gens

-module(gens).
-compile([no_auto_import, nowarn_unused_vars, nowarn_unused_function, nowarn_nomatch]).
-define(FILEPATH, "src/gens.gleam").
-export([get/1, gen/2, combine/2, from_list/1, list_repeat/1, merge/3, new/0, take/2, map/2, filter/2, drop/2, from_lazy_list/1, zip/2, list_zip/2]).
-export_type([generator/2, lazy_list/1]).

-if(?OTP_RELEASE >= 27).
-define(MODULEDOC(Str), -moduledoc(Str)).
-define(DOC(Str), -doc(Str)).
-else.
-define(MODULEDOC(Str), -compile([])).
-define(DOC(Str), -compile([])).
-endif.

-type generator(DTS, DTT) :: {generator,
        DTT,
        fun((DTT) -> gleam@option:option({DTS, DTT}))}.

-opaque lazy_list(DTU) :: {lazy_list,
        integer(),
        fun((integer()) -> DTU),
        fun((integer()) -> boolean())}.

-file("src/gens.gleam", 19).
?DOC(
    " Returns the next element of a generator and the updated gen\n"
    " ```gleam\n"
    " let counter =\n"
    "   Generator(state: 0, next: fn(c) { Some(#(c, c + 1)) })\n"
    " case get(counter).0 {\n"
    "   None -> Nil\n"
    "   Some(x) -> echo x // -> 0\n"
    " }\n"
    " ```\n"
).
-spec get(generator(DTV, DTW)) -> {gleam@option:option(DTV),
    generator(DTV, DTW)}.
get(G) ->
    case (erlang:element(3, G))(erlang:element(2, G)) of
        none ->
            {none, G};

        {some, {X, S}} ->
            {{some, X}, {generator, S, erlang:element(3, G)}}
    end.

-file("src/gens.gleam", 27).
?DOC(" Tail recursive function for gen\n").
-spec gen_acc(generator(DUC, DUD), integer(), list(DUC)) -> {list(DUC),
    generator(DUC, DUD)}.
gen_acc(G, N, Ls) ->
    case N > 0 of
        false ->
            {lists:reverse(Ls), G};

        true ->
            case get(G) of
                {none, _} ->
                    {lists:reverse(Ls), G};

                {{some, X}, G2} ->
                    gen_acc(G2, N - 1, [X | Ls])
            end
    end.

-file("src/gens.gleam", 49).
?DOC(
    " Generates at most n elements and returns the updated gen\n"
    " ```gleam\n"
    " let counter =\n"
    "   Generator(state: 0, next: fn(c) { Some(#(c, c + 1)) })\n"
    " let #(nums, _) = gen(counter, 5)\n"
    " echo nums // -> [0, 1, 2, 3, 4]\n"
    " ```\n"
).
-spec gen(generator(DUK, DUL), integer()) -> {list(DUK), generator(DUK, DUL)}.
gen(G, N) ->
    gen_acc(G, N, []).

-file("src/gens.gleam", 65).
?DOC(
    " Combines two generators into one, advancing them separately\n"
    " ```gleam\n"
    " let two_powers =\n"
    "   Generator(state: 1, next: fn(p) { Some(#(p, p * 2)) })\n"
    " let bellow_three =\n"
    "   Generator(state: 0, next: fn(n) { Some(#(n < 3, n + 1)) })\n"
    "\n"
    " let z = combine(two_powers, bellow_three)\n"
    " let #(res, _) = gen(z, 5)\n"
    " echo res\n"
    " // -> [#(1, True), #(2, True), #(4, True), #(8, False), #(16, False)]\n"
    " ```\n"
).
-spec combine(generator(DUR, DUS), generator(DUV, DUW)) -> generator({DUR, DUV}, {DUS,
    DUW}).
combine(G1, G2) ->
    {generator,
        {erlang:element(2, G1), erlang:element(2, G2)},
        fun(State) ->
            {State1, State2} = State,
            Res1 = (erlang:element(3, G1))(State1),
            Res2 = (erlang:element(3, G2))(State2),
            case {Res1, Res2} of
                {{some, {X, State3}}, {some, {Y, State4}}} ->
                    {some, {{X, Y}, {State3, State4}}};

                {_, _} ->
                    none
            end
        end}.

