<?php
/**
 * 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 log4php
 */

/**
 * LoggerAppenderRollingFile writes logging events to a specified file. The
 * file is rolled over after a specified size has been reached.
 *
 * This appender uses a layout.
 *
 * ## Configurable parameters: ##
 *
 * - **file** - Path to the target file.
 * - **append** - If set to true, the appender will append to the file,
 *     otherwise the file contents will be overwritten.
 * - **maxBackupIndex** - Maximum number of backup files to keep. Default is 1.
 * - **maxFileSize** - Maximum allowed file size (in bytes) before rolling
 *     over. Suffixes "KB", "MB" and "GB" are allowed. 10KB = 10240 bytes, etc.
 *     Default is 10M.
 * - **compress** - If set to true, rolled-over files will be compressed.
 *     Requires the zlib extension.
 *
 * @version $Revision: 1394975 $
 * @package log4php
 * @subpackage appenders
 * @license http://www.apache.org/licenses/LICENSE-2.0 Apache License, Version 2.0
 * @link http://logging.apache.org/log4php/docs/appenders/rolling-file.html Appender documentation
 */
class LoggerAppenderRollingFile extends LoggerAppenderFile {

    /** Compressing backup files is done in chunks, this determines how large. */
    const COMPRESS_CHUNK_SIZE = 102400; // 100KB

    /**
     * The maximum size (in bytes) that the output file is allowed to reach
     * before being rolled over to backup files.
     *
     * The default maximum file size is 10MB (10485760 bytes). Maximum value
     * for this option may depend on the file system.
     *
     * @var integer
     */
    protected $maxFileSize = 10485760;

    /**
     * Set the maximum number of backup files to keep around.
     *
     * Determines how many backup files are kept before the oldest is erased.
     * This option takes a positive integer value. If set to zero, then there
     * will be no backup files and the log file will be truncated when it
     * reaches <var>maxFileSize</var>.
     *
     * There is one backup file by default.
     *
     * @var integer
     */
    protected $maxBackupIndex = 1;

    /**
     * The <var>compress</var> parameter determindes the compression with zlib.
     * If set to true, the rollover files are compressed and saved with the .gz extension.
     * @var boolean
     */
    protected $compress = false;

    /**
     * Set to true in the constructor if PHP >= 5.3.0. In that case clearstatcache
     * supports conditional clearing of statistics.
     * @var boolean
     * @see http://php.net/manual/en/function.clearstatcache.php
     */
    private $clearConditional = false;

    /**
     * Get the maximum size that the output file is allowed to reach
     * before being rolled over to backup files.
     * @return integer
     */
    public function getMaximumFileSize() {
        return $this->maxFileSize;
    }

    public function __construct($name = '') {
        parent::__construct($name);
        if (version_compare(PHP_VERSION, '5.3.0') >= 0) {
            $this->clearConditional = true;
        }
    }

    /**
     * Implements the usual roll over behaviour.
     *
     * If MaxBackupIndex is positive, then files File.1, ..., File.MaxBackupIndex -1 are renamed to File.2, ..., File.MaxBackupIndex.
     * Moreover, File is renamed File.1 and closed. A new File is created to receive further log output.
     *
     * If MaxBackupIndex is equal to zero, then the File is truncated with no backup files created.
     *
     * Rollover must be called while the file is locked so that it is safe for concurrent access.
     *
     * @throws LoggerException If any part of the rollover procedure fails.
     */
    private function rollOver() {
        // If maxBackups <= 0, then there is no file renaming to be done.
        if ($this->maxBackupIndex > 0) {
            // Delete the oldest file, to keep Windows happy.
            $file = $this->file . '.' . $this->maxBackupIndex;

            if (file_exists($file) && !unlink($file)) {
                throw new LoggerException("Unable to delete oldest backup file from [$file].");
            }

            // Map {(maxBackupIndex - 1), ..., 2, 1} to {maxBackupIndex, ..., 3, 2}
            $this->renameArchievedLogs($this->file);

            // Backup the active file
            $this->moveToBackup($this->file);
        }

        // Truncate the active file
        ftruncate($this->fp, 0);
        rewind($this->fp);
    }

    private function moveToBackup($source) {
        if ($this->compress) {
            $target = $source . '.1.gz';
            $this->compressFile($source, $target);
        } else {
            $target = $source . '.1';
            copy($source, $target);
        }
    }

    private function compressFile($source, $target) {
        $target = 'compress.zlib://' . $target;

