yagit

01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74

#![allow(clippy::borrow_interior_mutable_const, clippy::declare_interior_mutable_const)]
use std::{fmt::{self, Display}, mem, ffi::{CStr, CString}, sync::LazyLock};
use libc::{self, time_t, c_char};
use git2::Time;

const MINUTES_IN_AN_HOUR: u64 = 60;

const DATE_TIME_FMT: LazyLock<CString> = LazyLock::new(
  || CString::new("%Y-%m-%d %H:%M").unwrap()
);

const DATE_FMT: LazyLock<CString> = LazyLock::new(
  || CString::new("%d/%m/%Y %H:%M").unwrap()
);

const FULL_DATE_FMT: LazyLock<CString> = LazyLock::new(
  || CString::new("%a, %d %b %Y %H:%M:%S").unwrap()
);

#[derive(Clone, Copy, Debug)]
pub struct DateTime(pub Time);

#[derive(Clone, Copy, Debug)]
pub struct Date(pub Time);

#[derive(Clone, Copy, Debug)]
pub struct FullDate(pub Time);

const FTIME_BUFF_LEN:  usize = 64;
// TODO: [safety]: make this thread-safe?
// the application is currently single-threaded, so this is a non-issue for now
static mut FTIME_BUFF: [c_char; FTIME_BUFF_LEN] = [0; FTIME_BUFF_LEN];

#[allow(static_mut_refs)]
fn strftime(
  fmt: &CString,
  time: &Time,
  f: &mut fmt::Formatter<'_>
) -> fmt::Result {
  let time = time.seconds() as time_t;

  unsafe {
    let mut tm = mem::zeroed();
    libc::localtime_r(&time, &mut tm);

    libc::strftime(FTIME_BUFF.as_mut_ptr(), FTIME_BUFF_LEN, fmt.as_ptr(), &tm);
    FTIME_BUFF[FTIME_BUFF_LEN - 1] = 0; // prevent buffer overflows when
                                        // converting back to a CStr
    write!(f, "{}", CStr::from_ptr(FTIME_BUFF.as_ptr()).to_str().unwrap())
  }
}

impl Display for DateTime {
  fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
    strftime(&DATE_TIME_FMT, &self.0, f)
  }
}

impl Display for Date {
  fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
    strftime(&DATE_FMT, &self.0, f)
  }
}

impl Display for FullDate {
  fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
    let timezone_sign = self.0.sign();
    let timezone_mins = self.0.offset_minutes().unsigned_abs() as u64;
    let timezone = timezone_mins / MINUTES_IN_AN_HOUR;

    strftime(&FULL_DATE_FMT, &self.0, f)?;
    write!(f, " {timezone_sign}{timezone:04}")
  }
}