<?php
namespace ActiveTwist\SEO\Features;

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

use ActiveTwist\SEO\Utils\Helpers;

class SitemapController
{
    const TRANSIENT_KEY_PREFIX = 'at_seo_sitemap_';
    const CACHE_TIME = 12 * HOUR_IN_SECONDS;

    public function init()
    {
        add_action('init', [$this, 'add_rewrites']);
        add_filter('query_vars', [$this, 'add_query_vars']);
        add_action('template_redirect', [$this, 'render_sitemap'], 1); // Priority 1 to run before canonical redirects
        add_action('save_post', [$this, 'invalidate_cache']);
        // Add more invalidation hooks if needed (e.g., term edits)
    }

    public function add_rewrites()
    {
        add_rewrite_rule('^sitemap\.xml$', 'index.php?at_sitemap=index', 'top');
        add_rewrite_rule('^sitemap-posts\.xml$', 'index.php?at_sitemap=posts', 'top');
        add_rewrite_rule('^sitemap-pages\.xml$', 'index.php?at_sitemap=pages', 'top');
        add_rewrite_rule('^sitemap-taxonomies\.xml$', 'index.php?at_sitemap=taxonomies', 'top');
    }

    public function add_query_vars($vars)
    {
        $vars[] = 'at_sitemap';
        return $vars;
    }

    public function render_sitemap()
    {
        $type = get_query_var('at_sitemap');

        // Fallback: Check REQUEST_URI if rewrite rules aren't flushed
        if (empty($type)) {
            $request_uri = isset($_SERVER['REQUEST_URI']) ? sanitize_text_field(wp_unslash($_SERVER['REQUEST_URI'])) : '';
            $path = trim((string) wp_parse_url($request_uri, PHP_URL_PATH), '/');
            // Remove installation path if exists
            $home_path = trim((string) wp_parse_url(home_url(), PHP_URL_PATH), '/');
            if (!empty($home_path) && strpos($path, $home_path) === 0) {
                $path = trim(substr($path, strlen($home_path)), '/');
            }

            if ($path === 'sitemap.xml')
                $type = 'index';
            elseif ($path === 'sitemap-posts.xml')
                $type = 'posts';
            elseif ($path === 'sitemap-pages.xml')
                $type = 'pages';
            elseif ($path === 'sitemap-taxonomies.xml')
                $type = 'taxonomies';
        }

        if (empty($type)) {
            return;
        }

        // Check cache
        $cache_key = self::TRANSIENT_KEY_PREFIX . $type;
        $cached = get_transient($cache_key);

        if ($cached) {
            $this->send_xml($cached);
            exit;
        }

        $xml = '';
        switch ($type) {
            case 'index':
                $xml = $this->generate_index();
                break;
            case 'posts':
                $xml = $this->generate_posts_sitemap('post');
                break;
            case 'pages':
                $xml = $this->generate_posts_sitemap('page');
                break;
            case 'taxonomies':
                $xml = $this->generate_taxonomies_sitemap();
                break;
            default:
                global $wp_query;
                $wp_query->set_404();
                status_header(404);
                return;
        }

        set_transient($cache_key, $xml, self::CACHE_TIME);
        $this->send_xml($xml);
        exit;
    }

    private function send_xml($content)
    {
        status_header(200);
        header('Content-Type: application/xml; charset=utf-8');
        header('X-Robots-Tag: noindex, follow');
        // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped -- XML output is generated and safe.
        echo $content;
    }

    private function generate_index()
    {
        $base_url = home_url('/');
        $sitemaps = [
            $base_url . 'sitemap-posts.xml',
            $base_url . 'sitemap-pages.xml',
            // Taxonomies optional or if enabled
        ];

        // Only add taxonomies request if there are public taxonomies
        // For simplicity in Phase 4, we just add it ensuring it returns empty set if none.
        $sitemaps[] = $base_url . 'sitemap-taxonomies.xml';

        $last_mod = wp_date('c'); // Use current time or query latest post

        $xml = '<?xml version="1.0" encoding="UTF-8"?>';
        $xml .= '<sitemapindex xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">';

        foreach ($sitemaps as $url) {
            $xml .= '<sitemap>';
            $xml .= '<loc>' . esc_url($url) . '</loc>';
            $xml .= '<lastmod>' . $last_mod . '</lastmod>';
            $xml .= '</sitemap>';
        }

        $xml .= '</sitemapindex>';
        return $xml;
    }

    private function generate_posts_sitemap($post_type)
    {
        // Query posts
        $query = new \WP_Query([
            'post_type' => $post_type,
            'post_status' => 'publish',
            'posts_per_page' => 1000, // Limit for Phase 4 safety
            'fields' => 'ids',
            'no_found_rows' => true,
            'update_post_meta_cache' => false,
            'update_post_term_cache' => false,
        ]);

        $xml = '<?xml version="1.0" encoding="UTF-8"?>';
        $xml .= '<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">';

        foreach ($query->posts as $post_id) {
            if ($this->is_excluded($post_id)) {
                continue;
            }

            $permalink = get_permalink($post_id);
            $modified = get_the_modified_date('c', $post_id);

            $xml .= '<url>';
            $xml .= '<loc>' . esc_url($permalink) . '</loc>';
            $xml .= '<lastmod>' . $modified . '</lastmod>';
            $xml .= '</url>';
        }

        $xml .= '</urlset>';
        return $xml;
    }

    private function generate_taxonomies_sitemap()
    {
        // Basic impl for categories/tags
        $taxonomies = get_taxonomies(['public' => true], 'names');
        $terms = get_terms([
            'taxonomy' => $taxonomies,
            'hide_empty' => true,
        ]);

        $xml = '<?xml version="1.0" encoding="UTF-8"?>';
        $xml .= '<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">';

        if (!is_wp_error($terms)) {
            foreach ($terms as $term) {
                // Todo: check for noindex on term meta if we added that feature
                $link = get_term_link($term);
                if (is_wp_error($link))
                    continue;

                $xml .= '<url>';
                $xml .= '<loc>' . esc_url($link) . '</loc>';
                $xml .= '</url>';
            }
        }

        $xml .= '</urlset>';
        return $xml;
    }

    private function is_excluded($post_id)
    {
        $meta = Helpers::get_post_meta($post_id);

        // 1. Check noindex
        $robots = !empty($meta['robots']) ? $meta['robots'] : 'index, follow';
        if (strpos($robots, 'noindex') !== false) {
            return true;
        }

        // 2. Check password protected? (WP Query handles post_status=publish, but password protected are publish)
        $post = get_post($post_id);
        if (!empty($post->post_password)) {
            return true;
        }

        return false;
    }

    public function invalidate_cache()
    {
        delete_transient(self::TRANSIENT_KEY_PREFIX . 'index');
        delete_transient(self::TRANSIENT_KEY_PREFIX . 'posts');
        delete_transient(self::TRANSIENT_KEY_PREFIX . 'pages');
        delete_transient(self::TRANSIENT_KEY_PREFIX . 'taxonomies');
    }
}