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

-export([accept_imprecision/1, error_on_imprecision/1, now_utc/0]).
-export_type([error/0, naive_date_time/0, date_time/0, offset/0, date/0, period/0, time/0, duration/0, uncertain_conversion/1, month_year/0, month/0]).

-type error() :: time_invalid_format |
    time_out_of_bounds |
    date_invalid_format |
    date_out_of_bounds |
    month_invalid_format |
    month_out_of_bounds |
    offset_invalid_format |
    offset_out_of_bounds |
    naive_date_time_invalid_format |
    date_time_invalid_format.

-type naive_date_time() :: {naive_date_time, date(), time()}.

-type date_time() :: {date_time, naive_date_time(), offset()}.

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

-type date() :: {date, integer(), month(), integer()}.

-type period() :: {naive_period, naive_date_time(), naive_date_time()} |
    {period, date_time(), date_time()}.

-type time() :: {time, integer(), integer(), integer(), integer()} |
    {time_milli, integer(), integer(), integer(), integer()} |
    {time_micro, integer(), integer(), integer(), integer()} |
    {time_nano, integer(), integer(), integer(), integer()}.

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

-type uncertain_conversion(FSI) :: {precise, FSI} | {imprecise, FSI}.

-type month_year() :: {month_year, month(), integer()}.

-type month() :: jan |
    feb |
    mar |
    apr |
    may |
    jun |
    jul |
    aug |
    sep |
    oct |
    nov |
    dec.

-spec accept_imprecision(uncertain_conversion(FSJ)) -> FSJ.
accept_imprecision(Conv) ->
    case Conv of
        {precise, A} ->
            A;

        {imprecise, A@1} ->
            A@1
    end.

-spec error_on_imprecision(uncertain_conversion(FSL)) -> {ok, FSL} |
    {error, nil}.
error_on_imprecision(Conv) ->
    case Conv of
        {precise, A} ->
            {ok, A};

        {imprecise, _} ->
            {error, nil}
    end.

-spec now_utc() -> integer().
now_utc() ->
    tempo_ffi:now().