-module(birl@duration).
-compile(no_auto_import).

-export([new/1, accurate_new/1, decompose/1, accurate_decompose/1]).
-export_type([duration/0, unit/0]).

-type duration() :: {duration, integer()}.

-type unit() :: milli_second |
    second |
    minute |
    hour |
    day |
    week |
    month |
    year.

-spec new(list({integer(), unit()})) -> duration().
new(Values) ->
    _pipe = Values,
    _pipe@1 = gleam@list:fold(
        _pipe,
        0,
        fun(Total, Current) ->
            {Amount, Unit} = Current,
            case Unit of
                milli_second ->
                    Total + Amount;

                second ->
                    Total + (Amount * 1000);

                minute ->
                    Total + (Amount * 60000);

                hour ->
                    Total + (Amount * 3600000);

                day ->
                    Total + (Amount * 86400000);

                week ->
                    Total + (Amount * 604800000);

                month ->
                    Total + (Amount * 2592000000);

                year ->
                    Total + (Amount * 31536000000)
            end
        end
    ),
    {duration, _pipe@1}.

-spec accurate_new(list({integer(), unit()})) -> duration().
accurate_new(Values) ->
    _pipe = Values,
    _pipe@1 = gleam@list:fold(
        _pipe,
        0,
        fun(Total, Current) ->
            {Amount, Unit} = Current,
            case Unit of
                milli_second ->
                    Total + Amount;

                second ->
                    Total + (Amount * 1000);

                minute ->
                    Total + (Amount * 60000);

                hour ->
                    Total + (Amount * 3600000);

                day ->
                    Total + (Amount * 86400000);

                week ->
                    Total + (Amount * 604800000);

                month ->
                    Total + (Amount * 2629746000);

                year ->
                    Total + (Amount * 31556952000)
            end
        end
    ),
    {duration, _pipe@1}.

-spec decompose(duration()) -> list({integer(), unit()}).
decompose(Duration) ->
    {duration, Value} = Duration,
    {Years, Remaining} = extract(Value, 31536000000),
    {Months, Remaining@1} = extract(Remaining, 2592000000),
    {Days, Remaining@2} = extract(Remaining@1, 86400000),
    {Hours, Remaining@3} = extract(Remaining@2, 3600000),
    {Minutes, Remaining@4} = extract(Remaining@3, 60000),
    {Seconds, Remaining@5} = extract(Remaining@4, 1000),
    _pipe = [{Years, year},
        {Months, month},
        {Days, day},
        {Hours, hour},
        {Minutes, minute},
        {Seconds, second},
        {Remaining@5, milli_second}],
    gleam@list:filter(_pipe, fun(Item) -> erlang:element(1, Item) > 0 end).

-spec accurate_decompose(duration()) -> list({integer(), unit()}).
accurate_decompose(Duration) ->
    {duration, Value} = Duration,
    {Years, Remaining} = extract(Value, 31556952000),
    {Months, Remaining@1} = extract(Remaining, 2629746000),
    {Days, Remaining@2} = extract(Remaining@1, 86400000),
    {Hours, Remaining@3} = extract(Remaining@2, 3600000),
    {Minutes, Remaining@4} = extract(Remaining@3, 60000),
    {Seconds, Remaining@5} = extract(Remaining@4, 1000),
    _pipe = [{Years, year},
        {Months, month},
        {Days, day},
        {Hours, hour},
        {Minutes, minute},
        {Seconds, second},
        {Remaining@5, milli_second}],
    gleam@list:filter(_pipe, fun(Item) -> erlang:element(1, Item) > 0 end).

-spec extract(integer(), integer()) -> {integer(), integer()}.
extract(Duration, Unit) ->
    {ok, Amount@1} = case gleam@int:divide(Duration, Unit) of
        {ok, Amount} -> {ok, Amount};
        _try ->
            erlang:error(#{gleam_error => assert,
                        message => <<"Assertion pattern match failed"/utf8>>,
                        value => _try,
                        module => <<"birl/duration"/utf8>>,
                        function => <<"extract"/utf8>>,
                        line => 126})
    end,
    {ok, Remaining@1} = case gleam@int:modulo(Duration, Unit) of
        {ok, Remaining} -> {ok, Remaining};
        _try@1 ->
            erlang:error(#{gleam_error => assert,
                        message => <<"Assertion pattern match failed"/utf8>>,
                        value => _try@1,
                        module => <<"birl/duration"/utf8>>,
                        function => <<"extract"/utf8>>,
                        line => 127})
    end,
    {Amount@1, Remaining@1}.