WooCommerce | Add a message to the Order Complete email based on if a product is in certain categories

woocommerce-order-email-message-for-categories.php

<?php 
add_action( 'woocommerce_email_before_order_table', 'add_content', 20, 4 );

function add_content($order, $sent_to_admin, $plain_text, $email) {

// Adds to "completed order" email only
if ( $email->id == 'customer_completed_order' ) {

	// set initial variables to false
	$both = false;
	$state = false;
	$associate = false;

	// look through each item in the order
	foreach ( $order->get_items() as $item ){

		// get the categories for each item
		$categories = get_the_terms( $item['product_id'] , 'product_cat' );

		// look through the categories
		foreach( $categories as $category ) {
			// if an item has this category, set this variable to true
			if ($category->slug == 'state') {
				$state = true;
			}
			// and if an item has this category, set this variable to true
			if( $category->slug == 'associate' ) {
				$associate = true;
			}
		}
	}
	// if the order contained item(s) with both State and Associate categories
	if ($state && $associate) {
		$variable_text = 'organization';
		$variable_text_short = 'organization';
		$variable_text_mailto = 'organization';
	}
	// if the order contained item(s) with State category
	elseif ($state) {
		$variable_text = 'state agency';
		$variable_text_short = 'agency';
		$variable_text_mailto = 'state%20agency';
	}
	// if the order contained item(s) with Associate category
	elseif ($associate) {
		$variable_text = 'company/organization';
		$variable_text_short = 'organization';
		$variable_text_mailto = 'company%2Forganization';
	}

	// OK, so if the order contained an item with the State or the Associate category, then do this...
	// ... which will fill the content with certain variable text based on whether it was in State, Associate, or bothh
	if ($state || $associate) {
		echo 	'<h2>You\'re a Member!</h2>
				<p>Thank you for your membership in ACME. Your membership extends to all individuals within your '.$variable_text.'.</p>
				<p>Individuals within your '.$variable_text_short.' may register for a new user account here: <a href="https://acmeorg.wpengine.com/register/" target="_blank">https://acmeorg.wpengine.com/register/</a>. The password is <strong><code>ACME</code></strong>.</p>
				<p>Existing users should review and update their account profile here: <a href="https://acmeorg.wpengine.com/login/" target="_blank">https://acmeorg.wpengine.com/login/</a>. Existing users will log in with their unique password.</p>
				<p>To facilitate the new user registration process and existing user account update process, you may <strong><a href="mailto:?subject=Join%20us%20on%20ACME&body=Your%20'.$variable_text_mailto.'%20is%20a%20member%20of%20ACME.%20%0D%0A%0D%0AIf%20you%20have%20never%20had%20a%20ACME%20account,%20register%20here:%20https%3A%2F%2Facmeorg.wpengine.com%2Fregister%2F%20%0D%0A%0D%0AThe%20password%20is%20ACME%20%0D%0A%0D%0AIf%20you%20currently%20have%20a%20ACME%20account,%20log%20in%20now%20to%20review%20and%20update%20your%20account%20information%20here:%20https%3A%2F%2Facmeorg.wpengine.com%2Flogin%2F">click here to send an email to your colleagues</a>.</p>';
	}

}

}