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Option Explicit On 
Option Strict On
Imports System
Imports System.Windows.Forms

''' <summary>
''' Sort a listview in details mode based on column header click.
''' </summary>
''' <remark>
''' Main feature 1: Handles the column types "Text", "Numeric" and "Date" (with optional autodetection).
''' Main feature 2: Handles culture settings (default is to use the current Windows settings).
''' </remark>
''' <example>
''' Usage example (for a listview named "ListView1")...:
''' <code>
''' Private Sub ListView1_ColumnClick(ByVal sender As Object, ByVal e As System.Windows.Forms.ColumnClickEventArgs) Handles ListView1.ColumnClick
'''  ' Description: Sort the listview based on column click.
'''  ' Note:    The listview View property has to be set to View.Details
'''  ' Info:    The listview Sorting property is not used at all because it is not needed. Sorting direction is handled by ListViewItemSorterClass.
'''
'''  If ListView1.View <> View.Details Then
'''    Debug.WriteLine("Info: The ColumnClick sort code only works if .View=View.Details.")
'''    Return
'''  End If
'''
'''  Static oSorter As ListViewItemSorterClass
'''  If oSorter Is Nothing Then
'''    oSorter = New ListViewItemSorterClass()
'''    ListView1.ListViewItemSorter = Nothing		 ' Make sure no other ItemSorter (for example set by the listview Sorting property) disturbes.
'''  End If
'''  'oSorter.CultureInfoName = "iv"		 ' Override locale system setting.
'''  oSorter.Column = e.Column
'''  oSorter.ColumnType = oSorter.DetectColumnType(ListView1, e.Column)	 ' Info: Optional - but preferred in most situations. Remove it to always use ColumnType=ListViewColumnType.Text. Replace it with other logic if you have a "special case".
'''  'oSorter.CompareMethod = Microsoft.VisualBasic.CompareMethod.Binary		 ' Specify case sensitivity (used if ColumnType=ListViewColumnType.Text).
'''  'oSorter.CompareFromLeftToDiff = False		 ' Compare as the dotNET framework does it (used if ColumnType=ListViewColumnType.Text).
'''  oSorter.InvertSortOrder()	 ' Invert the SortOrder.
'''  If ListView1.ListViewItemSorter Is Nothing Then
'''    ListView1.ListViewItemSorter = oSorter		 ' Info: Setting this property to a ItemSorter triggers a sort (the first time). Reassigning the property to the same ItemSorter does NOT trigger a sort.
'''  Else
'''    ListView1.Sort()		 ' Do a sort.
'''  End If
''' End Sub
''' </code>
''' </example>
''' 
Public Class ListViewItemSorterClass
	Implements Collections.IComparer
	' Note:				Please report any bugs or improvement suggestions to [email protected]
	' Info:				Visit http://dotnet.nbit.se/lal/prod/VB/ListViewItemSorter/Info.aspx
	' History:
	' 2001-08-03 LAL Created using VB.NET 7.0 Beta 2.
	' 2001-08-08 LAL Support culture settings that differ from the current Windows settings.
	' 2002-09-06 LAL More .NET-ified naming convention, Option Strict On and XML-documentation. Added the "Class" suffix to avoid problems when used in inherited ListView control.
	Private Const m_sTypeName As String = "ListViewItemSorterClass"	 ' For debug purposes.
	Protected m_nColumn As Integer = -1	 ' The column to sort on.
	Protected m_nColumnType As ListViewColumnType = ListViewColumnType.Text	' Text, Numeric or Date.
	Protected m_nCompareMethod As Microsoft.VisualBasic.CompareMethod = Microsoft.VisualBasic.CompareMethod.Text	 ' Text column CompareMethod can be Binary or Text.
	Protected m_bCompareFromLeftToDiff As Boolean = True
	Protected m_nSortOrder As Integer = CompareResult.FirstIsBiggerThanSecond	 ' Ascending or Descending sort.
	Protected m_oCulture As Globalization.CultureInfo = Globalization.CultureInfo.CurrentCulture	 ' Default to Current Culture Settings.

