-module(outil).
-compile(no_auto_import).

-export([command/4, print_usage/1, print_usage_and_exit/1, parse_bool/1]).
-export_type([command/0, argument/0, opt/0, opt_value/0, command_return/1]).

-type command() :: {command,
        binary(),
        binary(),
        list(argument()),
        list(opt()),
        list(binary())}.

-type argument() :: {bool_argument, binary()} |
    {float_argument, binary()} |
    {int_argument, binary()} |
    {string_argument, binary()}.

-type opt() :: {opt,
        binary(),
        gleam@option:option(binary()),
        binary(),
        opt_value()}.

-type opt_value() :: bool_opt |
    {float_opt, float()} |
    {int_opt, integer()} |
    {string_opt, binary()}.

-type command_return(ESM) :: {command_line_error,
        outil@error:reason(),
        binary()} |
    {command_error, ESM} |
    {help, binary()}.

-spec command(binary(), binary(), list(binary()), fun((command()) -> ETC)) -> ETC.
command(Name, Description, Argv, Continue) ->
    Continue({command, Name, Description, [], [], Argv}).

-spec print_usage(command_return(any())) -> nil.
print_usage(Return) ->
    case Return of
        {command_line_error, _, Usage} ->
            gleam@io:println(Usage);

        {help, Usage@1} ->
            gleam@io:println(Usage@1);

        _ ->
            nil
    end.

-spec print_usage_and_exit(command_return(any())) -> nil.
print_usage_and_exit(Return) ->
    print_usage(Return),
    case Return of
        {command_line_error, _, _} ->
            erlang:halt(2);

        {command_error, _} ->
            erlang:halt(1);

        {help, _} ->
            erlang:halt(0)
    end.

-spec parse_bool(binary()) -> {ok, boolean()} | {error, nil}.
parse_bool(Arg) ->
    case Arg of
        <<"true"/utf8>> ->
            {ok, true};

        <<"false"/utf8>> ->
            {ok, false};

        _ ->
            {error, nil}
    end.