src/ALZ/Private/Config-Helpers/Remove-UnrequiredFileSet.ps1

function Remove-UnrequiredFileSet {
    [CmdletBinding(SupportsShouldProcess = $true)]
    param (
        [Parameter(Mandatory = $false)]
        [string]$path,
        [Parameter(Mandatory = $false)]
        [array]$foldersOrFilesToRetain = @(),
        [Parameter(Mandatory = $false)]
        [array]$subFoldersOrFilesToRemove = @(),
        [Parameter(Mandatory = $false)]
        [switch]$writeVerboseLogs
    )

    if ($PSCmdlet.ShouldProcess("Remove files", "modify")) {
        if ($foldersOrFilesToRetain.Length -eq 0 -and $subFoldersOrFilesToRemove.Length -eq 0) {
            Write-Verbose "No folders or files to retain specified, so not removing aything from $path"
            return
        }

        $files = Get-ChildItem -Path $path -File -Recurse -Force
        $filesToRetain = @()

        foreach ($file in $files) {
            $fileRelativePath = $file.FullName.Replace($path, "").Replace("\", "/").TrimStart("/")
            $folderRelativePath = $file.Directory.FullName.Replace($path, "").Replace("\", "/").TrimStart("/")
            foreach ($folderOrFileToRetain in $foldersOrFilesToRetain) {
                # If we have an exact match of the file name and path, always retain it.
                if ($folderOrFileToRetain.TrimStart("./") -eq $fileRelativePath) {
                    if ($writeVerboseLogs) {
                        Write-Verbose "Exact Match - Retaining: $fileRelativePath at $($file.FullName)"
                    }
                    $filesToRetain += $file.FullName
                    continue
                }

                # If we match on a pattern, take into account the subfolders or files to remove.
                if ($fileRelativePath -like "$folderOrFileToRetain*") {
                    $skipFile = $false
                    foreach ($subfolderOrFileToRemove in $subFoldersOrFilesToRemove) {
                        if ($file.Name -eq $subfolderOrFileToRemove -or $file.Directory.Name -eq $subfolderOrFileToRemove -or $fileRelativePath.EndsWith("/$subfolderOrFileToRemove") -or $folderRelativePath.EndsWith("/$subfolderOrFileToRemove")) {
                            $skipFile = $true
                        }
                    }

                    if (!$skipFile) {
                        if ($writeVerboseLogs) {
                            Write-Verbose "Pattern Match - Retaining: $fileRelativePath at $($file.FullName)"
                        }
                        $filesToRetain += $file.FullName
                    }
                }
            }
        }

        foreach ($file in $files) {
            if ($filesToRetain -notcontains $file.FullName) {
                if ($writeVerboseLogs) {
                    Write-Verbose "Removing: $($file.FullName)"
                }
                Remove-Item -Path $file.FullName -Force | Out-Null
            }
        }

        $folders = Get-ChildItem -Path $path -Directory -Recurse -Force
        foreach ($folder in $folders) {
            if (Test-Path $folder.FullName) {
                $folderItems = Get-ChildItem -Path $folder.FullName -Recurse -File -Force
                if ($folderItems.Count -eq 0) {
                    if ($writeVerboseLogs) {
                        Write-Verbose "Removing empty folder: $($folder.FullName)"
                    }
                    Remove-Item -Path $folder.FullName -Force -Recurse | Out-Null
                }
            }
        }
    }
}