reorg of code so that sharing is easier + stub for dotnet-remove-p2p

src/dotnet/commands/dotnet-remove-p2p/Program.cs

@@ -0,0 +1,94 @@
+// Copyright (c) .NET Foundation and contributors. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+using Microsoft.DotNet.Cli.CommandLine;
+using Microsoft.DotNet.Cli.Utils;
+using Microsoft.Build.Construction;
+using Microsoft.DotNet.Tools.Common;
+using System.Collections.Generic;
+using System.IO;
+
+namespace Microsoft.DotNet.Tools.Remove.ProjectToProjectReference
+{
+    public class RemoveProjectToProjectReferenceCommand
+    {
+        public static int Run(string[] args)
+        {
+            DebugHelper.HandleDebugSwitch(ref args);
+
+            CommandLineApplication app = new CommandLineApplication(throwOnUnexpectedArg: false)
+            {
+                Name = "dotnet remove p2p",
+                FullName = ".NET Remove Project to Project (p2p) reference Command",
+                Description = "Command to remove project to project (p2p) reference",
+                AllowArgumentSeparator = true,
+                ArgumentSeparatorHelpText = "Project to project references to remove"
+            };
+
+            app.HelpOption("-h|--help");
+
+            CommandArgument projectArgument = app.Argument(
+                "<PROJECT>",
+                "The project file to modify. If a project file is not specified," +
+                " it searches the current working directory for an MSBuild file that has" +
+                " a file extension that ends in `proj` and uses that file.");
+
+            CommandOption frameworkOption = app.Option(
+                "-f|--framework <FRAMEWORK>",
+                "Remove reference only when targetting a specific framework",
+                CommandOptionType.SingleValue);
+
+            app.OnExecute(() => {
+                if (string.IsNullOrEmpty(projectArgument.Value))
+                {
+                    throw new GracefulException(LocalizableStrings.RequiredArgumentNotPassed, "<Project>");
+                }
+
+                ProjectRootElement project;
+                string projectDir;
+                if (File.Exists(projectArgument.Value))
+                {
+                    project = P2PHelpers.GetProjectFromFileOrThrow(projectArgument.Value);
+                    projectDir = new FileInfo(projectArgument.Value).DirectoryName;
+                }
+                else
+                {
+                    project = P2PHelpers.GetProjectFromDirectoryOrThrow(projectArgument.Value);
+                    projectDir = projectArgument.Value;
+                }
+
+                projectDir = PathUtility.EnsureTrailingSlash(projectDir);
+
+                if (app.RemainingArguments.Count == 0)
+                {
+                    throw new GracefulException(LocalizableStrings.SpecifyAtLeastOneReferenceToRemove);
+                }
+
+                List<string> references = app.RemainingArguments;
+                
+                int numberOfRemovedReferences = P2PHelpers.RemoveProjectToProjectReference(
+                    project,
+                    frameworkOption.Value(),
+                    references);
+
+                if (numberOfRemovedReferences != 0)
+                {
+                    project.Save();
+                }
+
+                return 0;
+            });
+
+            try
+            {
+                return app.Execute(args);
+            }
+            catch (GracefulException e)
+            {
+                Reporter.Error.WriteLine(e.Message.Red());
+                app.ShowHelp();
+                return 1;
+            }
+        }
+    }
+}