<?php
/**
 * SiteFix Scanner — quick check of recent rendered pages, generates report.
 * No content modifications. Pure analysis. Stores result in transient (expires).
 *
 * @package SiteFix
 * @since   5.0.0
 */

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

class SiteFix_Scanner {

    private static $instance = null;
    public static function get_instance() {
        if ( null === self::$instance ) self::$instance = new self();
        return self::$instance;
    }

    /**
     * Scan most recent N pages/posts; return findings array.
     */
    public function scan_recent_pages( $limit = 20 ) {
        $posts = get_posts( array(
            'post_type'      => array( 'post', 'page' ),
            'post_status'    => 'publish',
            'posts_per_page' => (int) $limit,
            'orderby'        => 'modified',
            'order'          => 'DESC',
        ) );

        $findings = array();
        foreach ( $posts as $p ) {
            $findings[] = $this->analyse_post( $p );
        }
        return $findings;
    }

    /**
     * Analyse a single post's content for accessibility issues.
     */
    public function analyse_post( $post ) {
        $content = $post->post_content;
        $issues  = array();

        // Missing alt
        $img_count        = preg_match_all( '/<img\b/i', $content, $imgs );
        $missing_alt      = preg_match_all( '/<img(?![^>]*\salt=)/i', $content );
        if ( $missing_alt > 0 ) {
            $issues[] = array(
                'severity' => 'critical',
                'rule'     => 'WCAG 1.1.1',
                'count'    => (int) $missing_alt,
                'label'    => sprintf( __( '%d image(s) missing alt text', 'sitefix' ), $missing_alt ),
            );
        }

        // No H1
        if ( $img_count > 0 && ! preg_match( '/<h1\b/i', $content ) && get_post_type( $post ) === 'post' ) {
            $issues[] = array(
                'severity' => 'warning',
                'rule'     => 'WCAG 1.3.1',
                'count'    => 1,
                'label'    => __( 'Post missing H1 heading', 'sitefix' ),
            );
        }

        // Heading skip detection
        if ( preg_match_all( '/<h([1-6])\b/i', $content, $hm ) ) {
            $levels = array_map( 'intval', $hm[1] );
            $prev   = 0;
            foreach ( $levels as $l ) {
                if ( $prev > 0 && $l > $prev + 1 ) {
                    $issues[] = array(
                        'severity' => 'warning',
                        'rule'     => 'WCAG 1.3.1',
                        'count'    => 1,
                        'label'    => sprintf( __( 'Heading skip: H%d → H%d', 'sitefix' ), $prev, $l ),
                    );
                    break;
                }
                $prev = $l;
            }
        }

        // Tables without TH
        if ( preg_match_all( '/<table\b/i', $content, $tm ) > 0
             && ! preg_match( '/<th\b/i', $content ) ) {
            $issues[] = array(
                'severity' => 'warning',
                'rule'     => 'WCAG 1.3.1',
                'count'    => 1,
                'label'    => __( 'Table without header cells (TH)', 'sitefix' ),
            );
        }

        // "Click here" / "Read more" link text
        if ( preg_match_all( '/<a\b[^>]*>(?:click here|read more|here|more)<\/a>/i', $content ) > 0 ) {
            $issues[] = array(
                'severity' => 'notice',
                'rule'     => 'WCAG 2.4.4',
                'count'    => 1,
                'label'    => __( 'Generic link text ("click here", "read more")', 'sitefix' ),
            );
        }

        $score = $this->score_post( $issues, $img_count );
        return array(
            'id'      => $post->ID,
            'url'     => get_permalink( $post ),
            'title'   => get_the_title( $post ),
            'images'  => $img_count,
            'issues'  => $issues,
            'score'   => $score,
        );
    }

    private function score_post( $issues, $img_count ) {
        $base = 100;
        foreach ( $issues as $i ) {
            switch ( $i['severity'] ) {
                case 'critical': $base -= 15 * min( 3, $i['count'] ); break;
                case 'warning':  $base -=  5 * min( 5, $i['count'] ); break;
                case 'notice':   $base -=  2; break;
            }
        }
        return max( 30, $base );
    }

    /**
     * Aggregate score across pages.
     */
    public function calculate_score( $findings ) {
        if ( empty( $findings ) ) return 100;
        $sum = 0;
        foreach ( $findings as $f ) $sum += (int) ( $f['score'] ?? 0 );
        return (int) round( $sum / count( $findings ) );
    }
}