#14 作成は完了

backend/app/controllers/preview_controller.rb

@@ -0,0 +1,37 @@
+class PreviewController < ApplicationController
+  def title
+    # TODO: # 既知サイトなら決まったフォーマットで title 取得するやぅに．
+    return head :unauthorized unless current_user
+
+    url = params[:url]
+    return head :bad_request unless url.present?
+
+    html = URI.open(url, open_timeout: 5, read_timeout: 5).read
+    doc = Nokogiri::HTML.parse(html)
+    title = doc.at('title')&.text&.strip
+
+    render json: { title: title }
+  rescue => e
+    render json: { error: e.message }, status: :bad_request
+  end
+
+  def thumbnail
+    # TODO: 既知ドメインであれば指定のアドレスからサムネールを取得するやぅにする．
+    return head :unauthorized unless current_user
+
+    url = params[:url]
+    return head :bad_request unless url.present?
+
+    path = Rails.root.join('tmp', "thumb_#{ SecureRandom.hex }.png")
+    system("node #{ Rails.root }/lib/screenshot.js #{ Shellwords.escape(url) } #{ path }")
+
+    if File.exist?(path)
+      image = MiniMagick::Image.open(path)
+      image.resize '180x180'
+      File.delete(path) rescue nil
+      send_file image.path, type: 'image/png', disposition: 'inline'
+    else
+      render json: { error: 'Failed to generate thumbnail' }, status: :internal_server_error
+    end
+  end
+end