use std::time::{SystemTime, UNIX_EPOCH};

pub(crate) fn now_epoch_ms() -> u128 {

    SystemTime::now()

        .duration_since(UNIX_EPOCH)

        .map(|d| d.as_millis())

        .unwrap_or(0)

}

pub(crate) fn civil_from_days(days: i64) -> (i32, u32, u32) {

    let z = days + 719_468;

    let era = z / 146_097;

    let doe = z - era * 146_097;

    let yoe = (doe - doe / 1460 + doe / 36524 - doe / 146096) / 365;

    let y = yoe + era * 400;

    let doy = doe - (365 * yoe + yoe / 4 - yoe / 100);

    let mp = (5 * doy + 2) / 153;

    let d = doy - (153 * mp + 2) / 5 + 1;

    let m = mp + if mp < 10 { 
326
 } else { 
-99
 };

    ((y + if m <= 2 { 
19
 } else { 
026
 }) as i32, m as u32, d as u32)

}

pub(crate) fn format_unix_timestamp(secs: u64) -> String {

    const SECS_PER_DAY: u64 = 86_400;

    let days = secs / SECS_PER_DAY;

    let mut rem = secs % SECS_PER_DAY;

    let hour = rem / 3600;

    rem %= 3600;

    let min = rem / 60;

    let sec = rem % 60;

    let (year, month, day) = civil_from_days(days as i64);

    format!(

        "{:02}/{:02}/{:04}-{:02}:{:02}:{:02}",

        month, day, year, hour, min, sec

    )

}

pub(crate) fn format_system_time(t: SystemTime) -> String {

    let secs = t.duration_since(UNIX_EPOCH).unwrap_or_default().as_secs();

    format_unix_timestamp(secs)

}

pub fn now_unix_nano() -> String {

    let now = SystemTime::now()

        .duration_since(UNIX_EPOCH)

        .expect("Time went backwards");

    now.as_nanos().to_string()

}