------------------------------------------------------------------------------
--                                                                          --
--                         GNAT RUN-TIME COMPONENTS                         --
--                                                                          --
--              A D A . C A L E N D A R . F O R M A T T I N G               --
--                                                                          --
--                                 B o d y                                  --
--                                                                          --
--          Copyright (C) 2006-2023, Free Software Foundation, Inc.         --
--                                                                          --
-- GNAT is free software;  you can  redistribute it  and/or modify it under --
-- terms of the  GNU General Public License as published  by the Free Soft- --
-- ware  Foundation;  either version 3,  or (at your option) any later ver- --
-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
-- or FITNESS FOR A PARTICULAR PURPOSE.                                     --
--                                                                          --
-- As a special exception under Section 7 of GPL version 3, you are granted --
-- additional permissions described in the GCC Runtime Library Exception,   --
-- version 3.1, as published by the Free Software Foundation.               --
--                                                                          --
-- You should have received a copy of the GNU General Public License and    --
-- a copy of the GCC Runtime Library Exception along with this program;     --
-- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
-- <http://www.gnu.org/licenses/>.                                          --
--                                                                          --
-- GNAT was originally developed  by the GNAT team at  New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc.      --
--                                                                          --
------------------------------------------------------------------------------

with Ada.Calendar.Time_Zones; use Ada.Calendar.Time_Zones;

package body Ada.Calendar.Formatting is

   --------------------------
   -- Implementation Notes --
   --------------------------

   --  All operations in this package are target and time representation
   --  independent, thus only one source file is needed for multiple targets.

   procedure Check_Char (S : String; C : Character; Index : Integer);
   --  Subsidiary to the two versions of Value. Determine whether the input
   --  string S has character C at position Index. Raise Constraint_Error if
   --  there is a mismatch.

   procedure Check_Digit (S : String; Index : Integer);
   --  Subsidiary to the two versions of Value. Determine whether the character
   --  of string S at position Index is a digit. This catches invalid input
   --  such as 1983-*1-j3 u5:n7:k9 which should be 1983-01-03 05:07:09. Raise
   --  Constraint_Error if there is a mismatch.

   procedure Split_Duration
     (Seconds    : Duration;
      Hour       : out Natural;
      Minute     : out Minute_Number;
      Second     : out Second_Number;
      Sub_Second : out Second_Duration);
   --  Version of Split that allows durations < 100 hours.
   --  Will raise Time_Error if Seconds >= 100 hours.

   ----------------
   -- Check_Char --
   ----------------

   procedure Check_Char (S : String; C : Character; Index : Integer) is
   begin
      if S (Index) /= C then
         raise Constraint_Error;
      end if;
   end Check_Char;

   -----------------
   -- Check_Digit --
   -----------------

   procedure Check_Digit (S : String; Index : Integer) is
   begin
      if S (Index) not in '0' .. '9' then
         raise Constraint_Error;
      end if;
   end Check_Digit;

   ---------
   -- Day --
   ---------

   function Day
     (Date      : Time;
      Time_Zone : Time_Zones.Time_Offset := 0) return Day_Number
   is
      Y  : Year_Number;
      Mo : Month_Number;
      D  : Day_Number;
      H  : Hour_Number;
      Mi : Minute_Number;
      Se : Second_Number;
      Ss : Second_Duration;
      Le : Boolean;

   begin
      Split (Date, Y, Mo, D, H, Mi, Se, Ss, Le, Time_Zone);
      return D;
   end Day;

   -----------------
   -- Day_Of_Week --
   -----------------

   function Day_Of_Week (Date : Time) return Day_Name is
   begin
      return Day_Name'Val (Formatting_Operations.Day_Of_Week (Date));
   end Day_Of_Week;

