initial commit

.gitignore

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+.vs
+bin
+obj

Checksum-Test.csproj

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+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net8.0</TargetFramework>
+    <RootNamespace>Checksum_Test</RootNamespace>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.Extensions.Hosting" Version="8.0.0" />
+  </ItemGroup>
+
+</Project>

Checksum-Test.sln

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+
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio Version 17
+VisualStudioVersion = 17.8.34330.188
+MinimumVisualStudioVersion = 10.0.40219.1
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Checksum-Test", "Checksum-Test.csproj", "{C2F5F38A-AD77-4A0E-8910-FF27863EE1D7}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|Any CPU = Debug|Any CPU
+		Release|Any CPU = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{C2F5F38A-AD77-4A0E-8910-FF27863EE1D7}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{C2F5F38A-AD77-4A0E-8910-FF27863EE1D7}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{C2F5F38A-AD77-4A0E-8910-FF27863EE1D7}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{C2F5F38A-AD77-4A0E-8910-FF27863EE1D7}.Release|Any CPU.Build.0 = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(SolutionProperties) = preSolution
+		HideSolutionNode = FALSE
+	EndGlobalSection
+	GlobalSection(ExtensibilityGlobals) = postSolution
+		SolutionGuid = {2EC0A183-6281-44F1-A6DF-0365CB5EDD2C}
+	EndGlobalSection
+EndGlobal

ChecksumWorker.cs

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+// 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;
+        }
+    }
+}

Program.cs

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+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Hosting;
+
+
+
+var host = Host.CreateApplicationBuilder(args);
+var services = host.Services;
+var configuration = host.Configuration;
+
+services.Configure<ChecksumWorkerConfig>(configuration.GetSection("ChecksumWorker"));
+services.AddHostedService<ChecksumWorker>();
+
+var app = host.Build();
+
+await app.RunAsync();

Properties/launchSettings.json

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+{
+  "profiles": {
+    "Checksum-Test": {
+      "commandName": "Project",
+      "commandLineArgs": "/ChecksumWorker:Directory=C:\\Users\\stefan.atzlesberger\\Downloads /ChecksumWorker:Extension=*.ifc"
+    }
+  }
+}