-module(ephp_lib_date).

-author('manuel@altenwald.com').

-behaviour(ephp_lib).

-export([init_func/0, init_config/0, init_const/0, handle_error/3, time/2, microtime/2,
         microtime/3, date/3, date/4, gmdate/3, gmdate/4, date_default_timezone_set/3,
         date_default_timezone_get/2, timezone_abbreviations_list/2]).

-include("ephp.hrl").

-spec init_func() -> ephp_lib:php_function_results().
init_func() ->
    [time,
     date,
     gmdate,
     microtime,
     date_default_timezone_get,
     date_default_timezone_set,
     timezone_abbreviations_list].

-spec init_config() -> ephp_lib:php_config_results().
init_config() ->
    [{<<"date.timezone">>, undefined}].

-spec init_const() -> ephp_lib:php_const_results().
init_const() ->
    [].

-spec handle_error(ephp_error:error_type(), ephp_error:error_level(), Args :: term()) ->
                      string() | ignore.
handle_error(etimezone, _Level, {Function, TZ}) ->
    io_lib:format("~s(): Timezone ID '~s' is invalid", [Function, TZ]);
handle_error(enotimezone, _Level, {Function}) ->
    io_lib:format("~s(): It is not safe to rely on the system's timezone "
                  "settings. You are *required* to use the date.timezone "
                  "setting or the date_default_timezone_set() function. "
                  "In case you used any of those methods and you are still "
                  "getting this warning, you most likely misspelled the "
                  "timezone identifier. We selected the timezone 'UTC' for "
                  "now, but please set date.timezone to select your "
                  "timezone.",
                  [Function]);
handle_error(_Type, _Level, _Args) ->
    ignore.

-spec time(ephp:context_id(), line()) -> integer().
time(_Context, _Line) ->
    ephp_datetime:posix_time().

-spec microtime(ephp:context_id(),
                line(),
                GetAsFloat :: {variable() | undefined, boolean()}) ->
                   float() | binary().
microtime(_Context, _Line, {_, true}) ->
    {MS, S, US} = ephp_datetime:timestamp(),
    MS * 1000000 + S + US div 1000 / 1000;
microtime(_Context, _Line, {_, false}) ->
    {MS, S, US} = ephp_datetime:timestamp(),
    Posix = ephp_data:to_bin(MS * 1000000 + S),
    MiliSec = ephp_data:to_bin(US div 1000 / 1000),
    <<MiliSec/binary, " ", Posix/binary>>;
microtime(Context, Line, {Var, Val}) ->
    microtime(Context, Line, {Var, ephp_data:to_boolean(Val)}).

-spec microtime(ephp:context_id(), line()) -> float() | binary().
microtime(Context, Line) ->
    microtime(Context, Line, {undefined, false}).

-spec date(ephp:context_id(), line(), Format :: var_value()) -> binary().
date(Context, Line, Format) ->
    {MS, S, US} = ephp_datetime:timestamp(),
    date(Context, Line, Format, {undefined, MS * 1000000 + S + trunc(US / 1000000)}).

-spec date(ephp:context_id(), line(), Format :: var_value(), Timestamp :: var_value()) ->
              binary().
date(Context, Line, {_, Format}, {_, Timestamp}) ->
    {M, S, U} = ephp_datetime:get_timestamp(Timestamp),
    TZ = ephp_datetime:get_tz(Context, Line),
    Date = ephp_datetime:to_zone({M, S, U}, TZ),
    date_format(Format, <<>>, {Timestamp, Date, TZ}).

-spec gmdate(ephp:context_id(), line(), Format :: var_value()) -> binary().
gmdate(Context, Line, {_, Format}) ->
    {MS, S, US} = ephp_datetime:timestamp(),
    gmdate(Context,
           Line,
           {undefined, Format},
           {undefined, MS * 1000000 + S + trunc(US / 1000000)}).

-spec gmdate(ephp:context_id(),
             line(),
             Format :: var_value(),
             Timestamp :: var_value()) ->
                binary().
gmdate(_Context, _Line, {_, Format}, {_, Timestamp}) ->
    {M, S, U} = ephp_datetime:get_timestamp(Timestamp),
    TZ = <<"GMT">>,
    Date = calendar:now_to_universal_time({M, S, U}),
    date_format(Format, <<>>, {Timestamp, Date, TZ}).

-spec date_default_timezone_get(ephp:context_id(), line()) -> binary().
date_default_timezone_get(Context, Line) ->
    ephp_datetime:get_tz(Context, Line).

