namespace OpenAC.MosswartMassacre.Sharing;

/// <summary>One character heard from through the backend.</summary>
internal sealed class Peer
{
    public Peer(string characterName)
    {
        CharacterName = characterName;
    }

    public string CharacterName { get; }

    public uint PlayerId { get; set; }

    public int CurrentHealth { get; set; }

    public int MaxHealth { get; set; }

    public int CurrentStamina { get; set; }

    public int MaxStamina { get; set; }

    public int CurrentMana { get; set; }

    public int MaxMana { get; set; }

    public double EW { get; set; }

    public double NS { get; set; }

    /// <summary>Height in metres.</summary>
    public double Z { get; set; }

    public double Heading { get; set; }

    public bool HasPosition { get; set; }

    public IReadOnlyList<string> Tags { get; set; } = [];

    public DateTime LastUpdateUtc { get; set; }
}

/// <summary>
/// The peers heard from, by name. A peer not heard from for fifteen seconds
/// drops out, the rule the host applies to its own peers; the original kept
/// logged-off peers forever.
/// </summary>
internal sealed class PeerTable
{
    public static readonly TimeSpan Staleness = TimeSpan.FromSeconds(15);

    private readonly Dictionary<string, Peer> _peers = new(StringComparer.OrdinalIgnoreCase);

    public Peer Upsert(string name, DateTime nowUtc)
    {
        if (!_peers.TryGetValue(name, out Peer? peer))
        {
            peer = new Peer(name);
            _peers[name] = peer;
        }
        peer.LastUpdateUtc = nowUtc;
        return peer;
    }

    public bool TryGet(string name, out Peer? peer) => _peers.TryGetValue(name, out peer);

    /// <summary>The peers heard from within the last fifteen seconds, by name.</summary>
    public IReadOnlyList<Peer> Current(DateTime nowUtc)
    {
        foreach (string stale in _peers.Values
                     .Where(peer => nowUtc - peer.LastUpdateUtc > Staleness)
                     .Select(peer => peer.CharacterName)
                     .ToList())
        {
            _peers.Remove(stale);
        }
        return [.. _peers.Values.OrderBy(peer => peer.CharacterName, StringComparer.OrdinalIgnoreCase)];
    }

    public void Clear() => _peers.Clear();
}