class CoursesService
  include ApplicationHelper
  #参数school_id为0或不传时返回所有课程，否则返回对应学校的课程
  #参数per_page_count分页功能，每页显示的课程数
  #参数page分页功能，当前页码
  def course_list params
    @school_id = params[:school_id]
    per_page_option = params[:per_page_count] || 10
    page_no = params[:page] || 1
    if @school_id == "0" || @school_id.nil?
      @courses_all = Course.active.visible.
        joins("LEFT JOIN #{CourseStatus.table_name} ON #{Course.table_name}.id = #{CourseStatus.table_name}.course_id")
    else
      @courses_all = Course.active.visible.
        joins("LEFT JOIN #{CourseStatus.table_name} ON #{Course.table_name}.id = #{CourseStatus.table_name}.course_id").
        where("#{Course.table_name}.school_id = ?", @school_id)
    end
    @course_count = @courses_all.count
    @course_pages = Redmine::Pagination::Paginator.new @course_count, per_page_option,page_no
    @courses = @courses_all.order("created_at desc")
    @courses = @courses.offset(@course_pages.offset).limit(@course_pages.per_page)
    course_list = []
    @courses.each do |course|
      course_list << {:course => course,:img_url => url_to_avatar(course)}
    end
    course_list
  end

end