   ----------
   -- Hour --
   ----------

   function Hour
     (Date      : Time;
      Time_Zone : Time_Zones.Time_Offset := 0) return Hour_Number
   is
      Y  : Year_Number;
      Mo : Month_Number;
      D  : Day_Number;
      H  : Hour_Number;
      Mi : Minute_Number;
      Se : Second_Number;
      Ss : Second_Duration;
      Le : Boolean;

   begin
      Split (Date, Y, Mo, D, H, Mi, Se, Ss, Le, Time_Zone);
      return H;
   end Hour;

   -----------
   -- Image --
   -----------

   function Image
     (Elapsed_Time          : Duration;
      Include_Time_Fraction : Boolean := False) return String
   is
      To_Char    : constant array (0 .. 9) of Character := "0123456789";
      Hour       : Natural;
      Minute     : Minute_Number;
      Second     : Second_Number;
      Sub_Second : Duration;
      SS_Nat     : Natural;

      --  Determine the two slice bounds for the result string depending on
      --  whether the input is negative and whether fractions are requested.

      First  : constant Integer := (if Elapsed_Time < 0.0 then 1 else 2);
      Last   : constant Integer := (if Include_Time_Fraction then 12 else 9);

      Result : String := "-00:00:00.00";

   begin
      Split_Duration (abs Elapsed_Time, Hour, Minute, Second, Sub_Second);

      --  Hour processing, positions 2 and 3

      Result (2) := To_Char (Hour / 10);
      Result (3) := To_Char (Hour mod 10);

      --  Minute processing, positions 5 and 6

      Result (5) := To_Char (Minute / 10);
      Result (6) := To_Char (Minute mod 10);

      --  Second processing, positions 8 and 9

      Result (8) := To_Char (Second / 10);
      Result (9) := To_Char (Second mod 10);

      --  Optional sub second processing, positions 11 and 12

      if Include_Time_Fraction and then Sub_Second > 0.0 then

         --  Prevent rounding up when converting to natural, avoiding the zero
         --  case to prevent rounding down to a negative number.

         SS_Nat := Natural (Duration'(Sub_Second * 100.0) - 0.5);

         Result (11) := To_Char (SS_Nat / 10);
         Result (12) := To_Char (SS_Nat mod 10);
      end if;

      return Result (First .. Last);
   end Image;

   -----------
   -- Image --
   -----------

   function Image
     (Date                  : Time;
      Include_Time_Fraction : Boolean := False;
      Time_Zone             : Time_Zones.Time_Offset := 0) return String
   is
      To_Char : constant array (0 .. 9) of Character := "0123456789";

      Year        : Year_Number;
      Month       : Month_Number;
      Day         : Day_Number;
      Hour        : Hour_Number;
      Minute      : Minute_Number;
      Second      : Second_Number;
      Sub_Second  : Duration;
      SS_Nat      : Natural;
      Leap_Second : Boolean;

      --  The result length depends on whether fractions are requested.

      Result : String := "0000-00-00 00:00:00.00";
      Last   : constant Positive :=
        Result'Last - (if Include_Time_Fraction then 0 else 3);

   begin
      Split (Date, Year, Month, Day,
             Hour, Minute, Second, Sub_Second, Leap_Second, Time_Zone);

      --  Year processing, positions 1, 2, 3 and 4

      Result (1) := To_Char (Year / 1000);
      Result (2) := To_Char (Year / 100 mod 10);
      Result (3) := To_Char (Year / 10 mod 10);
      Result (4) := To_Char (Year mod 10);

      --  Month processing, positions 6 and 7

      Result (6) := To_Char (Month / 10);
      Result (7) := To_Char (Month mod 10);

      --  Day processing, positions 9 and 10

      Result (9)  := To_Char (Day / 10);
      Result (10) := To_Char (Day mod 10);

      Result (12) := To_Char (Hour / 10);
      Result (13) := To_Char (Hour mod 10);

      --  Minute processing, positions 15 and 16

      Result (15) := To_Char (Minute / 10);
      Result (16) := To_Char (Minute mod 10);

      --  Second processing, positions 18 and 19

      Result (18) := To_Char (Second / 10);
      Result (19) := To_Char (Second mod 10);

      --  Optional sub second processing, positions 21 and 22

      if Include_Time_Fraction and then Sub_Second > 0.0 then

         --  Prevent rounding up when converting to natural, avoiding the zero
         --  case to prevent rounding down to a negative number.

