<?php

/**
 * Finally, a light, permissions-checking logging class.
 *
 * Originally written for use with wpSearch
 *
 * Usage:
 * $log = new KLogger('/var/log/', KLogger::INFO );
 * $log->logInfo('Returned a million search results'); //Prints to the log file
 * $log->logFatal('Oh dear.'); //Prints to the log file
 * $log->logDebug('x = 5'); //Prints nothing due to current severity threshhold
 *
 * @author  Kenny Katzgrau <katzgrau@gmail.com>
 * @since   July 26, 2008
 * @link    http://codefury.net
 * @version 0.1
 */

/**
 * Class documentation
 */
if(!class_exists('KLogger'))
{
    class KLogger
    {
        /**
         * Error severity, from low to high. From BSD syslog RFC, secion 4.1.1
         * @link http://www.faqs.org/rfcs/rfc3164.html
         */
        const EMERG  = 0;  // Emergency: system is unusable
        const ALERT  = 1;  // Alert: action must be taken immediately
        const CRIT   = 2;  // Critical: critical conditions
        const ERR    = 3;  // Error: error conditions
        const WARN   = 4;  // Warning: warning conditions
        const NOTICE = 5;  // Notice: normal but significant condition
        const INFO   = 6;  // Informational: informational messages
        const DEBUG  = 7;  // Debug: debug messages

        //custom logging level
        /**
         * Log nothing at all
         */
        const OFF    = 8;
        /**
         * Alias for CRIT
         * @deprecated
         */
        const FATAL  = 2;

        /**
         * Internal status codes
         */
        const STATUS_LOG_OPEN    = 1;
        const STATUS_OPEN_FAILED = 2;
        const STATUS_LOG_CLOSED  = 3;

        /**
         * Current status of the log file
         * @var integer
         */
        private $_logStatus         = self::STATUS_LOG_CLOSED;
        /**
         * Holds messages generated by the class
         * @var array
         */
        private $_messageQueue      = array();
        /**
         * Path to the log file
         * @var string
         */
        private $_logFilePath       = null;
        /**
         * Current minimum logging threshold
         * @var integer
         */
        private $_severityThreshold = self::INFO;
        /**
         * This holds the file handle for this instance's log file
         * @var resource
         */
        private $_fileHandle        = null;

        /**
         * Standard messages produced by the class. Can be modified for il8n
         * @var array
         */
        private $_messages = array(
            //'writefail'   => 'The file exists, but could not be opened for writing. Check that appropriate permissions have been set.',
            'writefail'   => 'The file could not be written to. Check that appropriate permissions have been set.',
            'opensuccess' => 'The log file was opened successfully.',
            'openfail'    => 'The file could not be opened. Check permissions.',
        );

        /**
         * Default severity of log messages, if not specified
         * @var integer
         */
        private static $_defaultSeverity    = self::DEBUG;
        /**
         * Valid PHP date() format string for log timestamps
         * @var string
         */
        private static $_dateFormat         = 'Y-m-d G:i:s';
        /**
         * Octal notation for default permissions of the log file
         * @var integer
         */
        private static $_defaultPermissions = 0777;
        /**
         * Array of KLogger instances, part of Singleton pattern
         * @var array
         */
        private static $instances           = array();

        /**
         * Partially implements the Singleton pattern. Each $logDirectory gets one
         * instance.
         *
         * @param string  $logDirectory File path to the logging directory
         * @param integer $severity     One of the pre-defined severity constants
         * @return KLogger
         */
        public static function instance($logDirectory = false, $severity = false)
        {
            if ($severity === false) {
                $severity = self::$_defaultSeverity;
            }

            if ($logDirectory === false) {
                if (count(self::$instances) > 0) {
                    return current(self::$instances);
                } else {
                    $logDirectory = dirname(__FILE__);
                }
            }

            if (in_array($logDirectory, self::$instances)) {
                return self::$instances[$logDirectory];
            }

            self::$instances[$logDirectory] = new self($logDirectory, $severity);

            return self::$instances[$logDirectory];
        }

        /**
         * Class constructor
         *
         * @param string  $logDirectory File path to the logging directory
         * @param integer $severity     One of the pre-defined severity constants
         * @return void
         */
        public function __construct($logDirectory, $severity, $logFile = false)
        {
            $logDirectory = rtrim($logDirectory, '\\/');

            if ($severity === self::OFF) {
                return;
            }

            $this->_logFilePath = $logDirectory
                . DIRECTORY_SEPARATOR . ($logFile ? $logFile : 'log_' . @date('Y-m-d') . '.txt');


            $this->_severityThreshold = $severity;
            if (!file_exists($logDirectory)) {
                mkdir($logDirectory, self::$_defaultPermissions, true);
            }

            if (file_exists($this->_logFilePath) && !is_writable($this->_logFilePath)) {
                $this->_logStatus = self::STATUS_OPEN_FAILED;
                $this->_messageQueue[] = $this->_messages['writefail'];
                return;
            }

            if (($this->_fileHandle = fopen($this->_logFilePath, 'a'))) {
                $this->_logStatus = self::STATUS_LOG_OPEN;
                $this->_messageQueue[] = $this->_messages['opensuccess'];
            } else {
                $this->_logStatus = self::STATUS_OPEN_FAILED;
                $this->_messageQueue[] = $this->_messages['openfail'];
            }
        }

