-module(ask@equivalence).
-compile([no_auto_import, nowarn_unused_vars, nowarn_unused_function, nowarn_nomatch]).

-export([trivial/0, 'and'/2, 'or'/2, 'not'/1, list/1, pair/2, map_input/2]).

-spec trivial() -> fun((FLQ, FLQ) -> boolean()).
trivial() ->
    fun(_, _) -> true end.

-spec 'and'(fun((FLS, FLS) -> boolean()), fun((FLS, FLS) -> boolean())) -> fun((FLS, FLS) -> boolean()).
'and'(First, Second) ->
    fun(Value, Other) -> First(Value, Other) andalso Second(Value, Other) end.

-spec 'or'(fun((FLW, FLW) -> boolean()), fun((FLW, FLW) -> boolean())) -> fun((FLW, FLW) -> boolean()).
'or'(First, Second) ->
    fun(Value, Other) -> First(Value, Other) orelse Second(Value, Other) end.

-spec 'not'(fun((FMA, FMA) -> boolean())) -> fun((FMA, FMA) -> boolean()).
'not'(Eq) ->
    fun(Value, Other) -> not Eq(Value, Other) end.

-spec do_list(fun((FMD, FMD) -> boolean()), list(FMD), list(FMD), boolean()) -> boolean().
do_list(Eq, Values, Others, Acc) ->
    case {Values, Others} of
        {[], []} ->
            Acc;

        {[Value | Values@1], [Other | Others@1]} ->
            do_list(Eq, Values@1, Others@1, Acc andalso Eq(Value, Other));

        {_, _} ->
            false
    end.

-spec list(fun((FMH, FMH) -> boolean())) -> fun((list(FMH), list(FMH)) -> boolean()).
list(Eq) ->
    fun(Values, Others) ->
        gleam@bool:guard(
            erlang:length(Values) /= erlang:length(Others),
            false,
            fun() -> do_list(Eq, Values, Others, true) end
        )
    end.

-spec pair(fun((FML, FML) -> boolean()), fun((FMN, FMN) -> boolean())) -> fun(({FML,
    FMN}, {FML, FMN}) -> boolean()).
pair(First, Second) ->
    fun(Value, Other) -> case {Value, Other} of
            {{Value1, Value2}, {Other1, Other2}} ->
                First(Value1, Other1) andalso Second(Value2, Other2)
        end end.

-spec map_input(fun((FMQ, FMQ) -> boolean()), fun((FMS) -> FMQ)) -> fun((FMS, FMS) -> boolean()).
map_input(Eq, Fun) ->
    fun(Value, Other) -> Eq(Fun(Value), Fun(Other)) end.