private static List GetPossibleApplicationPaths()

in resharper/resharper-unity/src/Unity/UnityEditorIntegration/UnityInstallationFinder.cs [134:239]
90 lines of code
11 McCabe index (conditional complexity)

        private static List<VirtualFileSystemPath> GetPossibleApplicationPaths(string engineName)
        {
            switch (PlatformUtil.RuntimePlatform)
            {
                case JetPlatform.MacOsX:
                {
                    var appsHome = VirtualFileSystemPath.Parse("/Applications", InteractionContext.SolutionContext);
                    var unityApps = appsHome.GetChildDirectories($"{engineName}*").Select(a=>a.Combine($"{engineName}.app")).ToList();

                    var defaultHubLocation = appsHome.Combine($"{engineName}/Hub/Editor");
                    var hubLocations = new List<VirtualFileSystemPath> {defaultHubLocation};

                    // Hub custom location
                    var home = Environment.GetEnvironmentVariable("HOME");
                    if (!string.IsNullOrEmpty(home))
                    {
                        var localAppData = VirtualFileSystemPath.Parse(home, InteractionContext.SolutionContext).Combine("Library/Application Support");
                        var hubCustomLocation = GetCustomHubInstallPath(engineName, localAppData);
                        if (!hubCustomLocation.IsEmpty)
                            hubLocations.Add(hubCustomLocation);
                    }

                    // /Applications/Unity/Hub/Editor/2018.1.0b4/Unity.app
                    unityApps.AddRange(hubLocations.SelectMany(l=>l.GetChildDirectories().Select(unityDir =>
                        unityDir.Combine($@"{engineName}.app"))));

                    return unityApps.Where(a=>a.ExistsDirectory).Distinct().OrderBy(b=>b.FullPath).ToList();
                }
                case JetPlatform.Linux:
                {
                    var unityApps = new List<VirtualFileSystemPath>();
                    var homeEnv = Environment.GetEnvironmentVariable("HOME");
                    var homes = new List<VirtualFileSystemPath> {VirtualFileSystemPath.Parse("/opt", InteractionContext.SolutionContext)};
                    if (!string.IsNullOrEmpty(homeEnv))
                    {
                        homes.Add(VirtualFileSystemPath.Parse(homeEnv, InteractionContext.SolutionContext));
                    }

                    // Old style installations
                    unityApps.AddRange(
                        homes.SelectMany(a => a.GetChildDirectories($"{engineName}*"))
                            .Select(unityDir => unityDir.Combine($@"Editor/{engineName}")));

                    // Installations with Unity Hub
                    if (!string.IsNullOrEmpty(homeEnv))
                    {
                        var home = VirtualFileSystemPath.Parse(homeEnv, InteractionContext.SolutionContext);
                        var defaultHubLocation = home.Combine($"{engineName}/Hub/Editor");
                        var hubLocations = new List<VirtualFileSystemPath> {defaultHubLocation};
                        // Hub custom location
                        var configPath = home.Combine(".config");
                        var customHubInstallPath = GetCustomHubInstallPath(engineName, configPath);
                        if (!customHubInstallPath.IsEmpty)
                            hubLocations.Add(customHubInstallPath);

                        unityApps.AddRange(hubLocations.SelectMany(l=>l.GetChildDirectories().Select(unityDir =>
                            unityDir.Combine($@"Editor/{engineName}"))));
                    }

                    return unityApps.Where(a=>a.ExistsFile).Distinct().OrderBy(b=>b.FullPath).ToList();
                }

                case JetPlatform.Windows:
                {
                    var unityApps = new List<VirtualFileSystemPath>();

                    var programFiles = GetProgramFiles();
                    unityApps.AddRange(
                        programFiles.GetChildDirectories($"{engineName}*")
                            .Select(unityDir => unityDir.Combine($@"Editor\{engineName}.exe"))
                        );

                    // default Hub location
                    //"C:\Program Files\Unity\Hub\Editor\2018.1.0b4\Editor\Data\MonoBleedingEdge"
                    unityApps.AddRange(
                        programFiles.Combine($@"{engineName}\Hub\Editor").GetChildDirectories()
                            .Select(unityDir => unityDir.Combine($@"Editor\{engineName}.exe"))
                    );

                    // custom Hub location
                    var appData = VirtualFileSystemPath.Parse(Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData), InteractionContext.SolutionContext);
                    var customHubInstallPath = GetCustomHubInstallPath(engineName, appData);
                    if (!customHubInstallPath.IsEmpty)
                    {
                        unityApps.AddRange(
                            customHubInstallPath.GetChildDirectories()
                                .Select(unityDir => unityDir.Combine($@"Editor\{engineName}.exe"))
                        );
                    }

                    var lnks = VirtualFileSystemPath.Parse(@"C:\ProgramData\Microsoft\Windows\Start Menu\Programs", InteractionContext.SolutionContext)
                        .GetChildDirectories($"{engineName}*").SelectMany(a => a.GetChildFiles($"{engineName}.lnk")).ToArray();
                    unityApps.AddRange(lnks
                        .Select(t => ShellLinkHelper.ResolveLinkTarget(t.ToNativeFileSystemPath()).ToVirtualFileSystemPath())
                        .OrderBy(c => new FileInfo(c.FullPath).CreationTime));

                    foreach (var VirtualFileSystemPath in unityApps)
                    {
                        ourLogger.Log(LoggingLevel.VERBOSE, "Possible unity path: " + VirtualFileSystemPath);
                    }
                    return unityApps.Where(a=>a.ExistsFile).Distinct().OrderBy(b=>b.FullPath).ToList();
                }
            }
            ourLogger.Error("Unknown runtime platform");
            return new List<VirtualFileSystemPath>();
        }