livebook/lib/livebook_web/live/output/control_form_component.ex

defmodule LivebookWeb.Output.ControlFormComponent do
  use LivebookWeb, :live_component

  @impl true
  def mount(socket) do
    {:ok, assign(socket, data: %{})}
  end

  @impl true
  def update(assigns, socket) do
    prev_data = socket.assigns.data

    socket = assign(socket, assigns)

    data =
      Map.new(assigns.attrs.fields, fn {field, input_attrs} ->
        {field, assigns.input_values[input_attrs.id]}
      end)

    if data != prev_data do
      change_data =
        for {field, value} <- data,
            assigns.attrs.report_changes[field],
            into: %{},
            do: {field, value}

      if change_data != %{} do
        report_event(socket, %{type: :change, data: change_data})
      end
    end

    {:ok, assign(socket, data: data)}
  end

  @impl true
  def render(%{attrs: %{type: :form}} = assigns) do
    ~H"""
    <div class="flex flex-col space-y-3">
      <%= for {_field, input_attrs} <- @attrs.fields do %>
        <.live_component module={LivebookWeb.Output.InputComponent}
          id={"#{@id}-#{input_attrs.id}"}
          attrs={input_attrs}
          input_values={@input_values}
          local={true} />
      <% end %>
      <%= if @attrs.submit do %>
        <div>
          <button class="button-base button-blue"
            type="button"
            phx-click="submit"
            phx-target={@myself}>
            <%= @attrs.submit %>
          </button>
        </div>
      <% end %>
    </div>
    """
  end

  @impl true
  def handle_event("submit", %{}, socket) do
    report_event(socket, %{type: :submit, data: socket.assigns.data})

    if socket.assigns.attrs.reset_on_submit do
      reset_inputs(socket)
    end

    {:noreply, socket}
  end

  defp report_event(socket, attrs) do
    topic = socket.assigns.attrs.ref
    event = Map.merge(%{origin: self()}, attrs)
    send(socket.assigns.attrs.destination, {:event, topic, event})
  end

  defp reset_inputs(socket) do
    values =
      for {field, input_attrs} <- socket.assigns.attrs.fields,
          field in socket.assigns.attrs.reset_on_submit,
          do: {input_attrs.id, input_attrs.default}

    send(self(), {:set_input_values, values, true})
  end
end