PiwigoDirectorySync/PiwigoDirectorySync/Commands/Scan/FileSystemScanner.cs

using System.Threading.Channels;
using NLog;
using PiwigoDirectorySync.Persistence;

namespace PiwigoDirectorySync.Commands.Scan;

public class FileSystemScanner
{
    private static readonly ILogger Logger = LogManager.GetCurrentClassLogger();

    private readonly Channel<string> _fileQueue;
    private readonly int _piwigoServerId;

    public FileSystemScanner(Channel<string> fileQueue, int piwigoServerId)
    {
        _fileQueue = fileQueue ?? throw new ArgumentNullException(nameof(fileQueue));
        _piwigoServerId = piwigoServerId;
    }

    public async Task ScanAsync(CancellationToken ct)
    {
        await using var db = new PersistenceContext();

        var piwigoServer = await db.PiwigoServers.GetByIdAsync(_piwigoServerId, ct);
        Logger.Info($"Scanning files for piwigo server {piwigoServer.Name} in directory {piwigoServer.RootDirectory}");

        await ScanRootDirectory(new DirectoryInfo(piwigoServer.RootDirectory), ct);
    }

    private async ValueTask ScanRootDirectory(DirectoryInfo directory, CancellationToken ct)
    {
        Logger.Info($"Scanning root directory {directory.FullName} for sidecars to delete");
        var parallelOptions = new ParallelOptions
        {
            CancellationToken = ct
        };
        await Parallel.ForEachAsync(GetDirectories(directory), parallelOptions, FindAndEnqueueFilesToAdd);
    }

    private async ValueTask FindAndEnqueueFilesToAdd(DirectoryInfo directory, CancellationToken ct)
    {
        try
        {
            Logger.Info($"Scanning directory {directory.FullName} for images");

            var imageFiles = AppSettings.SupportedExtensions.SelectMany(ext => directory.GetFiles($"*.{ext}", SearchOption.TopDirectoryOnly))
                .Select(f => f.FullName)
                .ToHashSet(StringComparer.OrdinalIgnoreCase);

            if (!imageFiles.Any())
            {
                Logger.Debug($"No iamges in {directory.FullName} found, skipping");
                return;
            }

            foreach (var imageFile in imageFiles.Select(f => new FileInfo(f)))
            {
                Logger.Debug($"Found image {imageFile.FullName}, enqueue index");
                await _fileQueue.Writer.WriteAsync(imageFile.FullName, ct);
            }
        }
        catch (Exception ex)
        {
            Logger.Error(ex, $"could not scan directory {directory.FullName}");
        }
    }

    private static IEnumerable<DirectoryInfo> GetDirectories(DirectoryInfo directoryInfo)
    {
        yield return directoryInfo;
        foreach (var directory in directoryInfo.EnumerateDirectories().SelectMany(GetDirectories))
        {
            yield return directory;
        }
    }
}