Added support for offline mode

app/Build/Commands/Pdfium.cs

@@ -7,18 +7,33 @@ namespace Build.Commands;
 
 public static class Pdfium
 {
-    public static async Task InstallAsync(RID rid, string version)
+    public static async Task InstallAsync(RID rid, string version, bool offline)
     {
         Console.Write($"- Installing Pdfium {version} for {rid.ToUserFriendlyName()} ...");
 
         var cwd = Environment.GetRustRuntimeDirectory();
-        var pdfiumTmpDownloadPath = Path.GetTempFileName();
-        var pdfiumTmpExtractPath = Directory.CreateTempSubdirectory();
         var pdfiumUrl = GetPdfiumDownloadUrl(rid, version);
+        var library = GetLibraryPath(rid);
+        var pdfiumLibTargetPath = Path.Join(cwd, "resources", "libraries", library.Filename);
+
+        if (offline)
+        {
+            if (File.Exists(pdfiumLibTargetPath))
+            {
+                Console.WriteLine(" offline mode enabled and library already exists, skipping download");
+                return;
+            }
+
+            Console.WriteLine($" failed because offline mode is enabled and '{pdfiumLibTargetPath}' does not exist");
+            return;
+        }
 
         //
         // Download the file:
         //
+        var pdfiumTmpDownloadPath = Path.GetTempFileName();
+        var pdfiumTmpExtractPath = Directory.CreateTempSubdirectory();
+
         Console.Write(" downloading ...");
         using (var client = new HttpClient())
         {
@@ -47,7 +62,6 @@ public static class Pdfium
         // Copy the library to the target directory:
         //
         Console.Write(" deploying ...");
-        var library = GetLibraryPath(rid);
         if (string.IsNullOrWhiteSpace(library.Path))
         {
             Console.WriteLine($" failed to find the library path for {rid.ToUserFriendlyName()}");
@@ -55,7 +69,6 @@ public static class Pdfium
         }
         
         var pdfiumLibSourcePath = Path.Join(pdfiumTmpExtractPath.FullName, library.Path);
-        var pdfiumLibTargetPath = Path.Join(cwd, "resources", "libraries", library.Filename);
         if (!File.Exists(pdfiumLibSourcePath))
         {
             Console.WriteLine($" failed to find the library file '{pdfiumLibSourcePath}'");

app/Build/Commands/UpdateMetadataCommands.cs

@@ -15,7 +15,8 @@ public sealed partial class UpdateMetadataCommands
     [Command("release", Description = "Prepare & build the next release")]
     public async Task Release(
         [Option("action", ['a'], Description = "The release action: patch, minor, or major")] PrepareAction action = PrepareAction.NONE,
-        [Option("version", ['v'], Description = "Set a specific version directly, e.g., 26.1.2")] string? version = null)
+        [Option("version", ['v'], Description = "Set a specific version directly, e.g., 26.1.2")] string? version = null,
+        [Option("offline", Description = "Skip downloads and use locally available build dependencies")] bool offline = false)
     {
         if(!Environment.IsWorkingDirectoryValid())
             return;
@@ -42,7 +43,7 @@ public sealed partial class UpdateMetadataCommands
         
         // Build once to allow the Rust compiler to read the changed metadata
         // and to update all .NET artifacts:
-        await this.Build();
+        await this.Build(offline);
         
         // Now, we update the web assets (which may were updated by the first build):
         new UpdateWebAssetsCommand().UpdateWebAssets();
@@ -53,7 +54,7 @@ public sealed partial class UpdateMetadataCommands
         
         // Build the final release, where Rust knows the updated metadata, the .NET
         // artifacts are already in place, and .NET knows the updated web assets, etc.:
-        await this.Build();
+        await this.Build(offline);
     }
 
     [Command("update-versions", Description = "The command will update the package versions in the metadata file")]
@@ -136,7 +137,8 @@ public sealed partial class UpdateMetadataCommands
     }
     
     [Command("build", Description = "Build MindWork AI Studio")]
-    public async Task Build()
+    public async Task Build(
+        [Option("offline", Description = "Skip downloads and use locally available build dependencies")] bool offline = false)
     {
         if(!Environment.IsWorkingDirectoryValid())
             return;
@@ -153,7 +155,7 @@ public sealed partial class UpdateMetadataCommands
         await this.UpdateVectorStoreVersion();
         
         var pdfiumVersion = await this.ReadPdfiumVersion();
-        await Pdfium.InstallAsync(rid, pdfiumVersion);
+        await Pdfium.InstallAsync(rid, pdfiumVersion, Environment.IsOfflineBuildRequested(offline));
         
         Console.Write($"- Start .NET build for {rid.ToUserFriendlyName()} ...");
         await this.ReadCommandOutput(pathApp, "dotnet", $"clean --configuration release --runtime {rid.AsMicrosoftRid()}");
@@ -750,4 +752,4 @@ public sealed partial class UpdateMetadataCommands
     
     [GeneratedRegex("""(?<major>[0-9]+)\.(?<minor>[0-9]+)\.(?<patch>[0-9]+)""")]
     private static partial Regex AppVersionRegex();
-}
+}

app/Build/Tools/Environment.cs

@@ -7,6 +7,7 @@ namespace Build.Tools;
 public static class Environment
 {
     public const string DOTNET_VERSION = "net9.0";
+    public const string BUILD_OFFLINE_ENVIRONMENT_VARIABLE = "AI_STUDIO_BUILD_OFFLINE";
     public static readonly Encoding UTF8_NO_BOM = new UTF8Encoding(false);
     
     private static readonly Dictionary<RID, string> ALL_RIDS = Enum.GetValues<RID>().Select(rid => new KeyValuePair<RID, string>(rid, rid.AsMicrosoftRid())).ToDictionary(kvp => kvp.Key, kvp => kvp.Value);
@@ -47,6 +48,19 @@ public static class Environment
         return Path.GetFullPath(directory);
     }
 
+    public static bool IsOfflineBuildRequested(bool offlineOption)
+    {
+        if (offlineOption)
+            return true;
+
+        var environmentValue = global::System.Environment.GetEnvironmentVariable(BUILD_OFFLINE_ENVIRONMENT_VARIABLE);
+        return environmentValue?.Trim().ToLowerInvariant() switch
+        {
+            "1" or "true" or "yes" or "on" => true,
+            _ => false,
+        };
+    }
+
     public static string? GetOS()
     {
         if(RuntimeInformation.IsOSPlatform(OSPlatform.Windows))