Add a button for downloading homework solutions

app/controllers/task_download_controller.rb

@@ -0,0 +1,23 @@
+class TaskDownloadController < ApplicationController
+  include ActionController::Live
+
+  before_action :require_admin
+
+  def create
+    task_id = params[:task_id]
+    task = Task.find task_id
+
+    response.headers['Content-Disposition'] = "attachment; filename=\"homework.tar.gz\""
+
+    TarGzipWriter.wrap(response.stream) do |tar|
+      task.solutions.each do |solution|
+        filename = "#{solution.user.id}-#{solution.user.faculty_number}.#{Language.extension}"
+        code = solution.code
+
+        tar.add_file_simple(filename, 0644, code.bytes.size) { |io| io.write(code) }
+      end
+    end
+  ensure
+    response.stream.close
+  end
+end

app/services/tar_gzip_writer.rb

@@ -0,0 +1,11 @@
+require 'rubygems/package'
+
+module TarGzipWriter
+  def self.wrap(io)
+    Zlib::GzipWriter.wrap(io) do |gzip|
+      Gem::Package::TarWriter.new(gzip) do |tar|
+        yield tar
+      end
+    end
+  end
+end

app/views/solutions/index.html.haml

@@ -13,6 +13,7 @@
         за повече информация.
   - else
     = link_to 'Пусни тестовете', task_check_path(@task), method: :create, class: :action
+  = link_to 'Свали като архив', task_download_path(@task), method: :post, class: :action
 
 %p
   %strong= @solutions.count

config/routes.rb

@@ -21,6 +21,7 @@
     end
     resource :my_solution, only: %w(show update)
     resource :check, controller: :task_checks, only: :create
+    resource :download, controller: :task_download, only: :create
   end
 
   resources :challenges, except: :destroy do