a.ex

defmodule WrangleTest.Disabled do
  use Wrangle

  plug :serve

  decide :service_available?, do: false
end

# compiled decision tree

defp(do_decide(:handle_service_not_available, var!(conn))) do
  Plug.Conn.resp(var!(conn), 503, "Service not available.")
end

b.ex

defmodule WrangleTest.Simple do
  use Wrangle

  plug :serve

  handle :ok, _ do
    "HELLO!"
  end
end

# compiled decision tree

defp(do_decide(:handle_ok, var!(conn))) do
  content = case(var!(conn)) do
    _ ->
      "HELLO!"
  end
  Plug.Conn.resp(var!(conn), 200, content)
end
defp(do_decide(:handle_precondition_failed, var!(conn))) do
  Plug.Conn.resp(var!(conn), 412, "Precondition failed.")
end
defp(do_decide(:if_match_exists?, var!(conn))) do
  if(has_header(var!(conn), "if-match")) do
    if(var!(conn).assigns().headers()["if-match"] == "*") do
      do_decide(:if_unmodified_since_exists?, var!(conn))
    else
      do_decide(:handle_precondition_failed, var!(conn))
    end
  else
    do_decide(:if_unmodified_since_exists?, var!(conn))
  end
end
defp(do_decide(:if_none_match_exists?, var!(conn))) do
  if(has_header(var!(conn), "if-none-match")) do
    if(var!(conn).assigns().headers()["if-none-match"] == "*") do
      if(var!(conn).method() in ["GET", "HEAD"]) do
        Plug.Conn.resp(var!(conn), 304, "")
      else
        do_decide(:handle_precondition_failed, var!(conn))
      end
    else
      do_decide(:handle_ok, var!(conn))
    end
  else
    do_decide(:handle_ok, var!(conn))
  end
end
defp(do_decide(:if_unmodified_since_exists?, var!(conn))) do
  if(has_header(var!(conn), "if-unmodified-since")) do
    case(handle_decision(var!(conn), (
      datestring = to_char_list(var!(conn).assigns().headers()["if-unmodified-since"])
      case(:httpd_util.convert_request_date(datestring)) do
        :bad_date ->
          false
        date ->
          {true, assign(var!(conn), :if_unmodified_since_date, date)}
      end
    ))) do
      {true, var!(conn)} ->
        do_decide(:handle_precondition_failed, var!(conn))
      {false, var!(conn)} ->
        do_decide(:if_none_match_exists?, var!(conn))
    end
  else
    do_decide(:if_none_match_exists?, var!(conn))
  end
end
defp(do_decide(:known_method?, var!(conn))) do
  if(var!(conn).method() in @known_methods) do
    if(var!(conn).method() in @allowed_methods) do
      if(var!(conn).method() == "OPTIONS") do
        Plug.Conn.resp(var!(conn), 200, "")
      else
        case(handle_decision(var!(conn), if(var!(conn).assigns().headers()["accept"]) do
          true
        else
          {false, assign(var!(conn), :media_type, ConNeg.find_best(:accept, "*/*", @available_media_types))}
        end)) do
          {true, var!(conn)} ->
            case(handle_decision(var!(conn), (
              type = ConNeg.find_best(:accept, var!(conn).assigns().headers()["accept"], @available_media_types)
              {!is_nil(type), assign(var!(conn), :media_type, type)}
            ))) do
              {true, var!(conn)} ->
                do_decide(:if_match_exists?, var!(conn))
              {false, var!(conn)} ->
                Plug.Conn.resp(var!(conn), 406, "No acceptable resource available.")
            end
          {false, var!(conn)} ->
            do_decide(:if_match_exists?, var!(conn))
        end
      end
    else
      Plug.Conn.resp(var!(conn), 405, "Method not allowed.")
    end
  else
    Plug.Conn.resp(var!(conn), 501, "Unknown method.")
  end
end

c.ex

defmodule WrangleTest.R do
  use Wrangle

  plug :serve

  def etag(_conn) do
    1635
  end

  @available_media_types ["text/html", "application/json"]
  @available_charsets ["utf-8"]

  handle :ok, %Plug.Conn{assigns: %{media_type: "text/html"}} do
    "HELLO"
  end

  handle :ok, %Plug.Conn{assigns: %{media_type: "application/json"}} do
    ~s({"message": "HELLO"})
  end

