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

-export([new/0, insert/2, get/2, keys/1, values/1, elements/1, update/2, add/2, subtract/2, unique_size/1, total/1, to_list/1, most_common/1, most_common_n/2, from_list/1, to_dict/1, from_dict/1]).
-export_type([counter/1]).

-opaque counter(OHQ) :: {counter, gleam@dict:dict(OHQ, integer())}.

-spec new() -> counter(any()).
new() ->
    {counter, gleam@dict:new()}.

-spec insert(counter(OHT), OHT) -> counter(OHT).
insert(Counter, Item) ->
    _pipe = erlang:element(2, Counter),
    _pipe@2 = gleam@dict:update(
        _pipe,
        Item,
        fun(Count) ->
            begin
                _pipe@1 = Count,
                gleam@option:unwrap(_pipe@1, 0)
            end
            + 1
        end
    ),
    {counter, _pipe@2}.

-spec get(counter(OHW), OHW) -> integer().
get(Counter, Item) ->
    _pipe = erlang:element(2, Counter),
    _pipe@1 = gleam@dict:get(_pipe, Item),
    gleam@result:unwrap(_pipe@1, 0).

-spec keys(counter(OIE)) -> list(OIE).
keys(Counter) ->
    _pipe = erlang:element(2, Counter),
    gleam@dict:keys(_pipe).

-spec values(counter(any())) -> list(integer()).
values(Counter) ->
    _pipe = erlang:element(2, Counter),
    gleam@dict:values(_pipe).

-spec prepend_repeated_item(OIN, integer(), list(OIN)) -> list(OIN).
prepend_repeated_item(Item, Times, Acc) ->
    gleam@bool:guard(
        Times =< 0,
        Acc,
        fun() -> prepend_repeated_item(Item, Times - 1, [Item | Acc]) end
    ).

-spec elements(counter(OIK)) -> list(OIK).
elements(Counter) ->
    _pipe = erlang:element(2, Counter),
    _pipe@1 = maps:to_list(_pipe),
    gleam@list:fold(
        _pipe@1,
        [],
        fun(Items, Item) ->
            prepend_repeated_item(
                erlang:element(1, Item),
                erlang:element(2, Item),
                Items
            )
        end
    ).

-spec update(counter(OIQ), list(OIQ)) -> counter(OIQ).
update(Counter, Items) ->
    gleam@list:fold(Items, Counter, fun(Counter@1, Item) -> _pipe = Counter@1,
            insert(_pipe, Item) end).

-spec add(counter(OIU), counter(OIU)) -> counter(OIU).
add(Counter_1, Counter_2) ->
    _pipe = gleam@dict:combine(
        erlang:element(2, Counter_1),
        erlang:element(2, Counter_2),
        fun gleam@int:add/2
    ),
    {counter, _pipe}.

-spec subtract(counter(OIY), counter(OIY)) -> counter(OIY).
subtract(Counter_1, Counter_2) ->
    Dict_1 = erlang:element(2, Counter_1),
    Dict_2 = erlang:element(2, Counter_2),
    Dict_2_exclusive = begin
        _pipe = Dict_2,
        gleam@dict:drop(_pipe, gleam@dict:keys(Dict_1))
    end,
    Dict_2_overlap = begin
        _pipe@1 = Dict_2,
        gleam@dict:drop(_pipe@1, gleam@dict:keys(Dict_2_exclusive))
    end,
    _pipe@2 = Dict_1,
    _pipe@3 = gleam@dict:combine(
        _pipe@2,
        Dict_2_overlap,
        fun gleam@int:subtract/2
    ),
    _pipe@4 = gleam@dict:filter(_pipe@3, fun(_, B) -> B > 0 end),
    {counter, _pipe@4}.

-spec unique_size(counter(any())) -> integer().
unique_size(Counter) ->
    _pipe = erlang:element(2, Counter),
    maps:size(_pipe).

-spec total(counter(any())) -> integer().
total(Counter) ->
    _pipe = erlang:element(2, Counter),
    _pipe@1 = maps:to_list(_pipe),
    _pipe@2 = gleam@list:map(_pipe@1, fun gleam@pair:second/1),
    gleam@int:sum(_pipe@2).

-spec to_list(counter(OJG)) -> list({OJG, integer()}).
to_list(Counter) ->
    _pipe = erlang:element(2, Counter),
    maps:to_list(_pipe).

-spec most_common(counter(OHY)) -> list({OHY, integer()}).
most_common(Counter) ->
    _pipe = Counter,
    _pipe@1 = to_list(_pipe),
    gleam@list:sort(
        _pipe@1,
        fun(A, B) ->
            gleam@int:compare(erlang:element(2, B), erlang:element(2, A))
        end
    ).

-spec most_common_n(counter(OIB), integer()) -> list({OIB, integer()}).
most_common_n(Counter, N) ->
    _pipe = Counter,
    _pipe@1 = most_common(_pipe),
    gleam@list:take(_pipe@1, N).

-spec from_list(list(OJJ)) -> counter(OJJ).
from_list(Items) ->
    update(new(), Items).

-spec to_dict(counter(OJM)) -> gleam@dict:dict(OJM, integer()).
to_dict(Counter) ->
    erlang:element(2, Counter).

-spec from_dict(gleam@dict:dict(OJQ, integer())) -> counter(OJQ).
from_dict(D) ->
    _pipe = D,
    {counter, _pipe}.