ConversionResultWriter.cs

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using ICSharpCode.CodeConverter.CommandLine.Util;

namespace ICSharpCode.CodeConverter.CommandLine;

public static class ConversionResultWriter
{
    private static readonly string[] FileSystemNamesToIgnore = { ".git", ".gitattributes", ".gitignore", "bin", "obj", ".vs" };

    public static async Task WriteConvertedAsync(IAsyncEnumerable<ConversionResult> conversionResultsEnumerable, string solutionFilePath, DirectoryInfo targetDirectory, bool wipeTargetDirectory, bool copyOriginalDirectory, IProgress<string> progress, CancellationToken cancellationToken)
    {
        var solutionFile = new FileInfo(solutionFilePath);
        var solutionFileDirectory = solutionFile.Directory ?? throw new InvalidOperationException("Solution file directory could not be found");
        var sourceAndTargetSame = string.Equals(solutionFileDirectory.FullName, targetDirectory.FullName, StringComparison.Ordinal);

        if (!sourceAndTargetSame) {
            if (wipeTargetDirectory) {
                progress.Report($"Removing {targetDirectory.FullName}");
                //Should never be writing output within a .git dir, so it's safe to leave it there, and massively reduces the chances of accidentally destroying work
                await targetDirectory.DeleteExceptAsync(FileSystemNamesToIgnore);
            }

            if (copyOriginalDirectory) {
                progress.Report($"Started copying contents of {solutionFileDirectory.FullName} to {targetDirectory.FullName} so that the output is a usable solution.{Environment.NewLine}" +
                                "If you don't see the 'Finished copying contents' message, consider running the conversion in-place by not specifying an output directory."
                );

                // Speed up the copy by skipping irrelevant binaries and caches. An alternative would be to attempt a git clone
                await solutionFileDirectory.CopyExceptAsync(targetDirectory, true, FileSystemNamesToIgnore);
                progress.Report($"Finished copying contents of {solutionFileDirectory.FullName} to {targetDirectory.FullName}.");
            }
        }

        var sourcePaths = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
        var targetPaths = new HashSet<string>(StringComparer.OrdinalIgnoreCase);

        await foreach (var conversionResult in conversionResultsEnumerable.Where(x => x.TargetPathOrNull != null)) {
            sourcePaths.Add(Path.GetFullPath(conversionResult.SourcePathOrNull));
            targetPaths.Add(Path.GetFullPath(conversionResult.TargetPathOrNull));
            cancellationToken.ThrowIfCancellationRequested();
            var targetFilePath =
                conversionResult.TargetPathOrNull.Replace(solutionFileDirectory.FullName, targetDirectory.FullName);
            var directory = Path.GetDirectoryName(targetFilePath);
            if (directory != null) {
                Directory.CreateDirectory(directory);
            }

            File.WriteAllText(targetFilePath, conversionResult.ConvertedCode);
        }

        if (!sourceAndTargetSame) {
            var filePathsToRemove = sourcePaths.Except(targetPaths);
            foreach (var filePathToRemove in filePathsToRemove) {
                string pathInTargetDir = filePathToRemove.Replace(solutionFileDirectory.FullName, targetDirectory.FullName);
                if (File.Exists(pathInTargetDir)) File.Delete(pathInTargetDir);
            }
        }
    }
}