/*

 * 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.

 */

#define __STDC_CONSTANT_MACROS

#define NOMINMAX /* tell wnidows not to define min/max macros */

#include <log4cxx/logstring.h>

#include <log4cxx/helpers/cacheddateformat.h>

#include <log4cxx/helpers/pool.h>

#include <limits>

#include <log4cxx/helpers/exception.h>

using namespace LOG4CXX_NS;

using namespace LOG4CXX_NS::helpers;

using namespace LOG4CXX_NS::pattern;

struct CachedDateFormat::CachedDateFormatPriv

{

  CachedDateFormatPriv(DateFormatPtr dateFormat, int expiration1) :

    formatter(dateFormat),

    millisecondStart(0),

    slotBegin(std::numeric_limits<log4cxx_time_t>::min()),

    cache(50, 0x20),

    expiration(expiration1),

    previousTime(std::numeric_limits<log4cxx_time_t>::min())

  {}

  /**

   *   Wrapped formatter.

   */

  LOG4CXX_NS::helpers::DateFormatPtr formatter;

  /**

   *  Index of initial digit of millisecond pattern or

   *   UNRECOGNIZED_MILLISECONDS or NO_MILLISECONDS.

   */

  mutable int millisecondStart;

  /**

   *  Integral second preceding the previous convered Date.

   */

  mutable log4cxx_time_t slotBegin;

  /**

   *  Cache of previous conversion.

   */

  mutable LogString cache;

  /**

   *  Maximum validity period for the cache.

   *  Typically 1, use cache for duplicate requests only, or

   *  1000000, use cache for requests within the same integral second.

   */

  const int expiration;

  /**

   *  Date requested in previous conversion.

   */

  mutable log4cxx_time_t previousTime;

};

/**

*  Supported digit set.  If the wrapped DateFormat uses

*  a different unit set, the millisecond pattern

*  will not be recognized and duplicate requests

*  will use the cache.

*/

const logchar CachedDateFormat::digits[] = { 0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0 };

/**

 * First magic number (in microseconds) used to detect

 * the millisecond position.

 */

const int CachedDateFormat::magic1 = 654000;

/**

 *  Expected representation of first magic number in milliseconds.

 */

const logchar CachedDateFormat::magicString1[] = { 0x36, 0x35, 0x34, 0 };

/**

 * Second magic number (in microseconds) used to detect

 * the millisecond position.

 */

const int CachedDateFormat::magic2 = 987000;

/**

 *  Expected representation of second magic number in milliseconds.

 */

const logchar CachedDateFormat::magicString2[] = { 0x39, 0x38, 0x37, 0};

/**

 *  Expected representation of 0 milliseconds.

 */

const logchar CachedDateFormat::zeroString[] = { 0x30, 0x30, 0x30, 0 };

/**

 *  Creates a new CachedDateFormat object.

 *  @param dateFormat Date format, may not be null.

 *  @param expiration maximum cached range in milliseconds.

 *    If the dateFormat is known to be incompatible with the

 *      caching algorithm, use a value of 0 to totally disable

 *      caching or 1 to only use cache for duplicate requests.

 */

CachedDateFormat::CachedDateFormat(const DateFormatPtr& dateFormat,

  int expiration1) :

  m_priv(std::make_unique<CachedDateFormatPriv>(dateFormat, expiration1))

{

  if (dateFormat == NULL)

  {

    throw IllegalArgumentException(LOG4CXX_STR("dateFormat cannot be null"));

  }

  if (expiration1 < 0)

  {

    throw IllegalArgumentException(LOG4CXX_STR("expiration must be non-negative"));

  }

}

CachedDateFormat::~CachedDateFormat() {}

/**

 * Finds start of millisecond field in formatted time.

