defmodule Mix.Tasks.SendIntroEmails do
  use Mix.Task
  use Plausible.Repo
  require Logger

  @doc """
  This is scheduled to run every 6 hours.
  """

  def run(args) do
    Application.ensure_all_started(:plausible)
    execute(args)
  end

  def execute(args \\ []) do
    q =
      from(u in Plausible.Auth.User,
        left_join: ie in "intro_emails", on: ie.user_id == u.id,
        where: is_nil(ie.id),
        where:
          u.inserted_at > fragment("(now() at time zone 'utc') - '24 hours'::interval") and
            u.inserted_at < fragment("(now() at time zone 'utc') - '6 hours'::interval")
      )

    for user <- Repo.all(q) do
      if Plausible.Auth.user_completed_setup?(user) do
        Logger.info("#{user.name} has completed the setup. Sending welcome email.")
        send_welcome_email(args, user)
      else
        Logger.info("#{user.name} has not completed the setup. Sending help email.")
        send_help_email(args, user)
      end
    end
  end

  defp send_welcome_email(["--dry-run"], user) do
    Logger.info("DRY RUN: welcome email to #{user.name}")
  end

  defp send_welcome_email(_, user) do
    PlausibleWeb.Email.welcome_email(user)
    |> Plausible.Mailer.deliver_now()

    intro_email_sent(user)
  end

  defp send_help_email(["--dry-run"], user) do
    Logger.info("DRY RUN: help email to #{user.name}")
  end

  defp send_help_email(_, user) do
    PlausibleWeb.Email.help_email(user)
    |> Plausible.Mailer.deliver_now()

    intro_email_sent(user)
  end

  defp intro_email_sent(user) do
    Repo.insert_all("intro_emails", [%{
      user_id: user.id,
      timestamp: NaiveDateTime.utc_now()
    }])
  end
end