defmodule PrymnWeb.ServerLive.Show do
  use PrymnWeb, :live_view

  require Logger
  alias Prymn.{Agents, Servers}

  @impl true
  def mount(_params, _session, socket) do
    {:ok, socket}
  end

  @impl true
  def handle_params(%{"id" => id}, _, socket) do
    server = Servers.get_server!(id)

    if connected?(socket) and server.status == :registered do
      Agents.subscribe_to_health(server.public_ip)
      Agents.start_connection(server.public_ip)
      send(self(), :get_sys_info)
    end

    health = Agents.get_health(server.public_ip)

    {:noreply,
     socket
     |> assign(:health, health || %{message: "Connecting...", tasks: []})
     |> assign(:page_title, server.name)
     |> assign(:server, server)
     |> assign(:dry_run, false)
     |> assign(:update_output, [])
     |> assign(:sys_info, nil)
     # TODO: Do not assign this to the socket - instead generate it in the HTML
     |> assign(:registration_command, Servers.create_setup_command(server))}
  end

  @impl true
  def handle_info(:get_sys_info, socket) do
    status = get_in(socket.assigns, [:health, Access.key(:status)])
    host_address = get_in(socket.assigns, [:server, Access.key(:public_ip)])
    pid = self()

    if host_address != nil and status == :connected do
      Task.start_link(fn ->
        {:ok, sys_info} = Agents.get_sys_info(host_address)
        send(pid, sys_info)
      end)
    end

    # 10 seconds is >5 which is gun's timeout duration (which might have a race
    # condition if they are equal)
    Process.send_after(self(), :get_sys_info, :timer.seconds(10))

    {:noreply, socket}
  end

  def handle_info(%PrymnProto.Prymn.SysInfoResponse{} = response, socket) do
    # TODO: GRPC calls should be done through wrapper functions. Necessary
    # calculations should be done then and there.
    {:noreply,
     socket
     |> assign(:sys_info, response)
     |> assign(:updates_available, response.updates_available)
     |> assign(:cpus, response.cpus)}
  end

  def handle_info(%PrymnProto.Prymn.SysUpdateResponse{} = response, socket) do
    output = String.split(response.output, "\n")
    socket = assign(socket, :update_output, output)
    {:noreply, socket}
  end

  def handle_info(%Agents.Health{} = health, socket) do
    {:noreply, assign(socket, :health, health)}
  end

  @impl true
  def handle_event("system_update", _params, socket) do
    host_address = get_in(socket.assigns, [:server, Access.key(:public_ip)])
    server_name = get_in(socket.assigns, [:server, Access.key(:name)])

    socket =
      if host_address do
        Agents.sys_update(host_address, socket.assigns.dry_run)
        put_flash(socket, :info, "Started a system update on server #{server_name}.")
      else
        put_flash(
          socket,
          :error,
          "Could not perform the update. Your server does not seem to have an address"
        )
      end

    {:noreply, socket}
  end

  def handle_event("change_dry_run", %{"dry_run" => enabled}, socket) do
    enabled = (enabled == "true" && true) || false
    {:noreply, assign(socket, :dry_run, enabled)}
  end

  defp calculate_cpu_usage(cpus) do
    (Enum.reduce(cpus, 0, fn x, acc -> x.usage + acc end) / Enum.count(cpus))
    |> Float.round(2)
  end

  defp bytes_to_gigabytes(bytes) do
    Float.round(bytes / Integer.pow(1024, 3), 2)
  end

  defp calculate_disk_used_percent(disks) do
    alias PrymnProto.Prymn.SysInfoResponse.Disk

    {used, total} =
      Enum.reduce(disks, {0, 0}, fn %Disk{} = disk, {used, total} ->
        {used + disk.total_bytes - disk.avail_bytes, total + disk.total_bytes}
      end)

    Float.round(100 * used / total, 2)
  end
end