         SS_Nat := Natural (Duration'(Sub_Second * 100.0) - 0.5);

         Result (21) := To_Char (SS_Nat / 10);
         Result (22) := To_Char (SS_Nat mod 10);
      end if;

      return Result (Result'First .. Last);
   end Image;

   ------------
   -- Minute --
   ------------

   function Minute
     (Date      : Time;
      Time_Zone : Time_Zones.Time_Offset := 0) return Minute_Number
   is
      Y  : Year_Number;
      Mo : Month_Number;
      D  : Day_Number;
      H  : Hour_Number;
      Mi : Minute_Number;
      Se : Second_Number;
      Ss : Second_Duration;
      Le : Boolean;

   begin
      Split (Date, Y, Mo, D, H, Mi, Se, Ss, Le, Time_Zone);
      return Mi;
   end Minute;

   -----------
   -- Month --
   -----------

   function Month
     (Date      : Time;
      Time_Zone : Time_Zones.Time_Offset := 0) return Month_Number
   is
      Y  : Year_Number;
      Mo : Month_Number;
      D  : Day_Number;
      H  : Hour_Number;
      Mi : Minute_Number;
      Se : Second_Number;
      Ss : Second_Duration;
      Le : Boolean;

   begin
      Split (Date, Y, Mo, D, H, Mi, Se, Ss, Le, Time_Zone);
      return Mo;
   end Month;

   ------------
   -- Second --
   ------------

   function Second (Date : Time) return Second_Number is
      Y  : Year_Number;
      Mo : Month_Number;
      D  : Day_Number;
      H  : Hour_Number;
      Mi : Minute_Number;
      Se : Second_Number;
      Ss : Second_Duration;
      Le : Boolean;

   begin
      Split (Date, Y, Mo, D, H, Mi, Se, Ss, Le);
      return Se;
   end Second;

   ----------------
   -- Seconds_Of --
   ----------------

   function Seconds_Of
     (Hour       : Hour_Number;
      Minute     : Minute_Number;
      Second     : Second_Number := 0;
      Sub_Second : Second_Duration := 0.0) return Day_Duration is

   begin
      --  Validity checks

      if        not Hour'Valid
        or else not Minute'Valid
        or else not Second'Valid
        or else not Sub_Second'Valid
      then
         raise Constraint_Error;
      end if;

      return Day_Duration (Hour   * 3_600) +
             Day_Duration (Minute *    60) +
             Day_Duration (Second)         +
             Sub_Second;
   end Seconds_Of;

   --------------------
   -- Split_Duration --
   --------------------

   procedure Split_Duration
     (Seconds    : Duration;
      Hour       : out Natural;
      Minute     : out Minute_Number;
      Second     : out Second_Number;
      Sub_Second : out Second_Duration)
   is
      Secs : Natural;
   begin
      --  Check that Seconds is below 100 hours

      if Seconds >= 3600.0 * 100.0 then
         raise Time_Error;
      end if;

      Secs := (if Seconds = 0.0 then 0 else Natural (Seconds - 0.5));

      Sub_Second := Second_Duration (Seconds - Duration (Secs));
      Hour       := Natural (Secs / 3_600);
      Secs       := Secs mod 3_600;
      Minute     := Minute_Number (Secs / 60);
      Second     := Second_Number (Secs mod 60);
   end Split_Duration;

   -----------
   -- Split --
   -----------

   procedure Split
     (Seconds    : Day_Duration;
      Hour       : out Hour_Number;
      Minute     : out Minute_Number;
      Second     : out Second_Number;
      Sub_Second : out Second_Duration)
   is
      Unchecked_Hour : Natural;
   begin
      --  Validity checks

      if not Seconds'Valid then
         raise Constraint_Error;
      end if;

