<?php

/**
 * Applies the affiliate's coupon to the cart, off the referral link.
 */

namespace Afileasy\WooCommerce;

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

/**
 * The tracking script stores the coupon the affiliate's link should apply in
 * the `afileasy_coupon` cookie, next to the referral. Reading it server-side
 * works the same for classic and block checkout, exactly like Attribution does
 * with `afileasy_ref`.
 *
 * WooCommerce cannot hold a coupon without a cart, so the code is applied when
 * totals are calculated rather than on the landing page. Three rules keep it
 * out of the shopper's way:
 *
 *  - a coupon the shopper applied themselves always wins;
 *  - each code is tried once per session, so removing it makes it stay removed
 *    and a code the cart does not qualify for is not retried on every render;
 *  - a code that does not exist in this store is skipped — coupons created
 *    before the integration was connected only exist here after the merchant
 *    syncs them from Afileasy.
 */
class Coupons
{
    private const COOKIE = 'afileasy_coupon';

    private const SESSION_KEY = 'afileasy_coupon_tried';

    /** Guards against the recursion of applying a coupon while totals run. */
    private bool $applying = false;

    public function register(): void
    {
        add_action('woocommerce_before_calculate_totals', [$this, 'maybeApply'], 10, 0);
    }

    public function maybeApply(): void
    {
        if ($this->applying || Connection::get() === null) {
            return;
        }

        if (is_admin() && ! wp_doing_ajax()) {
            return;
        }

        $code = $this->cookieCode();
        if ($code === null) {
            return;
        }

        $cart = function_exists('WC') && WC()->cart ? WC()->cart : null;
        if (! $cart || $cart->is_empty() || $cart->get_applied_coupons()) {
            return;
        }

        if ($this->alreadyTried($code)) {
            return;
        }

        $this->markTried($code);

        if (! wc_get_coupon_id_by_code($code)) {
            return;
        }

        $this->applying = true;
        $cart->apply_coupon($code);
        $this->applying = false;
    }

    private function cookieCode(): ?string
    {
        $raw = isset($_COOKIE[self::COOKIE]) ? sanitize_text_field(wp_unslash($_COOKIE[self::COOKIE])) : '';

        return $raw === '' ? null : wc_format_coupon_code($raw);
    }

    private function alreadyTried(string $code): bool
    {
        $session = function_exists('WC') && WC()->session ? WC()->session : null;

        return $session ? $session->get(self::SESSION_KEY) === $code : false;
    }

    private function markTried(string $code): void
    {
        $session = function_exists('WC') && WC()->session ? WC()->session : null;

        if ($session) {
            $session->set(self::SESSION_KEY, $code);
        }
    }
}