use chrono::{DateTime, TimeZone, Utc};
use cron_exp::Schedule;
use std::str::FromStr;

fn main() {
    //               sec  min   hour   day of month   month   day of week   year
    let expression = "0   30   9,12,15     1,15       May-Aug  Mon,Wed,Fri  2018/2";
    let schedule = Schedule::from_str(expression).unwrap();

    let mut last: Option<DateTime<Utc>> = None;
    let from_date = Utc.ymd(2022, 6, 1).and_hms(8, 40, 1);

    println!("Upcoming fire times:");
    for datetime in schedule.iter_from(&from_date).take(10) {
        last = Some(datetime);
        println!("next -> {:?}", datetime);
    }

    println!("\nPrevious fire times:");
    for datetime in schedule.iter_from(&last.unwrap()).rev().take(10) {
        println!("prev -> {:?}", datetime);
    }
}

/*
Upcoming fire times:
next -> 2022-06-01T09:30:00Z
next -> 2022-06-01T12:30:00Z
next -> 2022-06-01T15:30:00Z
next -> 2022-06-15T09:30:00Z
next -> 2022-06-15T12:30:00Z
next -> 2022-06-15T15:30:00Z
next -> 2022-07-01T09:30:00Z
next -> 2022-07-01T12:30:00Z
next -> 2022-07-01T15:30:00Z
next -> 2022-07-15T09:30:00Z

Previous fire times:
prev -> 2022-07-01T15:30:00Z
prev -> 2022-07-01T12:30:00Z
prev -> 2022-07-01T09:30:00Z
prev -> 2022-06-15T15:30:00Z
prev -> 2022-06-15T12:30:00Z
prev -> 2022-06-15T09:30:00Z
prev -> 2022-06-01T15:30:00Z
prev -> 2022-06-01T12:30:00Z
prev -> 2022-06-01T09:30:00Z
prev -> 2020-07-15T15:30:00Z
*/