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

-export([to_string/1, humanise/1]).
-export_type([time/0]).

-type time() :: {microseconds, float()} |
    {milliseconds, float()} |
    {seconds, float()} |
    {minutes, float()} |
    {hours, float()} |
    {days, float()} |
    {weeks, float()}.

-spec to_string(time()) -> binary().
to_string(Time) ->
    {N, Suffix} = case Time of
        {microseconds, Us} ->
            {Us, <<"us"/utf8>>};

        {milliseconds, Ms} ->
            {Ms, <<"ms"/utf8>>};

        {seconds, S} ->
            {S, <<"s"/utf8>>};

        {minutes, M} ->
            {M, <<"m"/utf8>>};

        {hours, H} ->
            {H, <<"h"/utf8>>};

        {days, D} ->
            {D, <<"d"/utf8>>};

        {weeks, W} ->
            {W, <<"w"/utf8>>}
    end,
    util:format(N, Suffix).

-spec to_us(time()) -> float().
to_us(Time) ->
    case Time of
        {microseconds, N} ->
            N;

        {milliseconds, N@1} ->
            N@1 * 1000.0;

        {seconds, N@2} ->
            N@2 * 1000000.0;

        {minutes, N@3} ->
            N@3 * 60000000.0;

        {hours, N@4} ->
            N@4 * 3600000000.0;

        {days, N@5} ->
            N@5 * 86400000000.0;

        {weeks, N@6} ->
            N@6 * 604800000000.0
    end.

-spec humanise(time()) -> time().
humanise(Time) ->
    Us = to_us(Time),
    gleam@bool:guard(
        Us < 1000.0,
        {microseconds, Us},
        fun() -> gleam@bool:guard(Us < 1000000.0, {milliseconds, case 1000.0 of
                        +0.0 -> +0.0;
                        -0.0 -> -0.0;
                        Gleam@denominator -> Us / Gleam@denominator
                    end}, fun() ->
                    gleam@bool:guard(
                        Us < 60000000.0,
                        {seconds, case 1000000.0 of
                                +0.0 -> +0.0;
                                -0.0 -> -0.0;
                                Gleam@denominator@1 -> Us / Gleam@denominator@1
                            end},
                        fun() ->
                            gleam@bool:guard(
                                Us < 3600000000.0,
                                {minutes, case 60000000.0 of
                                        +0.0 -> +0.0;
                                        -0.0 -> -0.0;
                                        Gleam@denominator@2 -> Us / Gleam@denominator@2
                                    end},
                                fun() ->
                                    gleam@bool:guard(
                                        Us < 86400000000.0,
                                        {hours, case 3600000000.0 of
                                                +0.0 -> +0.0;
                                                -0.0 -> -0.0;
                                                Gleam@denominator@3 -> Us / Gleam@denominator@3
                                            end},
                                        fun() ->
                                            gleam@bool:guard(
                                                Us < 604800000000.0,
                                                {days, case 86400000000.0 of
                                                        +0.0 -> +0.0;
                                                        -0.0 -> -0.0;
                                                        Gleam@denominator@4 -> Us
                                                        / Gleam@denominator@4
                                                    end},
                                                fun() ->
                                                    {weeks,
                                                        case 604800000000.0 of
                                                            +0.0 -> +0.0;
                                                            -0.0 -> -0.0;
                                                            Gleam@denominator@5 -> Us
                                                            / Gleam@denominator@5
                                                        end}
                                                end
                                            )
                                        end
                                    )
                                end
                            )
                        end
                    )
                end) end
    ).