DocumentFileConverterSelector.cs

namespace Vereinsmeisterschaften.Core.Documents.DocumentFileConverters
{
    public sealed class DocumentFileConverterSelector : IDocumentFileConverterSelector
    {
        private readonly IReadOnlyList<IDocumentFileConverter> _converters;

        public DocumentFileConverterSelector(IEnumerable<IDocumentFileConverter> converters)
        {
            _converters = converters.ToList();
        }

        public IDocumentFileConverter GetConverter(string docxFile, List<IDocumentFileConverter> ignoreConverters)
        {
            // Create a list with all useable converters (not in ignore list and available)
            List<IDocumentFileConverter> useableConverterList = _converters.Except(ignoreConverters).Where(c => c.IsAvailable).ToList();
 
            // Choose the preferred converter (available and the first one that states that the document was created with this converter)
            IDocumentFileConverter preferred = useableConverterList.FirstOrDefault(c => c.IsDocxCreateWithThisConverter(docxFile));
            if (preferred != null)
            {
                return preferred;
            }
 
            // Fallback: use first available converter
            IDocumentFileConverter fallback = useableConverterList.FirstOrDefault();
            if (fallback != null)
            {
                return fallback;
            }
            return null;
        }
    }
}