Retrospring/app/models/subscription.rb

class Subscription < ApplicationRecord
  belongs_to :user
  belongs_to :answer

  class << self
    def subscribe(recipient, target)
      existing = Subscription.find_by(user: recipient, answer: target)
      return true if existing.present?

      Subscription.create!(user: recipient, answer: target)
    end

    def unsubscribe(recipient, target)
      if recipient.nil? or target.nil?
        return nil
      end

      subs = Subscription.find_by(user: recipient, answer: target)
      subs&.destroy
    end

    def destruct(target)
      if target.nil?
        return nil
      end
      Subscription.where(answer: target).destroy_all
    end

    def notify(source, target)
      return nil if source.nil? || target.nil?

      notifications = Subscription.where(answer: target).where.not(user: target.user).map do |s|
        { target_id: source.id, target_type: Comment, recipient_id: s.user_id, new: true, type: Notification::Commented }
      end

      Notification.insert_all!(notifications)
    end

    def denotify(source, target)
      return nil if source.nil? or target.nil?

      subs = Subscription.where(answer: target)
      Notification.where(target:, recipient: subs.map(&:user)).delete_all
    end
  end
end