use crate::consts::{DJM0, IYMIN, MTAB};

/// Gregorian calendar to Julian Day number

pub fn cal2jd(iy: i32, im: i32, id: i32) -> Result<(f64, f64), i32> {

    if iy < IYMIN {

        return Err(-1);

    }

    match im {

        1..=12 => (),

        _ => return Err(-2),

    }

    let ly = if im == 2 && iy % 4 == 0 && (iy % 100 != 0 || iy % 400 == 0) {

        1

    } else {

        0

    };

    if id < 1 || id > (MTAB[(im - 1) as usize] + ly) {

        return Err(-3);

    }

    let my = (im - 14) / 12;

    let iypmy = (iy + my) as i64;

    let djm0 = DJM0;

    let djm = ((1461 * (iypmy + 4800)) / 4 + (367 * ((im - 2 - 12 * my) as i64)) / 12

        - (3 * ((iypmy + 4900) / 100)) / 4

        + (id as i64)

        - 2432076) as f64;

    Ok((djm0, djm))

}