hpi-swt2/workshop-portal

# == Schema Information
#
# Table name: agreement_letters
#
#  id          :integer          not null, primary key
#  user_id     :integer          not null
#  event_id    :integer          not null
#  path        :string           not null
#  created_at  :datetime         not null
#  updated_at  :datetime         not null
#
class AgreementLetter < ActiveRecord::Base
  belongs_to :user
  belongs_to :event
  validates :user, :event, :path, presence: true
  MAX_SIZE = 300_000_000
  ALLOWED_MIMETYPE = "application/pdf"
  STORAGE_DIR = Rails.root.join('storage', 'agreement_letters')

  # Generates a unique filename for an AgreementLetter's file
  #
  # @raise [ArgumentError] if user or event are nil
  # @param none
  # @return [String] for the AgreementLetter's file name
  def filename
    event.nil? ? nil : "#{event.id}_#{user.id}.pdf"
  end

  # Saves a file in the AgreementLetter's path
  #
  # @param [ActionDispatch::Http::UploadedFile] the file to save
  # @return [Boolean] whether saving the file was saved
  def save_file(file)
    unless valid_file?(file)
      self.destroy
      return false
    end
    begin
      File.write(path, file.read, mode: 'wb')
      true
    rescue IOError
      self.destroy
      errors.add(:file, I18n.t('agreement_letters.write_failed'))
      false
    end
  end

  # Calls super, adds an error if save fails
  def save(*args)
    if super
      true
    else
      errors.add(:file, I18n.t('agreement_letters.upload_failed'))
      false
    end
  end

  # Sets the AgreementLetter's path field to the path where the file should be saved
  #
  # @param none
  # @return [String] the set path
  def set_path
    self.path = File.join(STORAGE_DIR, filename).to_s unless filename.nil?
  end

  private
    def valid_file?(file)
      if !is_file?(file)
        errors.add(:file, I18n.t("agreement_letters.not_a_file"))
        false
      elsif too_big?(file)
        errors.add(:file, I18n.t("agreement_letters.file_too_big"))
        false
      elsif wrong_filetype?(file)
        errors.add(:file, I18n.t("agreement_letters.wrong_filetype"))
        false
      else
        true
      end
    end
    
    def is_file?(file)
      file.respond_to?(:open) && file.respond_to?(:content_type) && file.respond_to?(:size)
    end

    def too_big?(file)
      file.size > MAX_SIZE
    end

    def wrong_filetype?(file)
      file.content_type != ALLOWED_MIMETYPE
    end
end