Add component to read PDF files into assistants (#439)

app/Build/Commands/Pdfium.cs

@@ -0,0 +1,107 @@
+using System.Formats.Tar;
+using System.IO.Compression;
+
+using SharedTools;
+
+namespace Build.Commands;
+
+public static class Pdfium
+{
+    public static async Task InstallAsync(RID rid, string version)
+    {
+        Console.Write($"- Installing Pdfium {version} for {rid.ToUserFriendlyName()} ...");
+
+        var cwd = Environment.GetRustRuntimeDirectory();
+        var pdfiumTmpDownloadPath = Path.GetTempFileName();
+        var pdfiumTmpExtractPath = Directory.CreateTempSubdirectory();
+        var pdfiumUrl = GetPdfiumDownloadUrl(rid, version);
+
+        //
+        // Download the file:
+        //
+        Console.Write(" downloading ...");
+        using (var client = new HttpClient())
+        {
+            var response = await client.GetAsync(pdfiumUrl);
+            if (!response.IsSuccessStatusCode)
+            {
+                Console.WriteLine($" failed to download Pdfium {version} for {rid.ToUserFriendlyName()}");
+                return;
+            }
+
+            await using var fileStream = File.Create(pdfiumTmpDownloadPath);
+            await response.Content.CopyToAsync(fileStream);
+        }
+        
+        //
+        // Extract the downloaded file:
+        //
+        Console.Write(" extracting ...");
+        await using(var tgzStream = File.Open(pdfiumTmpDownloadPath, FileMode.Open, FileAccess.Read, FileShare.Read))
+        {
+            await using var uncompressedStream = new GZipStream(tgzStream, CompressionMode.Decompress);
+            await TarFile.ExtractToDirectoryAsync(uncompressedStream, pdfiumTmpExtractPath.FullName, true);
+        }
+        
+        //
+        // Copy the library to the target directory:
+        //
+        Console.Write(" deploying ...");
+        var library = GetLibraryPath(rid);
+        if (string.IsNullOrEmpty(library.Path))
+        {
+            Console.WriteLine($" failed to find the library path for {rid.ToUserFriendlyName()}");
+            return;
+        }
+        
+        var pdfiumLibSourcePath = Path.Join(pdfiumTmpExtractPath.FullName, library.Path);
+        var pdfiumLibTargetPath = Path.Join(cwd, "resources", "libraries", library.Filename);
+        if (!File.Exists(pdfiumLibSourcePath))
+        {
+            Console.WriteLine($" failed to find the library file '{pdfiumLibSourcePath}'");
+            return;
+        }
+        
+        Directory.CreateDirectory(Path.Join(cwd, "resources", "libraries"));
+        if (File.Exists(pdfiumLibTargetPath))
+            File.Delete(pdfiumLibTargetPath);
+        
+        File.Copy(pdfiumLibSourcePath, pdfiumLibTargetPath);
+        
+        //
+        // Cleanup:
+        //
+        Console.Write(" cleaning up ...");
+        File.Delete(pdfiumTmpDownloadPath);
+        Directory.Delete(pdfiumTmpExtractPath.FullName, true);
+        
+        Console.WriteLine(" done.");
+    }
+    
+    private static Library GetLibraryPath(RID rid) => rid switch
+    {
+        RID.LINUX_ARM64 or RID.LINUX_X64 => new(Path.Join("lib", "libpdfium.so"), "libpdfium.so"),
+        RID.OSX_ARM64 or RID.OSX_X64 => new(Path.Join("lib", "libpdfium.dylib"), "libpdfium.dylib"),
+        RID.WIN_ARM64 or RID.WIN_X64 => new(Path.Join("bin", "pdfium.dll"), "pdfium.dll"),
+        
+        _ => new(string.Empty, string.Empty),
+    };
+
+    private static string GetPdfiumDownloadUrl(RID rid, string version)
+    {
+        var baseUrl = $"https://github.com/bblanchon/pdfium-binaries/releases/download/chromium%2F{version}/pdfium-";
+        return rid switch
+        {
+            RID.LINUX_ARM64 => $"{baseUrl}linux-arm64.tgz",
+            RID.LINUX_X64 => $"{baseUrl}linux-x64.tgz",
+            
+            RID.OSX_ARM64 => $"{baseUrl}mac-arm64.tgz",
+            RID.OSX_X64 => $"{baseUrl}mac-x64.tgz",
+            
+            RID.WIN_ARM64 => $"{baseUrl}win-arm64.zip",
+            RID.WIN_X64 => $"{baseUrl}win-x64.zip",
+            
+            _ => string.Empty,
+        };
+    }
+}