defmodule Exddcutil do
  @moduledoc """
  Elixir wrapper for the `ddcutil` tool to control monitor settings via DDC/CI.

  This library provides a high-level interface to query and modify monitor settings
  on Linux systems using the DDC/CI protocol through the `ddcutil` command-line tool.

  ## Prerequisites

  - Linux system with `ddcutil` installed
  - DDC/CI compatible monitor(s) with DDC/CI enabled in the OSD

  ## Testing Status

  This library has been tested with:
  - Dell P2715Q

  Other DDC/CI compatible monitors should work, but behavior may vary depending
  on manufacturer implementation.

  ## Basic Usage

      # Detect available displays
      {:ok, displays} = Exddcutil.detect()

      # Get display capabilities
      {:ok, caps} = Exddcutil.capabilities(1)

      # Set brightness
      :ok = Exddcutil.set_brightness(1, 75)

      # Get current brightness
      {:ok, %{current: 75, max: 100}} = Exddcutil.get_brightness(1)

  Most functions take a display index (1-based) as the first argument, as returned
  by `detect/1`.
  """

  alias Exddcutil.{VCP, Parser, SystemRunner}

  @type runner_opt :: {:runner, module()}
  @type display_index :: pos_integer()
  @type bus_index :: pos_integer()
  @type target_opt :: {:display, display_index()} | {:bus, bus_index()}
  @type common_opt :: runner_opt | target_opt

  # Public API

  @doc """
  Detects all available displays connected to the system.

  Returns a list of maps containing display information including index, bus number,
  model, vendor, and serial number.

  ## Examples

      iex> Exddcutil.detect()
      {:ok, [
        %{index: 1, bus: 5, model: "DELL P2715Q", vendor: "DEL", serial: "ABC123"}
      ]}

  """
  @spec detect([runner_opt()]) :: {:ok, list()} | {:error, any()}
  def detect(opts \\ []) do
    with {:ok, raw} <- run_ddc(["detect"], opts) do
      {:ok, Parser.parse_detect(raw)}
    end
  end

  @doc """
  Gets the full capabilities of a display.

  Returns a map containing model, vendor, serial, and available features with their values.

  ## Examples

      iex> Exddcutil.capabilities(1)
      {:ok, %{
        model: "DELL P2715Q",
        vendor: "DEL",
        features: %{
          "Brightness" => %{code: 16, values: %{range: {0, 100}}},
          "Input Source" => %{code: 96, values: [%{code: "0x11", name: "HDMI-1"}]}
        },
        input_sources: [%{code: "0x11", name: "HDMI-1"}]
      }}

  """
  @spec capabilities(display_index(), [common_opt()]) :: {:ok, map()} | {:error, any()}
  def capabilities(display_index, opts \\ []) do
    with {:ok, raw} <- run_ddc(["capabilities"] ++ addressing_args(display_index, opts), opts) do
      {:ok, Parser.parse_capabilities(raw)}
    end
  end

  @doc """
  Lists available input sources from display capabilities.

  Returns a list of maps with code and name for each input source.

  ## Examples

      iex> Exddcutil.input_sources(1)
      {:ok, [
        %{code: "0x11", name: "HDMI-1"},
        %{code: "0x0f", name: "DisplayPort-1"}
      ]}

  """
  @spec input_sources(display_index(), [common_opt()]) :: {:ok, list()} | {:error, any()}
  def input_sources(display_index, opts \\ []) do
    case capabilities(display_index, opts) do
      {:ok, caps} -> {:ok, Map.get(caps, :input_sources, [])}
      {:error, reason} -> {:error, reason}
    end
  end

  @doc """
  Lists available input sources with an active flag indicating the current source.

  Combines `input_sources/2` and `get_input_source/2` to mark which input is currently active.

  ## Examples

      iex> Exddcutil.get_input_sources(1)
      {:ok, [
        %{code: "0x11", name: "HDMI-1", active: false},
        %{code: "0x0f", name: "DisplayPort-1", active: true}
      ]}

  """
  @spec get_input_sources(display_index(), [common_opt()]) :: {:ok, list()} | {:error, any()}
  def get_input_sources(display_index, opts \\ []) do
    with {:ok, sources} <- input_sources(display_index, opts),
         {:ok, current} <- get_input_source(display_index, opts) do
      current_code = current[:current]

      sources_with_active =
        Enum.map(sources, fn source ->
          Map.put(source, :active, source[:code] == current_code)
        end)

      {:ok, sources_with_active}
    end
  end

  @doc """
  Sets the display brightness.

