module ImageMosaic
  module Image
    #Takes an array of images and metrics and then returns a single image of compisited images.
    class Parent
      def initialize(items, width: 1000, height: 1000, colour: 'white', columns: 5, cell_dimension: 200)
        @items = items
        @width = width
        @height = height
        @colour = colour
        @columns = columns
        @cell_dimension = cell_dimension
      end

      def create
        image.run_command(:convert, '-size', "#{@width}x#{@height}", "xc:#{@colour}", image.path)
        y = 0
        sliced_grid.each do |row|
          x = 0
          row.each do |cell|
            @image = add_image(cell, x, y)
            x += @cell_dimension
          end
          y += @cell_dimension
        end
        image
      end

      private

      def sliced_grid
        @items.each_slice(@columns).to_a
      end

      def add_image(child_image, x, y)
        Operations::Compositor.new(@image, child_image).save(x, y, type: 'Over', dimension: @cell_dimension)
      end

      def temp_file
        @temp_file ||= Tempfile.new(['image_mosaic', '.png'])
      end

      def image
        @image ||= MiniMagick::Image.new(temp_file.path)
      end
    end
  end
end