Source file date.ml

(*********************************************************************************)
(*                Stog                                                           *)
(*                                                                               *)
(*    Copyright (C) 2012-2024 INRIA All rights reserved.                         *)
(*    Author: Maxence Guesdon, INRIA Saclay                                      *)
(*                                                                               *)
(*    This program is free software; you can redistribute it and/or modify       *)
(*    it under the terms of the GNU General Public License as                    *)
(*    published by the Free Software Foundation, version 3 of the License.       *)
(*                                                                               *)
(*    This program is distributed in the hope that it will be useful,            *)
(*    but WITHOUT ANY WARRANTY; without even the implied warranty of             *)
(*    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the               *)
(*    GNU General Public License for more details.                               *)
(*                                                                               *)
(*    You should have received a copy of the GNU General Public                  *)
(*    License along with this program; if not, write to the Free Software        *)
(*    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA                   *)
(*    02111-1307  USA                                                            *)
(*                                                                               *)
(*    As a special exception, you have permission to link this program           *)
(*    with the OCaml compiler and distribute executables, as long as you         *)
(*    follow the requirements of the GNU GPL in regard to all of the             *)
(*    software in the executable aside from the OCaml compiler.                  *)
(*                                                                               *)
(*    Contact: Maxence.Guesdon@inria.fr                                          *)
(*                                                                               *)
(*********************************************************************************)

(** *)

type t =
  { stamp : Ptime.t ;
    tz: Ptime.tz_offset_s option ;
  }

let of_string ?loc str =
  match Ptime.of_rfc3339 str with
     Ok (stamp, tz, _) -> { stamp ; tz }
   | Error (`RFC3339 ((p1,p2), e)) ->
      let b = Buffer.create 256 in
      let fmt = Format.formatter_of_buffer b in
      if p2 > p1 then
        Format.fprintf fmt "Characters %d-%d: " p1 p2
      else
        Format.fprintf fmt "Character %d: " p1;
      Ptime.pp_rfc3339_error fmt e;
      Format.pp_print_flush fmt () ;
      let err = Buffer.contents b in
      Error.invalid_date ?loc str err

let of_string_date ?loc str =
  try of_string ?loc (str^"T00:00:00Z")
  with e ->
      (* backward compatibility handling of YYYY/MM/DD *)
      try Scanf.sscanf str "%d/%d/%d"
        (fun y m d -> of_string ?loc (Printf.sprintf "%04d-%02d-%02dT00:00:00Z" y m d))
      with _ -> raise e

let to_string t = Ptime.to_rfc3339 ?tz_offset_s: t.tz t.stamp

let of_float t =
  match Ptime.of_float_s t with
  | Some stamp -> { stamp ; tz = None }
  | None -> failwith (Printf.sprintf "Could not create date from %f" t)

let now () = of_float (Unix.time())

let to_date_time t =
  Ptime.to_date_time ?tz_offset_s: t.tz t.stamp

let weekday t = Ptime.weekday ?tz_offset_s: t.tz t.stamp
  (* FIXME: give tz_offset_s parameter when weekday accepts it *)

let to_rfc_822 t =
  let wd =
    match weekday t with
    | `Sun -> "Sun"
    | `Mon -> "Mon"
    | `Tue -> "Tue"
    | `Wed -> "Wed"
    | `Thu -> "Thu"
    | `Fri -> "Fri"
    | `Sat -> "Sat"
  in
  let ((y,m,d),((h,mi,s),tz)) = to_date_time t in
  let mon =
    match m with
      1 -> "Jan"
    | 2 -> "Feb"
    | 3 -> "Mar"
    | 4 -> "Apr"
    | 5 -> "May"
    | 6 -> "Jun"
    | 7 -> "Jul"
    | 8 -> "Aug"
    | 9 -> "Sep"
    | 10 -> "Oct"
    | 11 -> "Nov"
    | _ -> "Dec"
  in
  let abs_tz = abs tz in
  Printf.sprintf "%s, %02d %s %04d %02d:%02d:%02d %c%02d%02d"
    wd d mon y h mi s
    (if tz < 0 then '-' else '+')
    (abs_tz mod 3600) (abs_tz mod 60)

let cp_percent = Uchar.of_char '%'
let format t fmt =
  match fmt with
    "rfc3339" -> to_string t
  | "rfc822" -> to_rfc_822 t
  | _ ->
      let b = Buffer.create 256 in
      let ((y,m,d),((h,mi,s),tz)) = to_date_time t in
      let f prev_cp i = function
        `Malformed str ->
          begin
            match prev_cp with
              None -> ()
            | Some prev_cp -> Uutf.Buffer.add_utf_8 b prev_cp 
          end;
          Buffer.add_string b str ;
          None
      | `Uchar cp ->
          match prev_cp with
          | Some prev_cp when Uchar.equal prev_cp cp_percent ->
              let () =
                match Uchar.to_int cp with
                | 89 (* Y *) -> Buffer.add_string b (string_of_int y)
                | 77 (* M *) -> Printf.bprintf b "%02d" m
                | 68 (* D *) -> Printf.bprintf b "%02d" d
                | 104 (* h *) -> Printf.bprintf b "%02d" h
                | 109 (* m *) -> Printf.bprintf b "%02d" mi
                | 115 (* s *) -> Printf.bprintf b "%02d" s
                | _ when Uchar.equal cp cp_percent -> Buffer.add_char b '%'
                | _ ->
                    Uutf.Buffer.add_utf_8 b prev_cp ;
                    Uutf.Buffer.add_utf_8 b cp
              in
              None
          | Some prev_cp ->
              Uutf.Buffer.add_utf_8 b prev_cp ;
              Some cp
          | None ->
              Some cp
      in
      (match Uutf.String.fold_utf_8 f None fmt with
         None -> ()
       | Some remain -> Uutf.Buffer.add_utf_8 b remain
      );
      Buffer.contents b