#![allow(unused)]

use chrono::{DateTime, Utc, NaiveDateTime};

fn nanos(utc: DateTime<Utc>) -> u64 {
    (utc.timestamp() as u64) * 1_000_000_000_u64 + (utc.timestamp_subsec_nanos() as u64)
}

fn get_time() -> (i64, i32) {
    let mut tv = libc::timespec { tv_sec: 0, tv_nsec: 0 };
    unsafe { libc::clock_gettime(libc::CLOCK_REALTIME, &mut tv); }
    (tv.tv_sec as i64, tv.tv_nsec as i32)
}

fn timespec_to_utc(sec: i64, nsec: i32) -> DateTime<Utc> {
    let naive = NaiveDateTime::from_timestamp(sec, nsec as u32);
    DateTime::from_utc(naive, Utc)
}

fn timespec_to_nanos(sec: i64, nsec: i32) -> u64 {
    (sec as u64) * 1_000_000_000_u64 + (nsec as u64)
}

fn main() {
    let args: clap::ArgMatches = clap::App::new("utcnow")
        .author("Jonathan Strong <jonathan.strong@gmail.com>")
        .version(clap::crate_version!())
        .about("\ncurrent time in utc with non-cryptic interface.\n\n\
                for your own safety and well-being, local time functionality is not provided.\n\n\
                default output format is rfc3339 with trailing 'Z', e.g. '1999-12-31T23:59:59.999999999Z'")
        .help_message("help")
        .version_message("version")
        .arg(clap::Arg::with_name("unix")
            .help("display elapsed nanoseconds since 1970-01-01T00:00:00Z")
            .long("unix")
            .short("u")
            .required(false)
            .takes_value(false))
        .arg(clap::Arg::with_name("rfc2822")
            .help("display in rfc2822 format")
            .long("rfc2822")
            .short("r")
            .required(false)
            .takes_value(false))
        .arg(clap::Arg::with_name("seconds")
            .help("display unix timestamp in seconds, instead of default nanoseconds")
            .long("seconds")
            .short("s")
            .requires("unix")
            .required(false)
            .takes_value(false))
        .arg(clap::Arg::with_name("timespec")
            .help("display as <sec>,<nsec>")
            .long("timespec")
            .short("t")
            .required(false)
            .takes_value(false))
        .get_matches();

    let (sec, nsec) = get_time();

    if args.is_present("timespec") {
        println!("{},{}", sec, nsec);
    } else if args.is_present("unix") {
        if args.is_present("seconds") {
            println!("{}", sec);
        } else {
            println!("{}", timespec_to_nanos(sec, nsec));
        }
    } else if args.is_present("rfc2822") {

        println!("{}", timespec_to_utc(sec, nsec).to_rfc2822());

    } else {
        // Debug view is iso format / rfc3339 that we want
        // Display has spaces - no go
        // to_rfc3339 uses +00:00 instead of Z, which I don't like
        println!("{:?}", timespec_to_utc(sec, nsec));
    }
}