	''' <summary>
	''' The column to sort on.
	''' </summary>
	''' 	
	Public Property Column() As Integer
		' History:
		' 2001-08-03 LAL Created.
		Get
			Return m_nColumn
		End Get
		Set(ByVal value As Integer)
			m_nColumn = value
		End Set
	End Property

	''' <summary>
	''' Text, Numeric or Date.
	''' </summary>
	''' 	
	Public Property ColumnType() As ListViewColumnType
		' History:
		' 2001-08-03 LAL Created.
		Get
			Return m_nColumnType
		End Get
		Set(ByVal value As ListViewColumnType)
			m_nColumnType = value
		End Set
	End Property

	''' <summary>
	''' Text columns can be sorted Binary (case sensitive sort order derived from the internal binary representations of the characters) or Text (case-insensitive text sort order determined by the system's LocaleID value).
	''' </summary>
	''' 
	Public Property CompareMethod() As Microsoft.VisualBasic.CompareMethod
		' History:
		' 2001-08-03 LAL Created.
		Get
			Return m_nCompareMethod
		End Get
		Set(ByVal value As Microsoft.VisualBasic.CompareMethod)
			m_nCompareMethod = value
		End Set
	End Property

	''' <summary>
	''' Specifies in which way a Text column should be handled.
	''' </summary>
	''' <remark>
	''' True = Compare each char from left until one is bigger or smaller than the other (i.e. "ab2" is smaller than "AB1" when casesensitive, because "a" is smaller than "A"). I.e. behave a lot like StrComp() - but honor the CultureInfo setting!
	''' False = Compare using the dotNET frameworks string.compare() method (which says that "ab" is smaller than "AB" when casesensitive, BUT "ab2" is BIGGER than "AB1" even when casesensitive...).
	''' </remark>
	''' 
	Public Property CompareFromLeftToDiff() As Boolean
		' History:
		' 2001-08-08 LAL Created.
		Get
			Return m_bCompareFromLeftToDiff
		End Get
		Set(ByVal value As Boolean)
			m_bCompareFromLeftToDiff = value
		End Set
	End Property

	''' <summary>
	''' Ascending or Descending sort.
	''' </summary>
	''' 
	Public Property SortOrder() As System.Windows.Forms.SortOrder	 ' Return a value from the enum named "SortOrder" in System.Windows.Forms.
		' History:
		' 2001-08-03 LAL Created.
		Get
			' Return last SortOrder.
			Select Case m_nSortOrder
				Case CompareResult.FirstIsSmallerThanSecond
					Return System.Windows.Forms.SortOrder.Ascending
				Case CompareResult.FirstIsBiggerThanSecond
					Return System.Windows.Forms.SortOrder.Descending
				Case Else
					Return System.Windows.Forms.SortOrder.None
			End Select
		End Get
		Set(ByVal value As System.Windows.Forms.SortOrder)
			' Set the SortOrder to be used at next sort.
			Const sMemberName As String = "SortOrder.Set"
			Select Case value
				Case System.Windows.Forms.SortOrder.Ascending
					m_nSortOrder = CompareResult.FirstIsSmallerThanSecond
				Case System.Windows.Forms.SortOrder.Descending
					m_nSortOrder = CompareResult.FirstIsBiggerThanSecond
				Case Else
					' Invalid value (i.e. CompareResult.FirstIsEqualToSecond).
					Debug.WriteLine(m_sTypeName & "." & sMemberName & ": Invalid Value. SortOrder is NOT set!")
					Return					 ' Abort.
			End Select
		End Set
	End Property

	''' <summary>
	''' The Culture Settings to use in variable type conversion and comparisons.
	''' </summary>
	''' <remark>
	''' The default is the current thread (i.e. system) locale setting. 
	''' Set it to "" to reset it to the default.
	''' Set it to "iv" to use an invariant culture (based on the English culture).
	''' </remark>
	''' 
	Public Property CultureInfoName() As String
		' Related info: 	http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpref/html/frlrfsystemglobalizationcultureinfoclasstopic.asp
		' History:
		' 2001-08-08 LAL Created.
		' 2001-08-29 LAL Added the cultureinfoname "neutral".
		Get
			Return m_oCulture.Name
		End Get
		Set(ByVal value As String)
			Select Case LCase(value)
				Case ""
					m_oCulture = Globalization.CultureInfo.CurrentCulture					 ' Use the current thread (i.e. system) locale setting.
				Case "iv", "inv", "invariant", "neutral", "culture-insensitive", "culture insensitive", "cultureinsensitive"
					m_oCulture = Globalization.CultureInfo.InvariantCulture					' Use an invariant culture (based on the english culture). Info: Dates convert well if they are in ISO format (i.e. "yyyy-MM-dd") or american format (i.e. "MM/dd/yyyy").
				Case Else
					m_oCulture = Globalization.CultureInfo.CreateSpecificCulture(value)					 ' Info: Raises an error if Value contains an invalid CultureInfoName.
			End Select
		End Set
	End Property

