Imports System.Text
''' <summary>
''' Provides common utility functions that do not require a specific context.
''' </summary>
Public Class Utils
    ''' <summary>
    ''' Generates a random short (8 characters) guid
    ''' </summary>
    ''' <returns>The generated guid as a String</returns>
    Public Shared Function ShortGUID() As String
        Return Guid.NewGuid().ToString().GetHashCode().ToString("x")
    End Function

    ''' <summary>
    ''' Converts a String value to the given Enum
    ''' </summary>
    ''' <typeparam name="T">The Enum Type</typeparam>
    ''' <param name="value">The string value to convert</param>
    Public Shared Function ToEnum(Of T)(value As String) As T
        Return [Enum].Parse(GetType(T), value)
    End Function

    ''' <summary>
    ''' Checks a value for three different `null` values,
    ''' Nothing, Empty String, DBNull
    ''' 
    ''' Returns the original value if the value is not null, or `defaultValue`
    ''' </summary>
    ''' <typeparam name="T">The type of the value</typeparam>
    ''' <param name="value">The value</param>
    ''' <param name="defaultValue">The default Value</param>
    Public Shared Function NotNull(Of T)(ByVal value As T, ByVal defaultValue As T) As T
        If IsNothing(value) OrElse String.IsNullOrEmpty(value.ToString) OrElse IsDBNull(value) Then
            Return defaultValue
        Else
            Return value
        End If
    End Function

    ''' <summary>
    ''' Creates a "slug" from text that can be used as part of a valid URL.
    ''' Invalid characters are converted to hyphens. Punctuation that Is
    ''' perfect valid in a URL Is also converted to hyphens to keep the
    ''' result mostly text. Steps are taken to prevent leading, trailing,
    ''' And consecutive hyphens.
    ''' </summary>
    ''' <param name="s">The string to convert</param>
    Public Shared Function ConvertTextToSlug(ByVal s As String) As String
        Dim oBuilder As StringBuilder = New StringBuilder()
        Dim oWasHyphen As Boolean = True

        For Each oChar As Char In s

            If Char.IsLetterOrDigit(oChar) Then
                oBuilder.Append(Char.ToLower(oChar))
                oWasHyphen = False
            ElseIf Char.IsWhiteSpace(oChar) AndAlso Not oWasHyphen Then
                oBuilder.Append("-"c)
                oWasHyphen = True
            End If
        Next

        If oWasHyphen AndAlso oBuilder.Length > 0 Then oBuilder.Length -= 1
        Return oBuilder.ToString()
    End Function
End Class