defmodule Raxol.Terminal.Parser.State.ManagerRefactored do
  @moduledoc """
  Refactored version of Terminal Parser State Manager using pattern matching
  instead of cond statements.

  This demonstrates Sprint 9's pattern matching improvements.
  """

  defstruct [
    :state,
    :params,
    :intermediate,
    :ignore,
    :osc_buffer,
    :dcs_buffer,
    :apc_buffer,
    :pm_buffer,
    :sos_buffer,
    :string_buffer,
    :string_terminator,
    :string_flags,
    :string_parser_state,
    :params_buffer,
    :intermediates_buffer,
    :payload_buffer,
    :final_byte,
    :designating_gset,
    :single_shift
  ]

  @type parser_state ::
          :ground
          | :escape
          | :csi_entry
          | :csi_param
          | :csi_intermediate
          | :csi_ignore
          | :osc_string
          | :dcs_entry
          | :dcs_param
          | :dcs_intermediate
          | :dcs_passthrough
          | :apc_string
          | :pm_string
          | :sos_string
          | :string

  @type t :: %__MODULE__{
          state: parser_state(),
          params: list(),
          intermediate: list()
          # ... other fields
        }

  # Character ranges
  # Unused constants (commented out since functions are commented out)
  # @c0_range 0x00..0x1F
  # @c1_range 0x80..0x9F
  # @printable_range 0x20..0x7E
  # @extended_range 0xA0..0xFF
  # @st 0x9C

  # Replace cond with pattern matching function heads

  # Ground state processing (commented out unused functions)
  # defp process_ground_state(manager, char) when char in @c0_range,
  #   do: handle_c0_control(manager, char)

  # defp process_ground_state(manager, char) when char in @c1_range,
  #   do: handle_c1_control(manager, char)

  # defp process_ground_state(manager, char) when char in @printable_range,
  #   do: handle_printable(manager, char)

  # defp process_ground_state(manager, char) when char in @extended_range,
  #   do: handle_extended(manager, char)

  # defp process_ground_state(manager, _char), do: manager

  # Escape state processing
  # defp process_escape_state(manager, char) when char in @c0_range,
  #   do: handle_c0_control(manager, char)

  # defp process_escape_state(manager, char) when char in @c1_range,
  #   do: handle_c1_control(manager, char)

  # defp process_escape_state(manager, char) when char in @printable_range,
  #   do: handle_escape_printable(manager, char)

  # defp process_escape_state(manager, char) when char in @extended_range,
  #   do: handle_escape_extended(manager, char)

  # defp process_escape_state(manager, _char), do: manager

  # CSI Entry state processing - using guards instead of cond
  # defp process_csi_entry_state(manager, char) when char in 0x30..0x3F//1,
  #   do: set_state(manager, :csi_param)

  # defp process_csi_entry_state(manager, char) when char in 0x20..0x2F//1,
  #   do: set_state(manager, :csi_intermediate)

  # defp process_csi_entry_state(manager, char) when char in 0x40..0x7E//1,
  #   do: set_state(manager, :ground)

  # defp process_csi_entry_state(manager, _char),
  #   do: set_state(manager, :csi_ignore)

  # CSI Param state processing
  # defp process_csi_param_state(manager, char) when char in 0x30..0x3F//1,
  #   do: manager

  # defp process_csi_param_state(manager, char) when char in 0x20..0x2F//1,
  #   do: set_state(manager, :csi_intermediate)

  # defp process_csi_param_state(manager, char) when char in 0x40..0x7E//1,
  #   do: set_state(manager, :ground)

  # defp process_csi_param_state(manager, _char),
  #   do: set_state(manager, :csi_ignore)

  # CSI Intermediate state processing
  # defp process_csi_intermediate_state(manager, char) when char in 0x20..0x2F//1,
  #   do: manager

  # defp process_csi_intermediate_state(manager, char) when char in 0x40..0x7E//1,
  #   do: set_state(manager, :ground)

  # defp process_csi_intermediate_state(manager, _char),
  #   do: set_state(manager, :csi_ignore)

  # CSI Ignore state - already uses if, but can be pattern matched
  # defp process_csi_ignore_state(manager, char) when char in 0x40..0x7E//1,
  #   do: set_state(manager, :ground)

  # defp process_csi_ignore_state(manager, _char), do: manager

  # DCS Entry state processing
  # defp process_dcs_entry_state(manager, char) when char in 0x30..0x3F//1,
  #   do: set_state(manager, :dcs_param)

  # defp process_dcs_entry_state(manager, char) when char in 0x20..0x2F//1,
  #   do: set_state(manager, :dcs_intermediate)

  # defp process_dcs_entry_state(manager, char) when char in 0x40..0x7E//1,
  #   do: set_state(manager, :dcs_passthrough)

  # defp process_dcs_entry_state(manager, _char),
  #   do: set_state(manager, :ground)

  # DCS Param state processing
  # defp process_dcs_param_state(manager, char) when char in 0x30..0x3F//1,
  #   do: manager

  # defp process_dcs_param_state(manager, char) when char in 0x20..0x2F//1,
  #   do: set_state(manager, :dcs_intermediate)

  # defp process_dcs_param_state(manager, char) when char in 0x40..0x7E//1,
  #   do: set_state(manager, :dcs_passthrough)

  # defp process_dcs_param_state(manager, _char),
  #   do: set_state(manager, :ground)

  # DCS Intermediate state processing
  # defp process_dcs_intermediate_state(manager, char) when char in 0x20..0x2F//1,
  #   do: manager

  # defp process_dcs_intermediate_state(manager, char) when char in 0x40..0x7E//1,
  #   do: set_state(manager, :dcs_passthrough)

  # defp process_dcs_intermediate_state(manager, _char),
  #   do: set_state(manager, :ground)

  # DCS Passthrough state - pattern match on ST character
  # defp process_dcs_passthrough_state(manager, @st),
  #   do: set_state(manager, :ground)

  # defp process_dcs_passthrough_state(manager, _char), do: manager

  # Example of refactoring nested if/else to with statement
  def parse_sequence(manager, input) do
    with {:ok, validated} <- validate_input(input),
         {:ok, preprocessed} <- preprocess(validated),
         {:ok, parsed} <- do_parse(manager, preprocessed) do
      {:ok, parsed}
    else
      {:error, _reason} = error -> error
    end
  end

  # Helper functions (stubs for demonstration - commented out unused functions)
  # defp set_state(manager, state), do: %{manager | state: state}
  # defp handle_c0_control(manager, _char), do: manager
  # defp handle_c1_control(manager, _char), do: manager
  # defp handle_printable(manager, _char), do: manager
  # defp handle_extended(manager, _char), do: manager
  # defp handle_escape_printable(manager, _char), do: manager
  # defp handle_escape_extended(manager, _char), do: manager

  defp validate_input(input), do: {:ok, input}
  defp preprocess(input), do: {:ok, input}
  defp do_parse(_manager, input), do: {:ok, input}
end
