<?php
declare(strict_types=1);

/** Public excerpt disclosure adapter for the existing metered scenario endpoint. */
final class TheDotDevAgenticBridge_Question_Provider
{
    /** Backend string limits count UTF-16 units, not Unicode code points. */
    private static function bounded_text(string $text, int $limit): string
    {
        $text = mb_substr($text, 0, $limit, 'UTF-8');
        while (strlen(mb_convert_encoding($text, 'UTF-16LE', 'UTF-8')) > $limit * 2) {
            $text = mb_substr($text, 0, mb_strlen($text, 'UTF-8') - 1, 'UTF-8');
        }
        return $text;
    }

    public static function fact(int $id): array|WP_Error
    {
        $post = get_post($id);
        if (!$post || !TheDotDevAgenticBridge_Content_Metadata::is_artifact_eligible($post)) {
            return new WP_Error('question_source', __('This page is no longer eligible. Run the local check again.', 'agentic-bridge'));
        }
        $text = self::bounded_text(trim(wp_strip_all_tags(strip_shortcodes($post->post_content), true)), 2000);
        if ($text === '') return new WP_Error('question_empty', __('This page has no text to send.', 'agentic-bridge'));
        $url = get_permalink($post);
        if (!is_string($url) || !filter_var($url, FILTER_VALIDATE_URL) || !preg_match('#^https?://#i', $url) || strlen(mb_convert_encoding($url, 'UTF-16LE', 'UTF-8')) > 4096) {
            return new WP_Error('question_url', __('This page needs a valid public URL before testing.', 'agentic-bridge'));
        }
        $label = trim(wp_strip_all_tags($post->post_title));
        return ['id'=>'page-' . $id, 'label'=>self::bounded_text($label !== '' ? $label : __('Untitled page', 'agentic-bridge'), 240), 'value'=>$text,
            'url'=>$url, 'withheld'=>false, 'privateOrIneligible'=>false];
    }

    public static function disclosure(string $question, array $fact): string
    {
        return hash('sha256', (string) wp_json_encode([$question, $fact]));
    }

    public static function prepare(string $question, int $id, string $reviewed, string $operation, bool $consent): array|WP_Error
    {
        if (!current_user_can('manage_options') || !$consent) return new WP_Error('question_consent', __('Review and approve the exact text before sending.', 'agentic-bridge'));
        if (!defined('TDAB_WP_SCENARIO_ENABLED') || TDAB_WP_SCENARIO_ENABLED !== true) return new WP_Error('question_disabled', __('Hosted question testing is not enabled on this site.', 'agentic-bridge'));
        if (mb_strlen($question) < 8 || mb_strlen($question) > 300 || strlen(mb_convert_encoding($question, 'UTF-16LE', 'UTF-8')) > 1000 || !preg_match('/^[a-f0-9]{8}-[a-f0-9]{4}-[a-f0-9]{4}-[a-f0-9]{4}-[a-f0-9]{12}$/i', $operation)) return new WP_Error('question_invalid', __('Run the local check again before sending.', 'agentic-bridge'));
        $fact = self::fact($id);
        if (is_wp_error($fact)) return $fact;
        if (!hash_equals(self::disclosure($question, $fact), $reviewed)) return new WP_Error('question_changed', __('The question or source changed. Review it again before sending.', 'agentic-bridge'));
        return ['schemaVersion'=>'1.0', 'consent'=>true, 'request'=>['question'=>$question, 'mode'=>'provider_context', 'questionAssessment'=>true, 'selectedSourceRef'=>$fact['id'], 'operationKey'=>$operation], 'facts'=>[$fact]];
    }
}