trustieforge/app/controllers/zipdown_controller.rb

require 'zip'
class ZipdownController < ApplicationController
  #查找项目（课程）
  before_filter :find_project_by_bid_id, :only => [:assort]
  #检查权限
  #勿删 before_filter :authorize, :only => [:assort,:download_user_homework]
  SAVE_FOLDER = "#{Rails.root}/files"
  OUTPUT_FOLDER = "#{Rails.root}/files/archiveZip"

  #统一下载功能
  def download
    if User.current.logged?
      begin
        send_file "#{OUTPUT_FOLDER}/#{params[:file]}", :filename => filename_for_content_disposition(params[:filename]), :type => detect_content_type(params[:file])
      rescue => e
        render file: 'public/no_file_found.html'
      end
    else
      render_403
    end
  end

  #一个作业下所有文件打包下载，只有admin和课程老师有权限
  def assort
    if params[:obj_class] == "Bid"
      bid = Bid.find params[:obj_id]
      render_403 if User.current.allowed_to?(:as_teacher,bid.courses.first)
      file_count = 0
      bid.homeworks.map { |homework| file_count += homework.attachments.count}
      if file_count > 0
        zipfile = zip_bid bid
      else
        zipfile = {:message => "no file"}
      end
    elsif params[:obj_class] == "HomeworkCommon"
      homework = HomeworkCommon.find params[:obj_id]
      render_403 if User.current.allowed_to?(:as_teacher,homework.course)
      file_count = 0
      homework.student_works.map { |work| file_count += work.attachments.count}
      if file_count > 0
        zipfile = zip_homework_common homework
      else
        zipfile = {:message => "no file"}
      end
    else
      logger.error "[ZipDown#assort] ===> #{params[:obj_class]} unKown !!"
    end
    respond_to do |format|
      format.json {
        render json: zipfile.to_json
      }
    end
  end

  #下载某一学生的作业的所有文件
  def download_user_homework
    homework = HomeworkAttach.find params[:homework]
    if User.current.admin? || User.current.member_of_course?(homework.bid.courses.first)
      if homework != nil
        unless homework.attachments.empty?
          zipfile = zip_homework_by_user homework
          filename = ((homework.user.user_extensions.nil? || homework.user.user_extensions.student_id.nil?) ? "" : homework.user.user_extensions.student_id) +
            "_" + homework.user.show_name +
            "_" + homework.name + ".zip"
          send_file zipfile.file_path, :filename => filename_for_content_disposition(filename), :type => detect_content_type(zipfile.file_path) if(zipfile)
        else
          render file: 'public/no_file_found.html'
        end
      else
        render file: 'public/file_not_found.html'
      end
    else
      render_403
    end
  #rescue => e
  #  render file: 'public/file_not_found.html'
  end

  private

  #通过作业Id找到项目（课程）
  def find_project_by_bid_id
    obj_class = params[:obj_class]
    obj_id = params[:obj_id]
    obj = obj_class.constantize.find(obj_id)
    case obj.class.to_s.to_sym
      when :Bid
        @project = obj.courses[0]
    end
  end

  def zip_bid(bid)
    # Todo: User Access Controll
    bid_homework_path = []
    digests = []
    bid.homeworks.each do |homeattach|
      unless homeattach.attachments.empty?
        out_file = zip_homework_by_user(homeattach)
        bid_homework_path << out_file.file_path
        digests << out_file.file_digest
      end
    end
    homework_id = bid.id
    user_id = bid.author_id
    out_file = find_or_pack(homework_id, user_id, digests.sort){
      zipping("#{Time.now.to_i}_#{bid.name}.zip",
              bid_homework_path, OUTPUT_FOLDER)
    }
    [{files:[out_file.file_path], count: 1, index: 1,
      real_file: out_file.file_path,  file: File.basename(out_file.file_path),
      size:(out_file.pack_size / 1024.0 / 1024.0).round(2)
     }]
  end

  def zip_homework_common homework_common
    bid_homework_path = []
    digests = []
    homework_common.student_works.each do |work|
      unless work.attachments.empty?
        out_file = zip_student_work_by_user(work)
        bid_homework_path << out_file.file_path
        digests << out_file.file_digest
      end
    end
    homework_id = homework_common.id
    user_id = homework_common.user_id
    out_file = find_or_pack(homework_id, user_id, digests.sort){
      zipping("#{Time.now.to_i}_#{homework_common.name}.zip",
              bid_homework_path, OUTPUT_FOLDER)
    }
    [{files:[out_file.file_path], count: 1, index: 1,
      real_file: out_file.file_path,  file: File.basename(out_file.file_path),
      size:(out_file.pack_size / 1024.0 / 1024.0).round(2)
     }]
  end