 * @param time long time, must be integral number of seconds

 * @param formatted String corresponding formatted string

 * @param formatter DateFormat date format

 * @return int position in string of first digit of milliseconds,

 *    -1 indicates no millisecond field, -2 indicates unrecognized

 *    field (likely RelativeTimeDateFormat)

 */

int CachedDateFormat::findMillisecondStart(

  log4cxx_time_t time, const LogString& formatted,

  const DateFormatPtr& formatter,

  Pool& pool)

{

  log4cxx_time_t slotBegin = (time / 1000000) * 1000000;

  if (slotBegin > time)

  {

    slotBegin -= 1000000;

  }

  int millis = (int) (time - slotBegin) / 1000;

  // the magic numbers are in microseconds

  int magic = magic1;

  LogString magicString(magicString1);

  if (millis == magic1 / 1000)

  {

    magic = magic2;

    magicString = magicString2;

  }

  LogString plusMagic;

  formatter->format(plusMagic, slotBegin + magic, pool);

  /**

   *   If the string lengths differ then

   *      we can't use the cache except for duplicate requests.

   */

  if (plusMagic.length() != formatted.length())

  {

    return UNRECOGNIZED_MILLISECONDS;

  }

  else

  {

    // find first difference between values

    for (LogString::size_type i = 0; i < formatted.length(); i++)

    {

      if (formatted[i] != plusMagic[i])

      {

        //

        //   determine the expected digits for the base time

        const logchar abc[] = { 0x41, 0x42, 0x43, 0 };

        LogString formattedMillis(abc);

        millisecondFormat(millis, formattedMillis, 0);

        LogString plusZero;

        formatter->format(plusZero, slotBegin, pool);

        // Test if the next 1..3 characters match the magic string, main problem is that magic

        // available millis in formatted can overlap. Therefore the current i is not always the

        // index of the first millis char, but may be already within the millis. Besides that

        // the millis can occur everywhere in formatted. See LOGCXX-420 and following.

        size_t  magicLength     = magicString.length();

        size_t  overlapping     = magicString.find(plusMagic[i]);

        int     possibleRetVal  = int(i - overlapping);

        if (plusZero.length() == formatted.length()

          && regionMatches(magicString,       0, plusMagic,   possibleRetVal, magicLength)

          && regionMatches(formattedMillis,   0, formatted,   possibleRetVal, magicLength)

          && regionMatches(zeroString,        0, plusZero,    possibleRetVal, magicLength)

          // The following will and should fail for patterns with more than one SSS because

          // we only seem to be able to change one SSS in e.g. format and need to reformat the

          // whole string in other cases.

          && (formatted.length() == possibleRetVal + magicLength

            || plusZero.compare(possibleRetVal + magicLength,

              LogString::npos, plusMagic, possibleRetVal + magicLength, LogString::npos) == 0))

        {

          return possibleRetVal;

        }

        else

        {

          return UNRECOGNIZED_MILLISECONDS;

        }

      }

    }

  }

  return NO_MILLISECONDS;

}

/**

 * Formats a millisecond count into a date/time string.

 *

 *  @param now Number of milliseconds after midnight 1 Jan 1970 GMT.

 *  @param sbuf the string buffer to write to

 */

void CachedDateFormat::format(LogString& buf, log4cxx_time_t now, Pool& p) const

{

  //

  // If the current requested time is identical to the previously

  //     requested time, then append the cache contents.

  //

  if (now == m_priv->previousTime)

  {

    buf.append(m_priv->cache);

    return;

  }

  //

  //   If millisecond pattern was not unrecognized

  //     (that is if it was found or milliseconds did not appear)

  //

  if (m_priv->millisecondStart != UNRECOGNIZED_MILLISECONDS)

  {

    //    Check if the cache is still valid.

    //    If the requested time is within the same integral second

    //       as the last request and a shorter expiration was not requested.

    if (now < m_priv->slotBegin + m_priv->expiration

      && now >= m_priv->slotBegin

      && now < m_priv->slotBegin + 1000000L)

    {

      //

      //    if there was a millisecond field then update it

      //

      if (m_priv->millisecondStart >= 0)

      {

        millisecondFormat((int) ((now - m_priv->slotBegin) / 1000), m_priv->cache, m_priv->millisecondStart);

      }

      //

      //   update the previously requested time

      //      (the slot begin should be unchanged)

      m_priv->previousTime = now;

      buf.append(m_priv->cache);

      return;

    }

  }

  //

  //  could not use previous value.

