initial commit

ChecksumWorker.cs

@@ -0,0 +1,83 @@
+// See https://aka.ms/new-console-template for more information
+using Microsoft.Extensions.Hosting;
+using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Options;
+using System.Diagnostics.CodeAnalysis;
+using System.Security.Cryptography;
+
+internal class ChecksumWorkerConfig
+{
+    public string Directory {
+        get; set;
+    } = ".";
+
+    public string Extension {
+        get; set;
+    } = "*";
+}
+
+internal class ChecksumWorker : BackgroundService
+{
+    private readonly SHA512 SHA = SHA512.Create();
+    private readonly ChecksumWorkerConfig _config;
+    private readonly ILogger<ChecksumWorker> _classLogger;
+
+    public ChecksumWorker(IOptions<ChecksumWorkerConfig> options, ILogger<ChecksumWorker> classLogger)
+    {
+        _config = options.Value;
+        _classLogger = classLogger;
+    }
+
+    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
+    {
+        var dateTime = DateTime.Now;
+        var directory = _config.Directory;
+        var extension = _config.Extension;
+        if (Directory.Exists(directory) == false) {
+            _classLogger.LogError($"Directory {directory} does not exist");
+            return;
+        }
+
+        _classLogger.LogInformation($"Watch in: {directory}");
+        _classLogger.LogInformation($"Watch for: {extension}");
+
+        while (stoppingToken.IsCancellationRequested == false) {
+            var items = Directory.GetFiles(directory, extension)
+                .Select(file => new {
+                    time = File.GetLastWriteTime(file),
+                    file = file,
+                })
+                .Where(x => x.time > dateTime)
+                .OrderBy(x => x.time);
+            foreach (var item in items) {
+                var fileTime = item.time;
+                if (fileTime > dateTime) {
+                    if (await TryCalculateChecksumAsync(item.file) is { } checksum) {
+                        _classLogger.LogInformation($"File {item.file} has changed {checksum}", checksum);
+                    }
+                    else {
+                        break; // try again later
+                    }
+                }
+
+                dateTime = fileTime;
+            }
+
+            await Task.Delay(1000, stoppingToken);
+        }
+    }
+
+    private async Task<string?> TryCalculateChecksumAsync(string file)
+    {
+        try {
+            using (var fs = File.Open(file, FileMode.Open, FileAccess.Read, FileShare.Read)) {
+                var checksum = await SHA.ComputeHashAsync(fs);
+
+                return Convert.ToBase64String(checksum);
+            }
+        }
+        catch {
+            return default;
+        }
+    }
+}