<?php

namespace StoreSuit;

defined( 'ABSPATH' ) || exit;
/**
 * The SEO health summary (free in both builds, owner's decision of 20 Oct 2026): a score out of 100 and the store's top
 * issues, read only. A handful of counting queries over the published products and four site settings, kept for six hours
 * (or read again on request), so the Marketing page never runs an audit. Nothing is fixed here: fixing, bulk SEO,
 * structured data, sitemaps and Search Console are StoreRuler Pro's SEO Center (SeoAudit is its full, per-page audit).
 */
final class SeoHealth {
    private const CACHE = 'storesuit_seo_health';

    private const TTL = 6 * HOUR_IN_SECONDS;

    /** Each check's weight in the score: a site check counts in full, a product check by the share of products it finds. */
    private const WEIGHTS = array(
        'hidden'           => 40,
        'plain_links'      => 10,
        'no_https'         => 10,
        'no_meta'          => 10,
        'no_description'   => 15,
        'no_image'         => 10,
        'no_alt'           => 8,
        'thin_description' => 5,
        'duplicate_title'  => 5,
        'uncategorized'    => 5,
        'long_title'       => 2,
    );

    private const SITE = array(
        'hidden',
        'plain_links',
        'no_https',
        'no_meta'
    );

    /** What each check found, and what helps. */
    private const TEXTS = array(
        'hidden'           => array('Search engines are asked not to index this site', 'Settings → Reading: untick "Discourage search engines from indexing this site" when the store is ready.'),
        'plain_links'      => array('Addresses use plain links (?p=123)', 'Settings → Permalinks: choose "Post name" for readable product addresses.'),
        'no_https'         => array('The site address does not use HTTPS', 'Search engines prefer secure addresses. Ask your host for an SSL certificate, then change the site address to https.'),
        'no_meta'          => array('Product pages have no meta description', 'Without an SEO tool, search engines write their own snippet from the page.'),
        'no_description'   => array('Products without a description', 'A description tells shoppers and search engines what the product is.'),
        'no_image'         => array('Products without a photo', 'Product photos appear in image search and next to search results.'),
        'no_alt'           => array('Product photos without alt text', 'Alt text describes the photo for image search and for screen readers.'),
        'thin_description' => array('Products with a very short description', 'A few more sentences about material, size and use help the product to be found.'),
        'duplicate_title'  => array('Products with the same name as another product', 'Search engines may treat pages with the same title as duplicates.'),
        'uncategorized'    => array('Products only in "Uncategorized"', 'Categories give search engines and shoppers a path to the product.'),
        'long_title'       => array('Product names longer than 70 characters', 'Search results cut long titles short.'),
    );

    /** SEO plugins that write meta descriptions: a constant each defines, and its plugin folder. */
    private const SEO_PLUGINS = array(
        'WPSEO_VERSION'             => 'wordpress-seo/',
        'RANK_MATH_VERSION'         => 'seo-by-rank-math/',
        'AIOSEO_VERSION'            => 'all-in-one-seo-pack/',
        'SEOPRESS_VERSION'          => 'wp-seopress/',
        'THE_SEO_FRAMEWORK_VERSION' => 'autodescription/',
        'SLIM_SEO_VERSION'          => 'slim-seo/',
    );

    /** seo_health_read: the summary, from the six-hour copy unless refresh is asked for. */
    public static function read( array $data = array() ) : array {
        Store::require_cap( 'manage_woocommerce' );
        $found = ( empty( $data['refresh'] ) ? get_transient( self::CACHE ) : false );
        if ( !is_array( $found ) || ($found['version'] ?? 0) !== 1 ) {
            $found = self::measure();
            set_transient( self::CACHE, $found, self::TTL );
        }
        return self::summary( $found );
    }

