-module(gleam@iterator_test).
-compile(no_auto_import).

-export([to_from_list_test/0, take_test/0, fold_test/0, map_test/0, filter_test/0, repeat_test/0, cycle_test/0, unfold_test/0, range_test/0, drop_test/0]).

to_from_list_test() ->
    Test = fun(Subject) ->
        gleam@should:equal(
            gleam@iterator:to_list(gleam@iterator:from_list(Subject)),
            Subject
        )
    end,
    Test([]),
    Test([1]),
    Test([1, 2]),
    Test([1, 2, 4, 8]).

take_test() ->
    Test = fun(N, Subject) ->
        gleam@should:equal(
            gleam@iterator:take(gleam@iterator:from_list(Subject), N),
            gleam@list:take(Subject, N)
        )
    end,
    Test(0, []),
    Test(1, []),
    Test(-1, []),
    Test(0, [0]),
    Test(1, [0]),
    Test(-1, [0]),
    Test(0, [0, 1, 2, 3, 4]),
    Test(1, [0, 1, 2, 3, 4]),
    Test(2, [0, 1, 2, 3, 4]),
    Test(22, [0, 1, 2, 3, 4]).

fold_test() ->
    Test = fun(Subject, Acc, F) ->
        gleam@should:equal(
            gleam@iterator:fold(gleam@iterator:from_list(Subject), Acc, F),
            gleam@list:fold(Subject, Acc, F)
        )
    end,
    F1 = fun(E, Acc1) -> [E | Acc1] end,
    Test([], [], F1),
    Test([1], [], F1),
    Test([1, 2, 3], [], F1),
    Test([1, 2, 3, 4, 5, 6, 7, 8], [], F1).

map_test() ->
    Test = fun(Subject, F) ->
        gleam@should:equal(
            gleam@iterator:to_list(
                gleam@iterator:map(gleam@iterator:from_list(Subject), F)
            ),
            gleam@list:map(Subject, F)
        )
    end,
    F1 = fun(E) -> E * 2 end,
    Test([], F1),
    Test([1], F1),
    Test([1, 2, 3], F1),
    Test([1, 2, 3, 4, 5, 6, 7, 8], F1).

filter_test() ->
    Test = fun(Subject, F) ->
        gleam@should:equal(
            gleam@iterator:to_list(
                gleam@iterator:filter(gleam@iterator:from_list(Subject), F)
            ),
            gleam@list:filter(Subject, F)
        )
    end,
    Even = fun(X) -> (X rem 2) =:= 0 end,
    Test([], Even),
    Test([1], Even),
    Test([1, 2], Even),
    Test([1, 2, 3], Even),
    Test([1, 2, 3, 4], Even),
    Test([1, 2, 3, 4, 5], Even),
    Test([1, 2, 3, 4, 5, 6], Even).

repeat_test() ->
    gleam@should:equal(
        gleam@iterator:take(gleam@iterator:repeat(1), 5),
        [1, 1, 1, 1, 1]
    ).

cycle_test() ->
    gleam@should:equal(
        gleam@iterator:take(
            gleam@iterator:cycle(gleam@iterator:from_list([1, 2, 3])),
            9
        ),
        [1, 2, 3, 1, 2, 3, 1, 2, 3]
    ).

unfold_test() ->
    gleam@should:equal(
        gleam@iterator:take(
            gleam@iterator:unfold(2, fun(Acc) -> {next, Acc, Acc * 2} end),
            5
        ),
        [2, 4, 8, 16, 32]
    ),
    gleam@should:equal(
        gleam@iterator:take(gleam@iterator:unfold(2, fun(_) -> done end), 5),
        []
    ),
    gleam@should:equal(
        gleam@iterator:to_list(gleam@iterator:unfold(5, fun(N) -> case N of
                        0 ->
                            done;

                        N1 ->
                            {next, N1, N1 - 1}
                    end end)),
        [5, 4, 3, 2, 1]
    ).

range_test() ->
    Test = fun(A, B, Expected) ->
        gleam@should:equal(
            gleam@iterator:to_list(gleam@iterator:range(A, B)),
            Expected
        )
    end,
    Test(0, 0, []),
    Test(1, 1, []),
    Test(-1, -1, []),
    Test(0, 1, [0]),
    Test(0, 5, [0, 1, 2, 3, 4]),
    Test(1, -5, [1, 0, -1, -2, -3, -4]).

drop_test() ->
    gleam@should:equal(
        gleam@iterator:to_list(
            gleam@iterator:drop(gleam@iterator:range(0, 10), 5)
        ),
        [5, 6, 7, 8, 9]
    ).