Console Application - Menu

[dday9]

I had a situation where I needed to provide users with a list of values and they had to select one. At first, I just had it loop over every item and prefix it with it's ordinal index. This worked, but I wanted to provide a more interactive way for the user to select an option, so I decided to whip something up that will allow the user to use their arrow keys to cycle through the items and select an option.

This is the code:

Private Function GetSelectedMenu(menuItems As IEnumerable(Of String), Optional selectedIndex As Integer = 0) As Integer
    If (Not menuItems.Any()) Then
        Throw New ArgumentOutOfRangeException(NameOf(menuItems))
    End If
    If (selectedIndex < 0 OrElse selectedIndex > menuItems.Count - 1) Then
        Throw New ArgumentOutOfRangeException(NameOf(selectedIndex))
    End If

    Console.Clear()
    DisplayMenu(menuItems, selectedIndex)

    Dim key = Console.ReadKey()
    Select Case key.Key
        Case ConsoleKey.UpArrow
            If selectedIndex > 0 Then
                selectedIndex -= 1
            End If
        Case ConsoleKey.DownArrow
            If (selectedIndex < menuItems.Count - 1) Then
                selectedIndex += 1
            End If
        Case ConsoleKey.Enter
            Return selectedIndex
    End Select

    Return GetSelectedMenu(menuItems, selectedIndex)
End Function

Private Sub DisplayMenu(menuItems As IEnumerable(Of String), selectedIndex As Integer)
    If (Not menuItems.Any()) Then
        Throw New ArgumentOutOfRangeException(NameOf(menuItems))
    End If
    If (selectedIndex < 0 OrElse selectedIndex > menuItems.Count - 1) Then
        Throw New ArgumentOutOfRangeException(NameOf(selectedIndex))
    End If

    For menuItemIndex = 0 To menuItems.Count - 1
        If menuItemIndex = selectedIndex Then
            Console.ForegroundColor = ConsoleColor.Green
        End If

        Dim menuItem = menuItems(menuItemIndex)
        Console.WriteLine(menuItem)
        Console.ResetColor()
    Next
End Sub

And this is the implementation:

Console.CursorVisible = False

Dim menuItems = Enumerable.Range(1, 5).Select(Function(i) $"Menu {i}")
Dim selectedMenuItem = GetSelectedMenu(menuItems)

Console.Clear()
Console.WriteLine("You selected {0}", selectedMenuItem)
Console.ReadLine()

The basic idea is that you essentially end up an in a recursive loop where it will do the following:

1. Clear the console
2. Loop over the menu items
   
   1. Print the currently iterated item
   2. If the currently iterated item is the currently "selected" item, change the forecolor to green
3. Call ReadKey
   
   1. If the key is enter, then return the selected index value.
   2. Otherwise...
      
      1. If the key is the up arrow, try to decrement the selected index value
      2. If the key is the down arrow, try to increment the selected index value
      3. Regardless of the input, recursively call the method by returning the method's value

Something that I didn't include that might be useful is a "title" argument to the GetSelectedMenu's event signature that will display text at the top of the console before all the menu items.