discourse/app/controllers/admin/emojis_controller.rb

class Admin::EmojisController < Admin::AdminController

  def index
    render_serialized(Emoji.custom, EmojiSerializer, root: false)
  end

  def create
    file = params[:file] || params[:files].first
    name = params[:name] || File.basename(file.original_filename, ".*")

    Scheduler::Defer.later("Upload Emoji") do
      # fix the name
      name = name.gsub(/[^a-z0-9]+/i, '_')
                 .gsub(/_{2,}/, '_')
                 .downcase

      upload = Upload.create_for(
        current_user.id,
        file.tempfile,
        file.original_filename,
        File.size(file.tempfile.path),
        image_type: 'custom_emoji'
      )

      data =
        if upload.persisted?
          custom_emoji = CustomEmoji.new(name: name, upload: upload)

          if custom_emoji.save
            Emoji.clear_cache
            { name: custom_emoji.name, url: custom_emoji.upload.url }
          else
            failed_json.merge(errors: custom_emoji.errors.full_messages)
          end
        else
          failed_json.merge(errors: upload.errors.full_messages)
        end

      MessageBus.publish("/uploads/emoji", data.as_json, user_ids: [current_user.id])
    end

    render json: success_json
  end

  def destroy
    name = params.require(:id)

    custom_emoji = CustomEmoji.find_by(name: name)
    raise Discourse::InvalidParameters unless custom_emoji

    CustomEmoji.transaction do
      custom_emoji.upload.destroy!
      custom_emoji.destroy!
    end

    Emoji.clear_cache

    Jobs.enqueue(:rebake_custom_emoji_posts, name: name)

    render json: success_json
  end

end