PHPMailer附件发送失败：动态生成文件时的时序问题与解决方案

// 错误的执行顺序示例（简化）
<?php
if (isset($_POST['generate'])) {
    // PHPMailer code block
    // 尝试添加附件，但此时文件可能还未生成
    $mail->AddAttachment("path/to/generated-file.png");
    $mail->send();
}

if (isset($_POST['generate'])) {
    // Certificate generation code block
    // 这里才真正生成并保存文件
    imagepng($createimage, "path/to/generated-file.png");
}
?>

<?php
// 引入PHPMailer类和设置
use PHPMailer\PHPMailer\PHPMailer;
use PHPMailer\PHPMailer\SMTP;
use PHPMailer\PHPMailer\Exception;

require 'PHPMailer-master/src/PHPMailer.php';
require 'PHPMailer-master/src/SMTP.php';
require 'PHPMailer-master/src/Exception.php';

// 确保所有操作都在表单提交后执行
if (isset($_POST['generate'])) {
    // 1. 获取并处理表单数据
    $name = ucwords($_POST['name']);
    $customerref = ($_POST['customerref']);
    $date = ($_POST['date']);
    $customeremail = ($_POST['customeremail']);
    $weight = ucwords($_POST['weight']); // 确保获取所有生成证书所需数据

    // 2. 表单数据验证
    if ($name == "" || $weight == "" || $date == "" || $customeremail == "" || $customerref == "") {
        echo "<div class='alert alert-danger col-sm-6' role='alert'>Not all form fields have been filled in. Please try again.</div>";
    } else {
        // 3. 核心：生成并保存证书文件
        $image = "CSD-Certificates/certi.png";
        $createimage = imagecreatefrompng($image);

        // 构建输出文件路径
        // 确保路径是相对于当前脚本的正确路径，或者使用绝对路径
        $output_filename = "destruction-cert(" . $customerref . "-" . $date . ").png";
        $output_dir = dirname(__FILE__) . "/CSD-Certificates/saved-certs/";
        $output_filepath = $output_dir . $output_filename;

        // 设置字体、颜色、文本位置等
        $white = imagecolorallocate($createimage, 254, 254, 254);
        $drFont = "CSD-Certificates/TitilliumWeb-Regular.ttf";
        // ... (省略具体的imagettftext调用，与原代码相同) ...
        imagettftext($createimage, 50, 0, 1600, 700, $white, $drFont, $name);
        imagettftext($createimage, 50, 0, 2300, 900, $white, $drFont, $weight);
        imagettftext($createimage, 50, 0, 1850, 900, $white, $drFont, $date);
        imagettftext($createimage, 50, 0, 2200, 1980, $white, $drFont, $date);
        imagettftext($createimage, 50, 0, 2200, 2180, $white, $drFont, $customerref);


        // 保存图片文件
        imagepng($createimage, $output_filepath, 3);
        imagedestroy($createimage); // 释放内存

        echo "<div class='alert alert-success col-sm-6' role='alert'>Congratulations! The certificate for $name has been generated and sent to $customeremail.</div>";

        // 4. PHPMailer发送邮件（确保文件已生成后再执行）
        $mail = new PHPMailer(true);
        try {
            // 服务器设置
            $mail->isSMTP();
            $mail->Host       = 'mail.smtp2go.com';
            $mail->SMTPAuth   = true;
            $mail->Username   = 'refurbsa.com';
            $mail->Password   = 'Y2F6ejMxbGFseTUw';
            $mail->SMTPSecure = PHPMailer::ENCRYPTION_SMTPS;
            $mail->Port       = 465;

            // 收件人
            $mail->setFrom('sender@example.com', 'Electronic Cemetery'); // 请替换为实际发件人邮箱
            $mail->addAddress($customeremail);
            $mail->addReplyTo('replyto@example.com', 'Electronic Cemetery'); // 请替换为实际回复邮箱

            // 添加附件，此时文件已存在
            // 确保PHPMailer使用的路径与文件生成时保存的路径一致
            if (file_exists($output_filepath)) {
                $mail->AddAttachment($output_filepath);
            } else {
                throw new Exception("Certificate file not found after generation: " . $output_filepath);
            }


            // 内容
            $mail->isHTML(true);
            $mail->Subject = 'Your E-Waste Disposal Certificate';
            $mail->Body    = "Good day $name,<br><br>
Thank you very much for making use of our services. Your collection has been processed and I have attached your destruction certificate to this email.  
<br><br>
If you were happy with our service then it would be very much appreciated if you would spare a moment to give us your review <a href='https://www.facebook.com/eastcoastewaste/reviews'>HERE</a>
<br><br>
We look forward to assisting you with all your e-Waste needs in the future.
<br><br>
Wishing you a wonderful day further!
<br><br>
The Electronic Cemetery Team";

            $mail->send();

        } catch (Exception $e) {
            echo "Message could not be sent. Mailer Error: {$mail->ErrorInfo}";
        }
    }
}
?>