Add custom email to WooCommerce

class-wc-check-availability-email.php

<?php
/**
 * An email to ask the vendor to check availability of a booking.
 *
 * @extends \WC_Email
 *
 * Code copied from: https://www.skyverge.com/blog/how-to-add-a-custom-woocommerce-email/
 */

if ( ! defined( 'ABSPATH' ) ) exit; // Exit if accessed directly
 
class WC_Check_Availability_Email extends WC_Email {

/**
 * Set email defaults
 *
 * @since 0.1
 */
public function __construct() {
    // set ID, this simply needs to be a unique name
    $this->id = 'wc_vendor_check_availability';
 
    // this is the title in WooCommerce Email settings
    $this->title = 'Vendor Check Availability';
 
    // this is the description in WooCommerce email settings
    $this->description = 'Send email to the vendor when an order with a booking calendar is received. Vendor will check availability.';
 
    // these are the default heading and subject lines that can be overridden using the settings
    $this->heading = 'Vendor Check Availability';
    $this->subject = '[{site_title}] Order: ({order_number}) - Check Date Availability for {product_title}';

    // Booking information for the product.
    // TODO: Retrieve this info from the order meta.
    $this->product_name = 'NONE';
    $this->booking_info = 'NONE';
    
    // Find/replace
    $this->find['product_name'] = '{product_title}';
    $this->replace['product_name'] = $this->product_name; //'TODO:Product_Name';

    // these define the locations of the templates that this email should use, we'll just use the new order template since this email is similar
    $this->template_html  = 'emails/vendor-check-availability.php';
    // Don't bother with a plain email - being lazy.
    $this->template_plain  = 'emails/vendor-check-availability.php';
    //$this->template_plain = 'emails/plain/admin-new-order.php';;
 
    // Trigger when a new order is received.
    add_action( 'woocommerce_order_status_processing', array( $this, 'trigger' ) );
 
    // Call parent constructor to load any other defaults not explicity defined here
    parent::__construct();
 
    // this sets the recipient to the settings defined below in init_form_fields()
    $this->recipient = get_option( 'admin_email' );  // TODO: Replace with vendor information.
}
 
 /**
 * Determine if the email should actually be sent and setup email merge variables
 *
 * @param int $order_id
 */
public function trigger( $order_id ) {
 
    // bail if no order ID is present
    if ( ! $order_id )
        return;
 
    // setup order object
    $this->object = new WC_Order( $order_id );
    
    $items = $this->object->get_items();
    
    foreach($items as $item) {
        if ('line_item' == $item['type']) {
            $_product = get_product($item['product_id']);
            $item_meta = new WC_Order_Item_Meta( $item, $_product );
            
            if ($_product->is_virtual()) {
                $calendar_or_time_left = get_field('calendar_or_time_left', $_product->id);
                if (!$calendar_or_time_left) { $calendar_or_time_left = 'time_left'; } // Default value.
                
                // A product with a booking calendar needs to be confirmed by vendor before it can be marked as completed.
                if ($calendar_or_time_left == 'calendar') {
                    $vendor_email = get_field('contact_email', $_product->id);
                    if ($vendor_email) {
                        $this->recipient = $vendor_email;
                        
                        $this->product_name = get_the_title($item['product_id']);
                        // replace variables in the subject/headings
                        $this->find[] = '{product_name}';
                        $this->replace[] = $this->product_name;
                        
                        $this->find[] = '{order_number}';
                        $this->replace[] = $this->object->get_order_number();

                        if (!empty($item_meta->meta)) {
                            $this->booking_info = nl2br($item_meta->display(true, true, '_', "\n"));
                            $this->find[] = '{booking_info}';
                            $this->replace[] = $this->booking_info;
                        }
                        
                        if ( ! $this->is_enabled() || ! $this->get_recipient() ) {
                            return;
                        }
                        
                        // woohoo, send the email!
                        $this->send( $this->get_recipient(), $this->get_subject(), $this->get_content(), $this->get_headers(), $this->get_attachments() );
                    }
                }
            }
        }
    } 
}

