<?php
namespace AntivirusAI\V1;

/** Native mail-boundary guards for one already-reserved notification attempt. */
final class NotificationDelivery {
	/** Invalid stored preferences never manufacture permission or a fallback recipient. */
	public static function recipient( mixed $settings ): ?string {
		if ( ! is_array( $settings ) || true !== ( $settings['email'] ?? null ) || ! is_string( $settings['email_to'] ?? null ) ) { return null; }
		$email = $settings['email_to'];
		return strlen( $email ) <= 254 && sanitize_email( $email ) === $email && is_email( $email ) ? $email : null;
	}
	/** Filter-stack depth identifies this call while leaving unrelated nested wp_mail calls alone. */
	private static function stack(): array {
		global $wp_current_filter;
		$counts = array_count_values( is_array( $wp_current_filter ) ? $wp_current_filter : array() );
		$out = array();
		foreach ( array( 'wp_mail', 'pre_wp_mail', 'phpmailer_init' ) as $name ) { $out[ $name ] = $counts[ $name ] ?? 0; }
		return $out;
	}
	public static function send( Store $store, array $claim, string $recipient, string $subject, string $body, string $lease, callable $currentBody ): array {
		$site = get_current_blog_id(); $base = self::stack(); $stopped = false; $reason = '';
		$own = static function ( string $phase ) use ( $base ): bool { $expected = $base; ++$expected[ $phase ]; return self::stack() === $expected; };
		$stop = static function ( string $message ) use ( &$stopped, &$reason ): void { $stopped = true; $reason = $message; throw new \RuntimeException( 'Notification delivery stopped before mail handoff.' ); };
		$current = static function () use ( $store, $claim, $recipient, $body, $lease, $site, $currentBody, $stop ): void {
			$writeObserved = false;
			$observer = static function ( string $sql ) use ( &$writeObserved ): string { if ( ! preg_match( '/^\s*(?:SELECT|SHOW|DESCRIBE|EXPLAIN)\b/i', $sql ) ) { $writeObserved = true; } return $sql; };
			add_filter( 'query', $observer, PHP_INT_MAX );
			try {
				$allowed = $site === get_current_blog_id() && $store->ownsLock( 'notifications', $lease ) && $store->get( $claim['_id'] ) === $claim && self::recipient( Store::freshOption( 'antivirus_ai_settings', array() ) ) === $recipient && $currentBody() === $body;
				if ( ! $allowed || $writeObserved || $site !== get_current_blog_id() ) { $stop( 'Notification permission, recipient, evidence or attempt changed before mail handoff. No automatic resend is scheduled.' ); }
			} finally { remove_filter( 'query', $observer, PHP_INT_MAX ); }
		};
		$arguments = static function ( array $atts ) use ( $recipient, $subject, $body, $stop ): void {
			$to = $atts['to'] ?? null;
			if ( $to !== $recipient && $to !== array( $recipient ) ) { $stop( 'A mail filter changed the notification recipient. Delivery was stopped.' ); }
			if ( ( $atts['subject'] ?? null ) !== $subject || ( $atts['message'] ?? null ) !== $body || ! empty( $atts['headers'] ) || ! empty( $atts['attachments'] ) || ! empty( $atts['embeds'] ) ) { $stop( 'A mail filter changed the notification content or added recipients or attachments. Delivery was stopped.' ); }
		};
		$mailGuard = static function ( $atts ) use ( $own, $current, $arguments, $stop ) {
			if ( ! $own( 'wp_mail' ) ) { return $atts; }
			if ( ! is_array( $atts ) ) { $stop( 'The notification mail arguments are invalid.' ); }
			$current(); $arguments( $atts ); return $atts;
		};
		$preGuard = static function ( $short, $atts ) use ( $own, $current, $arguments, $stop ) {
			if ( ! $own( 'pre_wp_mail' ) ) { return $short; }
			if ( ! is_array( $atts ) ) { $stop( 'The notification mail arguments are invalid.' ); }
			$current(); $arguments( $atts ); return $short;
		};
		$mailerGuard = static function ( $mailer ) use ( $own, $current, $recipient, $subject, $body, $stop ): void {
			if ( ! $own( 'phpmailer_init' ) ) { return; }
			$current();
			if ( ! $mailer instanceof \PHPMailer\PHPMailer\PHPMailer || $mailer->getToAddresses() !== array( array( $recipient, '' ) ) || $mailer->getCcAddresses() || $mailer->getBccAddresses() || $mailer->getReplyToAddresses() || $mailer->getAttachments() || $mailer->Subject !== $subject || $mailer->Body !== $body || '' !== $mailer->AltBody || 'text/plain' !== $mailer->ContentType ) { $stop( 'Mail preparation changed notification content, recipients or attachments. Delivery was stopped.' ); }
		};
		foreach ( array( -PHP_INT_MAX, PHP_INT_MAX ) as $priority ) { add_filter( 'wp_mail', $mailGuard, $priority ); add_filter( 'pre_wp_mail', $preGuard, $priority, 2 ); }
		add_action( 'phpmailer_init', $mailerGuard, PHP_INT_MAX );
		try {
			$current();
			$accepted = wp_mail( $recipient, $subject, $body );
			return array( 'accepted' => true === $accepted, 'stopped' => false, 'message' => true === $accepted ? '' : 'The mail outcome is unconfirmed. No automatic resend is scheduled; inspect your mail provider before taking further action.' );
		} catch ( \Throwable $error ) {
			return array( 'accepted' => false, 'stopped' => $stopped, 'message' => $stopped ? $reason : 'Mail processing was interrupted and its outcome is unconfirmed. No automatic resend is scheduled.' );
		} finally {
			foreach ( array( -PHP_INT_MAX, PHP_INT_MAX ) as $priority ) { remove_filter( 'wp_mail', $mailGuard, $priority ); remove_filter( 'pre_wp_mail', $preGuard, $priority ); }
			remove_action( 'phpmailer_init', $mailerGuard, PHP_INT_MAX );
		}
	}
}