        $fin = fopen($source, 'rb');
        if ($fin === false) {
            throw new LoggerException("Unable to open file for reading: [$source].");
        }

        $fout = fopen($target, 'wb');
        if ($fout === false) {
            throw new LoggerException("Unable to open file for writing: [$target].");
        }

        while (!feof($fin)) {
            $chunk = fread($fin, self::COMPRESS_CHUNK_SIZE);
            if (false === fwrite($fout, $chunk)) {
                throw new LoggerException("Failed writing to compressed file.");
            }
        }

        fclose($fin);
        fclose($fout);
    }

    private function renameArchievedLogs($fileName) {
        for ($i = $this->maxBackupIndex - 1; $i >= 1; $i--) {

            $source = $fileName . "." . $i;
            if ($this->compress) {
                $source .= '.gz';
            }

            if (file_exists($source)) {
                $target = $fileName . '.' . ($i + 1);
                if ($this->compress) {
                    $target .= '.gz';
                }

                rename($source, $target);
            }
        }
    }

    /**
     * Writes a string to the target file. Opens file if not already open.
     * @param string $string Data to write.
     */
    protected function write($string) {
        // Lazy file open
        if (!isset($this->fp)) {
            if ($this->openFile() === false) {
                return; // Do not write if file open failed.
            }
        }

        // Lock the file while writing and possible rolling over
        if (flock($this->fp, LOCK_EX)) {

            // Write to locked file
            if (fwrite($this->fp, $string) === false) {
                $this->warn("Failed writing to file. Closing appender.");
                $this->closed = true;
            }

            // Stats cache must be cleared, otherwise filesize() returns cached results
            // If supported (PHP 5.3+), clear only the state cache for the target file
            if ($this->clearConditional) {
                clearstatcache(true, $this->file);
            } else {
                clearstatcache();
            }

            // Rollover if needed
            if (filesize($this->file) > $this->maxFileSize) {
                try {
                    $this->rollOver();
                } catch (LoggerException $ex) {
                    $this->warn("Rollover failed: " . $ex->getMessage() . " Closing appender.");
                    $this->closed = true;
                }
            }

            flock($this->fp, LOCK_UN);
        } else {
            $this->warn("Failed locking file for writing. Closing appender.");
            $this->closed = true;
        }
    }

    public function activateOptions() {
        parent::activateOptions();

        if ($this->compress && !extension_loaded('zlib')) {
            $this->warn("The 'zlib' extension is required for file compression. Disabling compression.");
            $this->compression = false;
        }
    }

    /**
     * Set the 'maxBackupIndex' parameter.
     * @param integer $maxBackupIndex
     */
    public function setMaxBackupIndex($maxBackupIndex) {
        $this->setPositiveInteger('maxBackupIndex', $maxBackupIndex);
    }

    /**
     * Returns the 'maxBackupIndex' parameter.
     * @return integer
     */
    public function getMaxBackupIndex() {
        return $this->maxBackupIndex;
    }

    /**
     * Set the 'maxFileSize' parameter.
     * @param mixed $maxFileSize
     */
    public function setMaxFileSize($maxFileSize) {
        $this->setFileSize('maxFileSize', $maxFileSize);
    }

    /**
     * Returns the 'maxFileSize' parameter.
     * @return integer
     */
    public function getMaxFileSize() {
        return $this->maxFileSize;
    }

    /**
     * Set the 'maxFileSize' parameter (kept for backward compatibility).
     * @param mixed $maxFileSize
     * @deprecated Use setMaxFileSize() instead.
     */
    public function setMaximumFileSize($maxFileSize) {
        $this->warn("The 'maximumFileSize' parameter is deprecated. Use 'maxFileSize' instead.");
        return $this->setMaxFileSize($maxFileSize);
    }

    /**
     * Sets the 'compress' parameter.
     * @param boolean $compress
     */
    public function setCompress($compress) {
        $this->setBoolean('compress', $compress);
    }

    /**
     * Returns the 'compress' parameter.
     * @param boolean
     */
    public function getCompress() {
        return $this->compress;
    }
}