class DeviseNotifyMailer < Devise::Mailer
  require "notifications/client"

  def notify_client
    @notify_client ||= ::Notifications::Client.new(ENV["GOVUK_NOTIFY_API_KEY"])
  end

  def send_email(email, template_id, personalisation)
    return true if intercept_send?(email)

    notify_client.send_email(
      email_address: email,
      template_id:,
      personalisation:,
    )
  end

  def personalisation(record, token, url, username: false)
    {
      name: record.name || record.email,
      email: username || record.email,
      organisation: record.respond_to?(:organisation) ? record.organisation.name : "",
      link: "#{url}#{token}",
    }
  end

  def reset_password_instructions(record, token, _opts = {})
    base = public_send("edit_#{record.class.name.underscore}_password_url")
    url = "#{base}?reset_password_token="
    send_email(
      record.email,
      record.reset_password_notify_template,
      personalisation(record, token, url),
    )
  end

  def confirmation_instructions(record, token, _opts = {})
    username = record.email
    if email_changed(record)
      username = record.unconfirmed_email
      send_confirmation_email(record.unconfirmed_email, record, token, username)
    end
    send_confirmation_email(record.email, record, token, username)
  end

  def intercept_send?(email)
    return false unless email_allowlist

    email_domain = email.split("@").last.downcase
    !(Rails.env.production? || Rails.env.test?) && email_allowlist.exclude?(email_domain)
  end

  def email_allowlist
    Rails.application.credentials[:email_allowlist] || []
  end

private

  def email_changed(record)
    record.confirmable_template == User::CONFIRMABLE_TEMPLATE_ID && (record.unconfirmed_email.present? && record.unconfirmed_email != record.email)
  end

  def send_confirmation_email(email, record, token, username)
    url = "#{user_confirmation_url}?confirmation_token="

    send_email(
      email,
      record.confirmable_template,
      personalisation(record, token, url, username:),
    )
  end
end