-module(survey).
-compile([no_auto_import, nowarn_unused_vars, nowarn_unused_function, nowarn_nomatch]).

-export([new_question/5, new_confirmation/4, ask/2, ask_fn/3, ask_many_fn/3, ask_many/2]).
-export_type([survey/0, answer/0, ask_error/0]).

-type survey() :: {question,
        binary(),
        gleam@option:option(binary()),
        gleam@option:option(binary()),
        gleam@option:option(fun((binary()) -> boolean())),
        gleam@option:option(fun((binary()) -> binary()))} |
    {confirmation,
        binary(),
        gleam@option:option(binary()),
        gleam@option:option(boolean()),
        gleam@option:option(fun((boolean()) -> boolean()))}.

-type answer() :: {string_answer, binary()} |
    {bool_answer, boolean()} |
    {answer_error, ask_error()} |
    no_answer.

-type ask_error() :: input | invalid_type | validation.

-spec new_question(
    binary(),
    gleam@option:option(binary()),
    gleam@option:option(binary()),
    gleam@option:option(fun((binary()) -> boolean())),
    gleam@option:option(fun((binary()) -> binary()))
) -> survey().
new_question(Prompt, Help, Default, Validate, Transform) ->
    {question, Prompt, Help, Default, Validate, Transform}.

-spec new_confirmation(
    binary(),
    gleam@option:option(binary()),
    gleam@option:option(boolean()),
    gleam@option:option(fun((boolean()) -> boolean()))
) -> survey().
new_confirmation(Prompt, Help, Default, Transform) ->
    {confirmation, Prompt, Help, Default, Transform}.

-spec default_get_line(binary()) -> {ok, binary()} | {error, ask_error()}.
default_get_line(Prompt) ->
    case gleam_erlang_ffi:get_line(Prompt) of
        {ok, S} ->
            {ok, S};

        {error, _} ->
            {error, input}
    end.

-spec handle_transform(answer(), survey()) -> answer().
handle_transform(A, Q) ->
    case Q of
        {question, _, _, _, _, Transform} ->
            case Transform of
                none ->
                    A;

                {some, Tr} ->
                    case A of
                        {string_answer, S} ->
                            {string_answer, Tr(S)};

                        _ ->
                            {answer_error, invalid_type}
                    end
            end;

        {confirmation, _, _, _, Transform@1} ->
            case Transform@1 of
                none ->
                    A;

                {some, Tr@1} ->
                    case A of
                        {bool_answer, S@1} ->
                            {bool_answer, Tr@1(S@1)};

                        _ ->
                            {answer_error, invalid_type}
                    end
            end
    end.

-spec confirm_prompt(gleam@option:option(boolean())) -> binary().
confirm_prompt(Default) ->
    case Default of
        {some, Default_true} when Default_true ->
            <<" [Y/n] "/utf8>>;

        {some, _} ->
            <<" [y/N] "/utf8>>;

        none ->
            <<" [y/n] "/utf8>>
    end.

-spec handle_input(binary(), survey()) -> answer().
handle_input(Input, Q) ->
    _pipe = case Q of
        {question, _, _, _, Validate, _} ->
            Validate_fn = case Validate of
                {some, Val_fn} ->
                    Val_fn;

                none ->
                    fun(_) -> true end
            end,
            case Input of
                <<""/utf8>> ->
                    handle_default(Q);

                _ ->
                    case Validate_fn(Input) of
                        true ->
                            {string_answer, Input};

                        false ->
                            ask(Q, true)
                    end
            end;

        {confirmation, _, _, _, _} ->
            case Input of
                <<"Y"/utf8>> ->
                    {bool_answer, true};

                <<"y"/utf8>> ->
                    {bool_answer, true};

                <<"N"/utf8>> ->
                    {bool_answer, false};

                <<"n"/utf8>> ->
                    {bool_answer, false};

                <<""/utf8>> ->
                    handle_default(Q);

                _ ->
                    ask(Q, true)
            end
    end,
    handle_transform(_pipe, Q).

-spec ask(survey(), boolean()) -> answer().
ask(Q, Help) ->
    ask_fn(Q, fun default_get_line/1, Help).

-spec ask_fn(
    survey(),
    fun((binary()) -> {ok, binary()} | {error, ask_error()}),
    boolean()
) -> answer().
ask_fn(Q, Get_line, Help) ->
    Input = begin
        _pipe = (<<(case erlang:element(3, Q) of
                {some, Help_msg} when Help ->
                    <<Help_msg/binary, "\n"/utf8>>;

                none ->
                    <<""/utf8>>;

                {some, _} ->
                    <<""/utf8>>
            end)/binary, (case Q of
                {question, _, _, _, _, _} ->
                    <<(erlang:element(2, Q))/binary, " "/utf8>>;

                {confirmation, _, _, Default, _} ->
                    <<(erlang:element(2, Q))/binary,
                        (confirm_prompt(Default))/binary>>
            end)/binary>>),
        Get_line(_pipe)
    end,
    case Input of
        {ok, Result} ->
            _pipe@1 = Result,
            _pipe@2 = gleam@string:trim(_pipe@1),
            handle_input(_pipe@2, Q);

        {error, _} ->
            {answer_error, input}
    end.

-spec ask_many_loop(
    list({binary(), survey()}),
    list(fun((binary()) -> {ok, binary()} | {error, ask_error()})),
    boolean()
) -> list({binary(), answer()}).
ask_many_loop(Qs, Get_lines, Help) ->
    F = fun(Qs@1, Get_line, Get_lines@1) -> case Qs@1 of
            [] ->
                [];

            [{Key, Q}] ->
                [{Key, ask_fn(Q, Get_line, Help)}];

            [{Key@1, Q@1} | Tail] ->
                [{Key@1, ask_fn(Q@1, Get_line, Help)} |
                    ask_many_loop(Tail, Get_lines@1, Help)]
        end end,
    case Get_lines of
        [] ->
            F(Qs, fun default_get_line/1, []);

        [Get_line@1 | Get_lines_tail] ->
            F(Qs, Get_line@1, Get_lines_tail)
    end.

-spec ask_many_fn(
    list({binary(), survey()}),
    list(fun((binary()) -> {ok, binary()} | {error, ask_error()})),
    boolean()
) -> list({binary(), answer()}).
ask_many_fn(Qs, Get_lines, Help) ->
    ask_many_loop(Qs, Get_lines, Help).

-spec ask_many(list({binary(), survey()}), boolean()) -> list({binary(),
    answer()}).
ask_many(Qs, Help) ->
    ask_many_fn(Qs, [], Help).

-spec handle_default(survey()) -> answer().
handle_default(Q) ->
    case Q of
        {question, _, _, Default, _, _} ->
            case Default of
                {some, Def} ->
                    {string_answer, Def};

                none ->
                    ask(Q, true)
            end;

        {confirmation, _, _, Default@1, _} ->
            case Default@1 of
                {some, Def@1} ->
                    {bool_answer, Def@1};

                none ->
                    ask(Q, true)
            end
    end.