-spec date_default_timezone_set(ephp:context_id(), line(), TZ :: var_value()) ->
                                   undefined.
date_default_timezone_set(Context, Line, {_, TZ}) ->
    case ephp_datetime:set_tz(TZ) of
        true ->
            undefined;
        false ->
            Function = <<"date_default_timezone_set">>,
            File = ephp_context:get_active_file(Context),
            Params = {error, etimezone, Line, File, ?E_NOTICE, {Function, TZ}},
            ephp_error:handle_error(Context, Params),
            undefined
    end.

-spec timezone_abbreviations_list(ephp:context_id(), line()) -> ephp_array:ephp_array().
timezone_abbreviations_list(_Context, _Line) ->
    lists:foldl(fun(Abbr, Array) ->
                   Info =
                       lists:foldl(fun({Dst, Offset, TZID}, SubArray) ->
                                      A0 = ephp_array:new(),
                                      A1 = ephp_array:store(<<"dst">>, Dst, A0),
                                      A2 = ephp_array:store(<<"offset">>, Offset, A1),
                                      A3 = ephp_array:store(<<"timezone_id">>, TZID, A2),
                                      ephp_array:store(auto, A3, SubArray)
                                   end,
                                   ephp_array:new(),
                                   ephp_timezone:timezone_info(Abbr)),
                   ephp_array:store(
                       ephp_string:to_lower(Abbr), Info, Array)
                end,
                ephp_array:new(),
                ephp_timezone:abbreviations()).

%% ----------------------------------------------------------------------------
%% Internal functions
%% ----------------------------------------------------------------------------

