# Mentorenwahl: A fullstack application for assigning mentors to students based on their whishes.
# Copyright (C) 2022  Dominic Grimm

# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.

# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.

# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <https://www.gnu.org/licenses/>.

require "../../db/user"

module Backend
  module Worker
    module Jobs
      # Sends all unregistered teachers a polite registration mail to ask if they may input their data
      class SendTeachersRegistrationEmailJob < Mosquito::QueuedJob
        # :ditto:
        def perform : Nil
          users = Db::User.where(role: Db::UserRole::Teacher.to_s, teacher_id: nil)
          count = users.count.run.as(Int64).to_i

          channel = Channel(Nil).new(count)

          users.each do |user|
            spawn do
              unless Db::UserRole.parse(user.role).teacher?
                fail
              end

              log "Sending teacher registration email to #{user.email} (#{user.id})"
              Mailers::TeacherRegistrationMailer.new(user).deliver

              channel.send(nil)
            end
          end

          count.times do
            channel.receive
          end
          Fiber.yield
        end
      end
    end
  end
end