  ## Parameters

  - `display_index` - Display index (1-based)
  - `value` - Brightness value (typically 0..100, check capabilities for range)
  - `opts` - Optional keyword list (runner, bus)

  ## Examples

      iex> Exddcutil.set_brightness(1, 75)
      :ok

  """
  @spec set_brightness(display_index(), non_neg_integer(), [common_opt()]) ::
          :ok | {:error, any()}
  def set_brightness(display_index, value, opts \\ []) do
    set_vcp(display_index, VCP.brightness(), value, opts)
  end

  @doc """
  Sets the display contrast.

  ## Examples

      iex> Exddcutil.set_contrast(1, 50)
      :ok

  """
  @spec set_contrast(display_index(), non_neg_integer(), [common_opt()]) :: :ok | {:error, any()}
  def set_contrast(display_index, value, opts \\ []) do
    set_vcp(display_index, VCP.contrast(), value, opts)
  end

  @doc "Sets the red gain/drive."
  @spec set_red(display_index(), non_neg_integer(), [common_opt()]) :: :ok | {:error, any()}
  def set_red(display_index, value, opts \\ []) do
    set_vcp(display_index, VCP.red(), value, opts)
  end

  @doc "Sets the green gain/drive."
  @spec set_green(display_index(), non_neg_integer(), [common_opt()]) :: :ok | {:error, any()}
  def set_green(display_index, value, opts \\ []) do
    set_vcp(display_index, VCP.green(), value, opts)
  end

  @doc "Sets the blue gain/drive."
  @spec set_blue(display_index(), non_neg_integer(), [common_opt()]) :: :ok | {:error, any()}
  def set_blue(display_index, value, opts \\ []) do
    set_vcp(display_index, VCP.blue(), value, opts)
  end

  @doc "Sets the screen orientation. Note: may be read-only on some monitors."
  @spec set_screen_orientation(display_index(), term(), [common_opt()]) :: :ok | {:error, any()}
  def set_screen_orientation(display_index, orientation, opts \\ []) do
    code =
      cond do
        is_integer(orientation) -> orientation
        is_binary(orientation) and String.starts_with?(orientation, "0x") -> orientation
        true -> orientation
      end

    set_vcp(display_index, VCP.screen_orientation(), code, opts)
  end

  @doc "Sets the display mode."
  @spec set_display_mode(display_index(), term(), [common_opt()]) :: :ok | {:error, any()}
  def set_display_mode(display_index, mode, opts \\ []) do
    code =
      cond do
        is_integer(mode) -> mode
        is_binary(mode) and String.starts_with?(mode, "0x") -> mode
        true -> mode
      end

    set_vcp(display_index, VCP.display_mode(), code, opts)
  end

  @doc """
  Sets the input source.

  Accepts either a source name (e.g., "HDMI-1"), hex code (e.g., "0x11"), or integer code.

  ## Examples

      iex> Exddcutil.set_input_source(1, "DisplayPort-1")
      :ok

      iex> Exddcutil.set_input_source(1, "0x0f")
      :ok

  """
  @spec set_input_source(display_index(), term(), [common_opt()]) :: :ok | {:error, any()}
  def set_input_source(display_index, source, opts \\ []) do
    case capabilities(display_index, opts) do
      {:ok, caps} ->
        code =
          cond do
            is_integer(source) ->
              source

            is_binary(source) and String.starts_with?(source, "0x") ->
              source

            true ->
              caps
              |> Map.get(:input_sources, [])
              |> Enum.find_value(fn %{name: name, code: code} ->
                if String.downcase(name) == String.downcase(to_string(source)),
                  do: code,
                  else: nil
              end)
          end

        set_vcp(display_index, VCP.input_source(), code, opts)

      {:error, reason} ->
        {:error, reason}
    end
  end

  @doc """
  Sets the color preset.

  ## Examples

      iex> Exddcutil.set_color_preset(1, 0x05)
      :ok

      iex> Exddcutil.set_color_preset(1, "0x05")
      :ok

  """
  @spec set_color_preset(display_index(), term(), [common_opt()]) :: :ok | {:error, any()}
  def set_color_preset(display_index, value, opts \\ []) do
    set_vcp(display_index, VCP.color_preset(), value, opts)
  end

  @doc """
  Sets an arbitrary VCP code to a value.

