''' <summary>
''' Returns a collection of application versioned directories 
''' found within the specified base directory, sorted by version.
''' </summary>
''' 
''' <example> This is a code example.
''' <code language="VB">
''' Dim baseDir As String = "C:\Program Files\Squirrel Application"
''' Dim namePrefix As String = "app-" ' Case: "app-1.0.0"
''' Dim nameSuffix As String = Nothing
''' 
''' Dim versionedDirs As SortedList(Of Version, DirectoryInfo) = 
'''     GetVersionedDirectories(baseDir, namePrefix, nameSuffix)
''' 
''' Dim oldest As DirectoryInfo = versionedDirs.First.Value
''' Dim newest As DirectoryInfo = versionedDirs.Last.Value
''' 
''' Console.WriteLine($"Oldest versioned directory name: {oldest.Name}")
''' Console.WriteLine($"Newest versioned directory name: {newest.Name}")
''' </code>
''' </example>
''' 
''' <param name="baseDir">
''' The base directory that contains application versioned directories (for example: "<b>app-1.0.0</b>").
''' </param>
''' 
''' <param name="namePrefix">
''' Optional. If specified, only directory names that begin with this prefix are included.
''' <para></para>
''' Default value is null.
''' </param>
'''
''' <param name="nameSuffix">
''' Optional. If specified, only directory names that ends with this suffix are included.
''' <para></para>
''' Default value is null.
''' </param>
''' 
''' <returns>
''' A <see cref="SortedList(Of Version, DirectoryInfo)"/> where the keys are
''' <see cref="Version"/> objects parsed from the directory names, and the values
''' are the corresponding <see cref="DirectoryInfo"/> objects.
''' <para></para>
''' The collection is sorted in ascending order by version, 
''' so <see cref="Enumerable.First"/> returns the oldest application version directory, 
''' and <see cref="Enumerable.Last"/> returns the newest.
''' </returns>
''' 
''' <exception cref="ArgumentNullException">
''' Thrown when the specified <paramref name="baseDir"/> is null.
''' </exception>
''' 
''' <exception cref="DirectoryNotFoundException">
''' Thrown when the specified <paramref name="baseDir"/> does not exist.
''' </exception>
<DebuggerStepThrough>
Public Shared Function GetVersionedDirectories(baseDir As String,
                                               Optional namePrefix As String = Nothing,
                                               Optional nameSuffix As String = Nothing
                                              ) As SortedList(Of Version, DirectoryInfo)
 
    Dim prefixText As String = If(String.IsNullOrEmpty(namePrefix), "", Regex.Escape(namePrefix))
    Dim suffixText As String = If(String.IsNullOrEmpty(nameSuffix), "", Regex.Escape(nameSuffix))
    Dim versionGroup As String = "(?<version>\d+(\.\d+){0,3})"
 
    Dim pattern As String = $"^{prefixText}{versionGroup}{suffixText}$"
    Dim searchRegex As New Regex(pattern, RegexOptions.IgnoreCase Or RegexOptions.Compiled)
 
