rl-warmup-plugin/includes/class-rl-mailwarmer-email-handler.php

<?php
/**
 * Handles email sending for RL MailWarmer.
 */

if (!defined('ABSPATH')) {
    exit;
}

class RL_MailWarmer_Email_Handler
{
    /**
     * Initialize the email handler.
     */
    public static function init()
    {
        // Additional hooks or filters can be added here if needed
    }

    /**
     * Send an email based on the provided email data.
     *
     * @param array $email The email data, including sender, recipient, subject, and body.
     * @return bool True if the email was sent successfully, false otherwise.
     */
    public static function send_email(array $email): bool
    {
        // Load WordPress PHPMailer
        $phpmailer = wp_mail();

        // Configure SMTP settings
        add_action('phpmailer_init', function ($phpmailer) use ($email) {
            $phpmailer->isSMTP();
            $phpmailer->Host       = $email['smtp_host'];
            $phpmailer->SMTPAuth   = true;
            $phpmailer->Username   = $email['smtp_username'];
            $phpmailer->Password   = $email['smtp_password'];
            $phpmailer->SMTPSecure = $email['smtp_encryption']; // SSL or TLS
            $phpmailer->Port       = $email['smtp_port'];
        });

        // Prepare the email
        $to      = $email['recipient'];
        $subject = $email['subject'];
        $body    = $email['body'];
        $headers = [
            'From: ' . $email['sender_name'] . ' <' . $email['sender_email'] . '>',
            'Reply-To: ' . $email['reply_to'],
        ];

        // Send the email
        return wp_mail($to, $subject, $body, $headers);
    }

    /**
     * Generate random email content.
     *
     * @param int    $campaign_id The campaign ID.
     * @param string $recipient   The recipient email address.
     * @return array The email content including subject and body.
     */
    public static function generate_email_content(int $campaign_id, string $recipient): array
    {
        // Fetch predefined topics and names
        $topics      = explode("\n", get_field('default_topic_pool', 'option'));
        $first_names = explode("\n", get_field('valid_first_name_pool', 'option'));
        $last_names  = explode("\n", get_field('valid_last_name_pool', 'option'));

        // Randomize participants and topics
        $subject      = self::random_element($topics);
        $sender_name  = self::random_element($first_names) . ' ' . self::random_element($last_names);
        $body_content = "Hi {$recipient},\n\n" .
                        "I wanted to reach out to discuss {$subject}. Let's connect soon!\n\n" .
                        "Best,\n{$sender_name}";

        return [
            'subject' => $subject,
            'body'    => $body_content,
        ];
    }

    /**
     * Generate email schedule based on warmup calculations.
     *
     * @param int $campaign_id The campaign ID.
     * @return array The email schedule.
     */
    public static function generate_email_schedule(int $campaign_id): array
    {
        $start_date    = get_field('start_date', $campaign_id) ?: date('Ymd');
        $warmup_period = (int) get_field('warmup_period', $campaign_id);
        $target_volume = (int) get_field('target_volume', $campaign_id);
        $emails_per_day = $target_volume / ($warmup_period * 7);

        $schedule = [];
        $current_date = strtotime($start_date);

        for ($week = 0; $week < $warmup_period; $week++) {
            for ($day = 1; $day <= 7; $day++) {
                if (self::is_weekend($current_date)) {
                    $current_date = strtotime('+1 day', $current_date);
                    continue;
                }

                for ($email_count = 0; $email_count < $emails_per_day; $email_count++) {
                    $schedule[] = [
                        'send_time' => date('Y-m-d H:i:s', self::random_business_hour($current_date)),
                        'sent'      => false,
                    ];
                }

                $current_date = strtotime('+1 day', $current_date);
            }
        }

        return $schedule;
    }

    /**
     * Check if a timestamp falls on a weekend.
     *
     * @param int $timestamp The timestamp to check.
     * @return bool True if it's a weekend, false otherwise.
     */
    private static function is_weekend(int $timestamp): bool
    {
        $day = date('N', $timestamp);
        return $day >= 6;
    }

    /**
     * Generate a random business hour timestamp for a given day.
     *
     * @param int $timestamp The day's timestamp.
     * @return int The timestamp within business hours.
     */
    private static function random_business_hour(int $timestamp): int
    {
        $start_hour = 8;  // 8 AM
        $end_hour   = 18; // 6 PM
        $random_hour = mt_rand($start_hour, $end_hour - 1);
        $random_minute = mt_rand(0, 59);

        return strtotime(date('Y-m-d', $timestamp) . " {$random_hour}:{$random_minute}:00");
    }

    /**
     * Get a random element from an array.
     *
     * @param array $array The array to pick from.
     * @return mixed The random element.
     */
    private static function random_element(array $array)
    {
        return $array[array_rand($array)];
    }
}