<?php
if (!defined('ABSPATH')) exit;

class AIWEST_Internal_Links {
    public static function link_post($post_id, $limit = 12) {
        $post_id = intval($post_id);
        $post = get_post($post_id);
        if (!$post || !in_array($post->post_type, ['page', 'post'], true)) {
            return new WP_Error('aiwest_links_no_post', __('The page or post to link was not found.', 'ai-webmaster-studio'));
        }

        $active_header_id = intval(get_option('aiwest_active_header_page_id', 0));
        $active_footer_id = intval(get_option('aiwest_active_footer_page_id', 0));
        if ($post_id === $active_header_id || $post_id === $active_footer_id) {
            return new WP_Error(
                'aiwest_links_structural_area',
                __('This is the active AI Header or AI Footer. Use the dedicated header or footer linking action so structural navigation is not mixed with main-content linking.', 'ai-webmaster-studio')
            );
        }

        $content = $post->post_content;
        if (trim(wp_strip_all_tags($content)) === '') {
            return new WP_Error('aiwest_links_empty', __('The page content is empty.', 'ai-webmaster-studio'));
        }

        $targets = self::collect_targets($post_id);
        if (!$targets) {
            return new WP_Error('aiwest_links_no_targets', __('No published pages or posts are available as link targets.', 'ai-webmaster-studio'));
        }

        $linked = [];
        $new_content = $content;

        foreach ($targets as $target) {
            if (count($linked) >= $limit) break;

            foreach ($target['phrases'] as $phrase) {
                if (count($linked) >= $limit) break;
                $phrase = trim($phrase);
                if (mb_strlen($phrase) < 4) continue;
                if (self::content_already_links_to($new_content, $target['url'])) continue;

                $updated = self::link_first_plain_occurrence($new_content, $phrase, $target['url'], $target['title']);
                if ($updated !== $new_content) {
                    $new_content = $updated;
                    $linked[] = [
                        'phrase' => $phrase,
                        'post_id' => $target['id'],
                        'title' => $target['title'],
                        'url' => $target['url'],
                    ];
                    break;
                }
            }
        }

        if ($new_content === $content) {
            return [
                'changed' => false,
                'message' => __('No new safe link locations were found, or the links already exist.', 'ai-webmaster-studio'),
                'links' => [],
                'post_id' => $post_id,
            ];
        }

        if (class_exists('AIWEST_Undo')) {
            AIWEST_Undo::snapshot($post_id, 'internal_links', __('Snapshot before automatic AI Webmaster Studio internal linking.', 'ai-webmaster-studio'));
        }

        $heading_normalization = ['content' => $new_content, 'report' => []];
        if (class_exists('AIWEST_Page_Title_Heading_Normalizer')) {
            $heading_normalization = AIWEST_Page_Title_Heading_Normalizer::normalize($post_id, $new_content, [
                'post_title' => (string)$post->post_title,
                'post_type' => (string)$post->post_type,
                'mode' => 'standard',
            ]);
            $new_content = $heading_normalization['content'];
        }

        $result = wp_update_post([
            'ID' => $post_id,
            'post_content' => $new_content,
        ], true);

        if (is_wp_error($result)) return $result;

        if (class_exists('AIWEST_Page_Title_Heading_Normalizer')) {
            AIWEST_Page_Title_Heading_Normalizer::record_report($post_id, $heading_normalization['report']);
        }

        update_post_meta($post_id, '_aiwest_last_internal_links_at', current_time('mysql'));
        update_post_meta($post_id, '_aiwest_last_internal_links', $linked);

        if (class_exists('AIWEST_Logger')) {
            AIWEST_Logger::info('Internal links added.', [
                'post_id' => $post_id,
                'count' => count($linked),
            ]);
        }

        return [
            'changed' => true,
            'message' => __('Internal links were added without changing the content structure.', 'ai-webmaster-studio'),
            'links' => $linked,
            'post_id' => $post_id,
        ];
    }

    public static function collect_targets($exclude_id = 0) {
        $posts = get_posts([
            'numberposts' => 81,
            'post_type' => ['page', 'post'],
            'post_status' => 'publish',
            'orderby' => 'modified',
            'order' => 'DESC',
        ]);

        $targets = [];
        foreach ($posts as $p) {
            if (intval($p->ID) === intval($exclude_id)) continue;
            $title = trim(wp_strip_all_tags($p->post_title));
            if ($title === '') continue;

            $phrases = self::phrases_for_post($p);
            if (!$phrases) continue;