  //    Call underlying formatter to format date.

  m_priv->cache.erase(m_priv->cache.begin(), m_priv->cache.end());

  m_priv->formatter->format(m_priv->cache, now, p);

  buf.append(m_priv->cache);

  m_priv->previousTime = now;

  m_priv->slotBegin = (m_priv->previousTime / 1000000) * 1000000;

  if (m_priv->slotBegin > m_priv->previousTime)

  {

    m_priv->slotBegin -= 1000000;

  }

  //

  //    if the milliseconds field was previous found

  //       then reevaluate in case it moved.

  //

  if (m_priv->millisecondStart >= 0)

  {

    m_priv->millisecondStart = findMillisecondStart(now, m_priv->cache, m_priv->formatter, p);

  }

}

/**

 *   Formats a count of milliseconds (0-999) into a numeric representation.

 *   @param millis Millisecond count between 0 and 999.

 *   @buf String buffer, may not be null.

 *   @offset Starting position in buffer, the length of the

 *       buffer must be at least offset + 3.

 */

void CachedDateFormat::millisecondFormat(int millis,

  LogString& buf,

  int offset)

{

  buf[offset] = digits[millis / 100];

  buf[offset + 1] = digits[(millis / 10) % 10];

  buf[offset + 2] = digits[millis  % 10];

}

/**

 * Set timezone.

 *

 * @remarks Setting the timezone using getCalendar().setTimeZone()

 * will likely cause caching to misbehave.

 * @param timeZone TimeZone new timezone

 */

void CachedDateFormat::setTimeZone(const TimeZonePtr& timeZone)

{

  m_priv->formatter->setTimeZone(timeZone);

  m_priv->previousTime = std::numeric_limits<log4cxx_time_t>::min();

  m_priv->slotBegin = std::numeric_limits<log4cxx_time_t>::min();

}

void CachedDateFormat::numberFormat(LogString& s, int n, Pool& p) const

{

  m_priv->formatter->numberFormat(s, n, p);

}

/**

 * Gets maximum cache validity for the specified SimpleDateTime

 *    conversion pattern.

 *  @param pattern conversion pattern, may not be null.

 *  @returns Duration in microseconds from an integral second

 *      that the cache will return consistent results.

 */

int CachedDateFormat::getMaximumCacheValidity(const LogString& pattern)

{

  //

  //   If there are more "S" in the pattern than just one "SSS" then

  //      (for example, "HH:mm:ss,SSS SSS"), then set the expiration to

  //      one millisecond which should only perform duplicate request caching.

  //

  const logchar S = 0x53;

  const logchar SSS[] = { 0x53, 0x53, 0x53, 0 };

  size_t firstS = pattern.find(S);

  size_t len = pattern.length();

  //

  //   if there are no S's or

  //      three that start with the first S and no fourth S in the string

  //

  if (firstS == LogString::npos ||

    (len >= firstS + 3 && pattern.compare(firstS, 3, SSS) == 0

      && (len == firstS + 3 ||

        pattern.find(S, firstS + 3) == LogString::npos)))

  {

    return 1000000;

  }

  return 1000;

}

/**

* Tests if two string regions are equal.

* @param target target string.

* @param toffset character position in target to start comparison.

* @param other other string.

* @param ooffset character position in other to start comparison.

* @param len length of region.

* @return true if regions are equal.

*/

bool CachedDateFormat::regionMatches(

  const LogString& target,

  size_t toffset,

  const LogString& other,

  size_t ooffset,

  size_t len)

{

  return target.compare(toffset, len, other, ooffset, len) == 0;

}