<?php

/**
 * The abstract class which every cron job class needs to be extending for it
 * to function properly. Nothing here needs to be changed, but if you feel it's
 * required to do so, please contact the author first.
 *
 * @author Stefan van Beusekom
 * @version 1.1
 * @abstract
 */
abstract class Callcenter_Model_Cron_Abstract {

    protected $_errorList = array();
    protected $_handleExecList = false;
    protected $_lastExecuted = false;
    protected $_startScript = false;
    protected $_endScript = false;
    protected $_executionSuccessful = false;

    /**
     * Set the time limit for script execution
     *
     * @author Stefan van Beusekom
     * @since 1.1
     */
    protected function setTimelimit() {
        $childClass = get_called_class();
        set_time_limit(($childClass::CRON_TIMEOUT_MINUTES * 60) + $childClass::CRON_TIMEOUT_SECONDS);
        return $this;
    }

    /**
     * Set the date and time string of when this cronjob was started
     *
     * @author Stefan van Beusekom
     * @since 1.1
     */
    protected function setStartScript() {
        $dateTime = new DateTime();
        $this->_startScript = $dateTime->format("Y-m-d H:i:s");
        return $this;
    }

    /**
     * Set the date and time string of when this cronjob ended
     *
     * @author Stefan van Beusekom
     * @since 1.1
     */
    protected function setEndScript() {
        $dateTime = new DateTime();
        $this->_endScript = $dateTime->format("Y-m-d H:i:s");
        return $this;
    }

    /**
     * Get the path to the cronjob folder
     *
     * @author Stefan van Beusekom
     * @since 1.0
     * @return string
     */
    protected function getCronPath($file = null) {
        return APPLICATION_PATH . "/../cron/" . $file;
    }

    /**
     * Add an error for the current cronjob
     *
     * @author Stefan van Beusekom
     * @since 1.0
     * @param string $error Error message
     */
    protected function addError($error) {
        array_push($this->_errorList, $error);
    }

    /**
     * Return a list of errors for the current cronjob
     *
     * @author Stefan van Beusekom
     * @since 1.0
     * @return array
     */
    protected function getErrors() {
        return $this->_errorList;
    }

    /**
     * Set the current timestamp of when this cronjob was last executed
     *
     * @author Stefan van Beusekom
     * @since 1.0
     */
    protected function setLastExecuted() {
        $this->_handleExecList = fopen($this->getCronPath(get_called_class() . ".cron"), "w+");
        $cronArray = fread($this->_handleExecList, filesize($this->getCronPath(get_called_class() . ".cron")));
        if (($cronArray) == '')
            $cronArray = array();
        else
            $cronArray = unserialize($cronArray);
        $this->_lastExecuted = time();
        $cronArray[get_called_class()] = $this->_lastExecuted;
        fwrite($this->_handleExecList, serialize($cronArray));
        fclose($this->_handleExecList);
        return $this;
    }

    /**
     * Get the timestamp of when this cronjob was last executed
     *
     * @author Stefan van Beusekom
     * @since 1.0
     * @return int|boolean
     */
    protected function getLastExecuted() {
        if (!$this->_lastExecuted) {
            if (file_exists($this->getCronPath(get_called_class() . ".cron"))) {
                $this->_handleExecList = fopen($this->getCronPath(get_called_class() . ".cron"), "r");
                $cronArray = fread($this->_handleExecList, filesize($this->getCronPath(get_called_class() . ".cron")));
                if (!$cronArray)
                    $cronArray = array();
                else
                    $cronArray = unserialize($cronArray);
                return (key_exists(get_called_class(), $cronArray)) ? $cronArray[get_called_class()] : 0;
            } else {
                return 0;
            }
        } else {
            return $this->_lastExecuted;
        }
    }