            $targets[] = [
                'id' => intval($p->ID),
                'title' => $title,
                'url' => get_permalink($p->ID),
                'phrases' => $phrases,
            ];
        }

        return $targets;
    }

    protected static function phrases_for_post($post) {
        $title = trim(wp_strip_all_tags($post->post_title));
        $phrases = [$title];

        $normalized = self::normalize_title($title);
        if ($normalized && $normalized !== $title) $phrases[] = $normalized;

        if ($post->post_type === 'post') {
            $cats = wp_get_post_categories($post->ID, ['fields' => 'names']);
            $tags = wp_get_post_tags($post->ID, ['fields' => 'names']);
            foreach (array_merge((array)$cats, (array)$tags) as $term) {
                if (mb_strlen($term) >= 4) $phrases[] = $term;
            }
        }

        $phrases = array_map('trim', $phrases);
        $phrases = array_filter($phrases, function($v) {
            return mb_strlen($v) >= 4;
        });
        $phrases = array_values(array_unique($phrases));

        usort($phrases, function($a, $b) {
            return mb_strlen($b) <=> mb_strlen($a);
        });

        return $phrases;
    }

    protected static function normalize_title($title) {
        $title = preg_replace('/\s*[–—-]\s*.*$/u', '', $title);
        $title = preg_replace('/\b(current|practical|guide|overview|introduction|in 2026|in 2025|in 2024)\b/iu', '', $title);
        $title = trim(preg_replace('/\s+/', ' ', $title));
        return $title;
    }

    protected static function content_already_links_to($content, $url) {
        return stripos($content, 'href="' . esc_url($url) . '"') !== false || stripos($content, "href='" . esc_url($url) . "'") !== false;
    }

    protected static function link_first_plain_occurrence($content, $phrase, $url, $title) {
        $parts = preg_split('/(<a\b[^>]*>.*?<\/a>|<[^>]+>)/isu', $content, -1, PREG_SPLIT_DELIM_CAPTURE);
        if (!$parts || count($parts) === 1) {
            return self::replace_first_in_text($content, $phrase, $url, $title);
        }

        $out = '';
        $changed = false;

        foreach ($parts as $part) {
            if ($changed) {
                $out .= $part;
                continue;
            }

            // Skip tags and existing links.
            if (preg_match('/^<a\b/i', $part) || preg_match('/^<[^>]+>$/s', $part)) {
                $out .= $part;
                continue;
            }

            $new = self::replace_first_in_text($part, $phrase, $url, $title);
            if ($new !== $part) {
                $changed = true;
                $out .= $new;
            } else {
                $out .= $part;
            }
        }

        return $changed ? $out : $content;
    }

    protected static function replace_first_in_text($text, $phrase, $url, $title) {
        $pattern = '/(?<![\pL\pN])(' . preg_quote($phrase, '/') . ')(?![\pL\pN])/iu';
        $replacement = '<a href="' . esc_url($url) . '" title="' . esc_attr($title) . '">$1</a>';
        return preg_replace($pattern, $replacement, $text, 1);
    }

    public static function link_active_footer($create_missing = true) {
        $post_id = intval(get_option('aiwest_active_footer_page_id', 0));
        if (!$post_id) {
            return new WP_Error('aiwest_footer_no_active', __('No active AI Footer is available for linking.', 'ai-webmaster-studio'));
        }

        $post = get_post($post_id);
        if (!$post || $post->post_type !== 'page') {
            return new WP_Error('aiwest_footer_no_post', __('The active AI Footer page was not found.', 'ai-webmaster-studio'));
        }

        $content = $post->post_content;
        $linked = [];
        $created = [];

        $new_content = preg_replace_callback('/<li\b([^>]*)>(.*?)<\/li>/isu', function($m) use (&$linked, &$created, $post_id, $create_missing) {
            $attrs = $m[1];
            $inner = $m[2];

            if (stripos($inner, '<a ') !== false) return $m[0];
            $label = trim(wp_strip_all_tags($inner));
            if ($label === '' || stripos($label, '@') !== false || mb_strlen($label) < 3) return $m[0];

            $target = self::resolve_target_for_label($label, $create_missing);
            if (is_wp_error($target) || empty($target['url'])) return $m[0];

            if (!empty($target['created'])) {
                $created[] = $target;
            }

