// With Unity IAP, present when com.unity.purchasing is installed:
if (BestBridgeStoreUtilityIAP.IsStoreInRuRegion(product)) { /* route through BestBridge */ }

// Or pass the ISO currency code directly:
if (BestBridgeStoreUtility.IsStoreInRuRegion("RUB")) { /* route through BestBridge */ }

using BestBridge.Payments;

var config = new BestBridgeConfig(
    apiKey:   "your-project-api-key",
    isDevBuild: Debug.isDebugBuild,          // selects the built-in development / production environment
    identities: IdentitiesListCreator.Create(
        new DeviceIdIdentityProvider()
        // , new GooglePlayIdentityProvider(googlePlayId)  // a custom IIdentityProvider
    ));

var products = new[]
{
    new BestBridgeProduct("coins_small", "sku_coins_500",  BestBridgeProductType.Consumable),
    new BestBridgeProduct("remove_ads",  "sku_remove_ads", BestBridgeProductType.NonConsumable),
    new BestBridgeProduct("premium",     "sku_premium_1m", BestBridgeProductType.Subscription),
};

public class GamePurchaseListener : IBestBridgePurchaseListener
{
    public async Task<bool> OnPurchase(BestBridgePurchaseInfo purchase)
    {
        // _wallet, _ui and _profile belong to the game, not to the SDK:
        //   _wallet.Grant           — adds the product to the player's inventory or balance
        //   _ui.PlayPurchaseCelebration — plays the "purchase successful" animation
        //   _profile.Save           — writes the player profile to disk / cloud, true when it persisted
        _wallet.Grant(purchase.Product, purchase.Quantity);   // × Quantity — multi-buy!
        if (!purchase.IsRestored)
            _ui.PlayPurchaseCelebration(purchase.Product);    // skip celebration on restores

        bool saved = await _profile.Save();
        return saved;                                         // false → SDK retries later
    }
}

IBestBridgePaymentsService service = new BestBridgePaymentsService(
    products,
    new GamePurchaseListener(),
    popupController,      // the game's IBestBridgePopupController implementation; required, non-null
    config);

BestBridgeInitializationStatus status = await service.Initialize();
if (status.IsSuccess)             Debug.Log("BestBridge ready");
else if (status.IsConnectionError) Debug.LogWarning("No connection — the SDK will retry itself");
else if (status.IsCancelled)       Debug.Log("Initialization cancelled");
else                               Debug.LogError(status.Exception);

service.OnInitialized += status => { if (status.IsSuccess) Debug.Log("ready"); };
service.Initialize().Forget();

var result = await service.Purchase("coins_small");                 // one unit
var result = await service.Purchase("coins_small", quantity: 3);    // preselect x3

// RedrawShop() is a method of the game, not of the SDK: it repaints the shop screen
// (prices, "owned" marks, currency counter) after the balance changed.
if (result.IsDelivered) RedrawShop();   // the SDK has already told the player the outcome

// MarkOwnedInShop() is a method of the game, not of the SDK: it switches the shop item
// to the "owned" look — no price, no buy button.
if (service.IsNonConsumablePurchased("remove_ads")) MarkOwnedInShop();

// button, label, dateRow and warningRow are the game's own UI objects on the subscription
// screen; LabelFor() is the game's own method that turns an action kind into localized text.
var action = service.GetSubscriptionAction("premium");

button.interactable = action.IsEnabled;
label.text          = LabelFor(action.Kind);          // e.g. Subscribe → "Подписаться"
dateRow.SetActive(action.ShowsExpiration);            // render action.Data.ExpirationDate
warningRow.SetActive(action.HasPaymentProblem);

button.onClick.AddListener(async () => await service.InvokeSubscriptionActionAsync("premium"));

// Every Show*() below is a method of the game, not of the SDK: each one puts the subscription
// screen into one visual state (subscribe button, unsubscribe button with the next charge date,
// "active until <date>", resume button, payment-problem notice, loading spinner).
switch (service.GetSubscriptionState("premium", out var sub))
{
    case BestBridgeSubscriptionState.NotSubscribed:          ShowSubscribeButton();                      break;
    case BestBridgeSubscriptionState.Active:                 ShowUnsubscribeButton(sub.NextBillingDate); break;
    case BestBridgeSubscriptionState.CanceledUntilPeriodEnd: ShowActiveUntil(sub.ExpirationDate);        break;
    case BestBridgeSubscriptionState.Paused:                 ShowResumeButton();                         break;
    case BestBridgeSubscriptionState.Grace:                  ShowPaymentProblem(sub.ExpirationDate);     break;
    default:                                                 ShowSpinner();                              break;  // keep this
}

// Redraw() is the game's own method: it re-reads GetSubscriptionAction / GetSubscriptionState
// and rebuilds the whole subscription screen from what it finds.
private void OnEnable()
{
    _service.OnSubscriptionsChanged += Redraw;
    Redraw();                     // cached state, drawn without waiting for the network
    RefreshAsync().Forget();      // BestBridgeTaskExtensions.Forget()
}

private void OnDisable() => _service.OnSubscriptionsChanged -= Redraw;

private async Task RefreshAsync()
{
    await _service.RefreshSubscriptionStatusAsync();
    Redraw();
}

IReadOnlyList<BestBridgeProductInfo> catalog = await service.GetProductsAsync();  // no auth needed

BestBridgeProductInfo info = service.GetProductInfo("coins_small");
string price = service.GetLocalizedItemPrice("coins_small");   // "" if not cached yet

await service.RestorePurchases(showPopupOnResult: true);

await service.TryProcessUnfinishedPurchaseAsync();   // true if at least one product was delivered

// settingsUserIdLabel is the game's own UI label on the settings screen, not part of the SDK.
settingsUserIdLabel.text = $"User ID: {service.UserId}";   // add a copy button next to it

public sealed class MyTexts : BestBridgeMessagesDefaults
{
    public override string PurchaseSuccess   => "Спасибо за покупку!";
    public override string ConnectionProblem => "Нет соединения";
}

var service = new BestBridgePaymentsService(products, listener, popupController, config, new MyTexts());