defmodule DaProductAppWeb.QRController do
  use DaProductAppWeb, :controller
  require Logger

  #@default_provider "aani"
  @default_provider "alipay"

  def generate(conn, %{"device_id" => device_id, "amount" => amount_param} = params) do
    provider_key = Map.get(params, "provider", @default_provider)
    Logger.info("QR code request for device=#{device_id} amount=#{amount_param} via #{provider_key}")

    amount = parse_amount(conn, amount_param)
    amount = amount * 100

    with {:ok, mod} <- DaProductApp.QRProviderFactory.fetch(provider_key),
         {:ok, qrcode} <- mod.generate(device_id, amount),
         true <- PlatformCore.DeviceRegistry.is_online?(device_id) do

      topic   = "cmd/qr-device/#{device_id}"
      payload = Jason.encode!(%{amount: amount, qrcode: qrcode, ts: System.system_time(:second)})
      Logger.info("Publishing to #{topic}: #{payload}")

  case DaProductApp.MQTT.publish(topic, payload, qos: 1) do
         {:ok, _ref} ->
          conn
          |> put_status(:ok)
          |> json(%{status: "sent", device: device_id})

        {:error, reason} ->
          Logger.error("Publish failed: #{inspect(reason)}")
          conn
          |> put_status(:service_unavailable)
          |> json(%{error: "publish_failed"})
      end

    else
      {:error, :unknown_provider} ->
        conn
        |> put_status(:bad_request)
        |> json(%{error: "unsupported_provider"})

      {:error, reason} ->
        conn
        |> put_status(:internal_server_error)
        |> json(%{error: inspect(reason)})

      false ->
        conn
        |> put_status(:not_found)
        |> json(%{error: "device_offline"})
    end
  end

  defp parse_amount(conn, amount) when is_integer(amount) or is_float(amount), do: amount

  defp parse_amount(conn, amount) when is_binary(amount) do
    case Integer.parse(amount) do
      {int, ""} -> int
      _ ->
        case Float.parse(amount) do
          {flt, ""} -> flt
          _ ->
            conn
            |> put_status(:bad_request)
            |> json(%{error: "invalid_amount"})
            |> halt()
        end
    end
  end

  defp parse_amount(conn, _amount) do
    conn
    |> put_status(:bad_request)
    |> json(%{error: "invalid_amount"})
    |> halt()
  end
end