-file("src/gens.gleam", 103).
?DOC(
    " Generates the lists elements\n"
    " ```gleam\n"
    " let gen_fruit = from_list([\"apple\", \"banana\", \"orange\"])\n"
    " let #(fruit1, gen_fruit2) = get(gen_fruit)\n"
    " echo fruit1\n"
    " // -> Some(\"apple\")\n"
    " ```\n"
    " ```gleam\n"
    " let #(fruit2, gen_fruit3) = get(gen_fruit2)\n"
    " echo fruit2\n"
    " // -> Some(\"banana\")\n"
    " ```\n"
    " ```gleam\n"
    " let #(fruit3, gen_fruit4) = get(gen_fruit3)\n"
    " echo fruit3\n"
    " // -> Some(\"orange\")\n"
    " ```\n"
    " ```gleam\n"
    " let #(fruit4, _) = get(gen_fruit4)\n"
    " echo fruit4\n"
    " // -> None\n"
    " ```\n"
).
-spec from_list(list(DVB)) -> generator(DVB, list(DVB)).
from_list(L) ->
    {generator, L, fun(Ls) -> case Ls of
                [] ->
                    none;

                [X | Rest] ->
                    {some, {X, Rest}}
            end end}.

-file("src/gens.gleam", 119).
?DOC(
    " Generates the lists elements on repeat\n"
    " ```gleam\n"
    " let gen_fruit = list_repeat([\"apple\", \"banana\", \"orange\"])\n"
    " let #(fruits, _) = gen(gen_fruit, 5)\n"
    " echo fruits\n"
    " // -> [\"apple\", \"banana\", \"orange\", \"apple\", \"banana\"]\n"
    " ```\n"
).
-spec list_repeat(list(DVG)) -> generator(DVG, {list(DVG), list(DVG)}).
list_repeat(L) ->
    {generator,
        {L, L},
        fun(List_pair) ->
            {Current, Original} = List_pair,
            case Current of
                [] ->
                    none;

                [X | Rest] ->
                    case Rest of
                        [] ->
                            {some, {X, {Original, Original}}};

                        _ ->
                            {some, {X, {Rest, Original}}}
                    end
            end
        end}.

-file("src/gens.gleam", 160).
?DOC(
    " Merges two `sorted` generators into one\n"
    " ```gleam\n"
    " let counter1 = Generator(0, fn(c) { Some(#(c, c + 1)) })\n"
    " let counter2 = Generator(0, fn(c) { Some(#(c, c + 2)) })\n"
    " let merged = merge(counter1, counter2, int.compare)\n"
    " merged \n"
    " |> gen(8) \n"
    " |> echo\n"
    " // -> #([0, 0, 1, 2, 2, 3, 4, 4], Generator(#(5, 6), fn() { ... }))\n"
    " ```\n"
).
-spec merge(
    generator(DVR, DVS),
    generator(DVR, DVV),
    fun((DVR, DVR) -> gleam@order:order())
) -> generator(DVR, {DVS, DVV}).
merge(G1, G2, Comp) ->
    {generator,
        {erlang:element(2, G1), erlang:element(2, G2)},
        fun(S) ->
            {State1, State2} = S,
            case {(erlang:element(3, G1))(State1),
                (erlang:element(3, G2))(State2)} of
                {{some, {X1, St1}}, {some, {X2, St2}}} ->
                    case Comp(X1, X2) of
                        gt ->
                            {some, {X2, {State1, St2}}};

                        _ ->
                            {some, {X1, {St1, State2}}}
                    end;

                {{some, {X1@1, St1@1}}, none} ->
                    {some, {X1@1, {St1@1, State2}}};

                {none, {some, {X2@1, St2@1}}} ->
                    {some, {X2@1, {State1, St2@1}}};

                {none, none} ->
                    none
            end
        end}.

