<?php

defined( 'ABSPATH' ) or exit;

// get old log filename
$upload_dir = wp_upload_dir( null, false );
$old_filename = trailingslashit( $upload_dir['basedir'] ) . 'mc4wp-debug.log';
$new_filename = trailingslashit( $upload_dir['basedir'] ) . 'mc4wp-debug-log.php';

// check if old default log file exists
if( ! file_exists( $old_filename ) ) {
    return;
}

// rename to new file.
@rename( $old_filename, $new_filename );

// if success, insert php exit tag as first line
if( file_exists( $new_filename ) ) {
    $handle = fopen( $new_filename, 'r+' );

    if( is_resource( $handle ) ) {
        // make sure first line of log file is a PHP tag + exit statement (to prevent direct file access)
        $line = fgets( $handle );
        $php_exit_string = '<?php exit; ?>';
        if( strpos( $line, $php_exit_string ) !== 0 ) {
            rewind( $handle);
            fwrite( $handle, $php_exit_string . PHP_EOL . $line );
        }

        fclose( $handle );
    }
}