      Split_Duration (Seconds, Unchecked_Hour, Minute, Second, Sub_Second);

      if Unchecked_Hour > Hour_Number'Last then
         raise Time_Error;
      end if;

      Hour := Unchecked_Hour;
   end Split;

   -----------
   -- Split --
   -----------

   procedure Split
     (Date        : Time;
      Year        : out Year_Number;
      Month       : out Month_Number;
      Day         : out Day_Number;
      Seconds     : out Day_Duration;
      Leap_Second : out Boolean;
      Time_Zone   : Time_Zones.Time_Offset := 0)
   is
      H  : Integer;
      M  : Integer;
      Se : Integer;
      Su : Duration;
      Tz : constant Long_Integer := Long_Integer (Time_Zone);

   begin
      Formatting_Operations.Split
        (Date        => Date,
         Year        => Year,
         Month       => Month,
         Day         => Day,
         Day_Secs    => Seconds,
         Hour        => H,
         Minute      => M,
         Second      => Se,
         Sub_Sec     => Su,
         Leap_Sec    => Leap_Second,
         Use_TZ      => True,
         Is_Historic => True,
         Time_Zone   => Tz);

      --  Validity checks

      if not Year'Valid
        or else not Month'Valid
        or else not Day'Valid
        or else not Seconds'Valid
      then
         raise Time_Error;
      end if;
   end Split;

   -----------
   -- Split --
   -----------

   procedure Split
     (Date       : Time;
      Year       : out Year_Number;
      Month      : out Month_Number;
      Day        : out Day_Number;
      Hour       : out Hour_Number;
      Minute     : out Minute_Number;
      Second     : out Second_Number;
      Sub_Second : out Second_Duration;
      Time_Zone  : Time_Zones.Time_Offset := 0)
   is
      Dd : Day_Duration;
      Le : Boolean;
      Tz : constant Long_Integer := Long_Integer (Time_Zone);

   begin
      Formatting_Operations.Split
        (Date        => Date,
         Year        => Year,
         Month       => Month,
         Day         => Day,
         Day_Secs    => Dd,
         Hour        => Hour,
         Minute      => Minute,
         Second      => Second,
         Sub_Sec     => Sub_Second,
         Leap_Sec    => Le,
         Use_TZ      => True,
         Is_Historic => True,
         Time_Zone   => Tz);

      --  Validity checks

      if not Year'Valid
        or else not Month'Valid
        or else not Day'Valid
        or else not Hour'Valid
        or else not Minute'Valid
        or else not Second'Valid
        or else not Sub_Second'Valid
      then
         raise Time_Error;
      end if;
   end Split;

   -----------
   -- Split --
   -----------

   procedure Split
     (Date        : Time;
      Year        : out Year_Number;
      Month       : out Month_Number;
      Day         : out Day_Number;
      Hour        : out Hour_Number;
      Minute      : out Minute_Number;
      Second      : out Second_Number;
      Sub_Second  : out Second_Duration;
      Leap_Second : out Boolean;
      Time_Zone   : Time_Zones.Time_Offset := 0)
   is
      Dd : Day_Duration;
      Tz : constant Long_Integer := Long_Integer (Time_Zone);

   begin
      Formatting_Operations.Split
       (Date        => Date,
        Year        => Year,
        Month       => Month,
        Day         => Day,
        Day_Secs    => Dd,
        Hour        => Hour,
        Minute      => Minute,
        Second      => Second,
        Sub_Sec     => Sub_Second,
        Leap_Sec    => Leap_Second,
        Use_TZ      => True,
        Is_Historic => True,
        Time_Zone   => Tz);

      --  Validity checks

      if not Year'Valid
        or else not Month'Valid
        or else not Day'Valid
        or else not Hour'Valid
        or else not Minute'Valid
        or else not Second'Valid
        or else not Sub_Second'Valid
      then
         raise Time_Error;
      end if;
   end Split;

