-module(rexen@nfa@machine).
-compile([no_auto_import, nowarn_unused_vars, nowarn_unused_function, nowarn_nomatch]).

-export([new/0, set_initial_state/2, set_ending_states/2, add_state/2, declare_states/2, add_transition/4, evaluate/2]).
-export_type([nfa/0, stack_value/0]).

-type nfa() :: {nfa,
        gleam@dict:dict(binary(), rexen@nfa@state:state()),
        binary(),
        list(binary())}.

-type stack_value() :: {stack_value, integer(), rexen@nfa@state:state()}.

-file("src/rexen/nfa/machine.gleam", 14).
-spec new() -> nfa().
new() ->
    {nfa, maps:new(), <<""/utf8>>, []}.

-file("src/rexen/nfa/machine.gleam", 18).
-spec set_initial_state(nfa(), binary()) -> nfa().
set_initial_state(Nfa, State) ->
    {nfa, erlang:element(2, Nfa), State, erlang:element(4, Nfa)}.

-file("src/rexen/nfa/machine.gleam", 26).
-spec set_ending_states(nfa(), list(binary())) -> nfa().
set_ending_states(Nfa, Values) ->
    {nfa, erlang:element(2, Nfa), erlang:element(3, Nfa), Values}.

-file("src/rexen/nfa/machine.gleam", 34).
-spec add_state(nfa(), binary()) -> nfa().
add_state(Nfa, Name) ->
    {nfa,
        gleam@dict:insert(
            erlang:element(2, Nfa),
            Name,
            rexen@nfa@state:new(Name)
        ),
        erlang:element(3, Nfa),
        erlang:element(4, Nfa)}.

-file("src/rexen/nfa/machine.gleam", 42).
-spec declare_states(nfa(), list(binary())) -> nfa().
declare_states(Nfa, Names) ->
    case Names of
        [] ->
            Nfa;

        [Name | Rest] ->
            declare_states(add_state(Nfa, Name), Rest)
    end.

-file("src/rexen/nfa/machine.gleam", 49).
-spec add_transition(nfa(), binary(), binary(), rexen@nfa@state:matcher()) -> nfa().
add_transition(Nfa, From, To, Matcher) ->
    _assert_subject = gleam_stdlib:map_get(erlang:element(2, Nfa), From),
    {ok, From_state} = case _assert_subject of
        {ok, _} -> _assert_subject;
        _assert_fail ->
            erlang:error(#{gleam_error => let_assert,
                        message => <<"Pattern match failed, no pattern matched the value."/utf8>>,
                        value => _assert_fail,
                        module => <<"rexen/nfa/machine"/utf8>>,
                        function => <<"add_transition"/utf8>>,
                        line => 55})
    end,
    _assert_subject@1 = gleam_stdlib:map_get(erlang:element(2, Nfa), To),
    {ok, _} = case _assert_subject@1 of
        {ok, _} -> _assert_subject@1;
        _assert_fail@1 ->
            erlang:error(#{gleam_error => let_assert,
                        message => <<"Pattern match failed, no pattern matched the value."/utf8>>,
                        value => _assert_fail@1,
                        module => <<"rexen/nfa/machine"/utf8>>,
                        function => <<"add_transition"/utf8>>,
                        line => 56})
    end,
    Transitions = rexen@nfa@state:add_transition(
        erlang:element(3, From_state),
        {Matcher, To}
    ),
    New_state = {state, erlang:element(2, From_state), Transitions},
    {nfa,
        gleam@dict:insert(erlang:element(2, Nfa), From, New_state),
        erlang:element(3, Nfa),
        erlang:element(4, Nfa)}.

-file("src/rexen/nfa/machine.gleam", 110).
-spec process_transitions(
    nfa(),
    list({rexen@nfa@state:matcher(), binary()}),
    list(stack_value()),
    stack_value(),
    binary()
) -> list(stack_value()).
process_transitions(Nfa, Transitions, Stack, Stkv, Char) ->
    case Transitions of
        [] ->
            Stack;

        [{Matcher, Name} | Rest] ->
            case rexen@nfa@state:matches(Matcher, Char) of
                false ->
                    process_transitions(Nfa, Rest, Stack, Stkv, Char);

                true ->
                    Index = case rexen@nfa@state:is_epsilon(Matcher) of
                        true ->
                            erlang:element(2, Stkv);

                        false ->
                            erlang:element(2, Stkv) + 1
                    end,
                    _assert_subject = gleam_stdlib:map_get(
                        erlang:element(2, Nfa),
                        Name
                    ),
                    {ok, To} = case _assert_subject of
                        {ok, _} -> _assert_subject;
                        _assert_fail ->
                            erlang:error(#{gleam_error => let_assert,
                                        message => <<"Pattern match failed, no pattern matched the value."/utf8>>,
                                        value => _assert_fail,
                                        module => <<"rexen/nfa/machine"/utf8>>,
                                        function => <<"process_transitions"/utf8>>,
                                        line => 129})
                    end,
                    New_stack = lists:append(Stack, [{stack_value, Index, To}]),
                    process_transitions(Nfa, Rest, New_stack, Stkv, Char)
            end
    end.

-file("src/rexen/nfa/machine.gleam", 78).
-spec evaluate_loop(nfa(), binary(), list(stack_value())) -> boolean().
evaluate_loop(Nfa, Input, Stack) ->
    case Stack of
        [] ->
            false;

        [Value | Rest] ->
            case gleam@list:contains(
                erlang:element(4, Nfa),
                erlang:element(2, erlang:element(3, Value))
            ) of
                true ->
                    case string:length(Input) =:= erlang:element(2, Value) of
                        true ->
                            true;

                        false ->
                            Char = gleam@string:slice(
                                Input,
                                erlang:element(2, Value),
                                1
                            ),
                            New_stack = process_transitions(
                                Nfa,
                                erlang:element(3, erlang:element(3, Value)),
                                Rest,
                                Value,
                                Char
                            ),
                            evaluate_loop(Nfa, Input, New_stack)
                    end;

                false ->
                    Char@1 = gleam@string:slice(
                        Input,
                        erlang:element(2, Value),
                        1
                    ),
                    New_stack@1 = process_transitions(
                        Nfa,
                        erlang:element(3, erlang:element(3, Value)),
                        Rest,
                        Value,
                        Char@1
                    ),
                    evaluate_loop(Nfa, Input, New_stack@1)
            end
    end.

-file("src/rexen/nfa/machine.gleam", 72).
-spec evaluate(nfa(), binary()) -> boolean().
evaluate(Nfa, Input) ->
    _assert_subject = gleam_stdlib:map_get(
        erlang:element(2, Nfa),
        erlang:element(3, Nfa)
    ),
    {ok, S} = case _assert_subject of
        {ok, _} -> _assert_subject;
        _assert_fail ->
            erlang:error(#{gleam_error => let_assert,
                        message => <<"Pattern match failed, no pattern matched the value."/utf8>>,
                        value => _assert_fail,
                        module => <<"rexen/nfa/machine"/utf8>>,
                        function => <<"evaluate"/utf8>>,
                        line => 73})
    end,
    Stack = [{stack_value, 0, S}],
    evaluate_loop(Nfa, Input, Stack).