<?php

namespace Modules\Core\Payment\Support;

use Lunar\Models\Contracts\Currency as CurrencyContract;
use Stripe\Charge;
use Stripe\StripeClient;

/**
 * First-party replacement for Lunar\Stripe\Facades\Stripe +
 * Lunar\Stripe\Managers\StripeManager — lunarphp/stripe was removed once
 * Modules\Core\Payment\Drivers\StripePaymentDriver already replaced every
 * bit of Lunar's own Stripe payment flow (see that class's own docblock);
 * all that remained load-bearing from the package was raw API-client
 * access and amount conversion, neither of which is Lunar-specific. Only
 * the methods StripePaymentDriver actually called are kept — no
 * fetchOrCreateIntent()/cart-bound helpers, which belonged to Lunar's own
 * (unused) checkout flow.
 *
 * getClient()/getCharge() call the Stripe SDK directly rather than going
 * through a facade — StripePaymentDriver resolves this class via the
 * container instead, same as every other dependency it takes.
 */
class StripeManager
{
    public function getClient(): StripeClient
    {
        return new StripeClient([
            'api_key' => config('services.stripe.key'),
        ]);
    }

    public function getCharge(string $chargeId): Charge
    {
        return $this->getClient()->charges->retrieve($chargeId);
    }

    /**
     * Zero-decimal currencies, per Stripe. The amount sent to Stripe is the
     * major unit amount as-is.
     *
     * @see https://docs.stripe.com/currencies#zero-decimal
     */
    protected const ZERO_DECIMAL_CURRENCIES = [
        'bif', 'clp', 'djf', 'gnf', 'jpy', 'kmf', 'krw', 'mga', 'pyg',
        'rwf', 'ugx', 'vnd', 'vuv', 'xaf', 'xof', 'xpf',
    ];

    /**
     * Three-decimal currencies, per Stripe. The amount sent to Stripe is the
     * major unit amount multiplied by 1000.
     *
     * @see https://docs.stripe.com/currencies#three-decimal
     */
    protected const THREE_DECIMAL_CURRENCIES = ['bhd', 'jod', 'kwd', 'omr', 'tnd'];

    /**
     * HUF, TWD and UGX are ISO zero-decimal currencies, but Stripe still
     * requires amounts to be sent as if they had two decimal places.
     *
     * @see https://docs.stripe.com/currencies#special-cases
     */
    protected const SPECIAL_ZERO_DECIMAL_CURRENCIES = ['huf', 'twd', 'ugx'];

    /**
     * Convert a Lunar price value to the amount expected by Stripe.
     *
     * Lunar stores prices as integers scaled by `Currency::decimal_places`,
     * which merchants can set independently of what Stripe expects for a
     * given currency. This converts back to the major unit amount first,
     * then re-scales it to whatever sub-unit Stripe requires for the
     * currency, so the result is correct regardless of how the merchant has
     * configured `Currency::decimal_places`.
     *
     * @see https://docs.stripe.com/currencies
     */
    public static function toStripeAmount(int $value, CurrencyContract $currency): int
    {
        return self::rescale($value, max($currency->decimal_places, 0), self::stripeDecimalPlaces($currency));
    }

    /**
     * Convert an amount received from Stripe back to a Lunar price value,
     * scaled by `Currency::decimal_places`. Inverse of `toStripeAmount()`.
     */
    public static function fromStripeAmount(int $amount, CurrencyContract $currency): int
    {
        return self::rescale($amount, self::stripeDecimalPlaces($currency), max($currency->decimal_places, 0));
    }

    /**
     * The number of decimal places Stripe expects amounts in for a currency.
     */
    protected static function stripeDecimalPlaces(CurrencyContract $currency): int
    {
        $code = strtolower($currency->code);

        // UGX is also in the zero-decimal list; the special case takes precedence.
        if (in_array($code, self::SPECIAL_ZERO_DECIMAL_CURRENCIES, true)) {
            return 2;
        }

        if (in_array($code, self::ZERO_DECIMAL_CURRENCIES, true)) {
            return 0;
        }

        if (in_array($code, self::THREE_DECIMAL_CURRENCIES, true)) {
            return 3;
        }

        return 2;
    }

    protected static function rescale(int $value, int $fromDecimalPlaces, int $toDecimalPlaces): int
    {
        $exponent = $toDecimalPlaces - $fromDecimalPlaces;

        if ($exponent >= 0) {
            return $value * (10 ** $exponent);
        }

        $divisor = 10 ** (-$exponent);

        return intdiv(abs($value) + intdiv($divisor, 2), $divisor) * ($value < 0 ? -1 : 1);
    }
}