defmodule ArcadiaCloud.Provisioning.Steps.DestroyDroplet do
  @moduledoc """
  Destroys a droplet and marks its cloud_resources row deleted.

  Saga inputs:
    droplet_provider_id  — required; the DO numeric droplet id

  This is a terminal, irreversible action. `compensate/1` is therefore a
  noop with a log line — a destroyed droplet cannot be un-destroyed.
  Per the saga design, destroy-class steps don't roll back; a saga that
  needs to fail-safe should sequence DestroyDroplet last.

  Idempotent: a droplet already gone (404) is treated as success.
  """

  @behaviour ArcadiaCloud.Provisioning.Step

  import Ecto.Query
  require Logger

  alias ArcadiaCloud.Cloud.CloudResource
  alias ArcadiaCloud.DigitalOcean.Client
  alias ArcadiaCloud.Provisioning.SagaState
  alias ArcadiaCloud.Repo

  @impl true
  def name, do: "destroy_droplet"

  @impl true
  def execute(state) do
    droplet_id = SagaState.get_input(state, :droplet_provider_id)

    cond do
      is_nil(droplet_id) ->
        {:error, :missing_droplet_provider_id}

      true ->
        case Client.destroy_droplet(droplet_id) do
          {:ok, _} ->
            mark_resource_deleted(droplet_id)
            {:ok, SagaState.put_output(state, :destroyed_droplet_id, droplet_id)}

          {:error, {:http, 404, _}} ->
            mark_resource_deleted(droplet_id)
            {:ok, SagaState.put_output(state, :destroyed_droplet_id, droplet_id)}

          {:error, reason} ->
            {:error, reason}
        end
    end
  end

  @impl true
  def compensate(state) do
    Logger.warning(
      "[saga #{state.saga_id}] DestroyDroplet cannot be compensated — droplet destruction is terminal"
    )

    :ok
  end

  defp mark_resource_deleted(provider_id) do
    from(r in CloudResource,
      where: r.provider == "digitalocean" and r.kind == "droplet" and r.provider_id == ^to_string(provider_id)
    )
    |> Repo.update_all(set: [deleted_at: DateTime.utc_now() |> DateTime.truncate(:second)])
  end
end