            $linked[] = [
                'phrase' => $label,
                'post_id' => intval($target['id']),
                'title' => $target['title'],
                'url' => $target['url'],
                'created' => !empty($target['created']),
            ];

            return '<li' . $attrs . '><a href="' . esc_url($target['url']) . '" title="' . esc_attr($target['title']) . '">' . esc_html($label) . '</a></li>';
        }, $content);

        if ($new_content === $content) {
            return [
                'changed' => false,
                'message' => __('No new footer items were found to link, or the links already exist.', 'ai-webmaster-studio'),
                'links' => [],
                'created' => [],
                'post_id' => $post_id,
            ];
        }

        if (class_exists('AIWEST_Undo')) {
            AIWEST_Undo::snapshot($post_id, 'footer_internal_links', __('Snapshot before linking the active AI Footer.', 'ai-webmaster-studio'));
        }

        $result = wp_update_post([
            'ID' => $post_id,
            'post_content' => $new_content,
        ], true);

        if (is_wp_error($result)) return $result;

        update_post_meta($post_id, '_aiwest_last_footer_links_at', current_time('mysql'));
        update_post_meta($post_id, '_aiwest_last_footer_links', $linked);

        return [
            'changed' => true,
            'message' => __('The active AI Footer was linked.', 'ai-webmaster-studio'),
            'links' => $linked,
            'created' => $created,
            'post_id' => $post_id,
        ];
    }

    public static function link_active_header_menu($create_missing = false) {
        $post_id = intval(get_option('aiwest_active_header_page_id', 0));
        if (!$post_id) {
            return new WP_Error('aiwest_header_no_active', __('No active AI Header is available for linking.', 'ai-webmaster-studio'));
        }

        $post = get_post($post_id);
        if (!$post || $post->post_type !== 'page') {
            return new WP_Error('aiwest_header_no_post', __('The active AI Header page was not found.', 'ai-webmaster-studio'));
        }

        $content = $post->post_content;
        $linked = [];
        $created = [];

        /*
         * Existing AI Headers often use static <span> pills as pseudo-menu items.
         * This action converts only those simple spans into links, without changing
         * the visual structure of the header.
         */
        $new_content = preg_replace_callback('/<span\b([^>]*)>(.*?)<\/span>/isu', function($m) use (&$linked, &$created, $create_missing) {
            $attrs = $m[1];
            $inner = $m[2];

            if (stripos($inner, '<a ') !== false) return $m[0];
            $label = trim(wp_strip_all_tags($inner));
            if ($label === '' || mb_strlen($label) < 3) return $m[0];

            // Avoid linking legacy decorative labels and their translated equivalents.
            if (preg_match('/projekt\s+nagłówka|header\s+project/i', $label)) return $m[0];
            if (strcasecmp($label, get_bloginfo('name')) === 0) return $m[0];

            $target = self::resolve_target_for_label($label, $create_missing);
            if (is_wp_error($target) || empty($target['url'])) return $m[0];

            if (!empty($target['created'])) {
                $created[] = $target;
            }

            $linked[] = [
                'phrase' => $label,
                'post_id' => intval($target['id']),
                'title' => $target['title'],
                'url' => $target['url'],
                'created' => !empty($target['created']),
            ];

            return '<span' . $attrs . '><a href="' . esc_url($target['url']) . '" title="' . esc_attr($target['title']) . '" style="color:inherit;text-decoration:none">' . esc_html($label) . '</a></span>';
        }, $content);

        if ($new_content === $content) {
            return [
                'changed' => false,
                'message' => __('No static AI Header menu items were found to link, or the links already exist.', 'ai-webmaster-studio'),
                'links' => [],
                'created' => [],
                'post_id' => $post_id,
            ];
        }

        if (class_exists('AIWEST_Undo')) {
            AIWEST_Undo::snapshot($post_id, 'header_menu_links', __('Snapshot before linking the static AI Header menu.', 'ai-webmaster-studio'));
        }

        $result = wp_update_post([
            'ID' => $post_id,
            'post_content' => $new_content,
        ], true);

        if (is_wp_error($result)) return $result;

        update_post_meta($post_id, '_aiwest_last_header_menu_links_at', current_time('mysql'));
        update_post_meta($post_id, '_aiwest_last_header_menu_links', $linked);

        return [
            'changed' => true,
            'message' => __('Static AI Header items were linked.', 'ai-webmaster-studio'),
            'links' => $linked,
            'created' => $created,
            'post_id' => $post_id,
        ];
    }

    protected static function resolve_target_for_label($label, $create_missing = false) {
        $label = trim(wp_strip_all_tags($label));
        if ($label === '') {
            return new WP_Error('aiwest_empty_label', __('The link label is empty.', 'ai-webmaster-studio'));
        }