	''' <summary>
	''' An easy way to invert the sortorder of the next sort (ascending turns descending and vice versa).
	''' </summary>
	''' 
	Public Function InvertSortOrder() As System.Windows.Forms.SortOrder	 ' Return a value from the enum named "SortOrder" in System.Windows.Forms.
		' History:
		' 2001-08-03 LAL Created.
		Const sMemberName As String = "InvertSortOrder"
		Select Case m_nSortOrder
			Case CompareResult.FirstIsEqualToSecond
				m_nSortOrder = CompareResult.FirstIsSmallerThanSecond
				Return System.Windows.Forms.SortOrder.Ascending
			Case CompareResult.FirstIsSmallerThanSecond
				m_nSortOrder = CompareResult.FirstIsBiggerThanSecond
				Return System.Windows.Forms.SortOrder.Descending
			Case CompareResult.FirstIsBiggerThanSecond
				m_nSortOrder = CompareResult.FirstIsSmallerThanSecond
				Return System.Windows.Forms.SortOrder.Ascending
		End Select
	End Function

	''' <summary>
	''' Returns column type based on column contents.
	''' </summary>
	''' 
	Public Function DetectColumnType(ByVal theListView As ListView, ByVal columnIndex As Integer) As ListViewColumnType
		' History:
		' 2001-08-03 LAL Created.
		' 2001-08-04 LAL Optimized for better performance.
		' 2001-08-08 LAL Support different culture settings (i.e. changed IsNumeric() and IsDate() to <datatype>.Parse() and error handlers).
		Const sMemberName As String = "DetectColumnType"
		Dim nTextCount As Integer
		Dim nNumericCount As Integer
		Dim nDateCount As Integer
		Dim oRowItem As ListViewItem
		Dim sTxt As String
		Dim nValue As Double
		Dim dDate As Date
		If theListView Is Nothing Then
			Debug.WriteLine(m_sTypeName & "." & sMemberName & ": oListView Is Nothing. No ColumnType is detected.")
			Return ListViewColumnType.Text			 ' Invalid. Abort!
		End If
		If columnIndex < 0 Then
			Debug.WriteLine(m_sTypeName & "." & sMemberName & ": nColumn < 0. No ColumnType is detected.")
			Return ListViewColumnType.Text			 ' Invalid. Abort!
		End If
		Try
			theListView.Cursor = Cursors.WaitCursor
			For Each oRowItem In theListView.Items
				If columnIndex < oRowItem.SubItems.Count Then
					' The column exists in listview rowitem.
					sTxt = oRowItem.SubItems.Item(columnIndex).Text
					If Len(sTxt) > 0 Then
						' Not empty. Detect type...:
						If nNumericCount > 0 Then
							Try
								nValue = Double.Parse(sTxt, m_oCulture.NumberFormat)								 ' Convert to double.
							Catch
								Debug.WriteLine(m_sTypeName & "." & sMemberName & ": Column " & columnIndex & " is ColumnType Text.")
								Return ListViewColumnType.Text								 ' If one row in the column is text (i.e. not ANY other type) then the entire column is classed as columntype text.
							End Try

						ElseIf nDateCount > 0 Then
							Try
								dDate = Date.Parse(sTxt, m_oCulture.DateTimeFormat)								 ' Convert to date.
							Catch
								Debug.WriteLine(m_sTypeName & "." & sMemberName & ": Column " & columnIndex & " is ColumnType Text.")
								Return ListViewColumnType.Text								 ' If one row in the column is text (i.e. not ANY other type) then the entire column is classed as columntype text.
							End Try

