Count Declined Payments From exception.log per day

declinedTransactions.php

<?php
/**
* Just a rough script to parse the exception log, find all entries that match the Declined string, and group
* them by day.
* This effectively shows a major increase in a sites number of declind transactions, for which scripting was the cause
* Setup of reCapctha at checkout stopped this issue
*
* Log example: 
* 2017-06-22T15:17:06+00:00 ERR (3): 
* exception 'Mage_Core_Exception' with message 'Declined: 15005-This transaction cannot be processed.' in public_html/app/Mage.php:603
* Stack trace:
*
*
**/


$log = file("./var/log/exception.log");
$instances = [];
$prevLine = '';
foreach ($log as $line) {
    if(strpos($line,'with message \'Declined')) {
        $dateParts = explode('T', $prevLine);
        if(isset($instances[$dateParts[0]])) {
            $instances[$dateParts[0]] = $instances[$dateParts[0]] + 1;
        } else {
            $instances[$dateParts[0]] = 1;
        }
    }
    $prevLine = $line;
}
?>
<ul>
<?php foreach($instances as $instanceKey => $instanceValue): ?>
    <li><?php echo (string)$instanceKey?>:<?php echo $instanceValue?></li>
<?php endforeach; ?>
</ul>