Provide a prev command to quickly swap between versions

Author: simshaun

NodeSwap/Commands/PrevCommand.cs

@@ -0,0 +1,35 @@
+using System;
+using DotMake.CommandLine;
+using NodeSwap.Utils;
+
+namespace NodeSwap.Commands;
+
+[CliCommand(
+    Description = "Switch to the previously installed version of Node.js.",
+    Parent = typeof(RootCommand)
+)]
+public class PrevCommand(GlobalContext globalContext, NodeJs nodeLocal)
+{
+    public int Run()
+    {
+        var prevVersion = nodeLocal.GetPreviousVersion();
+        if (prevVersion == null)
+        {
+            Console.Error.WriteLine("No previous version found");
+            return 1;
+        }
+
+        if (!ProcessElevation.IsAdministrator())
+        {
+            // Restart the application with elevated privileges
+            return ProcessElevation.ElevateApplication();
+        }
+        
+        var useCommand = new UseCommand(globalContext, nodeLocal)
+        {
+            Version = prevVersion.ToString(),
+        };
+
+        return useCommand.Run();
+    }
+}

NodeSwap/Commands/UseCommand.cs

@@ -1,10 +1,8 @@
 using System;
-using System.Diagnostics;
 using System.IO;
-using System.Linq;
 using System.Runtime.InteropServices;
-using System.Security.Principal;
 using DotMake.CommandLine;
+using NodeSwap.Utils;
 
 namespace NodeSwap.Commands;
 
@@ -61,10 +59,20 @@ public int Run()
             }
         }
 
-        if (!IsAdministrator())
+        if (!ProcessElevation.IsAdministrator())
         {
             // Restart the application with elevated privileges
-            return ElevateApplication();
+            return ProcessElevation.ElevateApplication();
+        }
+        
+        //
+        // Track the previous NodeJS version used
+        //
+
+        var activeVersion = nodeLocal.GetActiveVersion();
+        if (activeVersion != null)
+        {
+            File.WriteAllText(globalContext.PreviousVersionTrackerFilePath, activeVersion.ToString());
         }
 
         //
@@ -103,42 +111,6 @@ public int Run()
         return 0;
     }
 
-    private static bool IsAdministrator()
-    {
-        using var identity = WindowsIdentity.GetCurrent();
-        var principal = new WindowsPrincipal(identity);
-        return principal.IsInRole(WindowsBuiltInRole.Administrator);
-    }
-
-    private static int ElevateApplication()
-    {
-        var currentProcessModule = Process.GetCurrentProcess().MainModule;
-        if (currentProcessModule == null) throw new Exception("Unable to get the current process module");
-
-        var process = new Process
-        {
-            StartInfo = new ProcessStartInfo
-            {
-                FileName = currentProcessModule.FileName,
-                UseShellExecute = true,
-                Verb = "runas", // Forces the application to run with elevated permissions
-                Arguments = string.Join(" ", Environment.GetCommandLineArgs().Skip(1)),
-            },
-        };
-
-        try
-        {
-            process.Start();
-            process.WaitForExit();
-            return process.ExitCode;
-        }
-        catch (Exception ex)
-        {
-            Console.Error.WriteLine("Could not restart as Administrator: " + ex.Message);
-            return 1;
-        }
-    }
-
     [DllImport("kernel32.dll")]
     private static extern bool CreateSymbolicLink(
         string lpSymlinkFileName,

NodeSwap/GlobalContext.cs

@@ -5,5 +5,6 @@ public class GlobalContext
     public string StoragePath;
     public string SymlinkPath;
     public string ActiveVersionTrackerFilePath;
+    public string PreviousVersionTrackerFilePath;
     public bool Is64Bit;
 }

NodeSwap/NodeJs.cs

@@ -29,19 +29,35 @@ public List<NodeJsVersion> GetInstalledVersions()
                     {
                         Path = dir,
                         Version = version,
-                        IsActive = version.Equals(activeVersion),
+                        IsActive = activeVersion != null && version.Equals(activeVersion),
                     };
                 })
                 .OrderByDescending(v => v.Version)
                 .ToList();
     }
 
-    private Version GetActiveVersion()
+    public Version? GetActiveVersion()
     {
+        if (!File.Exists(globalContext.ActiveVersionTrackerFilePath))
+        {
+            return null;
+        }
+
         var str = File.ReadAllText(globalContext.ActiveVersionTrackerFilePath);
         return VersionParser.Parse(str);
     }
 
+    public Version? GetPreviousVersion()
+    {
+        if (!File.Exists(globalContext.PreviousVersionTrackerFilePath))
+        {
+            return null;
+        }
+
+        var str = File.ReadAllText(globalContext.PreviousVersionTrackerFilePath);
+        return VersionParser.Parse(str);
+    }
+
     [GeneratedRegex(@"node-v(\d+\.\d+\.\d+)")]
     private static partial Regex NodeVersionRegex();
 }

NodeSwap/NodeSwap.csproj

@@ -4,7 +4,7 @@
         <OutputType>Exe</OutputType>
         <TargetFramework>net8.0-windows</TargetFramework>
         <AppendTargetFrameworkToOutputPath>false</AppendTargetFrameworkToOutputPath>
-        <Version>1.4.2</Version>
+        <Version>1.5.0</Version>
         <!-- Single file app – https://docs.microsoft.com/en-us/dotnet/core/deploying/single-file -->
         <PublishSingleFile>true</PublishSingleFile>
         <RuntimeIdentifier>win-x64</RuntimeIdentifier>

NodeSwap/Program.cs

@@ -23,6 +23,7 @@ static Program()
         };
 
         globalContext.ActiveVersionTrackerFilePath = Path.Combine(globalContext.StoragePath, "last-used");
+        globalContext.PreviousVersionTrackerFilePath = Path.Combine(globalContext.StoragePath, "previous-used");
 
         var services = new ServiceCollection();
         services.AddSingleton(globalContext);

NodeSwap/Utils/ProcessElevation.cs

@@ -0,0 +1,45 @@
+using System;
+using System.Diagnostics;
+using System.Linq;
+using System.Security.Principal;
+
+namespace NodeSwap.Utils;
+
+public class ProcessElevation
+{
+    public static bool IsAdministrator()
+    {
+        using var identity = WindowsIdentity.GetCurrent();
+        var principal = new WindowsPrincipal(identity);
+        return principal.IsInRole(WindowsBuiltInRole.Administrator);
+    }
+
+    public static int ElevateApplication()
+    {
+        var currentProcessModule = Process.GetCurrentProcess().MainModule;
+        if (currentProcessModule == null) throw new Exception("Unable to get the current process module");
+
+        var process = new Process
+        {
+            StartInfo = new ProcessStartInfo
+            {
+                FileName = currentProcessModule.FileName,
+                UseShellExecute = true,
+                Verb = "runas", // Forces the application to run with elevated permissions
+                Arguments = string.Join(" ", Environment.GetCommandLineArgs().Skip(1)),
+            },
+        };
+
+        try
+        {
+            process.Start();
+            process.WaitForExit();
+            return process.ExitCode;
+        }
+        catch (Exception ex)
+        {
+            Console.Error.WriteLine("Could not restart as Administrator: " + ex.Message);
+            return 1;
+        }
+    }
+}