using Steamworks;

namespace ytLive.Services.Entitlement;

/// <summary>
/// Reads ownership of the paid app from Steam. In the free Demo, this checks the associated paid
/// app ID; no key, server, or LlamaCasty account is involved. A missing ID, Steam client, or native
/// library fails closed so the app can continue with the free output profile.
/// </summary>
public sealed class SteamEntitlement : IEntitlement
{
    private readonly uint _paidAppId;
    private readonly Func<bool> _initializeSteam;
    private readonly Func<uint, bool> _isAppSubscribed;
    private readonly Action _shutdownSteam;

    private bool _initAttempted;
    private bool _available;
    private bool? _cached;
    private string? _errorMessage;

    public SteamEntitlement(uint paidAppId)
        : this(
            paidAppId,
            SteamAPI.Init,
            appId => SteamApps.BIsSubscribedApp(new AppId_t(appId)),
            SteamAPI.Shutdown)
    {
    }

    internal SteamEntitlement(
        uint paidAppId,
        Func<bool> initializeSteam,
        Func<uint, bool> isAppSubscribed,
        Action shutdownSteam)
    {
        _paidAppId = paidAppId;
        _initializeSteam = initializeSteam;
        _isAppSubscribed = isAppSubscribed;
        _shutdownSteam = shutdownSteam;
    }

    /// <summary>Configured with no paid app ID; ownership fails closed without touching Steam.</summary>
    public static SteamEntitlement NotConfigured() => new(0);

    public string? ErrorMessage => _errorMessage;

    public bool IsAppOwned
    {
        get
        {
            if (_paidAppId == 0)
            {
                _cached = false;
                _errorMessage = "Steam licensing is not configured in this build.";
                return false;
            }
            if (_cached is { } known) return known;

            if (!_initAttempted)
            {
                _initAttempted = true;
                try
                {
                    _available = _initializeSteam();
                }
                catch (Exception ex)
                {
                    _available = false;
                    _errorMessage = $"Steam could not start ({ex.Message}). Open Steam, sign in, then restart LlamaCasty.";
                }
            }

            if (!_available)
            {
                _cached = false;
                _errorMessage ??= "Steam could not verify ownership. Open Steam, sign in, then restart LlamaCasty.";
                return false;
            }

            try
            {
                var owned = _isAppSubscribed(_paidAppId);
                _cached = owned;
                _errorMessage = null;
                return owned;
            }
            catch (Exception ex)
            {
                _cached = false;
                _errorMessage = $"Steam could not check ownership ({ex.Message}). Open Steam, sign in, then restart LlamaCasty.";
                return false;
            }
        }
    }

    public void Shutdown()
    {
        if (_available) _shutdownSteam();
        _available = false;
        _cached = null;
        _initAttempted = false;
        _errorMessage = null;
    }
}