<?php
/**
 * AI Content Signals - Shared signal resolver
 *
 * Pure, side-effect-free helpers that resolve the effective signals
 * (global, optionally overridden per entry) and translate them to the
 * directives used by the different output surfaces (robots.txt, HTTP
 * headers, HTML meta, TDMRep). Every surface consumes this single source
 * of truth so they never diverge.
 *
 * @package AIContentSignals
 * @since   1.3.0
 */

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

/**
 * Normalize a value against the Content Signals vocabulary.
 *
 * The vocabulary is closed: 'yes', 'no' or '' (unspecified). Anything else is
 * discarded and treated as unspecified, so a value outside the vocabulary can
 * never reach robots.txt, an HTTP header, a meta tag or the TDMRep manifest.
 *
 * @since 1.3.2
 *
 * @param mixed $value Raw value.
 * @return string 'yes', 'no' or ''.
 */
function ayudawp_acs_sanitize_signal_value( $value ) {
	return in_array( $value, array( 'yes', 'no' ), true ) ? $value : '';
}

/**
 * Resolve the effective Content Signals.
 *
 * Returns the global signals, optionally overridden per post when a
 * 'post_id' is passed in the context. A per-entry value only overrides
 * when explicitly set ('yes' or 'no'); an empty value falls back to global.
 *
 * @param array $context Optional. Accepts 'post_id' to apply a per-entry override.
 * @return array {
 *     @type string $search   'yes'|'no'|''.
 *     @type string $ai_input 'yes'|'no'|''.
 *     @type string $ai_train 'yes'|'no'|''.
 * }
 */
function ayudawp_acs_get_effective_signals( $context = array() ) {
	$settings = get_option( 'ayudawp_acs_settings', array() );

	$signals = array(
		'search'   => ayudawp_acs_sanitize_signal_value( $settings['global_search'] ?? '' ),
		'ai_input' => ayudawp_acs_sanitize_signal_value( $settings['global_ai_input'] ?? '' ),
		'ai_train' => ayudawp_acs_sanitize_signal_value( $settings['global_ai_train'] ?? '' ),
	);

	// Per-entry override (written by the metabox module).
	if ( ! empty( $context['post_id'] ) ) {
		$override = get_post_meta( (int) $context['post_id'], '_ayudawp_acs_signals', true );

		if ( is_array( $override ) ) {
			foreach ( array( 'search', 'ai_input', 'ai_train' ) as $key ) {
				$value = ayudawp_acs_sanitize_signal_value( $override[ $key ] ?? '' );

				if ( '' !== $value ) {
					$signals[ $key ] = $value;
				}
			}
		}
	}

	return $signals;
}

/**
 * Translate resolved signals into opt-out directives for HTML meta and HTTP headers.
 *
 * Only opt-out tokens are emitted, so nothing is returned unless the user has
 * reserved training rights. noai and noimageai map to ai-train=no.
 *
 * @param array $signals Resolved signals from ayudawp_acs_get_effective_signals().
 * @return array List of directive tokens, e.g. array( 'noai', 'noimageai' ).
 */
function ayudawp_acs_signals_to_directives( $signals ) {
	$directives = array();

	if ( isset( $signals['ai_train'] ) && 'no' === $signals['ai_train'] ) {
		$directives[] = 'noai';
		$directives[] = 'noimageai';
	}

	return $directives;
}