defmodule OrgGarden.Health do
  @moduledoc """
  Health check HTTP endpoints.

  Provides liveness and readiness probes for systemd/kubernetes health checks.

  ## Endpoints

    * `GET /health/live` — Always returns 200 if the process is alive
    * `GET /health/ready` — Returns 200 if all components are ready, 503 otherwise
    * `GET /health` — Returns JSON status of all components
  """

  use Plug.Router

  plug(:match)
  plug(:dispatch)

  # Liveness probe — is the process alive?
  get "/health/live" do
    send_resp(conn, 200, "ok")
  end

  # Readiness probe — are all components ready to serve?
  get "/health/ready" do
    checks = run_checks()
    all_healthy = Enum.all?(checks, fn {_name, status} -> status == :ok end)

    if all_healthy do
      send_resp(conn, 200, "ready")
    else
      send_resp(conn, 503, "not ready")
    end
  end

  # Full health status as JSON
  get "/health" do
    checks = run_checks()
    all_healthy = Enum.all?(checks, fn {_name, status} -> status == :ok end)

    status =
      if all_healthy do
        "healthy"
      else
        "degraded"
      end

    body =
      Jason.encode!(%{
        status: status,
        checks:
          Map.new(checks, fn {name, status} ->
            {name, Atom.to_string(status)}
          end)
      })

    conn
    |> put_resp_content_type("application/json")
    |> send_resp(if(all_healthy, do: 200, else: 503), body)
  end

  match _ do
    send_resp(conn, 404, "not found")
  end

  # -------------------------------------------------------------------
  # Health checks
  # -------------------------------------------------------------------

  defp run_checks do
    [
      {:server, check_server()},
      {:watcher, check_watcher()},
      {:quartz, check_quartz()}
    ]
  end

  defp check_server do
    if Process.whereis(OrgGarden.Server), do: :ok, else: :not_running
  end

  defp check_watcher do
    if Process.whereis(OrgGarden.Watcher), do: :ok, else: :not_running
  end

  defp check_quartz do
    if Process.whereis(OrgGarden.Quartz), do: :ok, else: :not_running
  end
end