        /**
         * Class destructor
         */
        public function __destruct()
        {
            if ($this->_fileHandle) {
                fclose($this->_fileHandle);
            }
        }
        /**
         * Writes a $line to the log with a severity level of DEBUG
         *
         * @param string $line Information to log
         * @return void
         */
        public function logDebug($line)
        {
            $this->log($line, self::DEBUG);
        }

        /**
         * Returns (and removes) the last message from the queue.
         * @return string
         */
        public function getMessage()
        {
            return array_pop($this->_messageQueue);
        }

        /**
         * Returns the entire message queue (leaving it intact)
         * @return array
         */
        public function getMessages()
        {
            return $this->_messageQueue;
        }

        /**
         * Empties the message queue
         * @return void
         */
        public function clearMessages()
        {
            $this->_messageQueue = array();
        }

        /**
         * Sets the date format used by all instances of KLogger
         *
         * @param string $dateFormat Valid format string for date()
         */
        public static function setDateFormat($dateFormat)
        {
            self::$_dateFormat = $dateFormat;
        }

        /**
         * Writes a $line to the log with a severity level of INFO. Any information
         * can be used here, or it could be used with E_STRICT errors
         *
         * @param string $line Information to log
         * @return void
         */
        public function logInfo($line)
        {
            $this->log($line, self::INFO);
        }

        /**
         * Writes a $line to the log with a severity level of NOTICE. Generally
         * corresponds to E_STRICT, E_NOTICE, or E_USER_NOTICE errors
         *
         * @param string $line Information to log
         * @return void
         */
        public function logNotice($line)
        {
            $this->log($line, self::NOTICE);
        }

        /**
         * Writes a $line to the log with a severity level of WARN. Generally
         * corresponds to E_WARNING, E_USER_WARNING, E_CORE_WARNING, or
         * E_COMPILE_WARNING
         *
         * @param string $line Information to log
         * @return void
         */
        public function logWarn($line)
        {
            $this->log($line, self::WARN);
        }

        /**
         * Writes a $line to the log with a severity level of ERR. Most likely used
         * with E_RECOVERABLE_ERROR
         *
         * @param string $line Information to log
         * @return void
         */
        public function logError($line)
        {
            $this->log($line, self::ERR);
        }

        /**
         * Writes a $line to the log with a severity level of FATAL. Generally
         * corresponds to E_ERROR, E_USER_ERROR, E_CORE_ERROR, or E_COMPILE_ERROR
         *
         * @param string $line Information to log
         * @return void
         * @deprecated Use logCrit
         */
        public function logFatal($line)
        {
            $this->log($line, self::FATAL);
        }

        /**
         * Writes a $line to the log with a severity level of ALERT.
         *
         * @param string $line Information to log
         * @return void
         */
        public function logAlert($line)
        {
            $this->log($line, self::ALERT);
        }

        /**
         * Writes a $line to the log with a severity level of CRIT.
         *
         * @param string $line Information to log
         * @return void
         */
        public function logCrit($line)
        {
            $this->log($line, self::CRIT);
        }

        /**
         * Writes a $line to the log with a severity level of EMERG.
         *
         * @param string $line Information to log
         * @return void
         */
        public function logEmerg($line)
        {
            $this->log($line, self::EMERG);
        }

        /**
         * Writes a $line to the log with the given severity
         *
         * @param string  $line     Text to add to the log
         * @param integer $severity Severity level of log message (use constants)
         */
        public function log($line, $severity)
        {
            if ($this->_severityThreshold >= $severity) {
                $status = $this->_getTimeLine($severity);
                $this->writeFreeFormLine("$status $line \n");
            }
        }

        /**
         * Writes a line to the log without prepending a status or timestamp
         *
         * @param string $line Line to write to the log
         * @return void
         */
        public function writeFreeFormLine($line)
        {
            if ($this->_logStatus == self::STATUS_LOG_OPEN
                && $this->_severityThreshold != self::OFF) {
                if (fwrite($this->_fileHandle, $line) === false) {
                    $this->_messageQueue[] = $this->_messages['writefail'];
                }
            }
        }

        private function _getTimeLine($level)
        {
            $time = @date(self::$_dateFormat);

            switch ($level) {
                case self::EMERG:
                    return "$time - EMERG -->";
                case self::ALERT:
                    return "$time - ALERT -->";
                case self::CRIT:
                    return "$time - CRIT -->";
                case self::FATAL: # FATAL is an alias of CRIT
                    return "$time - FATAL -->";
                case self::NOTICE:
                    return "$time - NOTICE -->";
                case self::INFO:
                    return "$time - INFO -->";
                case self::WARN:
                    return "$time - WARN -->";
                case self::DEBUG:
                    return "$time - DEBUG -->";
                case self::ERR:
                    return "$time - ERROR -->";
                default:
                    return "$time - LOG -->";
            }
        }
    }
}