<?php
/**
 * Shop cart service.
 *
 * Extracted from AKSRT_Shop to isolate server-side cart storage
 * (user_meta['shop_cart']) and validation into a cohesive unit.
 *
 * @package AKSRT
 */

defined('ABSPATH') || exit;

class AKSRT_Shop_Cart_Service {

    private AKSRT_Shop $shop;

    public function __construct(AKSRT_Shop $shop) {
        $this->shop = $shop;
    }

    public function get_cart(int $user_id): array {
        if ($user_id <= 0) {
            return [];
        }
        $cart = get_user_meta($user_id, 'shop_cart', true);
        return is_array($cart) ? $cart : [];
    }

    public function get_cart_count(int $user_id): int {
        $cart = $this->get_cart($user_id);
        $count = 0;
        foreach ($cart as $opts) {
            if (is_array($opts)) {
                foreach ($opts as $qty) {
                    $count += (int) $qty;
                }
            }
        }
        return $count;
    }

    public function add_to_cart(int $user_id, int $product_id, string $options_string = '', int $count = 1): array {
        if ($user_id <= 0 || $product_id <= 0 || $count <= 0) {
            return ['error' => 'invalid_params'];
        }
        $validation = $this->validate_cart_item($product_id, $options_string);
        if ($validation !== true) {
            return ['error' => $validation];
        }

        $cart = $this->get_cart($user_id);
        $pid_key = (string) $product_id;
        $opt_key = $options_string !== '' ? $options_string : '_default';

        if (!isset($cart[$pid_key]) || !is_array($cart[$pid_key])) {
            $cart[$pid_key] = [];
        }
        $cart[$pid_key][$opt_key] = ((int) ($cart[$pid_key][$opt_key] ?? 0)) + $count;

        // Enforce limit_buy if set
        $limit = (int) get_post_meta($product_id, '_aksrt_limit_buy', true);
        if ($limit > 0 && $cart[$pid_key][$opt_key] > $limit) {
            $cart[$pid_key][$opt_key] = $limit;
        }

        update_user_meta($user_id, 'shop_cart', $cart);
        return ['success' => true, 'cart_count' => $this->get_cart_count($user_id)];
    }

    public function reduce_from_cart(int $user_id, int $product_id, string $options_string = '', int $count = 1): array {
        if ($user_id <= 0 || $product_id <= 0 || $count <= 0) {
            return ['error' => 'invalid_params'];
        }
        $cart = $this->get_cart($user_id);
        $pid_key = (string) $product_id;
        $opt_key = $options_string !== '' ? $options_string : '_default';

        if (isset($cart[$pid_key][$opt_key])) {
            $cart[$pid_key][$opt_key] -= $count;
            if ($cart[$pid_key][$opt_key] <= 0) {
                unset($cart[$pid_key][$opt_key]);
            }
        }
        if (empty($cart[$pid_key])) {
            unset($cart[$pid_key]);
        }

        update_user_meta($user_id, 'shop_cart', $cart);
        return ['success' => true, 'cart_count' => $this->get_cart_count($user_id)];
    }

    public function remove_from_cart(int $user_id, int $product_id, string $options_string = ''): array {
        if ($user_id <= 0) {
            return ['error' => 'invalid_params'];
        }
        $cart = $this->get_cart($user_id);
        $pid_key = (string) $product_id;
        $opt_key = $options_string !== '' ? $options_string : '_default';

        if ($options_string === '' && isset($cart[$pid_key])) {
            // Remove all options for this product
            unset($cart[$pid_key]);
        } elseif (isset($cart[$pid_key][$opt_key])) {
            unset($cart[$pid_key][$opt_key]);
            if (empty($cart[$pid_key])) {
                unset($cart[$pid_key]);
            }
        }

        update_user_meta($user_id, 'shop_cart', $cart);
        return ['success' => true, 'cart_count' => $this->get_cart_count($user_id)];
    }

    public function remove_multi_from_cart(int $user_id, array $items): array {
        if ($user_id <= 0) {
            return ['error' => 'invalid_params'];
        }
        $cart = $this->get_cart($user_id);
        foreach ($items as $item) {
            $pid_key = (string) ($item['product_id'] ?? 0);
            $opt_key = !empty($item['options_string']) ? $item['options_string'] : '_default';
            if (isset($cart[$pid_key][$opt_key])) {
                unset($cart[$pid_key][$opt_key]);
                if (empty($cart[$pid_key])) {
                    unset($cart[$pid_key]);
                }
            }
        }
        update_user_meta($user_id, 'shop_cart', $cart);
        return ['success' => true, 'cart_count' => $this->get_cart_count($user_id)];
    }

    public function empty_cart(int $user_id): array {
        if ($user_id <= 0) {
            return ['error' => 'invalid_params'];
        }
        delete_user_meta($user_id, 'shop_cart');
        return ['success' => true, 'cart_count' => 0];
    }

    /**
     * Validate a product for cart addition.
     * Returns true if valid, or a string error code.
     */
    public function validate_cart_item(int $product_id, string $options_string = '') {
        $post = get_post($product_id);
        if (!$post || $post->post_type !== 'aksrt_product') {
            return 'invalid_product';
        }
        if ($post->post_status !== 'publish') {
            return 'product_not_published';
        }

        // Check stock (unless unlimited)
        $stock = (int) get_post_meta($product_id, '_aksrt_stock', true);
        if ($stock > -1 && $stock <= 0) {
            return 'out_of_stock';
        }

        // Check guest_buy — if disabled and user not logged in
        if (!is_user_logged_in()) {
            $guest = get_post_meta($product_id, '_aksrt_guest_buy', true);
            if ($guest === '0' || $guest === '') {
                // Fall back to inheritance chain via AKSRT_Shop_Term_Meta
                if (class_exists('AKSRT_Shop_Term_Meta')) {
                    $resolved = AKSRT_Shop_Term_Meta::resolve_inheritance($product_id, 'guest_buy');
                    if (empty($resolved)) {
                        return 'login_required';
                    }
                }
            }
        }

        return true;
    }
}