[Feature]Add package download (#6910)

Author: Nigusu-Allehu

src/NuGet.Core/NuGet.CommandLine.XPlat/Commands/Package/Download/PackageDownloadArgs.cs

@@ -0,0 +1,21 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+#nullable enable
+
+using System.Collections.Generic;
+using NuGet.Common;
+
+namespace NuGet.CommandLine.XPlat.Commands.Package.PackageDownload;
+
+internal record PackageDownloadArgs
+{
+    public IReadOnlyList<PackageWithNuGetVersion>? Packages { get; set; }
+    public IList<string>? Sources { get; set; }
+    public string? OutputDirectory { get; set; }
+    public string? ConfigFile { get; set; }
+    public bool IncludePrerelease { get; set; }
+    public bool AllowInsecureConnections { get; set; }
+    public bool Interactive { get; set; }
+    public LogLevel LogLevel { get; set; }
+}

src/NuGet.Core/NuGet.CommandLine.XPlat/Commands/Package/Download/PackageDownloadCommand.cs

@@ -0,0 +1,97 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using System.Collections.Generic;
+using System.CommandLine;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace NuGet.CommandLine.XPlat.Commands.Package.PackageDownload
+{
+    internal class PackageDownloadCommand
+    {
+        internal static void Register(Command packageCommand, Option<bool> interactiveOption)
+        {
+            Register(packageCommand, interactiveOption, PackageDownloadRunner.RunAsync);
+        }
+
+        public static void Register(Command packageCommand, Option<bool> interactiveOption, Func<PackageDownloadArgs, CancellationToken, Task<int>> action)
+        {
+            var downloadCommand = new DocumentedCommand(
+                "download",
+                Strings.PackageDownloadCommand_Description,
+                "https://aka.ms/dotnet/package/download");
+
+            // Arguments
+            var packagesArguments = new Argument<IReadOnlyList<PackageWithNuGetVersion>>("packages")
+            {
+                Description = Strings.PackageUpdate_PackageArgumentDescription,
+                Arity = ArgumentArity.OneOrMore,
+                CustomParser = PackageWithNuGetVersion.Parse
+            };
+
+            // Options
+            var allowInsecureConnections = new Option<bool>("--allow-insecure-connections")
+            {
+                Description = Strings.PackageDownloadCommand_AllowInsecureConnectionsDescription,
+                Arity = ArgumentArity.Zero
+            };
+
+            var configFile = new Option<string>("--configfile")
+            {
+                Description = Strings.Option_ConfigFile,
+                Arity = ArgumentArity.ExactlyOne
+            };
+
+            var outputDirectory = new Option<string>("--output", "-o")
+            {
+                Description = Strings.PackageDownloadCommand_OutputDirectoryDescription,
+                Arity = ArgumentArity.ExactlyOne
+            };
+
+            var prerelease = new Option<bool>("--prerelease")
+            {
+                Description = Strings.Prerelease_Description,
+                Arity = ArgumentArity.Zero
+            };
+
+            var sources = new Option<List<string>>("--source", "-s")
+            {
+                Description = Strings.PackageDownloadCommand_SourcesDescription,
+                Arity = ArgumentArity.OneOrMore
+            };
+
+            var verbosity = CommonOptions.GetVerbosityOption();
+
+            downloadCommand.Arguments.Add(packagesArguments);
+            downloadCommand.Options.Add(allowInsecureConnections);
+            downloadCommand.Options.Add(configFile);
+            downloadCommand.Options.Add(interactiveOption);
+            downloadCommand.Options.Add(outputDirectory);
+            downloadCommand.Options.Add(prerelease);
+            downloadCommand.Options.Add(sources);
+            downloadCommand.Options.Add(verbosity);
+
+            downloadCommand.SetAction(async (parserResult, cancellationToken) =>
+            {
+                IReadOnlyList<PackageWithNuGetVersion> packages = parserResult.GetValue(packagesArguments) ?? [];
+                var args = new PackageDownloadArgs()
+                {
+                    Packages = packages,
+                    Sources = parserResult.GetValue(sources),
+                    OutputDirectory = parserResult.GetValue(outputDirectory),
+                    IncludePrerelease = parserResult.GetValue(prerelease),
+                    AllowInsecureConnections = parserResult.GetValue(allowInsecureConnections),
+                    Interactive = parserResult.GetValue(interactiveOption),
+                    ConfigFile = parserResult.GetValue(configFile),
+                    LogLevel = (parserResult.GetValue(verbosity) ?? VerbosityEnum.normal).ToLogLevel()
+                };
+
+                return await action(args, cancellationToken);
+            });
+
+            packageCommand.Subcommands.Add(downloadCommand);
+        }
+    }
+}