VBA - 2025 - focus cell - chat GPT recommended

Private Sub Worksheet_SelectionChange(ByVal Target As Range)
    Static prevRow As Integer, prevCol As Integer
    Static lastLeftRow As Integer ' Track last highlighted row in A:C
    Static wasOutside As Boolean  ' Track if last selection was outside main range

    Dim mainRange As Range, leftRange As Range, fullRange As Range
    Dim rowRange As Range, affectedCells As Range, leftRowRange As Range

    ' Define key ranges
    Set mainRange = Me.Range("D16:AL74") ' Main range for row & column highlighting
    Set leftRange = Me.Range("A16:C74")  ' Left-side range (A:C) for clearing when needed
    Set fullRange = Me.Range("A16:AL74") ' Full range for clearing old highlights

    ' If selecting the same cell again, exit immediately
    If Target.Row = prevRow And Target.Column = prevCol Then Exit Sub

    ' Disable UI updates for maximum performance
    Application.ScreenUpdating = False
    Application.EnableEvents = False
    Application.Calculation = xlCalculationManual

    ' If selecting outside the main range
    If Intersect(mainRange, Target) Is Nothing Then
        If Not wasOutside Then
            fullRange.Interior.ColorIndex = xlColorIndexNone ' Clear only once when leaving
            wasOutside = True ' Mark that we are outside
        End If
        prevRow = 0
        prevCol = 0
        lastLeftRow = 0 ' Reset left-side tracking
        GoTo RestoreSettings
    End If

    ' Reset outside flag since we are now inside main range
    wasOutside = False

    ' Clear previous row & column highlights **only if they were changed**
    If prevRow > 0 And prevRow <> Target.Row Then
        Set rowRange = Intersect(Me.Rows(prevRow), fullRange)
        If Not rowRange Is Nothing Then rowRange.Interior.ColorIndex = xlColorIndexNone
    End If
    If prevCol > 0 And prevCol <> Target.Column Then
        Set affectedCells = Intersect(Me.Columns(prevCol), mainRange)
        If Not affectedCells Is Nothing Then affectedCells.Interior.ColorIndex = xlColorIndexNone
    End If

    ' If the row changed, clear the left-side (`A16:C74`) of the previous row
    If lastLeftRow > 0 And lastLeftRow <> Target.Row Then
        Set leftRowRange = Intersect(Me.Rows(lastLeftRow), leftRange)
        If Not leftRowRange Is Nothing Then leftRowRange.Interior.ColorIndex = xlColorIndexNone
    End If

    ' Highlight the entire row within fullRange (A16:AL74)
    Set rowRange = Intersect(Me.Rows(Target.Row), fullRange)
    If Not rowRange Is Nothing Then rowRange.Interior.ColorIndex = 6 ' Yellow

    ' Highlight column only within mainRange (D16:AL74)
    Set affectedCells = Intersect(mainRange, Target.EntireColumn)
    If Not affectedCells Is Nothing Then affectedCells.Interior.ColorIndex = 35 ' Light Blue

    ' Remove highlight from the selected cell
    Target.Interior.ColorIndex = xlColorIndexNone

    ' Update previous selections
    prevRow = Target.Row
    prevCol = Target.Column
    lastLeftRow = Target.Row ' Track last row for left-side clearing

RestoreSettings:
    ' Restore application settings
    Application.Calculation = xlCalculationAutomatic
    Application.EnableEvents = True
    Application.ScreenUpdating = True
End Sub