photo.rb

class Photo < ActiveRecord::Base
  ATTACHMENT_STYLES = lambda do |attachment|
  
    # http://stackoverflow.com/a/23513608/69926
    # https://github.com/joehilton/hpvideos/blob/master/app/models/attachment.rb

    # if is_animated_gif?(attachment)
    if attachment.instance.is_animated_gif?
      {medium: {format: "flv"}, thumbnail: {format: "png"}}
    else
      {medium: "x300>", thumbnail: "50x50#"}
    end
  end
  # ATTACHMENT_PROCESSORS = lambda { |attachment| is_animated_gif?(attachment) ? [:ffmpeg] : [:thumbnail] }
  ATTACHMENT_PROCESSORS = lambda { |attachment| attachment.instance.is_animated_gif? ? [:ffmpeg] : [:thumbnail] }

  belongs_to :post, class_name: "Forem::Post"

  has_attached_file :attachment, styles: ATTACHMENT_STYLES, processors: ATTACHMENT_PROCESSORS

  validates_attachment :attachment, presence: true, content_type: { content_type: ["image/jpg", "image/jpeg", "image/png", "image/gif"] }

  def self.is_animated_gif?(attachment)
    # file = Magick::ImageList.new(attachment.instance_read(:file_name))
    # Appears it's not yet saved, so try something different
    # file = Magick::ImageList.new(attachment.queued_for_write[:original].path)
    # true if attachment.instance_read(:content_type) =~ /gif/ && file.scene > 0
    
    file = Magick::ImageList.new(attachment.instance.attachment_file_name)
    true if attachment.instance.attachment_content_type =~ /gif/ && file.scene > 0
  end
end