<?php

declare(strict_types=1);

namespace Mironsoft\Loyalty\ViewModel;

use Magento\Customer\Api\CustomerRepositoryInterface;
use Magento\Customer\Api\Data\CustomerInterface;
use Magento\Customer\Model\Session as CustomerSession;
use Magento\Framework\Exception\LocalizedException;
use Magento\Framework\Exception\NoSuchEntityException;
use Magento\Framework\View\Element\Block\ArgumentInterface;
use Mironsoft\Loyalty\Model\Config\LoyaltyConfig;
use Mironsoft\Loyalty\Model\Util\PointsFormatter;

/**
 * Exposes the logged-in customer's points balance and loyalty tier to the storefront.
 * Deliberately reusable across two independent layout locations (chapter 51's
 * dedicated widget, chapter 52's account dashboard) - a plain PHP object with no
 * Template\Context coupling can be wired into any number of blocks unmodified,
 * exactly the point made in chapter 47.
 */
class PointsBalance implements ArgumentInterface
{
    /**
     * Lazily loaded and cached for the lifetime of this instance, since a template
     * commonly calls several getters (balance, tier, formatted balance) per request.
     *
     * @var CustomerInterface|null
     */
    private ?CustomerInterface $customer = null;

    /**
     * @param CustomerSession $customerSession Provides the logged-in customer ID.
     * @param CustomerRepositoryInterface $customerRepository Loads the customer's custom attributes (chapter 21).
     * @param LoyaltyConfig $loyaltyConfig Confirms the loyalty program is enabled before showing anything.
     */
    public function __construct(
        private readonly CustomerSession $customerSession,
        private readonly CustomerRepositoryInterface $customerRepository,
        private readonly LoyaltyConfig $loyaltyConfig,
    ) {
    }

    /**
     * Whether the balance widget should render at all: the loyalty program must be
     * enabled for the current website (chapter 7) AND the visitor must be logged in.
     *
     * @return bool
     */
    public function canShow(): bool
    {
        return $this->loyaltyConfig->isEnabled() && $this->customerSession->isLoggedIn();
    }

    /**
     * Returns the raw points balance, 0 for a guest or a customer with no history yet.
     *
     * @return int
     */
    public function getPointsBalance(): int
    {
        $attribute = $this->getCustomer()?->getCustomAttribute('loyalty_points_balance');

        return $attribute !== null ? (int) $attribute->getValue() : 0;
    }

    /**
     * Returns the points balance formatted with a thousands separator, e.g. "1,250".
     *
     * @return string
     */
    public function getFormattedPointsBalance(): string
    {
        return PointsFormatter::formatPoints($this->getPointsBalance());
    }

    /**
     * Returns the customer's current loyalty tier, defaulting to bronze if unset.
     *
     * @return string
     */
    public function getTier(): string
    {
        $attribute = $this->getCustomer()?->getCustomAttribute('loyalty_tier');

        return $attribute !== null ? (string) $attribute->getValue() : 'bronze';
    }

    /**
     * Loads and caches the current customer via the repository - never via
     * CustomerSession::getCustomer(), which returns a legacy \Magento\Customer\Model\Customer
     * instance whose getData()/setData() cannot reliably see EAV custom attributes
     * (chapter 30 explains getCustomAttribute() vs. getData() in full).
     *
     * @return CustomerInterface|null Null for a guest or if the customer record vanished mid-session.
     */
    private function getCustomer(): ?CustomerInterface
    {
        if ($this->customer !== null) {
            return $this->customer;
        }

        if (!$this->customerSession->isLoggedIn()) {
            return null;
        }

        try {
            $this->customer = $this->customerRepository->getById(
                (int) $this->customerSession->getCustomerId()
            );
        } catch (NoSuchEntityException|LocalizedException) {
            return null;
        }

        return $this->customer;
    }
}