  def last_modified(_conn) do
    {{2014, 12, 13}, {11, 36, 32}}
  end
end

# compiled decision tree

defp(do_decide(:accept_charset_exists?, var!(conn))) do
  if(has_header(var!(conn), "accept-charset")) do
    case(handle_decision(var!(conn), (
      charset = ConNeg.find_best(:charset, var!(conn).assigns().headers()["accept-charset"], @available_charsets)
      {!is_nil(charset), assign(var!(conn), :charset, charset)}
    ))) do
      {true, var!(conn)} ->
        do_decide(:if_match_exists?, var!(conn))
      {false, var!(conn)} ->
        do_decide(:handle_not_acceptable, var!(conn))
    end
  else
    do_decide(:if_match_exists?, var!(conn))
  end
end
defp(do_decide(:handle_not_acceptable, var!(conn))) do
  Plug.Conn.resp(var!(conn), 406, "No acceptable resource available.")
end
defp(do_decide(:handle_not_modified, var!(conn))) do
  Plug.Conn.resp(var!(conn), 304, "")
end
defp(do_decide(:handle_ok, var!(conn))) do
  content = case(var!(conn)) do
    %Plug.Conn{assigns: %{media_type: "text/html"}} ->
      "HELLO"
    %Plug.Conn{assigns: %{media_type: "application/json"}} ->
      ~s"{\"message\": \"HELLO\"}"
  end
  Plug.Conn.resp(var!(conn), 200, content)
end
defp(do_decide(:handle_precondition_failed, var!(conn))) do
  Plug.Conn.resp(var!(conn), 412, "Precondition failed.")
end
defp(do_decide(:if_match_exists?, var!(conn))) do
  if(has_header(var!(conn), "if-match")) do
    if(var!(conn).assigns().headers()["if-match"] == "*") do
      do_decide(:if_unmodified_since_exists?, var!(conn))
    else
      case(handle_decision(var!(conn), (
        etag = format_etag(etag(var!(conn)))
        {etag == var!(conn).assigns().headers()["if-match"], assign(var!(conn), :etag, etag)}
      ))) do
        {true, var!(conn)} ->
          do_decide(:if_unmodified_since_exists?, var!(conn))
        {false, var!(conn)} ->
          do_decide(:handle_precondition_failed, var!(conn))
      end
    end
  else
    do_decide(:if_unmodified_since_exists?, var!(conn))
  end
end
defp(do_decide(:if_modified_since_exists?, var!(conn))) do
  if(has_header(var!(conn), "if-modified-since")) do
    case(handle_decision(var!(conn), (
      datestring = to_char_list(var!(conn).assigns().headers()["if-modified-since"])
      case(:httpd_util.convert_request_date(datestring)) do
        :bad_date ->
          false
        date ->
          {true, assign(var!(conn), :if_modified_since_date, date)}
      end
    ))) do
      {true, var!(conn)} ->
        case(handle_decision(var!(conn), case(last_modified(var!(conn))) do
          nil ->
            true
          last_modified ->
            modsincedate = var!(conn).assigns()[:if_modified_since_date]
            case(last_modified == modsincedate) do
              true ->
                false
              false ->
                {true, assign(var!(conn), :last_modified, last_modified)}
            end
        end)) do
          {true, var!(conn)} ->
            do_decide(:handle_ok, var!(conn))
          {false, var!(conn)} ->
            do_decide(:handle_not_modified, var!(conn))
        end
      {false, var!(conn)} ->
        do_decide(:handle_ok, var!(conn))
    end
  else
    do_decide(:handle_ok, var!(conn))
  end
end
defp(do_decide(:if_none_match?, var!(conn))) do
  if(var!(conn).method() in ["GET", "HEAD"]) do
    do_decide(:handle_not_modified, var!(conn))
  else
    do_decide(:handle_precondition_failed, var!(conn))
  end
end
defp(do_decide(:if_none_match_exists?, var!(conn))) do
  if(has_header(var!(conn), "if-none-match")) do
    if(var!(conn).assigns().headers()["if-none-match"] == "*") do
      do_decide(:if_none_match?, var!(conn))
    else
      case(handle_decision(var!(conn), (
        etag = format_etag(etag(var!(conn)))
        {etag == var!(conn).assigns().headers()["if-none-match"], assign(var!(conn), :etag, etag)}
      ))) do
        {true, var!(conn)} ->
          do_decide(:if_none_match?, var!(conn))
        {false, var!(conn)} ->
          do_decide(:if_modified_since_exists?, var!(conn))
      end
    end
  else
    do_decide(:if_modified_since_exists?, var!(conn))
  end
end
defp(do_decide(:if_unmodified_since_exists?, var!(conn))) do
  if(has_header(var!(conn), "if-unmodified-since")) do
    case(handle_decision(var!(conn), (
      datestring = to_char_list(var!(conn).assigns().headers()["if-unmodified-since"])
      case(:httpd_util.convert_request_date(datestring)) do
        :bad_date ->
          false
        date ->
          {true, assign(var!(conn), :if_unmodified_since_date, date)}
      end
    ))) do
      {true, var!(conn)} ->
        case(handle_decision(var!(conn), case(last_modified(var!(conn))) do
          nil ->
            true
          last_modified ->
            unmodsincedate = var!(conn).assigns()[:if_unmodified_since_date]
            case(last_modified == unmodsincedate) do
              true ->
                {false, assign(var!(conn), :last_modified, last_modified)}
              false ->
                true
            end
        end)) do
          {true, var!(conn)} ->
            do_decide(:handle_precondition_failed, var!(conn))
          {false, var!(conn)} ->
            do_decide(:if_none_match_exists?, var!(conn))
        end
      {false, var!(conn)} ->
        do_decide(:if_none_match_exists?, var!(conn))
    end
  else
    do_decide(:if_none_match_exists?, var!(conn))
  end
end
defp(do_decide(:known_method?, var!(conn))) do
  if(var!(conn).method() in @known_methods) do
    if(var!(conn).method() in @allowed_methods) do
      if(var!(conn).method() == "OPTIONS") do
        Plug.Conn.resp(var!(conn), 200, "")
      else
        case(handle_decision(var!(conn), if(var!(conn).assigns().headers()["accept"]) do
          true
        else
          {false, assign(var!(conn), :media_type, ConNeg.find_best(:accept, "*/*", @available_media_types))}
        end)) do
          {true, var!(conn)} ->
            case(handle_decision(var!(conn), (
              type = ConNeg.find_best(:accept, var!(conn).assigns().headers()["accept"], @available_media_types)
              {!is_nil(type), assign(var!(conn), :media_type, type)}
            ))) do
              {true, var!(conn)} ->
                do_decide(:accept_charset_exists?, var!(conn))
              {false, var!(conn)} ->
                do_decide(:handle_not_acceptable, var!(conn))
            end
          {false, var!(conn)} ->
            do_decide(:accept_charset_exists?, var!(conn))
        end
      end
    else
      Plug.Conn.resp(var!(conn), 405, "Method not allowed.")
    end
  else
    Plug.Conn.resp(var!(conn), 501, "Unknown method.")
  end
end