module NSWTopo::RasterImport

def get_raster(temp_dir)
  @path = Pathname(@path).expand_path(@source ? @source.parent : Pathname.pwd)
  temp_dir.join("import.vrt").tap do |vrt_path|
    JSON.parse(OS.gdalinfo "-json", @path).fetch("bands").any? do |band|
      "Palette" == band["colorInterpretation"]
    end.then do |palette|
      args = ["-expand", "rgba"] if palette
      OS.gdal_translate *args, @path, vrt_path
    end
  end
rescue OS::Error
  raise "invalid raster file: #{@path}"
end