        $map = [
            mb_strtolower(__('Contact form', 'ai-webmaster-studio')) => __('Contact', 'ai-webmaster-studio'),
            mb_strtolower(__('Email', 'ai-webmaster-studio')) => __('Contact', 'ai-webmaster-studio'),
            mb_strtolower(__('Ask a question', 'ai-webmaster-studio')) => __('Contact', 'ai-webmaster-studio'),
            mb_strtolower(__('Home page', 'ai-webmaster-studio')) => __('Home', 'ai-webmaster-studio'),
            mb_strtolower(__('About the website', 'ai-webmaster-studio')) => __('About', 'ai-webmaster-studio'),
        ];

        $key = mb_strtolower($label);
        $target_title = $map[$key] ?? $label;

        $post = self::find_post_by_title_or_slug($target_title);
        if (!$post && $target_title !== $label) {
            $post = self::find_post_by_title_or_slug($label);
        }

        if ($post) {
            return [
                'id' => intval($post->ID),
                'title' => get_the_title($post->ID),
                'url' => get_permalink($post->ID),
                'created' => false,
            ];
        }

        if (!$create_missing) {
            return new WP_Error(
                'aiwest_target_missing',
                sprintf(
                    /* translators: %s: Requested internal-link target label. */
                    __('No page was found for the label: %s', 'ai-webmaster-studio'),
                    $label
                )
            );
        }

        $placeholder_content = '<h1>' . esc_html($target_title) . '</h1><p>' . esc_html(__('This page was created as an AI Webmaster Studio draft to complete internal linking. Expand it in Content Development before publishing.', 'ai-webmaster-studio')) . '</p>';
        $heading_normalization = ['content' => $placeholder_content, 'report' => []];
        if (class_exists('AIWEST_Page_Title_Heading_Normalizer')) {
            $heading_normalization = AIWEST_Page_Title_Heading_Normalizer::normalize(0, $placeholder_content, [
                'post_title' => $target_title,
                'post_type' => 'page',
                'mode' => 'standard',
                'theme_title_visible' => true,
            ]);
            $placeholder_content = $heading_normalization['content'];
        }

        $new_id = wp_insert_post([
            'post_title' => $target_title,
            'post_name' => sanitize_title($target_title),
            'post_type' => 'page',
            'post_status' => 'draft',
            'post_content' => $placeholder_content,
            'post_author' => class_exists('AIWEST_Technical_Operator') ? AIWEST_Technical_Operator::post_author_id(get_current_user_id()) : (get_current_user_id() ?: 1),
        ], true);

        if (is_wp_error($new_id)) return $new_id;

        update_post_meta($new_id, '_aiwest_generated', 'yes');
        update_post_meta($new_id, '_aiwest_created_for_internal_link', 'yes');
        if (class_exists('AIWEST_Page_Title_Heading_Normalizer')) {
            AIWEST_Page_Title_Heading_Normalizer::record_report($new_id, $heading_normalization['report']);
        }
        if (class_exists('AIWEST_Technical_Operator')) {
            AIWEST_Technical_Operator::annotate_post($new_id, 'create_internal_link_target', AIWEST_Technical_Operator::explain_decision('create_page', 'content_page_create', ['post_type'=>'page','post_status'=>'draft']));
        }

        return [
            'id' => intval($new_id),
            'title' => get_the_title($new_id),
            'url' => get_permalink($new_id),
            'created' => true,
        ];
    }

    protected static function find_post_by_title_or_slug($title) {
        $title = trim(wp_strip_all_tags($title));
        if ($title === '') return null;

        $slug = sanitize_title($title);

        $by_slug = get_page_by_path($slug, OBJECT, ['page', 'post']);
        if ($by_slug && $by_slug->post_status !== 'trash') return $by_slug;

        $posts = get_posts([
            'numberposts' => 1,
            'post_type' => ['page', 'post'],
            'post_status' => ['publish', 'draft', 'pending', 'private'],
            'title' => $title,
        ]);
        if ($posts) return $posts[0];

        // Fallback: loose search by title.
        $search = get_posts([
            'numberposts' => 8,
            'post_type' => ['page', 'post'],
            'post_status' => ['publish', 'draft', 'pending', 'private'],
            's' => $title,
        ]);

        foreach ($search as $p) {
            if (stripos(get_the_title($p), $title) !== false || stripos($title, get_the_title($p)) !== false) {
                return $p;
            }
        }

        return null;
    }

}