<?php
/**
 * Upsell Service - Handles CUW (UpsellWP) campaign data
 */

class UpsellService
{
    /**
     * Build a map: product_id => related product ids from CUW (UpsellWP) campaigns.
     * Uses {$wpdb->prefix}cuw_campaigns table.
     * 
     * @return array<int, int[]>
     */
    public static function buildProductMap(): array
    {
        if (!function_exists('get_post_type')) {
            return [];
        }

        global $wpdb;

        $table = $wpdb->prefix . 'cuw_campaigns';
        
        // Safety: table might not exist
        $exists = $wpdb->get_var($wpdb->prepare("SHOW TABLES LIKE %s", $table));
        if ($exists !== $table) {
            return [];
        }

        $rows = $wpdb->get_results("
            SELECT id, type, filters, data
            FROM {$table}
            WHERE enabled = 1
            ORDER BY priority DESC, id DESC
        ");

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

        $map = [];

        foreach ($rows as $row) {
            $filters = json_decode((string) $row->filters, true);
            if (!is_array($filters)) {
                continue;
            }

            $filterProductLists = self::extractProductListsFromFilters($filters);

            if (empty($filterProductLists)) {
                continue;
            }

            // For each list: if a product is in that list, relate it to the other products in that list
            foreach ($filterProductLists as $list) {
                foreach ($list as $pid) {
                    $related = array_values(array_diff($list, [$pid]));
                    if (empty($related)) {
                        continue;
                    }

                    // Keep only real Woo products
                    $related = array_values(array_filter($related, function ($id) {
                        $pt = get_post_type($id);
                        return $pt === 'product' || $pt === 'product_variation';
                    }));

                    if (empty($related)) {
                        continue;
                    }

                    if (!isset($map[$pid])) {
                        $map[$pid] = [];
                    }
                    $map[$pid] = array_values(array_unique(array_merge($map[$pid], $related)));
                }
            }
        }

        return $map;
    }

    /**
     * Build deals map for buy_more_save_more campaigns
     * 
     * @return array<int, array>
     */
    public static function buildDealsMap(): array
    {
        global $wpdb;

        $table = $wpdb->prefix . 'cuw_campaigns';

        $exists = $wpdb->get_var($wpdb->prepare("SHOW TABLES LIKE %s", $table));
        if ($exists !== $table) {
            return [];
        }

        $rows = $wpdb->get_results("
            SELECT id, type, title, priority, filters, data
            FROM {$table}
            WHERE enabled = 1
            ORDER BY priority DESC, id DESC
        ");

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

        $map = [];

        foreach ($rows as $row) {
            $type = (string) $row->type;
            if ($type !== 'buy_more_save_more') {
                continue;
            }

            $filters = json_decode((string) $row->filters, true);
            $data = json_decode((string) $row->data, true);

            if (!is_array($filters) || !is_array($data)) {
                continue;
            }

            $product_ids = self::extractProductIdsFromFilters($filters);

            if (empty($product_ids)) {
                continue;
            }

            // Deal details from data
            $cta_text = $data['template']['cta_text'] ?? '';
            $display_location = $data['display_location'] ?? ($data['template']['display_location'] ?? '');

            $discounts = $data['discounts'] ?? [];
            if (!is_array($discounts) || empty($discounts)) {
                continue;
            }

            foreach ($discounts as $disc) {
                if (!is_array($disc)) {
                    continue;
                }

                $qty = isset($disc['qty']) ? (int) $disc['qty'] : 0;
                $dType = isset($disc['type']) ? (string) $disc['type'] : '';
                $value = isset($disc['value']) ? (float) $disc['value'] : 0.0;

                if ($qty <= 0 || $dType === '' || $value <= 0) {
                    continue;
                }

                $deal = [
                    'campaign_id' => (int) $row->id,
                    'campaign_type' => $type,
                    'title' => (string) $row->title,
                    'priority' => (int) $row->priority,
                    'qty' => $qty,
                    'discount_type' => $dType,
                    'value' => $value,
                    'cta_text' => (string) $cta_text,
                    'display_location' => (string) $display_location,
                ];

                foreach ($product_ids as $pid) {
                    if (!isset($map[$pid])) {
                        $map[$pid] = [];
                    }
                    $map[$pid][] = $deal;
                }
            }
        }

        return $map;
    }

    /**
     * Extract product lists from campaign filters
     * 
     * @param array $filters
     * @return array<int[]>
     */
    private static function extractProductListsFromFilters(array $filters): array
    {
        $filterProductLists = [];

        foreach ($filters as $k => $v) {
            if ($k === 'relation') {
                continue;
            }
            if (!is_array($v)) {
                continue;
            }

            $type = $v['type'] ?? '';
            $method = $v['method'] ?? '';
            $values = $v['values'] ?? [];

            if ($type !== 'products') {
                continue;
            }
            if (!in_array($method, ['in_list', 'in', 'include', 'equals'], true)) {
                continue;
            }
            if (!is_array($values)) {
                continue;
            }

            $ids = array_values(array_unique(array_map('intval', $values)));
            $ids = array_values(array_filter($ids));

            if (!empty($ids)) {
                $filterProductLists[] = $ids;
            }
        }

        return $filterProductLists;
    }

    /**
     * Extract product IDs from campaign filters
     * 
     * @param array $filters
     * @return int[]
     */
    private static function extractProductIdsFromFilters(array $filters): array
    {
        $product_ids = [];

        foreach ($filters as $k => $v) {
            if ($k === 'relation') {
                continue;
            }
            if (!is_array($v)) {
                continue;
            }

            $f_type = $v['type'] ?? '';
            $f_method = $v['method'] ?? '';
            $values = $v['values'] ?? [];

            if ($f_type !== 'products') {
                continue;
            }
            if (!in_array($f_method, ['in_list', 'in', 'include', 'equals'], true)) {
                continue;
            }
            if (!is_array($values)) {
                continue;
            }

            foreach ($values as $pid) {
                $pid = (int) $pid;
                if ($pid > 0) {
                    $product_ids[] = $pid;
                }
            }
        }

        return array_values(array_unique(array_filter($product_ids)));
    }
}