using Vanguard.Rules.Engine;

namespace Vanguard.Rules.Replay;

/// <summary>FNV-1a по тексту событий. Не криптография, а быстрая проверка расхождений.</summary>
public static class EventHasher
{
    private const ulong Offset = 14695981039346656037UL;
    private const ulong Prime = 1099511628211UL;

    public static string Hash(IEnumerable<GameEvent> events)
    {
        unchecked
        {
            var hash = Offset;

            foreach (var gameEvent in events)
            {
                foreach (var ch in gameEvent.ToString() ?? string.Empty)
                {
                    hash ^= ch;
                    hash *= Prime;
                }

                hash ^= '\n';
                hash *= Prime;
            }

            return hash.ToString("x16");
        }
    }
}