-spec date_format(ToAnalyze :: binary(),
                  Result :: binary(),
                  {Timestamp :: integer(), Date :: calendar:datetime(), TZ :: binary()}) ->
                     binary().
date_format(<<>>, Result, _Date) ->
    Result;
date_format(<<"d", R/binary>>, Result, {_, {{_, _, D}, _}, _} = Date) ->
    Day = ephp_data:pad_to_bin(D, 2),
    date_format(R, <<Result/binary, Day/binary>>, Date);
date_format(<<"D", R/binary>>, Result, {_, {D, _}, _} = Date) ->
    Day = ephp_datetime:get_abbr_weekday(
              calendar:day_of_the_week(D)),
    date_format(R, <<Result/binary, Day/binary>>, Date);
date_format(<<"j", R/binary>>, Result, {_, {{_, _, D}, _}, _} = Date) ->
    Month = ephp_data:to_bin(D),
    date_format(R, <<Result/binary, Month/binary>>, Date);
date_format(<<"l", R/binary>>, Result, {_, {D, _}, _} = Date) ->
    Day = ephp_datetime:get_weekday(
              calendar:day_of_the_week(D)),
    date_format(R, <<Result/binary, Day/binary>>, Date);
date_format(<<"N", R/binary>>, Result, {_, {D, _}, _} = Date) ->
    Day = calendar:day_of_the_week(D),
    DayBin = ephp_data:to_bin(Day),
    date_format(R, <<Result/binary, DayBin/binary>>, Date);
date_format(<<"S", R/binary>>, Result, {_, {{_, _, D}, _}, _} = Date) ->
    Suffix =
        if D =:= 1 orelse D =:= 21 orelse D =:= 31 ->
               <<"st">>;
           D =:= 2 orelse D =:= 22 ->
               <<"nd">>;
           D =:= 3 orelse D =:= 23 ->
               <<"rd">>;
           true ->
               <<"th">>
        end,
    date_format(R, <<Result/binary, Suffix/binary>>, Date);
date_format(<<"w", R/binary>>, Result, {_, {D, _}, _} = Date) ->
    Day = calendar:day_of_the_week(D),
    DayBin =
        ephp_data:to_bin(if Day =:= 7 ->
                                0;
                            true ->
                                Day
                         end),
    date_format(R, <<Result/binary, DayBin/binary>>, Date);
date_format(<<"z", R/binary>>, Result, {_, {{Y, M, D}, _}, _} = Date) ->
    Days1 = calendar:date_to_gregorian_days(Y, 1, 1),
    Days2 = calendar:date_to_gregorian_days(Y, M, D),
    Days = ephp_data:to_bin(Days2 - Days1),
    date_format(R, <<Result/binary, Days/binary>>, Date);
date_format(<<"W", R/binary>>, Result, {_, {D, _}, _} = Date) ->
    {_Y, WY} = calendar:iso_week_number(D),
    WeekOfYear = ephp_data:pad_to_bin(WY, 2),
    date_format(R, <<Result/binary, WeekOfYear/binary>>, Date);
date_format(<<"F", R/binary>>, Result, {_, {{_, M, _}, _}, _} = Date) ->
    Month = ephp_datetime:get_month(M),
    date_format(R, <<Result/binary, Month/binary>>, Date);
date_format(<<"m", R/binary>>, Result, {_, {{_, M, _}, _}, _} = Date) ->
    Month = ephp_data:pad_to_bin(M, 2),
    date_format(R, <<Result/binary, Month/binary>>, Date);
date_format(<<"M", R/binary>>, Result, {_, {{_, M, _}, _}, _} = Date) ->
    Month = ephp_datetime:get_abbr_month(M),
    date_format(R, <<Result/binary, Month/binary>>, Date);
date_format(<<"n", R/binary>>, Result, {_, {{_, M, _}, _}, _} = Date) ->
    Month = ephp_data:to_bin(M),
    date_format(R, <<Result/binary, Month/binary>>, Date);
date_format(<<"t", R/binary>>, Result, {_, {{Y, M, _}, _}, _} = Date) ->
    Month =
        ephp_data:to_bin(
            calendar:last_day_of_the_month(Y, M)),
    date_format(R, <<Result/binary, Month/binary>>, Date);
date_format(<<"L", R/binary>>, Result, {_, {{Y, _, _}, _}, _} = Date) ->
    Leap =
        case calendar:is_leap_year(Y) of
            true ->
                <<"1">>;
            false ->
                <<"0">>
        end,
    date_format(R, <<Result/binary, Leap/binary>>, Date);
date_format(<<"o", R/binary>>, Result, {_, {D, _}, _} = Date) ->
    {Y, _WY} = calendar:iso_week_number(D),
    YearOfWeek = ephp_data:to_bin(Y),
    date_format(R, <<Result/binary, YearOfWeek/binary>>, Date);
date_format(<<"Y", R/binary>>, Result, {_, {{Y, _, _}, _}, _} = Date) ->
    Year = ephp_data:to_bin(Y),
    date_format(R, <<Result/binary, Year/binary>>, Date);
date_format(<<"y", R/binary>>, Result, {_, {{Y, _, _}, _}, _} = Date) ->
    Year = ephp_data:pad_to_bin(Y rem 100, 2),
    date_format(R, <<Result/binary, Year/binary>>, Date);
date_format(<<"a", R/binary>>, Result, {_, {_, {H, _, _}}, _} = Date) ->
    Type =
        if H >= 0 andalso H =< 11 ->
               <<"am">>;
           true ->
               <<"pm">>
        end,
    date_format(R, <<Result/binary, Type/binary>>, Date);
date_format(<<"A", R/binary>>, Result, {_, {_, {H, _, _}}, _} = Date) ->
    Type =
        if H >= 0 andalso H =< 11 ->
               <<"AM">>;
           true ->
               <<"PM">>
        end,
    date_format(R, <<Result/binary, Type/binary>>, Date);
date_format(<<"B", R/binary>>, Result, {Timestamp, _, _} = Date) ->
