using SVSim.Database.Models;

namespace SVSim.Database.Services;

public class CurrencySpendService : ICurrencySpendService
{
    private readonly IViewerEntitlements _entitlements;

    public CurrencySpendService(IViewerEntitlements entitlements) => _entitlements = entitlements;

    public Task<SpendResult> TrySpendAsync(Viewer viewer, SpendCurrency currency, long cost, CancellationToken ct = default)
    {
        if (cost < 0) cost = 0;

        // Freeplay bypass applies only to the three main currencies; SpotPoint always real.
        if (_entitlements.IsFreeplay && currency != SpendCurrency.SpotPoint)
        {
            return Task.FromResult(new SpendResult(
                SpendOutcome.Success, _entitlements.EffectiveBalance(viewer, currency)));
        }

        ulong current = GetBalance(viewer, currency);
        if (current < (ulong)cost)
            return Task.FromResult(new SpendResult(SpendOutcome.Insufficient, (long)current));

        ulong post = current - (ulong)cost;
        SetBalance(viewer, currency, post);
        return Task.FromResult(new SpendResult(SpendOutcome.Success, (long)post));
    }

    private static ulong GetBalance(Viewer v, SpendCurrency c) => c switch
    {
        SpendCurrency.Crystal => v.Currency.Crystals,
        SpendCurrency.Rupee => v.Currency.Rupees,
        SpendCurrency.RedEther => v.Currency.RedEther,
        SpendCurrency.SpotPoint => v.Currency.SpotPoints,
        _ => throw new ArgumentOutOfRangeException(nameof(c)),
    };

    private static void SetBalance(Viewer v, SpendCurrency c, ulong value)
    {
        switch (c)
        {
            case SpendCurrency.Crystal: v.Currency.Crystals = value; break;
            case SpendCurrency.Rupee: v.Currency.Rupees = value; break;
            case SpendCurrency.RedEther: v.Currency.RedEther = value; break;
            case SpendCurrency.SpotPoint: v.Currency.SpotPoints = value; break;
            default: throw new ArgumentOutOfRangeException(nameof(c));
        }
    }
}