
		if (r0 != null && r1 != null && !r0.equals(r1)) {
		    return i;
		}
	    }
	}
	return TOP_OF_TROUBLE; // Deliberately head for trouble...
    }

    /**
     * Rollover the current file to a new file.
     */
    void rollOver() throws IOException {

	/* Compute filename, but only if datePattern is specified */
	if (datePattern == null) {
	    errorHandler.error("Missing DatePattern option in rollOver().");
	    return;
	}

	String datedFilename = fileName + sdf.format(now);
	// It is too early to roll over because we are still within the
	// bounds of the current interval. Rollover will occur once the
	// next interval is reached.
	if (scheduledFilename.equals(datedFilename)) {
	    return;
	}

	// close current file, and rename it to datedFilename
	this.closeFile();

	File target = new File(scheduledFilename);
	if (target.exists()) {
	    target.delete();
	}

	File file = new File(fileName);
	boolean result = file.renameTo(target);
	if (result) {
	    LogLog.debug(fileName + " -> " + scheduledFilename);
	} else {
	    LogLog.error("Failed to rename [" + fileName + "] to [" + scheduledFilename + "].");
	}

	try {
	    // This will also close the file. This is OK since multiple
	    // close operations are safe.
	    this.setFile(fileName, true, this.bufferedIO, this.bufferSize);
	} catch (IOException e) {
	    errorHandler.error("setFile(" + fileName + ", true) call failed.");
	}
	scheduledFilename = datedFilename;
    }

    /**
     * This method differentiates DailyRollingFileAppender from its super class.
     *
     * <p>
     * Before actually logging, this method will check whether it is time to do a
     * rollover. If it is, it will schedule the next rollover time and then
     * rollover.
     */
    protected void subAppend(LoggingEvent event) {
	long n = System.currentTimeMillis();
	if (n >= nextCheck) {
	    now.setTime(n);
	    nextCheck = rc.getNextCheckMillis(now);
	    try {
		rollOver();
	    } catch (IOException ioe) {
		if (ioe instanceof InterruptedIOException) {
		    Thread.currentThread().interrupt();
		}
		LogLog.error("rollOver() failed.", ioe);
	    }
	}
	super.subAppend(event);
    }
}

/**
 * RollingCalendar is a helper class to DailyRollingFileAppender. Given a
 * periodicity type and the current time, it computes the start of the next
 * interval.
 */
class RollingCalendar extends GregorianCalendar {
    private static final long serialVersionUID = -3560331770601814177L;

    int type = DailyRollingFileAppender.TOP_OF_TROUBLE;

    RollingCalendar() {
	super();
    }

    RollingCalendar(TimeZone tz, Locale locale) {
	super(tz, locale);
    }

    void setType(int type) {
	this.type = type;
    }

    public long getNextCheckMillis(Date now) {
	return getNextCheckDate(now).getTime();
    }

    public Date getNextCheckDate(Date now) {
	this.setTime(now);

	switch (type) {
	case DailyRollingFileAppender.TOP_OF_MINUTE:
	    this.set(Calendar.SECOND, 0);
	    this.set(Calendar.MILLISECOND, 0);
	    this.add(Calendar.MINUTE, 1);
	    break;
	case DailyRollingFileAppender.TOP_OF_HOUR:
	    this.set(Calendar.MINUTE, 0);
	    this.set(Calendar.SECOND, 0);
	    this.set(Calendar.MILLISECOND, 0);
	    this.add(Calendar.HOUR_OF_DAY, 1);
	    break;
	case DailyRollingFileAppender.HALF_DAY:
	    this.set(Calendar.MINUTE, 0);
	    this.set(Calendar.SECOND, 0);
	    this.set(Calendar.MILLISECOND, 0);
	    int hour = get(Calendar.HOUR_OF_DAY);
	    if (hour < 12) {
		this.set(Calendar.HOUR_OF_DAY, 12);
	    } else {
		this.set(Calendar.HOUR_OF_DAY, 0);
		this.add(Calendar.DAY_OF_MONTH, 1);
	    }
	    break;
	case DailyRollingFileAppender.TOP_OF_DAY:
	    this.set(Calendar.HOUR_OF_DAY, 0);
	    this.set(Calendar.MINUTE, 0);
	    this.set(Calendar.SECOND, 0);
	    this.set(Calendar.MILLISECOND, 0);
	    this.add(Calendar.DATE, 1);
	    break;
	case DailyRollingFileAppender.TOP_OF_WEEK:
	    this.set(Calendar.DAY_OF_WEEK, getFirstDayOfWeek());
	    this.set(Calendar.HOUR_OF_DAY, 0);
	    this.set(Calendar.MINUTE, 0);
	    this.set(Calendar.SECOND, 0);
	    this.set(Calendar.MILLISECOND, 0);
	    this.add(Calendar.WEEK_OF_YEAR, 1);
	    break;
	case DailyRollingFileAppender.TOP_OF_MONTH:
	    this.set(Calendar.DATE, 1);
	    this.set(Calendar.HOUR_OF_DAY, 0);
	    this.set(Calendar.MINUTE, 0);
	    this.set(Calendar.SECOND, 0);
	    this.set(Calendar.MILLISECOND, 0);
	    this.add(Calendar.MONTH, 1);
	    break;
	default:
	    throw new IllegalStateException("Unknown periodicity type.");
	}
	return getTime();
    }
}
