// =========================================================================
// Schema Markup (Video + FAQ) for Product Pages
// =========================================================================
function add_custom_schema_to_head() {
    if (is_page()) {
        $allowed_templates = array('indoor-led-display.php', 'list-series.php');
        $current_template = get_page_template_slug();

        if (in_array($current_template, $allowed_templates, true)) {
            global $post;
            $post_id = $post->ID;

            if (have_rows('list_video', $post_id)) {
                $video_count = 0;

                while (have_rows('list_video', $post_id) && $video_count < 5) {
                    the_row();

                    if (have_rows('youtube-body')) {
                        while (have_rows('youtube-body')) {
                            the_row();
                            $youtube_id = get_sub_field('youtube-number');

                            if ($youtube_id) {
                                $video_title = get_sub_field('youtube-title') ?: get_sub_field('video-title', $post_id);
                                $video_desc  = get_sub_field('video-body', $post_id) ?: 'Professional LED display solutions';
                                $upload_date = get_post_meta($post_id, 'video_upload_date', true) ?: get_the_date('c', $post_id);

                                $video_schema = array(
                                    '@context' => 'https://schema.org',
                                    '@type' => 'VideoObject',
                                    'name' => sanitize_text_field($video_title),
                                    'description' => sanitize_text_field(wp_trim_words($video_desc, 30, '')),
                                    'thumbnailUrl' => array(
                                        "https://img.youtube.com/vi/{$youtube_id}/maxresdefault.jpg",
                                        "https://img.youtube.com/vi/{$youtube_id}/hqdefault.jpg"
                                    ),
                                    'uploadDate' => $upload_date,
                                    'contentUrl' => "https://www.youtube.com/watch?v={$youtube_id}",
                                    'embedUrl' => "https://www.youtube.com/embed/{$youtube_id}",
                                    'duration' => 'PT1M30S',
                                    'interactionCount' => '1500'
                                );

                                echo '<script type="application/ld+json">' . wp_json_encode($video_schema, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES | JSON_HEX_TAG | JSON_HEX_APOS) . '</script>';
                                $video_count++;
                            }
                        }
                    }
                }
            }

            $qas = get_field('common_qa', $post_id);
            if ($qas && is_array($qas)) {
                $faq_items = array();
                $unique_questions = array();

                foreach (array_slice($qas, 0, 10) as $faq_post) {
                    $question = get_the_title($faq_post);

                    // FIX: FAQ 答案与页面可见 <p> 完全同源，统一取 get_the_excerpt()，
                    //      杜绝 schema 与可见文本长度不一致（原 wp_trim_words 长文分支已移除）
                    $answer = get_the_excerpt($faq_post);

                    $clean_question = sanitize_text_field(strip_shortcodes($question));
                    $clean_answer = sanitize_text_field(strip_shortcodes($answer));

                    // FIX: 去掉 strlen < 50 过滤，避免丢弃短答案导致 schema 条数与可见不一致
                    if (
                        empty($clean_question) ||
                        empty($clean_answer) ||
                        in_array(md5($clean_question), $unique_questions, true)
                    ) {
                        continue;
                    }

                    $unique_questions[] = md5($clean_question);

                    $faq_items[] = array(
                        '@type' => 'Question',
                        'name' => $clean_question,
                        'acceptedAnswer' => array(
                            '@type' => 'Answer',
                            'text' => $clean_answer
                        )
                    );
                }

                if (!empty($faq_items)) {
                    $faq_schema = array(
                        '@context' => 'https://schema.org',
                        '@type' => 'FAQPage',
                        'mainEntity' => $faq_items
                    );

                    echo '<script type="application/ld+json">' . wp_json_encode($faq_schema, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES | JSON_HEX_TAG | JSON_HEX_APOS) . '</script>';
                }
            }
        }
    }
}