magic_resize_cover_image.rb

class ProcessImage
  class ResizeCover < ProcessImage::Base
    include Interactor
    include MomCatalogModels::Fileable

    GRID_W = 960
    GRID_H = 1200

    def call
      magic_resize_cover
    end

    private

    def magic_resize_cover
      resize_worker
    rescue => error
      context.fail! :message => "Failed to resize image file #{work_path_file} with errors: #{error}"
    end

    def image
      @_image ||= GraphicsMagick::Image.new work_path_file
    end

    def work_file_ratio
      @_work_file_ratio ||= get_ratio
    end

    def height
      @_height ||= image.height
    end

    def width
      @_width ||= image.width
    end

    def bg_img_file
      @_bg_img_file ||= File.join(File.expand_path(work_path), "tmp_bg_#{File.basename(work_path_file)}")
    end

    def resize_worker
      if work_file_ratio >= 0.75 && work_file_ratio <= 0.85
        expand_img_with_4x5
      elsif work_file_ratio < 0.8 # TODO: is this correct, shouldn't it be 0.75? Check with K.
        doing_img_for_less_75
      else
        doing_img_for_greater_85
      end
    end

    def expand_img_with_4x5
      grid = if height >= GRID_H
               "#{GRID_W}x#{GRID_H}!"
             else
               "#{(height * 0.8).to_i}x#{height}!"
             end

      image.resize grid
      image.write dest_file
    rescue
      nil
    end

    def doing_img_for_less_75
      if width >= GRID_W
        # img > default grid
        bg_grid_w = GRID_W
        bg_grid_h = GRID_H
      else
        # img < default grid
        bg_grid_w = (height * 0.8).to_i
        bg_grid_h = height
      end

      # calculate all image params
      bg_resize_after_h   = (bg_grid_w / work_file_ratio).to_i
      bg_resize_opt       = "#{bg_grid_w}x#{bg_resize_after_h}!"
      bg_crop_offset      = (bg_resize_after_h - bg_grid_h) / 2
      bg_crop_opt         = "#{bg_grid_w}x#{bg_grid_h}+0+#{bg_crop_offset}"
      over_resize_w       = (bg_grid_h * work_file_ratio).to_i
      over_resize_opt     = "#{over_resize_w}x#{bg_grid_h}!"
      over_off_set        = (bg_grid_w - over_resize_w) / 2
      over_geometry_opt   = "+#{over_off_set}"

      # making cover image
      make_tmp_bg_img bg_resize_opt, bg_crop_opt
      make_composite_img over_resize_opt, over_geometry_opt
      safe_remove bg_img_file
    end

    def doing_img_for_greater_85
      if height >= GRID_W
        # img > default grid
        bg_grid_w = GRID_W
        bg_grid_h = GRID_H
      else
        # img < default grid
        bg_grid_w = width
        bg_grid_h = (width / 0.8).to_i
      end

      # calculate all image params
      bg_resize_after_w   = (bg_grid_h * work_file_ratio).to_i
      bg_resize_opt       = "#{bg_resize_after_w}x#{bg_grid_h}!"
      bg_crop_offset      = (bg_resize_after_w - bg_grid_w) / 2
      bg_crop_opt         = "#{bg_grid_w}x#{bg_grid_h}+#{bg_crop_offset}+0"
      over_resize_h       = (bg_grid_w / work_file_ratio).to_i
      over_resize_opt     = "#{bg_grid_w}x#{over_resize_h}!"
      over_off_set        = (bg_grid_h - over_resize_h) / 2
      over_geometry_opt   = "+0+#{over_off_set}"

      # making cover image
      make_tmp_bg_img bg_resize_opt, bg_crop_opt
      make_composite_img over_resize_opt, over_geometry_opt
      safe_remove bg_img_file
    end

    def get_ratio
      (width.to_f / height.to_f).round(2)
    end

    def make_tmp_bg_img(bg_resize_opt, bg_crop_opt)
      image.resize(bg_resize_opt).blur('0x7').crop(bg_crop_opt).fill('black').colorize('50%').quality('92')
      image.write bg_img_file
    end

    def make_composite_img(over_resize_opt, over_geometry_opt)
      image.resize(over_resize_opt).composite(bg_img_file).geometry(over_geometry_opt).quality('92')
      image.write dest_file
    end
  end
end