<?php

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

class Twokcs_Taxonomy_Exporter
{
    /**
     * Export paginated product categories.
     *
     * @param WP_REST_Request $request Request object.
     * @return WP_REST_Response|WP_Error
     */
    public function export_categories(WP_REST_Request $request)
    {
        $per_page = $this->get_per_page($request);
        $page     = $this->get_page($request);
        $offset   = ($page - 1) * $per_page;
        $exclude  = $this->get_id_list_param($request, 'exclude');

        $count_args = [
            'taxonomy'   => 'product_cat',
            'hide_empty' => false,
        ];

        if (!empty($exclude)) {
            // phpcs:ignore WordPressVIPMinimum.Performance.WPQueryParams.PostNotIn_exclude -- Optional client-driven term exclusion for catalog sync.
            $count_args['exclude'] = $exclude;
        }

        $total = (int) wp_count_terms($count_args);

        if (is_wp_error($total)) {
            return $total;
        }

        $term_args = [
            'taxonomy'   => 'product_cat',
            'hide_empty' => false,
            'number'     => $per_page,
            'offset'     => $offset,
            'orderby'    => 'term_id',
            'order'      => 'DESC',
        ];

        if (!empty($exclude)) {
            // phpcs:ignore WordPressVIPMinimum.Performance.WPQueryParams.PostNotIn_exclude -- Optional client-driven term exclusion for catalog sync.
            $term_args['exclude'] = $exclude;
        }

        $terms = get_terms($term_args);

        if (is_wp_error($terms)) {
            return $terms;
        }

        $controller = new Twokcs_REST_Categories_Controller();
        $items      = [];

        foreach ($terms as $term) {
            $items[] = $controller->prepare_item_for_response($term, $request)->get_data();
        }

        return $this->build_response('results', $items, $total, $per_page, $request);
    }

    /**
     * Export paginated product attributes.
     *
     * @param WP_REST_Request $request Request object.
     * @return WP_REST_Response|WP_Error
     */
    public function export_attributes(WP_REST_Request $request)
    {
        $per_page   = $this->get_per_page($request);
        $page       = $this->get_page($request);
        $offset     = ($page - 1) * $per_page;
        $exclude    = $this->get_id_list_param($request, 'exclude');
        $attributes = wc_get_attribute_taxonomies();

        if (!empty($exclude)) {
            $attributes = array_values(array_filter($attributes, function ($attribute) use ($exclude) {
                return !in_array((int) $attribute->attribute_id, $exclude, true);
            }));
        }

        $total = count($attributes);
        $slice = array_slice($attributes, $offset, $per_page);

        $controller = new Twokcs_REST_Attributes_Controller();
        $items      = [];

        foreach ($slice as $attribute) {
            $items[] = $controller->prepare_item_for_response($attribute, $request)->get_data();
        }

        return $this->build_response('results', $items, $total, $per_page, $request);
    }

    /**
     * Export paginated attribute terms.
     *
     * @param WP_REST_Request $request Request object.
     * @return WP_REST_Response|WP_Error
     */
    public function export_attribute_terms(WP_REST_Request $request)
    {
        $per_page     = $this->get_per_page($request);
        $page         = $this->get_page($request);
        $offset       = ($page - 1) * $per_page;
        $attribute_id = (int) $request->get_param('attribute_id');

        $taxonomy_map = $this->get_attribute_taxonomy_map();

        if ($attribute_id > 0) {
            if (!isset($taxonomy_map[$attribute_id])) {
                return new WP_Error(
                    'twokcs_invalid_attribute',
                    __('Invalid attribute ID.', '2khat-catalog-sync'),
                    ['status' => 400]
                );
            }

            $taxonomy_map = [$attribute_id => $taxonomy_map[$attribute_id]];
        }

        $taxonomies = array_values($taxonomy_map);

        if (empty($taxonomies)) {
            return $this->build_response('attribute_terms', [], 0, $per_page, $request);
        }

        $exclude = $this->get_id_list_param($request, 'exclude');

        $count_args = [
            'taxonomy'   => $taxonomies,
            'hide_empty' => false,
        ];

        if (!empty($exclude)) {
            // phpcs:ignore WordPressVIPMinimum.Performance.WPQueryParams.PostNotIn_exclude -- Optional client-driven term exclusion for catalog sync.
            $count_args['exclude'] = $exclude;
        }

