<?php
/**
 * AI Content Signals - HTTP header surface
 *
 * Sends an X-Robots-Tag response header with AI opt-out directives
 * (noai, noimageai) on the front-end when AI training is blocked. Opt-in
 * via the settings page.
 *
 * Hooked on template_redirect so the main query is already resolved and the
 * per-entry override is applied consistently with the HTML meta tag. This
 * hook does not run for REST or robots.txt requests, so those are never
 * touched.
 *
 * @package AIContentSignals
 * @since   1.3.0
 */

// Exit if accessed directly.
if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

/**
 * Send the X-Robots-Tag header with AI opt-out directives.
 */
function ayudawp_acs_send_ai_headers() {
	$settings = get_option( 'ayudawp_acs_settings', array() );

	if ( 'yes' !== ( $settings['emit_http_headers'] ?? 'no' ) ) {
		return;
	}

	// Front-end content responses only.
	if ( is_robots() || is_feed() || is_404() ) {
		return;
	}

	if ( headers_sent() ) {
		return;
	}

	$context    = is_singular() ? array( 'post_id' => get_queried_object_id() ) : array();
	$signals    = ayudawp_acs_get_effective_signals( $context );
	$directives = ayudawp_acs_signals_to_directives( $signals );

	if ( empty( $directives ) ) {
		return;
	}

	// Append without replacing an existing X-Robots-Tag (e.g. from an SEO plugin).
	header( 'X-Robots-Tag: ' . implode( ', ', $directives ), false );
}
add_action( 'template_redirect', 'ayudawp_acs_send_ai_headers' );