  def zip_homework_by_user(homework_attach)
    homeworks_attach_path = []
    not_exist_file = []
    # 需要将所有homework.attachments遍历加入zip
    digests = []
    homework_attach.attachments.each do |attach|
      if File.exist?(attach.diskfile)
        homeworks_attach_path << attach.diskfile
        digests << attach.digest
      else
        not_exist_file << attach.filename
        digests << 'not_exist_file'
      end
    end
    out_file = find_or_pack(homework_attach.bid_id, homework_attach.user_id, digests.sort){
      zipping("#{homework_attach.user.show_name}_#{((homework_attach.user.user_extensions.nil? || homework_attach.user.user_extensions.student_id.nil?) ? "" : homework_attach.user.user_extensions.student_id)}_#{Time.now.to_i.to_s}.zip",
              homeworks_attach_path, OUTPUT_FOLDER, true, not_exist_file)
    }
  end

  def zip_student_work_by_user work
    homeworks_attach_path = []
    not_exist_file = []
    # 需要将所有homework.attachments遍历加入zip
    digests = []
    work.attachments.each do |attach|
      if File.exist?(attach.diskfile)
        homeworks_attach_path << attach.diskfile
        digests << attach.digest
      else
        not_exist_file << attach.filename
        digests << 'not_exist_file'
      end
    end
    out_file = find_or_pack(work.homework_common_id, work.user_id, digests.sort){
      zipping("#{work.user.show_name}_#{((work.user.user_extensions.nil? || work.user.user_extensions.student_id.nil?) ? "" : work.user.user_extensions.student_id)}_#{Time.now.to_i.to_s}.zip",
              homeworks_attach_path, OUTPUT_FOLDER, true, not_exist_file)
    }
  end


  def find_or_pack(homework_id, user_id, digests)
    raise "please given a pack block" unless block_given?

    out_file = ZipPack.packed?(homework_id, user_id, digests.sort)

    unless out_file && out_file.file_valid?
      file = yield

      ZipPack.where(homework_id: homework_id,
                    user_id: user_id).delete_all

      out_file = ZipPack.create(homework_id: homework_id,
                                user_id: user_id,
                                file_digest: Trustie::Utils.digest(file),
                                file_path: file,
                                pack_size: File.size(file),
                                file_digests: digests.join(',')
      )
    else
      out_file.pack_times = out_file.pack_times + 1
      out_file.save
    end

    out_file
  end


  def zipping(zip_name_refer, files_paths, output_path, is_attachment=false, not_exist_file=[])
    rename_zipfile = zip_name_refer ||= "#{Time.now.to_i.to_s}.zip"
    zipfile_name = "#{output_path}/#{rename_zipfile}"

    Dir.mkdir(File.dirname(zipfile_name)) unless File.exist?(File.dirname(zipfile_name))
    Zip::File.open(zipfile_name, Zip::File::CREATE) do |zipfile|
      files_paths.each do |filename|
        rename_file = File.basename(filename)
        rename_file = filename_to_real( File.basename(filename)) if is_attachment

        begin
          zipfile.add(rename_file, filename)
        rescue Exception => e
          zipfile.get_output_stream('FILE_NOTICE.txt'){|os| os.write l(:label_file_exist)}
          next
        end
      end
      unless not_exist_file.empty?
        zipfile.get_output_stream('FILE_LOST.txt'){|os| os.write l(:label_file_lost) + not_exist_file.join(',').to_s}
      end
    end
    zipfile_name
  end

  # 合理分配文件打包
  # 如果小于 pack_attachment_max_size, 则返回单个文件
  # 反之则切分为多个文件组返回
  def split_pack_files(files, pack_attachment_max_size)
    max_size = 0
    last_files = []
    ret_files = []
    files.each_with_index do |f,i|
      if (max_size += File.size(f)) > pack_attachment_max_size
        max_size = 0
        if last_files.empty? #如果单个文件超过大小，也将此文件作为一组
          ret_files << {files: [f], count: 1, index: ret_files.count+1}
          last_files.clear
        else
          ret_files << {files:last_files, count: last_files.count, index: ret_files.count+1}
          last_files.clear
          redo
        end
      else
        last_files << f
      end
    end

    ret_files << {files:last_files, count: last_files.count, index: ret_files.count+1} unless last_files.empty?
    ret_files
  end

  def detect_content_type(name)
    content_type = Redmine::MimeType.of(name)
    content_type.to_s
  end

  def filename_to_real(name)
    attach = Attachment.find_by_disk_filename(name)
    attach.filename
  end
end