    /** The counts behind the summary: no text, so the summary follows the reader's language. */
    public static function measure() : array {
        global $wpdb;
        $checks = array();
        $checks['hidden'] = array(
            'n' => ( (string) get_option( 'blog_public', '1' ) === '0' ? 1 : 0 ),
        );
        $checks['plain_links'] = array(
            'n' => ( (string) get_option( 'permalink_structure', '' ) === '' ? 1 : 0 ),
        );
        $checks['no_https'] = array(
            'n' => ( wp_parse_url( home_url(), PHP_URL_SCHEME ) === 'https' ? 0 : 1 ),
        );
        $checks['no_meta'] = array(
            'n' => ( self::writes_meta() ? 0 : 1 ),
        );
        $total = (int) $wpdb->get_var( $wpdb->prepare( "SELECT COUNT(*) FROM %i WHERE post_type='product' AND post_status='publish'", $wpdb->posts ) );
        if ( $total > 0 ) {
            $checks['no_description'] = self::row( $wpdb->get_row( $wpdb->prepare( "SELECT COUNT(*) AS n, SUBSTRING_INDEX(GROUP_CONCAT(ID ORDER BY post_date DESC), ',', 3) AS ids FROM %i WHERE post_type='product' AND post_status='publish' AND TRIM(post_content)=''", $wpdb->posts ), ARRAY_A ) );
            $checks['thin_description'] = self::row( $wpdb->get_row( $wpdb->prepare( "SELECT COUNT(*) AS n, SUBSTRING_INDEX(GROUP_CONCAT(ID ORDER BY post_date DESC), ',', 3) AS ids FROM %i WHERE post_type='product' AND post_status='publish' AND TRIM(post_content)<>'' AND CHAR_LENGTH(post_content)<%d", $wpdb->posts, 300 ), ARRAY_A ) );
            $checks['no_image'] = self::row( $wpdb->get_row( $wpdb->prepare( "SELECT COUNT(*) AS n, SUBSTRING_INDEX(GROUP_CONCAT(p.ID ORDER BY p.post_date DESC), ',', 3) AS ids FROM %i p WHERE p.post_type='product' AND p.post_status='publish' AND NOT EXISTS (SELECT 1 FROM %i m WHERE m.post_id=p.ID AND m.meta_key='_thumbnail_id' AND m.meta_value NOT IN ('','0'))", $wpdb->posts, $wpdb->postmeta ), ARRAY_A ) );
            $checks['no_alt'] = self::row( $wpdb->get_row( $wpdb->prepare(
                "SELECT COUNT(DISTINCT p.ID) AS n, SUBSTRING_INDEX(GROUP_CONCAT(p.ID ORDER BY p.post_date DESC), ',', 3) AS ids FROM %i p JOIN %i t ON t.post_id=p.ID AND t.meta_key='_thumbnail_id' AND t.meta_value NOT IN ('','0') WHERE p.post_type='product' AND p.post_status='publish' AND NOT EXISTS (SELECT 1 FROM %i a WHERE a.post_id=CAST(t.meta_value AS UNSIGNED) AND a.meta_key='_wp_attachment_image_alt' AND TRIM(a.meta_value)<>'')",
                $wpdb->posts,
                $wpdb->postmeta,
                $wpdb->postmeta
            ), ARRAY_A ) );
            $checks['duplicate_title'] = self::row( $wpdb->get_row( $wpdb->prepare( "SELECT COUNT(*) AS n, SUBSTRING_INDEX(GROUP_CONCAT(p.ID ORDER BY p.post_title, p.post_date DESC), ',', 3) AS ids FROM %i p JOIN (SELECT LOWER(TRIM(post_title)) AS title FROM %i WHERE post_type='product' AND post_status='publish' AND TRIM(post_title)<>'' GROUP BY LOWER(TRIM(post_title)) HAVING COUNT(*)>1) d ON LOWER(TRIM(p.post_title))=d.title WHERE p.post_type='product' AND p.post_status='publish'", $wpdb->posts, $wpdb->posts ), ARRAY_A ) );
            $checks['uncategorized'] = self::row( $wpdb->get_row( $wpdb->prepare(
                "SELECT COUNT(*) AS n, SUBSTRING_INDEX(GROUP_CONCAT(q.ID ORDER BY q.post_date DESC), ',', 3) AS ids FROM (SELECT p.ID, p.post_date FROM %i p LEFT JOIN %i r ON r.object_id=p.ID LEFT JOIN %i x ON x.term_taxonomy_id=r.term_taxonomy_id AND x.taxonomy='product_cat' WHERE p.post_type='product' AND p.post_status='publish' GROUP BY p.ID, p.post_date HAVING SUM(x.term_id IS NOT NULL AND x.term_id<>%d)=0) q",
                $wpdb->posts,
                $wpdb->term_relationships,
                $wpdb->term_taxonomy,
                (int) get_option( 'default_product_cat', 0 )
            ), ARRAY_A ) );
            $checks['long_title'] = self::row( $wpdb->get_row( $wpdb->prepare( "SELECT COUNT(*) AS n, SUBSTRING_INDEX(GROUP_CONCAT(ID ORDER BY post_date DESC), ',', 3) AS ids FROM %i WHERE post_type='product' AND post_status='publish' AND CHAR_LENGTH(post_title)>%d", $wpdb->posts, 70 ), ARRAY_A ) );
        }
        return array(
            'version' => 1,
            'at'      => time(),
            'total'   => $total,
            'checks'  => $checks,
        );
    }

