Ruby code to copy images from or within 3 bucket, without reprocessing

assign_images_s3.rb

module AssignImagesS3
  
  def assign_images(src_parent_obj, dest_parent_obj)

    # 1. get parent image object
    src_parent_obj.images.each do |src_img|
      # 2. create new image object and save it without any attachment
      dest_img = dest_parent_obj.images.create(is_processed: true)
      # 3. While assigning src image attributes to dest obj,
      #    assign attribute 'uploading_via_copy' to true so
      #    it will not process image assigned to it
      dest_img.uploading_via_copy = true

      # 4. This step will assign src object attributes to dest obj
      #    & will provide new image url for this new obj,
      #    without processing assigned image
      dest_img.image = src_img.image.clone

      # 5. Copy images to this new object's location within s3 bucket
      copy_files(src_img.image.path, dest_img.image.path, PAPERCLIP_S3[:bucket])

      # 6. Save new object
      dest_img.save
    end unless src_parent_obj.images.blank?
    
  end

  # This method takes parameters as
  # 1. source image path => from where to fetch images
  # 2. destination_image_path => images will be saved with this path under bucket
  # 3. bucket_name => within/from which we need to copy images  

  # we pass path of new and old images for processing
  # paperclip config has path option as "path, as
  # ':class/:attachment/:id/:style.:extension' 
  # Eg. "images/images/50f668b758507c0002000349/original.jpg"

  def copy_files(source_image_path, destination_image_path, bucket_name)

    #create s3 object, assign bucket name to it
    s3 = AWS::S3.new
    bucket = s3.buckets[bucket_name]

    # SOURCE path processing
    # returns array of strings splitted by '/'
    image_info = source_image_path.split('/')
     
    # remove file name, which is at the
    # end after splitting
    image_info.pop                                
                                                
    # join '/' to get path upto object_id
    # i.e "images/images/50f668b758507c0002000349/" 
    image_prefix = image_info.join('/') + '/'     
                                                
    # DEST path processing
    dest_image_info = destination_image_path.split('/')
  
    # remove file name, which is at the
    # end after splitting
    dest_image_info.pop                          
                                               
    dest_image_prefix = dest_image_info.join('/')

    bucket.objects.with_prefix(image_prefix).each do |photo|

      #create destination bucket url with new destination_object_id
      # path of image within the bucket
      # i.e "/images/images/5114dcc27260f70002000025/original.jpg"
      key = photo.key         
                               
      # split key i.e path of img using '/'
      info = key.split('/')   
   
      # get image name from it
      name = info.last        

      # generate destination file name by joining dest image id with src image name
      # this is nothing but image path under a bucket
      destination_file_name = dest_image_prefix + '/' + name

      # copy files from one directory to other, 
      # with public-read permissions
      bucket.objects[destination_file_name].copy_from(photo.key, {acl: 'public-read'})
    end if bucket.exists?
  end
end