using SVSim.Database.Models;

namespace SVSim.Database.Services;

/// <summary>
/// Centralized debit primitive — the symmetric twin of <c>RewardGrantService.ApplyAsync</c>.
/// Encapsulates the affordability-check + deduction + post-state-total pattern that was inlined
/// across the shop/pack controllers. Does NOT call <c>SaveChangesAsync</c>; the caller saves.
/// Freeplay (for Crystal/Rupee/RedEther) makes spends always succeed without deducting.
/// </summary>
public interface ICurrencySpendService
{
    Task<SpendResult> TrySpendAsync(Viewer viewer, SpendCurrency currency, long cost, CancellationToken ct = default);
}