play.cr

OPERATIONS_ORDER = %i[crop scale grayscale]
alias CropTuple = NamedTuple(x_coord: Int32, y_coord: Int32, width: Int32, height: Int32)

abstract struct Operation
end

struct Crop < Operation
  getter x_coord : Int32, y_coord : Int32, width : Int32, height : Int32

  def initialize(**args)
    @x_coord = args[:x_coord]
    @y_coord = args[:y_coord]
    @width = args[:width]
    @height = args[:height]
  end
end

struct Grayscale < Operation
end

params = {crop: {x_coord: 2, y_coord: 1, width: 40, height: 100}.as(CropTuple?), grayscale: nil.as(Bool?), id: "foo"}

def operations(params)
  operations = OPERATIONS_ORDER.map do |op|
    op_params = params[op]?
    puts op_params
    case op_params
    when NamedTuple
      case op
      when :crop then Crop.new(**op_params)
      end
    when Bool
      case op
      when :grayscale then Grayscale.new if op_params
      end
    end
  end

  operations.compact
end

operations(params)