   ----------------
   -- Sub_Second --
   ----------------

   function Sub_Second (Date : Time) return Second_Duration is
      Y  : Year_Number;
      Mo : Month_Number;
      D  : Day_Number;
      H  : Hour_Number;
      Mi : Minute_Number;
      Se : Second_Number;
      Ss : Second_Duration;
      Le : Boolean;

   begin
      Split (Date, Y, Mo, D, H, Mi, Se, Ss, Le);
      return Ss;
   end Sub_Second;

   -------------
   -- Time_Of --
   -------------

   function Time_Of
     (Year        : Year_Number;
      Month       : Month_Number;
      Day         : Day_Number;
      Seconds     : Day_Duration := 0.0;
      Leap_Second : Boolean := False;
      Time_Zone   : Time_Zones.Time_Offset := 0) return Time
   is
      H  : constant Integer := 1;
      M  : constant Integer := 1;
      Se : constant Integer := 1;
      Ss : constant Duration := 0.1;
      Tz : constant Long_Integer := Long_Integer (Time_Zone);

   begin
      --  Validity checks

      if not Year'Valid
        or else not Month'Valid
        or else not Day'Valid
        or else not Seconds'Valid
        or else not Time_Zone'Valid
      then
         raise Constraint_Error;
      end if;

      return
        Formatting_Operations.Time_Of
          (Year         => Year,
           Month        => Month,
           Day          => Day,
           Day_Secs     => Seconds,
           Hour         => H,
           Minute       => M,
           Second       => Se,
           Sub_Sec      => Ss,
           Leap_Sec     => Leap_Second,
           Use_Day_Secs => True,
           Use_TZ       => True,
           Is_Historic  => True,
           Time_Zone    => Tz);
   end Time_Of;

   -------------
   -- Time_Of --
   -------------

   function Time_Of
     (Year        : Year_Number;
      Month       : Month_Number;
      Day         : Day_Number;
      Hour        : Hour_Number;
      Minute      : Minute_Number;
      Second      : Second_Number;
      Sub_Second  : Second_Duration := 0.0;
      Leap_Second : Boolean := False;
      Time_Zone   : Time_Zones.Time_Offset := 0) return Time
   is
      Dd : constant Day_Duration := Day_Duration'First;
      Tz : constant Long_Integer := Long_Integer (Time_Zone);

   begin
      --  Validity checks

      if not Year'Valid
        or else not Month'Valid
        or else not Day'Valid
        or else not Hour'Valid
        or else not Minute'Valid
        or else not Second'Valid
        or else not Sub_Second'Valid
        or else not Time_Zone'Valid
      then
         raise Constraint_Error;
      end if;

      return
        Formatting_Operations.Time_Of
          (Year         => Year,
           Month        => Month,
           Day          => Day,
           Day_Secs     => Dd,
           Hour         => Hour,
           Minute       => Minute,
           Second       => Second,
           Sub_Sec      => Sub_Second,
           Leap_Sec     => Leap_Second,
           Use_Day_Secs => False,
           Use_TZ       => True,
           Is_Historic  => True,
           Time_Zone    => Tz);
   end Time_Of;

   -----------
   -- Value --
   -----------

   function Value
     (Date      : String;
      Time_Zone : Time_Zones.Time_Offset := 0) return Time
   is
      D          : String (1 .. 22);
      Year       : Year_Number;
      Month      : Month_Number;
      Day        : Day_Number;
      Hour       : Hour_Number;
      Minute     : Minute_Number;
      Second     : Second_Number;
      Sub_Second : Second_Duration := 0.0;

   begin
      --  Validity checks

      if not Time_Zone'Valid then
         raise Constraint_Error;
      end if;

      --  Length checks

      if Date'Length /= 19
        and then Date'Length /= 22
      then
         raise Constraint_Error;
      end if;

      --  After the correct length has been determined, it is safe to copy the
      --  Date in order to avoid Date'First + N indexing.

