raxol

defmodule Raxol.Terminal.Modes.Handlers.StandardHandler do
  @moduledoc """
  Handles standard mode operations and their side effects.
  Manages standard terminal modes like insert mode and line feed mode.
  """

  require Raxol.Core.Runtime.Log

  alias Raxol.Terminal.Emulator
  alias Raxol.Terminal.Modes.Types.ModeTypes

  @doc """
  Handles a standard mode change and applies its effects to the emulator.
  """
  @spec handle_mode_change(atom(), ModeTypes.mode_value(), Emulator.t()) ::
          {:ok, Emulator.t()} | {:error, term()}
  def handle_mode_change(mode_name, value, emulator) do
    case find_mode_definition(mode_name) do
      %{category: :standard} = mode_def ->
        apply_mode_effects(mode_def, value, emulator)

      _ ->
        {:error, :invalid_mode}
    end
  end

  # Private Functions

  defp find_mode_definition(mode_name) do
    ModeTypes.get_all_modes()
    |> Map.values()
    |> Enum.find(&(&1.name == mode_name))
  end

  defp apply_mode_effects(mode_def, value, emulator) do
    case mode_def.name do
      :irm ->
        handle_insert_mode(value, emulator)

      :lnm ->
        handle_line_feed_mode(value, emulator)

      _ ->
        {:error, :unsupported_mode}
    end
  end

  defp handle_insert_mode(true, emulator) do
    # Insert Mode (IRM)
    # When enabled, new text is inserted at the cursor position
    {:ok, %{emulator | insert_mode: true}}
  end

  defp handle_insert_mode(false, emulator) do
    # Replace Mode (default)
    # When disabled, new text overwrites existing text
    {:ok, %{emulator | insert_mode: false}}
  end

  defp handle_line_feed_mode(true, emulator) do
    # Line Feed Mode (LNM)
    # When enabled, line feed also performs carriage return
    {:ok, %{emulator | line_feed_mode: true}}
  end

  defp handle_line_feed_mode(false, emulator) do
    # New Line Mode (default)
    # When disabled, line feed only moves down one line
    {:ok, %{emulator | line_feed_mode: false}}
  end
end