private static IEnumerable <Project> Convert(this ProjectConverter self, string target, ILogger logger)
        {
            var extension = Path.GetExtension(target) ?? throw new ArgumentNullException(nameof(target));

            if (extension.Length > 0)
            {
                var file = new FileInfo(target);

                switch (extension)
                {
                case ".sln":
                {
                    var solution = SolutionReader.Instance.Read(file, logger);
                    foreach (var project in self.ProcessSolutionFile(solution))
                    {
                        yield return(project);
                    }
                    break;
                }

                case string s when ProjectConverter.ProjectFileMappings.ContainsKey(extension):
                {
                    yield return(self.ProcessProjectFile(file, null));

                    break;
                }

                default:
                    logger.LogCritical("Please specify a project or solution file.");
                    break;
                }

                yield break;
            }

            // Process the only solution in given directory
            var solutionFiles = Directory.EnumerateFiles(target, "*.sln", SearchOption.TopDirectoryOnly).ToArray();

            if (solutionFiles.Length == 1)
            {
                var solution = SolutionReader.Instance.Read(solutionFiles[0], logger);
                foreach (var project in self.ProcessSolutionFile(solution))
                {
                    yield return(project);
                }

                yield break;
            }

            var projectsProcessed = 0;

            // Process all csprojs found in given directory
            foreach (var fileExtension in ProjectConverter.ProjectFileMappings.Keys)
            {
                var projectFiles = Directory.EnumerateFiles(target, "*" + fileExtension, SearchOption.AllDirectories).ToArray();
                if (projectFiles.Length == 0)
                {
                    continue;
                }

                if (projectFiles.Length > 1)
                {
                    logger.LogInformation($"Multiple project files found under directory {target}:");
                }

                logger.LogInformation(string.Join(Environment.NewLine, projectFiles));

                foreach (var projectFile in projectFiles)
                {
                    // todo: rewrite both directory enumerations to use FileInfo instead of raw strings
                    yield return(self.ProcessProjectFile(new FileInfo(projectFile), null));

                    projectsProcessed++;
                }
            }

            if (projectsProcessed == 0)
            {
                logger.LogCritical("Please specify a project file.");
            }
        }