sirius-press/plugins/sirius-press-compat/sirius-press-compat.php

<?php
/**
 * Plugin Name:       Sirius Press Compatibility
 * Plugin URI:        https://code.silentmode.st/silentmode/sirius-press
 * Description:       Keeps plugins that hard-require an administrator email address installable and activatable on a site that has none.
 * Version:           0.1.0
 * Requires at least: 6.5
 * Requires PHP:      7.4
 * Requires Plugins:  sirius-press-core
 * Author:            Silent Mode
 * Author URI:        https://silentmode.st
 * License:           GPL-2.0-or-later
 * License URI:       https://www.gnu.org/licenses/gpl-2.0.html
 * Text Domain:       sirius-press
 *
 * @package SiriusPress
 *
 * ---------------------------------------------------------------------------
 *
 * A large part of the WordPress ecosystem assumes `get_option('admin_email')`
 * returns something, and a smaller but important part refuses to finish its
 * setup wizard if it does not. WooCommerce wants a store address for order
 * emails. Contact Form 7 defaults a form's "To" field to it. Yoast reads it
 * while building schema. None of these are wrong to do so — they were written
 * for a WordPress where that value always exists.
 *
 * Rather than patch each of them, this plugin makes the assumption true: the
 * site always has an admin email, and it is permanently undeliverable. The
 * `.invalid` top-level domain is reserved by RFC 2606 for exactly this — it
 * is guaranteed never to resolve, anywhere, ever. So a plugin that stores it,
 * validates it or puts it in a "From" header behaves normally, and a plugin
 * that tries to *send* to it has its message caught by the Sirius Press inbox
 * before it reaches a mail transport.
 *
 * What this plugin deliberately does NOT do is disable `wp_mail()`. A site
 * owner who configures SMTP gets working contact forms and working order
 * receipts, because those go to real addresses that real people gave. The
 * fork's objection was never to email as a feature — only to email as an
 * identity.
 */

defined( 'ABSPATH' ) || exit;

define( 'SIRIUS_PRESS_COMPAT_VERSION', '0.1.0' );

/**
 * Supply a placeholder wherever WordPress or a plugin reads the admin email.
 *
 * Filtered rather than written to the database so that a site owner who does
 * set a real address keeps it: the filter defers to any non-empty stored
 * value and only fills a gap.
 */
function sirius_press_admin_email( $value ) {
	if ( is_string( $value ) && '' !== trim( $value ) ) {
		return $value;
	}
	return 'admin@' . SP_Settings::stub_email_domain();
}
add_filter( 'option_admin_email', 'sirius_press_admin_email' );
add_filter( 'default_option_admin_email', 'sirius_press_admin_email' );
add_filter( 'pre_option_new_admin_email', '__return_empty_string' );

/**
 * Fill a blank `user_email` on save rather than letting one persist.
 *
 * `$user->user_email` is read in thousands of places across the ecosystem,
 * usually without a null check, so an account with an empty one leaves
 * warnings and blank "From" headers scattered through other people's code.
 * An account created before this fork was installed, or by a plugin calling
 * `wp_insert_user()` directly, can have exactly that.
 *
 * Runs late so a plugin that supplies a real address wins.
 */
add_filter(
	'wp_pre_insert_user_data',
	function ( $data, $update, $user_id ) {
		if ( ! class_exists( 'SP_Identity' ) ) {
			return $data;
		}
		if ( ! empty( $data['user_email'] ) ) {
			return $data;
		}
		$address = $user_id ? SP_Identity::address_of( (int) $user_id ) : '';
		$data['user_email'] = SP_Identity::stub_email( $address );
		return $data;
	},
	20,
	3
);

/**
 * Stop core nagging about an unconfirmed administrator email change.
 *
 * The "Your admin email is still <x>, please confirm" prompt sends a
 * confirmation link to an address that cannot receive it, which makes the
 * prompt permanent and unactionable.
 */
add_filter( 'admin_email_check_interval', '__return_zero' );

/**
 * WooCommerce.
 *
 * Its setup wizard and its system-status report both read the store address
 * out of `woocommerce_email_from_address`, and the onboarding profiler posts
 * to a remote service with it. Supplying the placeholder lets the wizard
 * finish; order emails to real customers are unaffected, because those use
 * the address the customer typed at checkout.
 */
add_filter(
	'pre_option_woocommerce_email_from_address',
	function ( $value ) {
		if ( ! empty( $value ) || ! class_exists( 'SP_Settings' ) ) {
			return $value;
		}
		return 'shop@' . SP_Settings::stub_email_domain();
	}
);

/**
 * Contact Form 7.
 *
 * CF7 validates a form's mail template on save and marks the form as
 * misconfigured if the "To" address is empty, which it will be on a site with
 * no admin email. The placeholder makes new forms save cleanly; a site owner
 * who wants the form to actually deliver replaces it with a real address and
 * configures SMTP, which is documented in docs/smtp.md.
 */
add_filter(
	'wpcf7_default_template',
	function ( $template, $prop ) {
		if ( 'mail' !== $prop || ! is_array( $template ) || ! class_exists( 'SP_Settings' ) ) {
			return $template;
		}
		if ( empty( $template['recipient'] ) ) {
			$template['recipient'] = 'admin@' . SP_Settings::stub_email_domain();
		}
		return $template;
	},
	10,
	2
);

/*
 * Note on is_email(): no filter is needed.
 *
 * It would be reasonable to assume WordPress rejects a `.invalid` address,
 * since RFC 2606 reserves that TLD precisely so it can never resolve — and an
 * earlier version of this file carried a filter to force such addresses
 * through on that assumption. The assumption is wrong. `is_email()` validates
 * syntax, not whether a domain could ever exist, so `noreply@…​.invalid`
 * already passes and the filter never fired.
 *
 * Leaving it in would have been worse than useless: a filter that appears to
 * relax a validation rule, but does not, is exactly the kind of thing someone
 * later reasons from. Verified against WordPress 7.1.1.
 */

/**
 * A short explanation on the plugins screen, next to anything known to want
 * an address. Better a sentence here than a confused hour later.
 */
add_action(
	'after_plugin_row',
	function ( $plugin_file ) {
		static $notes = array(
			'woocommerce/woocommerce.php'           => 'WooCommerce will work, including checkout. Order emails need SMTP — see docs/smtp.md.',
			'contact-form-7/wp-contact-form-7.php'  => 'Forms save and submit. Delivery needs SMTP and a real recipient address — see docs/smtp.md.',
			'wordpress-seo/wp-seo.php'              => 'Yoast works unchanged. Its sitemaps are exported to your name along with everything else.',
		);
		if ( ! isset( $notes[ $plugin_file ] ) || ! is_plugin_active( $plugin_file ) ) {
			return;
		}
		printf(
			'<tr class="plugin-update-tr active"><td colspan="4" class="plugin-update"><div class="update-message notice inline notice-info notice-alt"><p>%s</p></div></td></tr>',
			esc_html( $notes[ $plugin_file ] )
		);
	}
);