  ## Examples

      iex> Exddcutil.set_vcp(1, 0x14, 6500)  # Color temperature
      :ok

  """
  @spec set_vcp(display_index(), non_neg_integer() | String.t(), non_neg_integer() | String.t(), [
          common_opt()
        ]) :: :ok | {:error, any()}
  def set_vcp(display_index, code, value, opts \\ []) do
    args =
      ["setvcp", VCP.to_code_arg(code), VCP.to_value_arg(value)] ++
        addressing_args(display_index, opts)

    case run_ddc(args, opts) do
      {:ok, _} -> :ok
      {:error, reason} -> {:error, reason}
    end
  end

  @doc """
  Reads an arbitrary VCP code.

  Returns a map with code, name, current value, and optionally max value and current label.

  ## Examples

      iex> Exddcutil.get_vcp(1, 0x10)
      {:ok, %{code: "0x10", name: "Brightness", current: 75, max: 100}}

  """
  @spec get_vcp(display_index(), non_neg_integer() | String.t(), [common_opt()]) ::
          {:ok, map()} | {:error, any()}
  def get_vcp(display_index, code, opts \\ []) do
    with {:ok, raw} <-
           run_ddc(
             ["getvcp", VCP.to_code_arg(code)] ++ addressing_args(display_index, opts),
             opts
           ) do
      {:ok, Parser.parse_getvcp(raw)}
    end
  end

  @doc "Gets the current brightness setting."
  @spec get_brightness(display_index(), [common_opt()]) :: {:ok, map()} | {:error, any()}
  def get_brightness(display_index, opts \\ []) do
    get_vcp(display_index, VCP.brightness(), opts)
  end

  @doc "Gets the current contrast setting."
  @spec get_contrast(display_index(), [common_opt()]) :: {:ok, map()} | {:error, any()}
  def get_contrast(display_index, opts \\ []) do
    get_vcp(display_index, VCP.contrast(), opts)
  end

  @doc "Gets the current red gain/drive."
  @spec get_red(display_index(), [common_opt()]) :: {:ok, map()} | {:error, any()}
  def get_red(display_index, opts \\ []) do
    get_vcp(display_index, VCP.red(), opts)
  end

  @doc "Gets the current green gain/drive."
  @spec get_green(display_index(), [common_opt()]) :: {:ok, map()} | {:error, any()}
  def get_green(display_index, opts \\ []) do
    get_vcp(display_index, VCP.green(), opts)
  end

  @doc "Gets the current blue gain/drive."
  @spec get_blue(display_index(), [common_opt()]) :: {:ok, map()} | {:error, any()}
  def get_blue(display_index, opts \\ []) do
    get_vcp(display_index, VCP.blue(), opts)
  end

  @doc "Gets the current screen orientation."
  @spec get_screen_orientation(display_index(), [common_opt()]) :: {:ok, map()} | {:error, any()}
  def get_screen_orientation(display_index, opts \\ []) do
    get_vcp(display_index, VCP.screen_orientation(), opts)
  end

  @doc """
  Gets the current input source.

  Returns a map with the current source code and label.

  ## Examples

      iex> Exddcutil.get_input_source(1)
      {:ok, %{code: "0x60", name: "Input Source", current: "0x0f", current_label: "DisplayPort-1"}}

  """
  @spec get_input_source(display_index(), [common_opt()]) :: {:ok, map()} | {:error, any()}
  def get_input_source(display_index, opts \\ []) do
    get_vcp(display_index, VCP.input_source(), opts)
  end

  @doc "Gets the current color preset/temperature."
  @spec get_color_preset(display_index(), [common_opt()]) :: {:ok, map()} | {:error, any()}
  def get_color_preset(display_index, opts \\ []) do
    get_vcp(display_index, VCP.color_preset(), opts)
  end

  @doc "Gets the current display mode."
  @spec get_display_mode(display_index(), [common_opt()]) :: {:ok, map()} | {:error, any()}
  def get_display_mode(display_index, opts \\ []) do
    get_vcp(display_index, VCP.display_mode(), opts)
  end

  defp addressing_args(display_index, opts) do
    []
    |> maybe_put_opt("--display", display_index)
    |> maybe_put_opt("--bus", opts[:bus])
  end

  defp maybe_put_opt(args, _flag, nil), do: args
  defp maybe_put_opt(args, flag, value), do: args ++ [flag, to_string(value)]

  @spec run_ddc([String.t()], [common_opt()]) :: {:ok, String.t()} | {:error, any()}
  def run_ddc(args, opts \\ []) do
    runner = opts[:runner] || Application.get_env(:exddcutil, :runner, SystemRunner)

    case runner.run(args) do
      {:ok, out} -> {:ok, out}
      {:error, reason} -> {:error, reason}
    end
  end
end