defmodule Rx.Kino do
  @compile {:no_warn_undefined, {Kino.Image, :new, 2}}
  @compile {:no_warn_undefined, {Kino.Layout, :grid, 2}}

  @moduledoc """
  Optional helpers for rendering captured Rx plots with Kino.

  Requires the optional `{:kino, "~> 0.19.0"}` dependency. This module does not
  depend on Livebook directly; it only calls Kino rendering APIs when available.
  """

  @doc """
  Renders one captured `%Rx.Plot{}` as a Kino image.
  """
  def image(%Rx.Plot{format: :png, data: data}) when is_binary(data) do
    ensure_kino!()
    kino_adapter().image(data, :png)
  end

  def image(%Rx.Plot{} = plot) do
    raise ArgumentError,
          "Rx.Kino.image/1 supports only PNG plots, got: #{inspect(plot.format)}"
  end

  def image(_other) do
    raise ArgumentError, "Rx.Kino.image/1 expects a %Rx.Plot{}"
  end

  @doc """
  Renders captured plots as one image or a Kino grid.

  A single plot returns a single `Kino.Image`. Multiple plots return
  `Kino.Layout.grid/2` with `columns: 2` by default.
  """
  def plots(plots, opts \\ [])

  def plots([%Rx.Plot{} = plot], opts) when is_list(opts) do
    validate_plots_opts!(opts)
    image(plot)
  end

  def plots(plots, opts) when is_list(plots) and is_list(opts) do
    opts = validate_plots_opts!(opts)
    ensure_kino!()

    images = Enum.map(plots, &image/1)
    kino_adapter().grid(images, columns: opts[:columns])
  end

  def plots(%Rx.PlotResult{plots: plots}, opts) when is_list(opts) do
    plots(plots, opts)
  end

  def plots(_other, _opts) do
    raise ArgumentError,
          "Rx.Kino.plots/2 expects a list of %Rx.Plot{} structs"
  end

  @doc """
  Captures R plots with `Rx.plot/3` and renders them with Kino.

  The `:columns` option controls the Kino grid and is not passed to
  `Rx.plot/3`.
  """
  def plot(source, globals \\ %{}, opts \\ [])

  def plot(source, opts, []) when is_binary(source) and is_list(opts) do
    plot(source, %{}, opts)
  end

  def plot(source, globals, opts) when is_binary(source) and is_map(globals) and is_list(opts) do
    {columns, plot_opts} = Keyword.pop(opts, :columns, 2)
    validate_columns!(columns, "Rx.Kino.plot/3")
    ensure_kino!()

    source
    |> Rx.plot(globals, plot_opts)
    |> plots(columns: columns)
  end

  def plot(source, globals, opts) when is_binary(source) and is_list(opts) do
    raise ArgumentError, "globals must be a map with string keys, got: #{inspect(globals)}"
  end

  defp validate_plots_opts!(opts) do
    opts = Keyword.validate!(opts, columns: 2)
    columns = opts[:columns]

    validate_columns!(columns, "Rx.Kino.plots/2")

    opts
  end

  defp validate_columns!(columns, function) do
    unless is_integer(columns) and columns > 0 do
      raise ArgumentError, "#{function} option :columns must be a positive integer"
    end
  end

  defp ensure_kino! do
    case Application.get_env(:rx, :kino_adapter) do
      nil ->
        unless Code.ensure_loaded?(Kino.Image) and Code.ensure_loaded?(Kino.Layout) do
          raise RuntimeError,
                "Kino is not available. Add `{:kino, \"~> 0.19.0\"}` to your deps."
        end

      adapter ->
        if function_exported?(adapter, :ensure_available!, 0) do
          adapter.ensure_available!()
        else
          :ok
        end
    end
  end

  defp kino_adapter do
    Application.get_env(:rx, :kino_adapter, Rx.Kino.Adapter)
  end
end

defmodule Rx.Kino.Adapter do
  @compile {:no_warn_undefined, {Kino.Image, :new, 2}}
  @compile {:no_warn_undefined, {Kino.Layout, :grid, 2}}

  @moduledoc false

  def image(data, type), do: Kino.Image.new(data, type)
  def grid(terms, opts), do: Kino.Layout.grid(terms, opts)
end