    Return GetVersionedDirectories(baseDir, searchRegex)
End Function
 
''' <summary>
''' Returns a collection of application versioned directories 
''' found within the specified base directory, sorted by version.
''' </summary>
''' 
''' <example> This is a code example.
''' <code language="VB">
''' Dim baseDir As String = "C:\Program Files\Squirrel Application"
''' Dim pattern As String = "^app-(?&lt;version&gt;\d+(\.\d+){0,3})$" ' Case: "app-1.0.0"
''' Dim searchRegex As New Regex(pattern, RegexOptions.IgnoreCase Or RegexOptions.Compiled)
''' 
''' Dim versionedDirs As SortedList(Of Version, DirectoryInfo) = 
'''     GetVersionedDirectories(baseDir, searchRegex)
''' 
''' Dim oldest As DirectoryInfo = versionedDirs.First.Value
''' Dim newest As DirectoryInfo = versionedDirs.Last.Value
''' 
''' Console.WriteLine($"Oldest versioned directory name: {oldest.Name}")
''' Console.WriteLine($"Newest versioned directory name: {newest.Name}")
''' </code>
''' </example>
''' 
''' <param name="baseDir">
''' The base directory that contains application versioned directories (for example: "<b>app-1.0.0</b>").
''' </param>
''' 
''' <param name="searchRegex">
''' A <see cref="Regex"/> used to filter the directory names.
''' <para></para>
''' &#9888;&#65039; This regex must contain a named group called <b>version</b>, 
''' which will be used to extract the version number from the directory name.
''' <para></para>
''' For example: <c>"^app-(?&lt;version&gt;\d+(\.\d+){0,3})$"</c>
''' </param>
''' 
''' <returns>
''' A <see cref="SortedList(Of Version, DirectoryInfo)"/> where the keys are
''' <see cref="Version"/> objects parsed from the directory names, and the values
''' are the corresponding <see cref="DirectoryInfo"/> objects.
''' <para></para>
''' The collection is sorted in ascending order by version, 
''' so <see cref="Enumerable.First"/> returns the oldest application version directory, 
''' and <see cref="Enumerable.Last"/> returns the newest.
''' </returns>
''' 
''' <exception cref="ArgumentNullException">
''' Thrown when the specified <paramref name="baseDir"/> or <paramref name="searchRegex"/> is null.
''' </exception>
''' 
''' <exception cref="ArgumentException">
''' Thrown when the pattern of the specified <paramref name="searchRegex"/> does not contain a named group 'version'.
''' </exception>
''' 
''' <exception cref="DirectoryNotFoundException">
''' Thrown when the specified <paramref name="baseDir"/> does not exist.
''' </exception>
<DebuggerStepThrough>
Public Shared Function GetVersionedDirectories(baseDir As String,
                                               searchRegex As Regex
                                              ) As SortedList(Of Version, DirectoryInfo)
 
    If String.IsNullOrWhiteSpace(baseDir) Then
        Throw New ArgumentNullException(NameOf(baseDir))
    End If
 
    If searchRegex Is Nothing Then
        Throw New ArgumentNullException(NameOf(searchRegex))
    End If
 
    If Not searchRegex.GetGroupNames().Contains("version") Then
        Throw New ArgumentException("The provided regex pattern must contain a named group 'version'.", NameOf(searchRegex))
    End If
 
    If Not Directory.Exists(baseDir) Then
        Throw New DirectoryNotFoundException(baseDir)
    End If
 
    Dim topLevelDirs As DirectoryInfo() =
        New DirectoryInfo(baseDir).
            GetDirectories("*", SearchOption.TopDirectoryOnly)
 
    Dim versionedDirs As New SortedList(Of Version, DirectoryInfo)(
        topLevelDirs.Length, Comparer(Of Version).Default
    )
 
    For Each topLevelDir As DirectoryInfo In topLevelDirs
 
        Dim match As Match = searchRegex.Match(topLevelDir.Name)
        If match.Success Then
            Dim versionPart As String = match.Groups("version").Value
            Dim ver As Version = Nothing
            If Version.TryParse(versionPart, ver) Then
                If Not versionedDirs.ContainsKey(ver) Then
                    versionedDirs.Add(ver, topLevelDir)
                End If
            End If
        End If
    Next
 
    Return versionedDirs
End Function

Dim baseDir As String = "C:\Program Files\Squirrel Application"
Dim namePrefix As String = "app-" ' Case: "app-1.0.0"
Dim nameSuffix As String = Nothing
 
Dim versionedDirs As SortedList(Of Version, DirectoryInfo) =
    GetVersionedDirectories(baseDir, namePrefix, nameSuffix)
 
Dim oldest As DirectoryInfo = versionedDirs.First.Value
Dim newest As DirectoryInfo = versionedDirs.Last.Value
 
Console.WriteLine($"Oldest versioned directory name: {oldest.Name}")
Console.WriteLine($"Newest versioned directory name: {newest.Name}")

Dim baseDir As String = "C:\Program Files\Squirrel Application"
Dim pattern As String = "^app-(?<version>\d+(\.\d+){0,3})$" ' Case: "app-1.0.0"
Dim searchRegex As New Regex(pattern, RegexOptions.IgnoreCase Or RegexOptions.Compiled)
 
Dim versionedDirs As SortedList(Of Version, DirectoryInfo) = 
    GetVersionedDirectories(baseDir, searchRegex)
 
Dim oldest As DirectoryInfo = versionedDirs.First.Value
Dim newest As DirectoryInfo = versionedDirs.Last.Value
 
Console.WriteLine($"Oldest versioned directory name: {oldest.Name}")
Console.WriteLine($"Newest versioned directory name: {newest.Name}")