						Else
							Try
								nValue = Double.Parse(sTxt, m_oCulture.NumberFormat)								 ' Convert to double.
								nNumericCount += 1
							Catch
								' Not a numeric.
								Try
									dDate = Date.Parse(sTxt, m_oCulture.DateTimeFormat)									' Convert to date.
									nDateCount += 1
								Catch
									' Not a numeric and not a date = a text.
									Debug.WriteLine(m_sTypeName & "." & sMemberName & ": Column " & columnIndex & " is ColumnType Text.")
									Return ListViewColumnType.Text									 ' If one row in the column is text (i.e. not ANY other type) then the entire column is classed as columntype text.
								End Try
							End Try
						End If
					Else
						' Ignore empty strings.
					End If
				Else
					' Ignore rows with missing subitems.
				End If
			Next
			' All rows are checked. Return the result of the autodetection.
			If nDateCount > 0 Then
				Debug.WriteLine(m_sTypeName & "." & sMemberName & ": Column " & columnIndex & " is ColumnType Date.")
				Return ListViewColumnType.Date
			End If
			If nNumericCount > 0 Then
				Debug.WriteLine(m_sTypeName & "." & sMemberName & ": Column " & columnIndex & " is ColumnType Numeric.")
				Return ListViewColumnType.Numeric
			End If
			Debug.WriteLine(m_sTypeName & "." & sMemberName & ": Column " & columnIndex & " is ColumnType Text.")
			Return ListViewColumnType.Text
		Finally
			theListView.Cursor = Cursors.Default
		End Try
	End Function

	''' <summary>
	''' Compare two strings using the CurrentCulture CultureInfo.
	''' </summary>
	''' 	
	Protected Overloads Function StringCompare( _
	 ByVal string1 As String, _
	 ByVal string2 As String, _
	 Optional ByVal compare As Microsoft.VisualBasic.CompareMethod = Microsoft.VisualBasic.CompareMethod.Text _
	) As CompareResult
		Return Me.StringCompare(string1, string2, System.Globalization.CultureInfo.CurrentCulture, compare:=compare)
	End Function

	''' <summary>
	''' Compare two strings using the specified CultureInfo.
	''' </summary>
	''' 	
	Protected Overloads Function StringCompare( _
	 ByVal string1 As String, _
	 ByVal string2 As String, _
	 ByVal culture As System.Globalization.CultureInfo, _
	 Optional ByVal compare As Microsoft.VisualBasic.CompareMethod = Microsoft.VisualBasic.CompareMethod.Text _
	) As CompareResult
		Dim bIgnoreCase As Boolean = (m_nCompareMethod = Microsoft.VisualBasic.CompareMethod.Text)
		Dim sChar1 As String
		Dim sChar2 As String
		Dim nCompRC As Integer
		Dim nPos As Integer
		For nPos = 1 To Len(string1)
			sChar1 = Mid(string1, nPos, 1)
			sChar2 = Mid(string2, nPos, 1)
			nCompRC = String.Compare(sChar1, sChar2, bIgnoreCase, culture)
			If nCompRC <> CompareResult.FirstIsEqualToSecond Then
				' They are NOT equal.
				Return CType(nCompRC, CompareResult)				' Return the result of the comparison.
			End If
			' They are identical. Continue with the next char.
		Next
		' No more characters in string1.
		If Len(Mid(string2, nPos + 1)) > 0 Then
			' More characters in string2.
			Return CompareResult.FirstIsSmallerThanSecond
		End If
		Return CompareResult.FirstIsEqualToSecond
	End Function

	''' <summary>
	''' Returns a value indicating the result of the comparison.
	''' </summary>
	''' <remark>
	''' Return values:
	''' If object1 < object2 Then Return -n
	''' If object1 = object2 Then Return 0
	''' If object1 > object2 Then Return n
	''' </remark>
	''' 	
	Public Function Compare(ByVal object1 As Object, ByVal object2 As Object) As Integer Implements Collections.IComparer.Compare
		' History:
		' 2001-08-03 LAL Created.
		' 2001-08-08 LAL Support for culture settings.
		Const sMemberName As String = "Compare"
		Dim oRowItem1 As ListViewItem
		Dim oRowItem2 As ListViewItem
		Dim sTxt1 As String
		Dim sTxt2 As String
		Try
			' Convert from Object type to ListViewItem type...:
			oRowItem1 = CType(object1, ListViewItem)
			oRowItem2 = CType(object2, ListViewItem)
		Catch
			Debug.WriteLine(m_sTypeName & "." & sMemberName & ": Wrong type of objects. Class misuse detected! No sorting is performed!")
			Return CompareResult.FirstIsEqualToSecond			 ' No sorting.
		End Try
		If m_nColumn < 0 Then
			' Invalid column.
			Debug.WriteLine(m_sTypeName & "." & sMemberName & ": m_nColumn < 0. No sorting is performed!")
			Return CompareResult.FirstIsEqualToSecond			 ' No sorting.
		End If
		' Get the text in the column in the rowitem...:
		If m_nColumn < oRowItem1.SubItems.Count Then
			' The subitem exists in listview rowitem 1.
			sTxt1 = oRowItem1.SubItems.Item(m_nColumn).Text
		End If
		If m_nColumn < oRowItem2.SubItems.Count Then
			' The subitem exists in listview rowitem 2.
			sTxt2 = oRowItem2.SubItems.Item(m_nColumn).Text
		End If