    DateTime = ephp_datetime:get_datetime(Timestamp),
    BeatsTime = ephp_datetime:to_bmt(DateTime),
    Beats = ephp_data:to_bin(BeatsTime),
    date_format(R, <<Result/binary, Beats/binary>>, Date);
date_format(<<"g", R/binary>>, Result, {_, {_, {H, _, _}}, _} = Date) ->
    Hour = ephp_data:to_bin((H + 11) rem 12 + 1),
    date_format(R, <<Result/binary, Hour/binary>>, Date);
date_format(<<"G", R/binary>>, Result, {_, {_, {H, _, _}}, _} = Date) ->
    Hour = ephp_data:to_bin(H),
    date_format(R, <<Result/binary, Hour/binary>>, Date);
date_format(<<"h", R/binary>>, Result, {_, {_, {H, _, _}}, _} = Date) ->
    Hour = ephp_data:pad_to_bin((H + 11) rem 12 + 1, 2),
    date_format(R, <<Result/binary, Hour/binary>>, Date);
date_format(<<"H", R/binary>>, Result, {_, {_, {H, _, _}}, _} = Date) ->
    Hour = ephp_data:pad_to_bin(H, 2),
    date_format(R, <<Result/binary, Hour/binary>>, Date);
date_format(<<"i", R/binary>>, Result, {_, {_, {_, M, _}}, _} = Date) ->
    Minute = ephp_data:pad_to_bin(M, 2),
    date_format(R, <<Result/binary, Minute/binary>>, Date);
date_format(<<"s", R/binary>>, Result, {_, {_, {_, _, S}}, _} = Date) ->
    Second = ephp_data:pad_to_bin(S, 2),
    date_format(R, <<Result/binary, Second/binary>>, Date);
date_format(<<"u", R/binary>>, Result, {Timestamp, _, _} = Date) ->
    US = Timestamp * 1000000 rem 1000000,
    MSecond = ephp_data:pad_to_bin(US, 6),
    date_format(R, <<Result/binary, MSecond/binary>>, Date);
date_format(<<"e", R/binary>>, Result, {_, _, TZ} = Date) ->
    TimeZone = ephp_data:to_bin(TZ),
    date_format(R, <<Result/binary, TimeZone/binary>>, Date);
date_format(<<"I", R/binary>>, Result, {_, DT, TZ} = Date) ->
    Daylight =
        case ephp_datetime:is_dst(DT, TZ) of
            true ->
                <<"1">>;
            false ->
                <<"0">>
        end,
    date_format(R, <<Result/binary, Daylight/binary>>, Date);
date_format(<<"O", R/binary>>, Result, {_, DT, TZ} = Date) ->
    Timezone = ephp_datetime:get_tz_time(DT, TZ, <<>>),
    date_format(R, <<Result/binary, Timezone/binary>>, Date);
date_format(<<"P", R/binary>>, Result, {_, DT, TZ} = Date) ->
    Timezone = ephp_datetime:get_tz_time(DT, TZ, <<":">>),
    date_format(R, <<Result/binary, Timezone/binary>>, Date);
date_format(<<"T", R/binary>>, Result, {_, DT, TZ} = Date) ->
    IsDst = ephp_datetime:is_dst(DT, TZ),
    Timezone = ephp_timezone:timezone_to_abbreviation(IsDst, ephp_data:to_bin(TZ)),
    date_format(R, <<Result/binary, Timezone/binary>>, Date);
date_format(<<"Z", R/binary>>, Result, {_, DT, TZ} = Date) ->
    <<S:1/binary, H:2/binary, M:2/binary>> = ephp_datetime:get_tz_time(DT, TZ, <<>>),
    Secs = integer_to_binary((binary_to_integer(H) * 60 + binary_to_integer(M)) * 60),
    Timezone =
        case S of
            <<"+">> ->
                Secs;
            <<"-">> ->
                <<S/binary, Secs/binary>>
        end,
    date_format(R, <<Result/binary, Timezone/binary>>, Date);
date_format(<<"c", R/binary>>, Result, {_, {{Y, M, D}, {H, I, S}} = DT, TZ} = Date) ->
    YB = ephp_data:to_bin(Y),
    MB = ephp_data:pad_to_bin(M, 2),
    DB = ephp_data:pad_to_bin(D, 2),
    HB = ephp_data:pad_to_bin(H, 2),
    IB = ephp_data:pad_to_bin(I, 2),
    SB = ephp_data:pad_to_bin(S, 2),
    TZtime = ephp_datetime:get_tz_time(DT, TZ, <<":">>),
    DateTime =
        <<YB/binary,
          "-",
          MB/binary,
          "-",
          DB/binary,
          "T",
          HB/binary,
          ":",
          IB/binary,
          ":",
          SB/binary,
          TZtime/binary>>,
    date_format(R, <<Result/binary, DateTime/binary>>, Date);
date_format(<<"r", R/binary>>,
            Result,
            {_, {{Y, M, D} = Dt, {H, I, S}} = DT, TZ} = Date) ->
    WB = ephp_datetime:get_abbr_weekday(
             calendar:day_of_the_week(Dt)),
    DB = ephp_data:pad_to_bin(D, 2),
    MB = ephp_datetime:get_abbr_month(M),
    YB = ephp_data:to_bin(Y),
    HB = ephp_data:pad_to_bin(H, 2),
    IB = ephp_data:pad_to_bin(I, 2),
    SB = ephp_data:pad_to_bin(S, 2),
    TZtime = ephp_datetime:get_tz_time(DT, TZ, <<>>),
    DateTime =
        <<WB/binary,
          ", ",
          DB/binary,
          " ",
          MB/binary,
          " ",
          YB/binary,
          " ",
          HB/binary,
          ":",
          IB/binary,
          ":",
          SB/binary,
          " ",
          TZtime/binary>>,
    date_format(R, <<Result/binary, DateTime/binary>>, Date);
date_format(<<"U", R/binary>>, Result, {Timestamp, _, _} = Date) ->
    DateTime = ephp_data:to_bin(trunc(Timestamp)),
    date_format(R, <<Result/binary, DateTime/binary>>, Date);
date_format(<<Other:1/binary, R/binary>>, Result, Date) ->
    date_format(R, <<Result/binary, Other/binary>>, Date).