      D (1 .. Date'Length) := Date;

      --  Format checks

      Check_Char (D, '-', 5);
      Check_Char (D, '-', 8);
      Check_Char (D, ' ', 11);
      Check_Char (D, ':', 14);
      Check_Char (D, ':', 17);

      if Date'Length = 22 then
         Check_Char (D, '.', 20);
      end if;

      --  Leading zero checks

      Check_Digit (D, 6);
      Check_Digit (D, 9);
      Check_Digit (D, 12);
      Check_Digit (D, 15);
      Check_Digit (D, 18);

      if Date'Length = 22 then
         Check_Digit (D, 21);
      end if;

      --  Value extraction

      Year   := Year_Number   (Year_Number'Value   (D (1 .. 4)));
      Month  := Month_Number  (Month_Number'Value  (D (6 .. 7)));
      Day    := Day_Number    (Day_Number'Value    (D (9 .. 10)));
      Hour   := Hour_Number   (Hour_Number'Value   (D (12 .. 13)));
      Minute := Minute_Number (Minute_Number'Value (D (15 .. 16)));
      Second := Second_Number (Second_Number'Value (D (18 .. 19)));

      --  Optional part

      if Date'Length = 22 then
         Sub_Second := Second_Duration (Second_Duration'Value (D (20 .. 22)));
      end if;

      --  Sanity checks

      if not Year'Valid
        or else not Month'Valid
        or else not Day'Valid
        or else not Hour'Valid
        or else not Minute'Valid
        or else not Second'Valid
        or else not Sub_Second'Valid
      then
         raise Constraint_Error;
      end if;

      return Time_Of (Year, Month, Day,
                      Hour, Minute, Second, Sub_Second, False, Time_Zone);

   exception
      when others => raise Constraint_Error;
   end Value;

   -----------
   -- Value --
   -----------

   function Value (Elapsed_Time : String) return Duration is
      D          : String (1 .. 11);
      Hour       : Hour_Number;
      Minute     : Minute_Number;
      Second     : Second_Number;
      Sub_Second : Second_Duration := 0.0;

   begin
      --  Length checks

      if Elapsed_Time'Length /= 8
        and then Elapsed_Time'Length /= 11
      then
         raise Constraint_Error;
      end if;

      --  After the correct length has been determined, it is safe to copy the
      --  Elapsed_Time in order to avoid Date'First + N indexing.

      D (1 .. Elapsed_Time'Length) := Elapsed_Time;

      --  Format checks

      Check_Char (D, ':', 3);
      Check_Char (D, ':', 6);

      if Elapsed_Time'Length = 11 then
         Check_Char (D, '.', 9);
      end if;

      --  Leading zero checks

      Check_Digit (D, 1);
      Check_Digit (D, 4);
      Check_Digit (D, 7);

      if Elapsed_Time'Length = 11 then
         Check_Digit (D, 10);
      end if;

      --  Value extraction

      Hour   := Hour_Number   (Hour_Number'Value   (D (1 .. 2)));
      Minute := Minute_Number (Minute_Number'Value (D (4 .. 5)));
      Second := Second_Number (Second_Number'Value (D (7 .. 8)));

      --  Optional part

      if Elapsed_Time'Length = 11 then
         Sub_Second := Second_Duration (Second_Duration'Value (D (9 .. 11)));
      end if;

      --  Sanity checks

      if not Hour'Valid
        or else not Minute'Valid
        or else not Second'Valid
        or else not Sub_Second'Valid
      then
         raise Constraint_Error;
      end if;

      return Seconds_Of (Hour, Minute, Second, Sub_Second);

   exception
      when others => raise Constraint_Error;
   end Value;

   ----------
   -- Year --
   ----------

   function Year
     (Date      : Time;
      Time_Zone : Time_Zones.Time_Offset := 0) return Year_Number
   is
      Y  : Year_Number;
      Mo : Month_Number;
      D  : Day_Number;
      H  : Hour_Number;
      Mi : Minute_Number;
      Se : Second_Number;
      Ss : Second_Duration;
      Le : Boolean;

   begin
      Split (Date, Y, Mo, D, H, Mi, Se, Ss, Le, Time_Zone);
      return Y;
   end Year;

end Ada.Calendar.Formatting;