Gab Social. All are welcome.

app/models/concerns/attachmentable.rb

@@ -0,0 +1,50 @@
+# frozen_string_literal: true
+
+require 'mime/types'
+
+module Attachmentable
+  extend ActiveSupport::Concern
+
+  MAX_MATRIX_LIMIT = 16_777_216 # 4096x4096px or approx. 16MB
+
+  included do
+    before_post_process :set_file_extensions
+    before_post_process :check_image_dimensions
+  end
+
+  private
+
+  def set_file_extensions
+    self.class.attachment_definitions.each_key do |attachment_name|
+      attachment = send(attachment_name)
+
+      next if attachment.blank?
+
+      attachment.instance_write :file_name, [Paperclip::Interpolations.basename(attachment, :original), appropriate_extension(attachment)].delete_if(&:blank?).join('.')
+    end
+  end
+
+  def check_image_dimensions
+    self.class.attachment_definitions.each_key do |attachment_name|
+      attachment = send(attachment_name)
+
+      next if attachment.blank? || !/image.*/.match?(attachment.content_type) || attachment.queued_for_write[:original].blank?
+
+      width, height = FastImage.size(attachment.queued_for_write[:original].path)
+
+      raise GabSocial::DimensionsValidationError, "#{width}x#{height} images are not supported" if width.present? && height.present? && (width * height >= MAX_MATRIX_LIMIT)
+    end
+  end
+
+  def appropriate_extension(attachment)
+    mime_type = MIME::Types[attachment.content_type]
+
+    extensions_for_mime_type = mime_type.empty? ? [] : mime_type.first.extensions
+    original_extension       = Paperclip::Interpolations.extension(attachment, :original)
+    proper_extension         = extensions_for_mime_type.first.to_s
+    extension                = extensions_for_mime_type.include?(original_extension) ? original_extension : proper_extension
+    extension                = 'jpeg' if extension == 'jpe'
+
+    extension
+  end
+end