ersatztv/ErsatzTV.Core/FFmpeg/TempFilePool.cs

using System.Collections.Generic;
using System.IO;
using ErsatzTV.Core.Interfaces.FFmpeg;

namespace ErsatzTV.Core.FFmpeg
{
    public class TempFilePool : ITempFilePool
    {
        private const int ItemLimit = 10;
        private readonly Dictionary<TempFileCategory, int> _state = new();
        private readonly object _lock = new();

        public string GetNextTempFile(TempFileCategory category)
        {
            lock (_lock)
            {
                var index = 0;

                if (_state.TryGetValue(category, out int current))
                {
                    index = (current + 1) % ItemLimit;
                }

                _state[category] = index;

                return GetFileName(category, index);
            }
        }

        private static string GetFileName(TempFileCategory category, int index)
        {
            return Path.Combine(FileSystemLayout.TempFilePoolFolder, $"{category}_{index}".ToLowerInvariant());
        }
    }
}