    private static function row( $row ) : array {
        $row = ( is_array( $row ) ? $row : array() );
        return array(
            'n'   => (int) ($row['n'] ?? 0),
            'ids' => array_values( array_unique( array_filter( array_map( 'intval', explode( ',', (string) ($row['ids'] ?? '') ) ) ) ) ),
        );
    }

    /** Whether something writes product meta descriptions: an SEO plugin, or StoreRuler Pro's own SEO output. */
    private static function writes_meta() : bool {
        $active = array_merge( (array) get_option( 'active_plugins', array() ), array_keys( (array) get_site_option( 'active_sitewide_plugins', array() ) ) );
        foreach ( self::SEO_PLUGINS as $constant => $folder ) {
            if ( defined( $constant ) ) {
                return true;
            }
            foreach ( $active as $file ) {
                if ( is_string( $file ) && str_starts_with( $file, $folder ) ) {
                    return true;
                }
            }
        }
        $writes = false;
        return $writes;
    }

    /** The score, the issues (worst first) and the way to fix them, in the reader's language. */
    public static function summary( array $found ) : array {
        $total = (int) ($found['total'] ?? 0);
        $penalty = 0.0;
        $issues = array();
        $passed = 0;
        foreach ( self::WEIGHTS as $code => $weight ) {
            $check = (array) ($found['checks'][$code] ?? array());
            $n = (int) ($check['n'] ?? 0);
            $site = in_array( $code, self::SITE, true );
            if ( !$site && $total === 0 ) {
                continue;
            }
            if ( $n <= 0 ) {
                $passed++;
                continue;
            }
            $share = ( $site ? 1.0 : min( 1.0, $n / $total ) );
            $cost = $weight * $share;
            $penalty += $cost;
            $examples = array();
            foreach ( (array) ($check['ids'] ?? array()) as $id ) {
                $title = get_the_title( (int) $id );
                if ( $title !== '' ) {
                    $examples[] = array(
                        'id'   => (int) $id,
                        'name' => html_entity_decode( wp_strip_all_tags( $title ), ENT_QUOTES, 'UTF-8' ),
                        'url'  => admin_url( 'admin.php?page=storesuit-products&id=' . (int) $id ),
                    );
                }
            }
            $issues[] = array(
                'code'     => $code,
                'level'    => ( $code === 'hidden' ? 'critical' : (( $site || $share >= 0.5 ? 'warning' : 'notice' )) ),
                'count'    => ( $site ? 0 : $n ),
                'total'    => ( $site ? 0 : $total ),
                'title'    => I18n::t( self::TEXTS[$code][0] ),
                'hint'     => I18n::t( self::TEXTS[$code][1] ),
                'examples' => $examples,
                'cost'     => round( $cost, 2 ),
            );
        }
        usort( $issues, static fn( array $a, array $b ): int => $b['cost'] <=> $a['cost'] );
        $score = (int) max( 0, min( 100, round( 100 - $penalty ) ) );
        $fix = array(
            'url'   => ProPage::url() . '#ss-pro-compare',
            'label' => I18n::t( 'Fix the issues with StoreRuler Pro' ),
            'text'  => I18n::t( 'Audit your store, fix titles and descriptions in bulk, add structured data and sitemaps, and follow Search Console and rankings.' ),
        );
        return array(
            'score'       => $score,
            'grade'       => ( $score >= 85 ? 'good' : (( $score >= 60 ? 'fair' : 'poor' )) ),
            'grade_label' => I18n::t( ( $score >= 85 ? 'Good' : (( $score >= 60 ? 'Needs work' : 'Poor' )) ) ),
            'products'    => $total,
            'issues'      => $issues,
            'top'         => array_slice( $issues, 0, 5 ),
            'passed'      => $passed,
            'checked'     => wp_date( (string) get_option( 'date_format' ) . ' ' . (string) get_option( 'time_format' ), (int) ($found['at'] ?? time()) ),
            'fix'         => $fix,
        );
    }

    /** Forgets the six-hour copy (after an AI text was applied to a product), so the next summary counts again. */
    public static function forget() : void {
        delete_transient( self::CACHE );
    }

}