    /**
     * Return a true or false if the current cronjob is allowed to run based on
     * the timestamps.
     *
     * @author Stefan van Beusekom
     * @since 1.0
     * @return boolean
     */
    protected function allowExecute() {
        $childClass = get_called_class();
        $dateTimePre = new DateTime();
        $dateTimePre->setTimestamp($this->getLastExecuted());
        $dateTimePre->setTime($dateTimePre->format("H"), $dateTimePre->format("i"), 0);

        if ($childClass::CRON_INTERVAL_HOURS != 0)
            $dateTimePre->setTime($dateTimePre->format("H"), 0, 0);
        if ($childClass::CRON_INTERVAL_DAYS != 0)
            $dateTimePre->setTime(0, 0, 0);

        $currentSeconds = (time() - $dateTimePre->getTimestamp());
        $intervalSeconds = ($childClass::CRON_INTERVAL_DAYS * 24 * 60 * 60) + ($childClass::CRON_INTERVAL_HOURS * 60 * 60) + ($childClass::CRON_INTERVAL_MINUTES * 60);

        $curDateObj = new DateTime();
        $allDateObj = new DateTime($childClass::CRON_START_DATETIME);

        if ($curDateObj->getTimestamp() < $allDateObj->getTimestamp())
            return false;

        if ($currentSeconds >= $intervalSeconds)
            return true;
        else
            return false;
    }

    /**
     * Append the log with data pertaining to the execution, or failure thereof
     *
     * @author Stefan van Beusekom
     * @since 1.0
     */
    protected function addLog() {
        $fileHandle = fopen($this->getCronPath(get_called_class() . ".txt"), "a");
        $dateObjectStart = new DateTime($this->_startScript);
        $dateObjectEnd = new DateTime($this->_endScript);
        $datePrefix = "[" . $dateObjectStart->format("d-m-Y H:i:s") . "][" . $dateObjectEnd->format("d-m-Y H:i:s") . "] ";
        $logEntry = "";
        if ($this->isSuccessful()) {
            $logEntry .= $datePrefix . "Cronjob was completed successfully." . "\r\n";
        } else {
            $errorPrefix = str_pad("", strlen($datePrefix), " ", STR_PAD_LEFT);
            $logEntry .= $datePrefix . "Cronjob could not be completed. The following errors occured:" . "\r\n";
            foreach ($this->getErrors() as $error) {
                $logEntry .= $errorPrefix . $error . "\r\n";
            }
        }
        fwrite($fileHandle, $logEntry);
        fclose($fileHandle);
    }

    /**
     * Return a true or false if the current cronjob has been successful
     *
     * @author Stefan van Beusekom
     * @since 1.0
     * @return boolean
     */
    protected function isSuccessful() {
        return ((count($this->getErrors()) == 0) ? true : false);
    }

    /**
     * The on exit callback which will produce an error message despite an
     * uncatchable error being thrown.
     *
     * @author Stefan van Beusekom
     * @since 1.1
     * @todo Although this method logs the error, nothing can be done about its
     *       ability to continue running other cronjobs. Search for possible
     *       solution to this problem.
     * @return boolean
     */
    public function onExecute() {
        if (!$this->_executionSuccessful) {
            $errorMessage = "CRITICAL ERROR - Entire cron process was abruptly halted due to an uncatchable error. Please disable this class until the problem has been resolved. - No stack trace is available for debugging, but common errors are: faulty code, maximum execution time exceeded, or a server crash.";
            $this->addError($errorMessage);
            $this->addLog();
        }
    }

    /**
     * Execute the cronjob
     *
     * @author Stefan van Beusekom
     * @since 1.0
     * @return boolean
     */
    public function execute() {
        register_shutdown_function(array($this, "onExecute"));
        $this->setTimelimit();
        if ($this->allowExecute()) {
            $this->setStartScript();
            try {
                $this->task();
            } catch (Exception $e) {
                $this->addError("The current task generated an exception, message: " . $e->getMessage());
            }
            if ($this->isSuccessful()) {
                $this->addLog();
                $this->setEndScript();
                $this->setLastExecuted();
            } else {
                $this->addLog();
            }
            $this->_executionSuccessful = true;
            return $this->isSuccessful();
        }
        $this->_executionSuccessful = true;
        return false;
    }

    /**
     * Task to be executed
     *
     * @author Stefan van Beusekom
     * @since 1.0
     */
    protected abstract function task();
}

?>