<?php
namespace ToDownload\Cart;

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

use ToDownload\Support\Arr;
use ToDownload\Sellers\Sellers;

final class Cart {
    private static ?Cart $instance = null;

    const COOKIE = 'ToDownload_cart_v1';
    const USER_META = 'ToDownload_cart_v1';

    public static function instance(): Cart {
        if (!self::$instance) {
            self::$instance = new Cart();
        }
        return self::$instance;
    }

    private function __construct() {
        add_action('init', [$this, 'maybe_load']);
    }

    private array $items = [];

    private function get_item_price(int $download_id, ?int $price_id = null): float {
        $tiers = get_post_meta($download_id, '_ToDownload_variable_prices', true);
        if (is_array($tiers) && $price_id !== null && isset($tiers[$price_id]) && is_array($tiers[$price_id])) {
            $amount = (float) ($tiers[$price_id]['amount'] ?? 0);
            return max(0.0, $amount);
        }

        return max(0.0, (float) get_post_meta($download_id, '_ToDownload_price', true));
    }

    public function maybe_load(): void {
        $this->items = $this->read_storage();
    }

    public function all(): array {
        return $this->items;
    }

    public function add(int $download_id, array $options = []): void {
        // Quantity capped at 1 for now
        $price_id = isset($options['price_id']) ? (int) $options['price_id'] : null;
        $price = $this->get_item_price($download_id, $price_id);
        $this->items[(string)$download_id] = [
            'download_id' => $download_id,
            'qty' => 1,
            'price_id' => $price_id,
            'price' => $price,
        ];
        $this->write_storage();
        do_action('ToDownload_cart_item_added', $download_id, $this->items);
    }

    public function remove(int $download_id): void {
        unset($this->items[(string)$download_id]);
        $this->write_storage();
        do_action('ToDownload_cart_item_removed', $download_id, $this->items);
    }

    public function clear(): void {
        $this->items = [];
        $this->write_storage();
        do_action('ToDownload_cart_cleared');
    }

    public function subtotal(): float {
        $sum = 0.0;
        foreach ($this->items as $it) {
            $price = isset($it['price']) ? (float) $it['price'] : 0.0;
            $sum += max(0.0, $price);
        }
        return (float) apply_filters('ToDownload_cart_subtotal', $sum, $this->items);
    }

    public function tax(): float {
        // v1: global tax with optional seller-level override (single-seller checkout)
        $settings = get_option('ToDownload_settings', []);
        $enabled = is_array($settings) && !empty($settings['enable_tax']);
        $rate = is_array($settings) ? (float) ($settings['tax_percent'] ?? 0) : 0.0;
        $rate = max(0.0, min(100.0, $rate));

        $seller_user_id = $this->get_single_seller_user_id_from_cart();
        if ($seller_user_id > 0) {
            $seller_enabled = Sellers::seller_tax_enabled($seller_user_id);
            $seller_rate = Sellers::seller_tax_percent($seller_user_id);
            if ($seller_enabled !== null) {
                $enabled = $seller_enabled;
            }
            if ($seller_rate !== null) {
                $rate = $seller_rate;
            }
        }

        $tax = 0.0;
        if ($enabled && $rate > 0) {
            $tax = $this->subtotal() * ($rate / 100.0);
            $tax = (float) round($tax, 2);
        }
        return (float) apply_filters('ToDownload_cart_tax', $tax, $this->items);
    }

    private function get_single_seller_user_id_from_cart(): int {
        $seller_user_id = 0;
        foreach ($this->items as $it) {
            $download_id = (int) ($it['download_id'] ?? 0);
            if ($download_id <= 0) {
                continue;
            }
            $author_id = (int) get_post_field('post_author', $download_id);
            if ($author_id <= 0) {
                continue;
            }
            if ($seller_user_id === 0) {
                $seller_user_id = $author_id;
                continue;
            }
            if ($seller_user_id !== $author_id) {
                // Multi-seller carts are blocked elsewhere in v1; treat as no override.
                return 0;
            }
        }
        return $seller_user_id;
    }

    public function discount(): float {
        $discount = 0.0;
        return (float) apply_filters('ToDownload_cart_discount', $discount, $this->items);
    }

    public function total(): float {
        $total = max(0.0, $this->subtotal() + $this->tax() - $this->discount());
        return (float) apply_filters('ToDownload_cart_total', $total, $this->items);
    }

    private function read_storage(): array {
        $user_id = is_user_logged_in() ? (int) get_current_user_id() : 0;
        if ($user_id > 0) {
            $raw = get_user_meta($user_id, self::USER_META, true);
            if (is_array($raw) && !empty($raw)) {
                return $raw;
            }
        }

        if (!empty($_COOKIE[self::COOKIE])) {
            $json = sanitize_text_field(wp_unslash((string) $_COOKIE[self::COOKIE]));
            $data = json_decode($json, true);
            if (is_array($data)) {
                // If the user is logged in but meta is empty/unset, hydrate it from cookie.
                if ($user_id > 0) {
                    update_user_meta($user_id, self::USER_META, $data);
                }
                return $data;
            }
        }
        return [];
    }

    private function write_storage(): void {
        $payload = wp_json_encode($this->items);

        // Cookie for guests and as a fallback
        $cookie_args = [
            'expires' => time() + DAY_IN_SECONDS * 7,
            'path' => COOKIEPATH ?: '/',
            'secure' => is_ssl(),
            'httponly' => true,
            'samesite' => 'Lax',
        ];

        // Prefer a host-scoped cookie to avoid cross-tenant bleed and misconfigured COOKIE_DOMAIN.
        $host = (string) (wp_parse_url(home_url('/'), PHP_URL_HOST) ?? '');
        $host = strtolower(trim($host));
        if ($host !== '') {
            $cookie_args['domain'] = $host;
        }

        setcookie(self::COOKIE, $payload, $cookie_args);
        $_COOKIE[self::COOKIE] = $payload;

        if (is_user_logged_in()) {
            update_user_meta(get_current_user_id(), self::USER_META, $this->items);
        }
    }
}