Umbra-Bookshelf/bd-bookshelf-plugin/includes/class-bdm-seo.php

<?php
/**
 * SEO Metadata Manager class
 *
 * @package BD_Bookshelf
 */

if (!defined('ABSPATH')) {
    exit;
}

class BDM_SEO {

    /**
     * Constructor
     */
    public function __construct() {
        add_action('wp_head', [$this, 'output_meta_tags'], 1);
        add_action('wp_head', [$this, 'output_open_graph'], 2);
        add_action('wp_head', [$this, 'output_twitter_cards'], 3);
        
        // Add sitemap entries
        add_filter('wp_sitemaps_posts_entry', [$this, 'filter_sitemap_entry'], 10, 2);
    }

    /**
     * Get book SEO data
     */
    public static function get_book_seo($book_id) {
        global $wpdb;

        $table = BDM_Database::table('book_seo');
        
        $seo = $wpdb->get_row(
            $wpdb->prepare(
                "SELECT * FROM {$table} WHERE book_id = %d",
                $book_id
            )
        );
        
        return $seo;
    }

    /**
     * Update book SEO data
     */
    public static function update_book_seo($book_id, $data) {
        global $wpdb;

        $table = BDM_Database::table('book_seo');
        
        $existing = self::get_book_seo($book_id);
        
        $update_data = [
            'book_id' => absint($book_id),
            'seo_title' => sanitize_text_field($data['seo_title'] ?? ''),
            'seo_description' => wp_kses_post($data['seo_description'] ?? ''),
            'seo_keywords' => sanitize_text_field($data['seo_keywords'] ?? ''),
            'og_title' => sanitize_text_field($data['og_title'] ?? ''),
            'og_description' => wp_kses_post($data['og_description'] ?? ''),
            'og_image' => esc_url_raw($data['og_image'] ?? ''),
        ];
        
        if ($existing) {
            $result = $wpdb->update(
                $table,
                $update_data,
                ['book_id' => $book_id],
                null,
                ['%d']
            );
        } else {
            $result = $wpdb->insert($table, $update_data);
        }
        
        return $result !== false;
    }

    /**
     * Delete book SEO data
     */
    public static function delete_book_seo($book_id) {
        global $wpdb;

        $table = BDM_Database::table('book_seo');
        return $wpdb->delete($table, ['book_id' => $book_id], ['%d']) !== false;
    }

    /**
     * Output meta tags
     */
    public function output_meta_tags() {
        if (!is_singular()) {
            return;
        }

        $post_id = get_queried_object_id();
        $book_id = $this->get_book_id_for_post($post_id);
        
        if (!$book_id) {
            return;
        }

        $seo = self::get_book_seo($book_id);
        if (!$seo) {
            return;
        }

        if (!empty($seo->seo_title)) {
            echo '<meta name="title" content="' . esc_attr($seo->seo_title) . '">' . "\n";
        }
        
        if (!empty($seo->seo_description)) {
            echo '<meta name="description" content="' . esc_attr($seo->seo_description) . '">' . "\n";
        }
        
        if (!empty($seo->seo_keywords)) {
            echo '<meta name="keywords" content="' . esc_attr($seo->seo_keywords) . '">' . "\n";
        }
    }

    /**
     * Output Open Graph tags
     */
    public function output_open_graph() {
        if (!is_singular()) {
            return;
        }

        $post_id = get_queried_object_id();
        $book_id = $this->get_book_id_for_post($post_id);
        
        if (!$book_id) {
            return;
        }

        $seo = self::get_book_seo($book_id);
        $book = BDM_Book_Manager::get_book($book_id);
        
        if (!$book) {
            return;
        }

        $og_title = !empty($seo->og_title) ? $seo->og_title : get_the_title($post_id);
        $og_description = !empty($seo->og_description) ? $seo->og_description : wp_trim_words(get_the_excerpt($post_id), 30);
        $og_image = !empty($seo->og_image) ? $seo->og_image : get_the_post_thumbnail_url($post_id, 'large');
        
        echo '<meta property="og:type" content="book">' . "\n";
        echo '<meta property="og:title" content="' . esc_attr($og_title) . '">' . "\n";
        echo '<meta property="og:description" content="' . esc_attr($og_description) . '">' . "\n";
        echo '<meta property="og:url" content="' . esc_url(get_permalink($post_id)) . '">' . "\n";
        
        if ($og_image) {
            echo '<meta property="og:image" content="' . esc_url($og_image) . '">' . "\n";
        }
    }

    /**
     * Output Twitter Card tags
     */
    public function output_twitter_cards() {
        if (!is_singular()) {
            return;
        }

        $post_id = get_queried_object_id();
        $book_id = $this->get_book_id_for_post($post_id);
        
        if (!$book_id) {
            return;
        }

        $seo = self::get_book_seo($book_id);
        
        $twitter_title = !empty($seo->og_title) ? $seo->og_title : get_the_title($post_id);
        $twitter_description = !empty($seo->og_description) ? $seo->og_description : wp_trim_words(get_the_excerpt($post_id), 30);
        $twitter_image = !empty($seo->og_image) ? $seo->og_image : get_the_post_thumbnail_url($post_id, 'large');
        
        echo '<meta name="twitter:card" content="summary_large_image">' . "\n";
        echo '<meta name="twitter:title" content="' . esc_attr($twitter_title) . '">' . "\n";
        echo '<meta name="twitter:description" content="' . esc_attr($twitter_description) . '">' . "\n";
        
        if ($twitter_image) {
            echo '<meta name="twitter:image" content="' . esc_url($twitter_image) . '">' . "\n";
        }
    }

    /**
     * Get book ID for a WordPress post
     */
    private function get_book_id_for_post($post_id) {
        // Check if there's a book ID stored in post meta
        return get_post_meta($post_id, '_bd_bookshelf_book_id', true);
    }

    /**
     * Filter sitemap entry for book posts
     */
    public function filter_sitemap_entry($entry, $post) {
        $book_id = $this->get_book_id_for_post($post->ID);
        
        if (!$book_id) {
            return $entry;
        }

        $book = BDM_Book_Manager::get_book($book_id);
        
        if (!$book) {
            return $entry;
        }

        // Higher rating = higher priority
        $rating = max($book->rating_amazon, $book->rating_goodreads);
        $priority = 0.5 + ($rating / 10); // 0.5 to 1.0 based on rating
        
        $entry['loc'] = get_permalink($post->ID);
        $entry['lastmod'] = get_the_modified_date('c', $post);
        $entry['changefreq'] = 'monthly';
        $entry['priority'] = round($priority, 1);
        
        return $entry;
    }
}