메타 태그 & 스키마 자동 생성

// 동적 메타 태그 자동 생성 클래스
class Dynamic_Meta_Generator {
    public function __construct() {
        add_action('wp_head', array($this, 'output_meta_tags'), 1);
        // Yoast/Rank Math가 없을 때만 작동
        if (!defined('WPSEO_VERSION') && !class_exists('RankMath')) {
            add_filter('pre_get_document_title', array($this, 'generate_title'));
        }
    }

    // SEO 최적 타이틀 자동 생성
    public function generate_title($title) {
        if (is_singular()) {
            global $post;
            $custom_title = get_post_meta($post->ID, '_seo_title', true);
            if ($custom_title) return $custom_title;

            $site_name = get_bloginfo('name');
            $post_title = get_the_title();

            // 60자 제한 내에서 최적화
            $max_title_length = 60 - mb_strlen(" | {$site_name}") - 1;
            if (mb_strlen($post_title) > $max_title_length) {
                $post_title = mb_substr($post_title, 0, $max_title_length - 3) . '...';
            }

            return "{$post_title} | {$site_name}";
        }

        if (is_category()) {
            $cat = get_queried_object();
            return "{$cat->name} 카테고리 글 모음 | " . get_bloginfo('name');
        }

        return $title;
    }

    // 메타 태그 출력
    public function output_meta_tags() {
        if (is_singular()) {
            global $post;
            $this->singular_meta($post);
        } elseif (is_category() || is_tag()) {
            $this->taxonomy_meta();
        } elseif (is_front_page()) {
            $this->home_meta();
        }
    }

    private function singular_meta($post) {
        // Meta Description 자동 생성
        $description = get_post_meta($post->ID, '_seo_description', true);
        if (!$description) {
            $description = $this->auto_generate_description($post);
        }

        $image = get_the_post_thumbnail_url($post->ID, 'large') ?: '';
        $author = get_the_author_meta('display_name', $post->post_author);
        $published = get_the_date('c', $post);
        $modified = get_the_modified_date('c', $post);

        // 기본 메타
        echo '<meta name="description" content="' . esc_attr($description) . '">' . "\n";
        echo '<meta name="author" content="' . esc_attr($author) . '">' . "\n";

        // Open Graph (Facebook/카카오톡)
        echo '<meta property="og:type" content="article">' . "\n";
        echo '<meta property="og:title" content="' . esc_attr(get_the_title($post)) . '">' . "\n";
        echo '<meta property="og:description" content="' . esc_attr($description) . '">' . "\n";
        echo '<meta property="og:url" content="' . esc_url(get_permalink($post)) . '">' . "\n";
        if ($image) {
            echo '<meta property="og:image" content="' . esc_url($image) . '">' . "\n";
        }
        echo '<meta property="article:published_time" content="' . $published . '">' . "\n";
        echo '<meta property="article:modified_time" content="' . $modified . '">' . "\n";

        // Twitter Card
        echo '<meta name="twitter:card" content="summary_large_image">' . "\n";
        echo '<meta name="twitter:title" content="' . esc_attr(get_the_title($post)) . '">' . "\n";
        echo '<meta name="twitter:description" content="' . esc_attr($description) . '">' . "\n";
        if ($image) {
            echo '<meta name="twitter:image" content="' . esc_url($image) . '">' . "\n";
        }

        // Canonical URL
        echo '<link rel="canonical" href="' . esc_url(get_permalink($post)) . '">' . "\n";

        // Naver 웹마스터 도구용
        echo '<meta name="naver-site-verification" content="YOUR_CODE">' . "\n";
    }

    // 콘텐츠에서 자동 Description 생성
    private function auto_generate_description($post) {
        $content = strip_tags($post->post_content);
        $content = strip_shortcodes($content);
        $content = preg_replace('/\s+/', ' ', trim($content));

        // 첫 번째 문장 또는 155자
        $first_sentence = preg_match('/^(.+?[.!?])\s/', $content, $matches)
            ? $matches[1] : '';

        if ($first_sentence && mb_strlen($first_sentence) = 50) {
            return $first_sentence;
        }

        // 155자로 자르기 (단어 단위)
        if (mb_strlen($content) > 155) {
            $content = mb_substr($content, 0, 155);
            $last_space = mb_strrpos($content, ' ');
            if ($last_space !== false) {
                $content = mb_substr($content, 0, $last_space);
            }
            $content .= '...';
        }

        return $content;
    }

    private function taxonomy_meta() {
        $term = get_queried_object();
        $description = $term->description ?: "{$term->name} 관련 글 모음 - " . get_bloginfo('description');

        echo '<meta name="description" content="' . esc_attr($description) . '">' . "\n";
        echo '<meta property="og:type" content="website">' . "\n";
        echo '<meta property="og:title" content="' . esc_attr($term->name) . '">' . "\n";
        echo '<meta property="og:description" content="' . esc_attr($description) . '">' . "\n";
    }

    private function home_meta() {
        $description = get_bloginfo('description');
        $site_name = get_bloginfo('name');

        echo '<meta name="description" content="' . esc_attr($description) . '">' . "\n";
        echo '<meta property="og:type" content="website">' . "\n";
        echo '<meta property="og:title" content="' . esc_attr($site_name) . '">' . "\n";
        echo '<meta property="og:description" content="' . esc_attr($description) . '">' . "\n";
        echo '<meta property="og:site_name" content="' . esc_attr($site_name) . '">' . "\n";
    }
}

new Dynamic_Meta_Generator();