namespace Explorer.Analysis;

internal sealed class AnalysisResultCache
{
    private const int MaxEntries = 32;
    private static readonly TimeSpan Ttl = TimeSpan.FromSeconds(20);

    private readonly object _gate = new();
    private readonly Dictionary<string, Entry> _items = new(StringComparer.Ordinal);

    public bool TryGet<T>(string key, long stamp, out T value)
    {
        lock (_gate)
        {
            if (_items.TryGetValue(key, out var entry)
                && entry.Stamp == stamp
                && entry.Utc + Ttl > DateTime.UtcNow
                && entry.Value is T typed)
            {
                value = typed;
                return true;
            }
        }

        value = default!;
        return false;
    }

    public void Set<T>(string key, long stamp, T value)
    {
        lock (_gate)
        {
            _items[key] = new Entry(stamp, value!, DateTime.UtcNow);
            if (_items.Count <= MaxEntries)
            {
                return;
            }

            var oldest = _items.OrderBy(p => p.Value.Utc).First().Key;
            _items.Remove(oldest);
        }
    }

    private readonly record struct Entry(long Stamp, object Value, DateTime Utc);
}