-file("src/gens.gleam", 189).
?DOC(
    " Default LazyList for the list of `natural numbers` [0..]\n"
    " ```gleam\n"
    " new() |> take(5)\n"
    " // -> [0, 1, 2, 3, 4]\n"
    " ```\n"
).
-spec new() -> lazy_list(integer()).
new() ->
    {lazy_list, 0, fun(X) -> X end, fun(_) -> true end}.

-file("src/gens.gleam", 194).
?DOC(" `Tail recursive` function for **take**\n").
-spec take_acc(
    integer(),
    integer(),
    integer(),
    fun((integer()) -> DWB),
    fun((integer()) -> boolean()),
    list(DWB)
) -> list(DWB).
take_acc(Index, Step, Total, Fmap, Filt, Acc) ->
    case Step < Total of
        false ->
            _pipe = Acc,
            lists:reverse(_pipe);

        true ->
            case Filt(Index) of
                false ->
                    take_acc(Index + 1, Step, Total, Fmap, Filt, Acc);

                true ->
                    case Step >= 0 of
                        false ->
                            take_acc(
                                Index + 1,
                                Step + 1,
                                Total,
                                Fmap,
                                Filt,
                                Acc
                            );

                        true ->
                            take_acc(
                                Index + 1,
                                Step + 1,
                                Total,
                                Fmap,
                                Filt,
                                [Fmap(Index) | Acc]
                            )
                    end
            end
    end.

-file("src/gens.gleam", 225).
?DOC(
    " **Takes** a `finite` number of elements from a LazyList\n"
    " ```gleam\n"
    " take(new(), 5)\n"
    " // -> [0, 1, 2, 3, 4]\n"
    " ```\n"
).
-spec take(lazy_list(DWE), integer()) -> list(DWE).
take(Ga, N) ->
    case Ga of
        {lazy_list, Index, Amap, Afilt} ->
            take_acc(Index, 0, N, Amap, Afilt, [])
    end.

-file("src/gens.gleam", 239).
?DOC(
    " **Maps** each element of the takeerated list\n"
    " ```gleam\n"
    " new()\n"
    " |> map(fn(x) { x + 3 })\n"
    " |> map(int.to_string)\n"
    " |> take(5)\n"
    " // -> [\"3\", \"4\", \"5\", \"6\", \"7\"]\n"
    " ```\n"
).
-spec map(lazy_list(DWH), fun((DWH) -> DWJ)) -> lazy_list(DWJ).
map(Ga, F) ->
    case Ga of
        {lazy_list, Index, Amap, Afilt} ->
            {lazy_list, Index, fun(N) -> F(Amap(N)) end, Afilt}
    end.

-file("src/gens.gleam", 253).
?DOC(
    " **Filters** elements from the takeerated list\n"
    " ```gleam\n"
    " new()\n"
    " |> filter(fn(x) { x % 2 == 0 })\n"
    " |> filter(fn(x) { x != 4 })\n"
    " |> take(5)\n"
    " // -> [0, 2, 6, 8, 10]\n"
    " ```\n"
).
-spec filter(lazy_list(DWL), fun((DWL) -> boolean())) -> lazy_list(DWL).
filter(Ga, F) ->
    case Ga of
        {lazy_list, Index, Amap, Afilt} ->
            {lazy_list, Index, Amap, fun(N) -> Afilt(N) andalso F(Amap(N)) end}
    end.

-file("src/gens.gleam", 261).
-spec advance(integer(), integer(), fun((integer()) -> boolean())) -> integer().
advance(Index, Steps, Filt) ->
    case Steps >= 0 of
        false ->
            Index - 1;

        true ->
            case Filt(Index) of
                false ->
                    advance(Index + 1, Steps, Filt);

                true ->
                    advance(Index + 1, Steps - 1, Filt)
            end
    end.