        $total = (int) wp_count_terms($count_args);

        if (is_wp_error($total)) {
            return $total;
        }

        $term_args = [
            'taxonomy'   => $taxonomies,
            'hide_empty' => false,
            'number'     => $per_page,
            'offset'     => $offset,
            'orderby'    => 'term_id',
            'order'      => 'DESC',
        ];

        if (!empty($exclude)) {
            // phpcs:ignore WordPressVIPMinimum.Performance.WPQueryParams.PostNotIn_exclude -- Optional client-driven term exclusion for catalog sync.
            $term_args['exclude'] = $exclude;
        }

        $terms = get_terms($term_args);

        if (is_wp_error($terms)) {
            return $terms;
        }

        $taxonomy_to_attribute = array_flip($taxonomy_map);
        $controller            = new Twokcs_REST_Attribute_Terms_Controller();
        $items                 = [];

        foreach ($terms as $term) {
            $term_attribute_id = $taxonomy_to_attribute[$term->taxonomy] ?? 0;
            $request->set_param('attribute_id', $term_attribute_id);

            $item_data = $controller->prepare_item_for_response($term, $request)->get_data();
            $item_data['attribute_id'] = $term_attribute_id;

            $items[] = $item_data;
        }

        return $this->build_response('results', $items, $total, $per_page, $request);
    }

    /**
     * Map attribute IDs to their taxonomy names.
     *
     * @return array<int, string>
     */
    private function get_attribute_taxonomy_map()
    {
        $map = [];

        foreach (wc_get_attribute_taxonomies() as $attribute) {
            $map[(int) $attribute->attribute_id] = wc_attribute_taxonomy_name($attribute->attribute_name);
        }

        return $map;
    }

    /**
     * @param string          $key      Response collection key.
     * @param array           $items    Prepared items.
     * @param int             $total    Total item count.
     * @param int             $per_page Items per page.
     * @param WP_REST_Request $request  Request object.
     * @return WP_REST_Response
     */
    private function build_response($key, array $items, $total, $per_page, WP_REST_Request $request)
    {
        $data = [
            'count'     => (int) $total,
            'max_pages' => $total > 0 ? (int) ceil($total / $per_page) : 0,
            $key        => $items,
        ];

        if ($this->is_debug_enabled($request)) {
            $this->append_debug_data($data);
        }

        return new WP_REST_Response($data, 200);
    }

    /**
     * Append read-only SQL debug stats when debug mode is enabled.
     *
     * @param array $data Response data array.
     */
    private function append_debug_data(array &$data)
    {
        global $wpdb;

        $data['debug'] = ['num_queries' => $wpdb->num_queries];

        if (defined('SAVEQUERIES') && SAVEQUERIES && !empty($wpdb->queries)) {
            $data['debug']['queries'] = $wpdb->queries;
        }
    }

    /**
     * Parse a comma-separated or array request param into a list of positive integers.
     *
     * @param WP_REST_Request $request Request object.
     * @param string          $name    Parameter name.
     * @return int[]
     */
    private function get_id_list_param(WP_REST_Request $request, $name)
    {
        $value = $request->get_param($name);

        if (empty($value)) {
            return [];
        }

        if (!is_array($value)) {
            $value = explode(',', (string) $value);
        }

        $ids = array_map('intval', $value);

        return array_values(array_filter($ids, function ($id) {
            return $id > 0;
        }));
    }

    /**
     * @param WP_REST_Request $request Request object.
     * @return int
     */
    private function get_per_page(WP_REST_Request $request)
    {
        $per_page = (int) $request->get_param('per_page');

        if ($per_page < 1) {
            $per_page = Twokcs_Constants::DEFAULT_PER_PAGE;
        }

        return min($per_page, Twokcs_Constants::MAX_PER_PAGE);
    }

    /**
     * @param WP_REST_Request $request Request object.
     * @return int
     */
    private function get_page(WP_REST_Request $request)
    {
        $page = (int) $request->get_param('page');

        return max($page, 1);
    }

    /**
     * @param WP_REST_Request $request Request object.
     * @return bool
     */
    private function is_debug_enabled(WP_REST_Request $request)
    {
        if (!(bool) $request->get_param('debug')) {
            return false;
        }

        if (apply_filters('twokcs_allow_debug', false)) {
            return true;
        }

        return defined('WP_DEBUG') && WP_DEBUG && defined('TWOKCS_DEBUG') && TWOKCS_DEBUG;
    }
}