		' Handle empty values...:
		If Len(sTxt1) = 0 Then
			If Len(sTxt2) = 0 Then
				Return CompareResult.FirstIsEqualToSecond				' Both are zero length = No sorting.
			End If
			Return m_nSortOrder			 ' The first is empty, but not the second = first is smaller than the second.
		ElseIf Len(sTxt2) = 0 Then
			Return -m_nSortOrder			 ' The second is empty, but not the first = first is bigger than the second.
		End If

		' Compare the two values...:
		Select Case m_nColumnType
			Case ListViewColumnType.Text
				If m_bCompareFromLeftToDiff = True Then
					Return -m_nSortOrder * StringCompare(sTxt1, sTxt2, m_oCulture, Compare:=m_nCompareMethod)
				Else
					Return -m_nSortOrder * String.Compare(sTxt1, sTxt2, (m_nCompareMethod = Microsoft.VisualBasic.CompareMethod.Text), m_oCulture)
				End If
			Case ListViewColumnType.Numeric
				Dim nValue1 As Double
				Dim nValue2 As Double
				Try
					nValue1 = CType(sTxt1, Double)
					nValue1 = Double.Parse(sTxt1, m_oCulture.NumberFormat)					' Convert to double.
				Catch
					Debug.WriteLine(m_sTypeName & "." & sMemberName & ": Column " & m_nColumn & " is NOT of ColumnType Numeric.")
					Return CompareResult.FirstIsEqualToSecond					 ' No sorting.
				End Try
				Try
					nValue2 = Double.Parse(sTxt2, m_oCulture.NumberFormat)					 ' Convert to double.
				Catch
					Debug.WriteLine(m_sTypeName & "." & sMemberName & ": Column " & m_nColumn & " is NOT of ColumnType Numeric.")
					Return CompareResult.FirstIsEqualToSecond					 ' No sorting.
				End Try
				If nValue1 < nValue2 Then
					Return m_nSortOrder
				End If
				If nValue1 > nValue2 Then
					Return -m_nSortOrder
				End If
				Return CompareResult.FirstIsEqualToSecond				 ' No sorting.
			Case ListViewColumnType.Date
				Dim dDate1 As Date
				Dim dDate2 As Date
				Try
					dDate1 = Date.Parse(sTxt1, m_oCulture.DateTimeFormat)					 ' Convert to date.
				Catch
					Debug.WriteLine(m_sTypeName & "." & sMemberName & ": Column " & m_nColumn & " is NOT of ColumnType Date.")
					Return CompareResult.FirstIsEqualToSecond					 ' No sorting.
				End Try
				Try
					dDate2 = Date.Parse(sTxt2, m_oCulture.DateTimeFormat)					 ' Convert to date.
				Catch
					Debug.WriteLine(m_sTypeName & "." & sMemberName & ": Column " & m_nColumn & " is NOT of ColumnType Date.")
					Return CompareResult.FirstIsEqualToSecond					 ' No sorting.
				End Try
				Return -m_nSortOrder * Date.Compare(dDate1, dDate2)
			Case Else
				Debug.WriteLine(m_sTypeName & "." & sMemberName & ": m_nColumnType=" & m_nColumnType & " is not a handled Column Type. No sorting is performed!")
				Return CompareResult.FirstIsEqualToSecond				 ' No sorting.
		End Select
	End Function

End Class

' - - -

Public Enum ListViewColumnType
	[Text] = 1
	[Numeric]
	[Date]
	[AutoDetect]
End Enum

' - - -

Public Enum CompareResult
	[FirstIsSmallerThanSecond] = -1
	[FirstIsEqualToSecond] = 0
	[FirstIsBiggerThanSecond] = 1
End Enum