using System.Collections.Concurrent;
using NATS.Server.Subscriptions;

namespace NATS.Server.Auth;

public sealed class Account : IDisposable
{
    public const string GlobalAccountName = "$G";

    public string Name { get; }
    public SubList SubList { get; } = new();
    public Permissions? DefaultPermissions { get; set; }
    public int MaxConnections { get; set; } // 0 = unlimited
    public int MaxSubscriptions { get; set; } // 0 = unlimited

    private readonly ConcurrentDictionary<ulong, byte> _clients = new();
    private int _subscriptionCount;

    public Account(string name)
    {
        Name = name;
    }

    public int ClientCount => _clients.Count;
    public int SubscriptionCount => Volatile.Read(ref _subscriptionCount);

    /// <summary>Returns false if max connections exceeded.</summary>
    public bool AddClient(ulong clientId)
    {
        if (MaxConnections > 0 && _clients.Count >= MaxConnections)
            return false;
        _clients[clientId] = 0;
        return true;
    }

    public void RemoveClient(ulong clientId) => _clients.TryRemove(clientId, out _);

    public bool IncrementSubscriptions()
    {
        if (MaxSubscriptions > 0 && Volatile.Read(ref _subscriptionCount) >= MaxSubscriptions)
            return false;
        Interlocked.Increment(ref _subscriptionCount);
        return true;
    }

    public void DecrementSubscriptions()
    {
        Interlocked.Decrement(ref _subscriptionCount);
    }

    public void Dispose() => SubList.Dispose();
}