Next friday at 12pm

next_friday.rs

use chrono::{Duration, NaiveDate, NaiveDateTime, NaiveTime, Weekday, Datelike};

/// Gets the next day of the week at the given time. If the current date is already the given
/// weekday **and** after the given time, it will return the next one.
fn get_next_day_of_week_at_time(
    weekday: Weekday,
    at_time: NaiveTime,
) -> Option<NaiveDateTime> {
    let mut date = chrono::offset::Local::now();
    let one_day = Duration::days(1);
    
    // It is currently the weekday we want and after the given time.
    if date.weekday() == weekday && date.time() > at_time {
        // Add a day so we scroll over to the next day we're looking for.
        date = date + one_day;
    }
   
    while date.weekday() != weekday {
        // Keep adding a day until we reach the day we're looking for.
        date = date + one_day;
    }
    
    Some(NaiveDate::from_ymd_opt(
        date.year(),
        date.month(),
        date.day(),
    )?.and_time(at_time))
}

fn main() {
    let time = NaiveTime::from_hms_opt(12, 0, 0).unwrap();
    let next_friday_at_12pm = get_next_day_of_week_at_time(Weekday::Fri, time);
    
    println!("{next_friday_at_12pm:?}");
}