add a script that can downsize uploads

script/downsize_uploads.rb

@@ -0,0 +1,31 @@
+require File.expand_path("../../config/environment", __FILE__)
+
+# no less than 1 megapixel
+max_image_pixels = [ARGV[0].to_i, 1_000_000].max
+
+puts '', "Downsizing uploads size to no more than #{max_image_pixels} pixels"
+
+Upload.where("lower(extension) in (?)", ['jpg', 'gif', 'png']).find_each do |upload|
+  absolute_path = Discourse.store.path_for(upload)
+  if absolute_path && FileHelper.is_image?(upload.original_filename)
+    file = File.new(absolute_path) rescue nil
+    next unless file
+
+    image_info = FastImage.new(file) rescue nil
+    pixels = image_info.size&.reduce(:*).to_i
+
+    if pixels > max_image_pixels
+      OptimizedImage.downsize(file.path, file.path, "#{max_image_pixels}@", filename: upload.original_filename)
+
+      upload.filesize = File.size(file)
+      upload.width, upload.height = ImageSizer.resize(*FastImage.new(file).size)
+      upload.save!
+
+      upload.posts.each do |post|
+        Jobs.enqueue(:process_post, post_id: post.id, bypass_bump: true, cook: true)
+      end
+    end
+  end
+end
+
+puts '', 'Done', ''