-file("src/gens.gleam", 287).
?DOC(
    " **Drops** the first n elements of a LazyList\n"
    " ```gleam\n"
    " new()                   // [0, 1, 2, 3, 4..]\n"
    " |> drop(4)              // [4, 5, 6, 7..]\n"
    " |> filter(int.is_even)  // [4, 6, 8..]\n"
    " |> take(5)\n"
    " // -> [4, 6, 8, 10, 12]\n"
    " ```\n"
    " ```gleam\n"
    " new()                   // [0, 1, 2, 3, 4..]\n"
    " |> filter(int.is_even)  // [0, 2, 4, 6, 8..]\n"
    " |> drop(4)              // [8, 10, 12..]\n"
    " |> take(5)\n"
    " // -> [8, 10, 12, 14, 16]\n"
    " ```\n"
).
-spec drop(lazy_list(DWO), integer()) -> lazy_list(DWO).
drop(Ga, Steps) ->
    case Steps >= 0 of
        false ->
            Ga;

        true ->
            case Ga of
                {lazy_list, Index, Amap, Afilt} ->
                    {lazy_list, advance(Index, Steps, Afilt), Amap, Afilt}
            end
    end.

-file("src/gens.gleam", 141).
?DOC(
    " Generates elements from the lazy list\n"
    " ```gleam\n"
    " let infinite_list = new() |> drop(3) |> map(fn(x) { x * 10 })\n"
    " let ten_gen = from_lazy_list(infinite_list)\n"
    " let #(res, _) = gen(ten_gen, 10)\n"
    " echo res\n"
    " // -> [30, 40, 50, 60, 70, 80, 90, 100, 110, 120]\n"
    " ```\n"
).
-spec from_lazy_list(lazy_list(DVM)) -> generator(DVM, lazy_list(DVM)).
from_lazy_list(L) ->
    {generator, L, fun(Ls) -> case take(Ls, 1) of
                [] ->
                    none;

                [X | _] ->
                    {some,
                        {X,
                            begin
                                _pipe = Ls,
                                drop(_pipe, 1)
                            end}}
            end end}.

-file("src/gens.gleam", 309).
?DOC(
    " **Zips** two LazyLists into one\n"
    " - The resulting index is the maximum of the two takes \n"
    " - The filters get combined\n"
    " - For separate indexes, do `list.zip(take(g1,  n), take(g2, n))`\n"
    " ```gleam\n"
    " let g1 = new() |> map(fn(x) { x + 2 })\n"
    " let g2 = new() |> filter(int.is_even)\n"
    " zip(g1, g2)\n"
    " |> take(3)\n"
    " // -> [#(2, 0), #(4, 2), #(6, 4)]\n"
    " ```\n"
).
-spec zip(lazy_list(DWR), lazy_list(DWT)) -> lazy_list({DWR, DWT}).
zip(Ga, Gb) ->
    {lazy_list, Aindex, Amap, Afilt} = Ga,
    {lazy_list, Bindex, Bmap, Bfilt} = Gb,
    {lazy_list,
        gleam@int:max(Aindex, Bindex),
        fun(N) -> {Amap(N), Bmap(N)} end,
        fun(N@1) -> Afilt(N@1) andalso Bfilt(N@1) end}.

-file("src/gens.gleam", 323).
?DOC(
    " **Zips** a list with an infinite list\n"
    " ```gleam\n"
    " [\"a\", \"b\", \"c\"] \n"
    " |> list_zip(new())\n"
    " // -> [#(\"a\", 0), #(\"b\", 1), #(\"c\", 2)]\n"
    " ```\n"
).
-spec list_zip(list(DWW), lazy_list(DWY)) -> list({DWW, DWY}).
list_zip(La, Gb) ->
    gleam@list:zip(La, take(Gb, erlang:length(La))).