/**
 * get_content_html function.
 *
 * @since 0.1
 * @return string
 */
public function get_content_html() {
    return wc_get_template_html( $this->template_html, array(
	    'order'		=> $this->object,
	    'email_heading'	=> $this->get_heading(),
	    'sent_to_admin'	=> true,
	    'plain_text'	=> false,
	    'email'		=> $this,
	    // Send additional info to the email template.
	    'booking_info'	=> $this->booking_info,
	    'product_name'	=> $this->product_name,
    ) );
}


function get_heading() {
	return $this->format_string( $this->heading );
} 
 
 
/**
 * get_content_plain function.
 *
 * @since 0.1
 * @return string
 */
public function get_content_plain() {
    return wc_get_template_html( $this->template_plain, array(
	    'order'		=> $this->object,
	    'email_heading'	=> $this->get_heading(),
	    'sent_to_admin'	=> true,
	    'plain_text'	=> false,
	    'email'		=> $this,
	    'booking_info'	=> $this->booking_info,
	    'product_name'	=> $this->product_name,
    ) ); 
}


/**
 * Initialize Settings Form Fields
 *
 * @since 0.1
 */
public function init_form_fields() {
 
    $this->form_fields = array(
        'enabled'    => array(
            'title'   => 'Enable/Disable',
            'type'    => 'checkbox',
            'label'   => 'Enable this email notification',
            'default' => 'yes'
        ),
        'recipient'  => array(
            'title'       => 'Recipient(s)',
            'type'        => 'text',
            'description' => sprintf( 'Enter recipients (comma separated) for this email. Defaults to <code>%s</code>.', esc_attr( get_option( 'admin_email' ) ) ),
            'placeholder' => '',
            'default'     => ''
        ),
        'subject'    => array(
            'title'       => 'Subject',
            'type'        => 'text',
            'description' => sprintf( 'This controls the email subject line. Leave blank to use the default subject: <code>%s</code>.', $this->subject ),
            'placeholder' => '',
            'default'     => ''
        ),
        'heading'    => array(
            'title'       => 'Email Heading',
            'type'        => 'text',
            'description' => sprintf( __( 'This controls the main heading contained within the email notification. Leave blank to use the default heading: <code>%s</code>.' ), $this->heading ),
            'placeholder' => '',
            'default'     => ''
        ),
        'email_type' => array(
            'title'       => 'Email type',
            'type'        => 'select',
            'description' => 'Choose which format of email to send.',
            'default'     => 'html',
            'class'       => 'email_type',
            'options'     => array(
            'plain'     => 'Plain text',
            'html'      => 'HTML', 'woocommerce',
            'multipart' => 'Multipart', 'woocommerce',
            )
        )
    );
}

} // end \WC_Check_Availability_Email class

functions.php

<?php

/**
 *  Add a custom email to the list of emails WooCommerce should load
 */
function add_check_availability_woocommerce_email( $email_classes ) {
 
    // include our custom email class
    require_once( dirname( __FILE__ ).'/class-wc-check-availability-email.php' );
 
    // add the email class to the list of email classes that WooCommerce loads
    $email_classes['WC_Check_Availability_Email'] = new WC_Check_Availability_Email();

    return $email_classes;
}
add_filter( 'woocommerce_email_classes', 'add_check_availability_woocommerce_email' );

vendor-check-availability.php

<?php
/**
 * Vendor Check Availability
 */

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

/**
 * @hooked WC_Emails::email_header() Output the email header
 */
do_action( 'woocommerce_email_header', $email_heading, $email ); ?>
<style>
.buttons { margin-top: 3em; }
.button { border-radius: 0; color:#fff; display: inline-block; padding:10px; text-decoration:none; text-align: center; text-transform:uppercase; width: 15em; }
.button-yes { background-color: green; }
.button-no { background-color: red; }
</style>
<p>Hi,</p>
<p>We have received an order for your <strong><?php echo $product_name; ?></strong>.</p>
<p>Please check the availability and click the appropriate button at the bottom of this email.</p>
<p>Order ID: <?php echo $order->id; ?></p>

<?php

echo '<p>Booking info:<br/>', $booking_info, '</p>';
echo "<p>Heading: $email_heading</p>";
echo "<p>Product Name: $product_name</p>";

// TODO: Write a standalone script that will change the status of the order.
$booking_yes_url = $site_url;
$booking_no_url = $site_url;
?>
<div class="buttons">
<p><a class="button button-yes" href="<?php echo $booking_yes_url; ?>">Yes, booking accepted</a></p>
<p><a class="button button-no" href="<?php echo $booking_no_url; ?>">No, date unavailable</a></p>
</div>
<?php
/**
 * @hooked WC_Emails::email_footer() Output the email footer
 */
do_action( 'woocommerce_email_footer', $email );