use super::ld;

///  Light deflection by the Sun

///

///  Deflection of starlight by the Sun.

///

///  This function is part of the International Astronomical Union's

///  SOFA (Standards of Fundamental Astronomy) software collection.

///

///  Status:  support function.

///

///  Given:

///  ```text

///     p      double[3]  direction from observer to star (unit vector)

///     e      double[3]  direction from Sun to observer (unit vector)

///     em     double     distance from Sun to observer (au)

///  ```

///  Returned:

///  ```text

///     p1     double[3]  observer to deflected star (unit vector)

///  ```

///

///  Notes:

///

///  1) The source is presumed to be sufficiently distant that its

///     directions seen from the Sun and the observer are essentially

///     the same.

///

///  2) The deflection is restrained when the angle between the star and

///     the center of the Sun is less than a threshold value, falling to

///     zero deflection for zero separation.  The chosen threshold value

///     is within the solar limb for all solar-system applications, and

///     is about 5 arcminutes for the case of a terrestrial observer.

///

///  3) The arguments p and p1 can be the same array.

///

///  Called:

///  ```text

///     iauLd        light deflection by a solar-system body

///  ```

pub fn ldsun(p: [f64; 3], e: [f64; 3], em: f64) -> [f64; 3] {

    /* Deflection limiter (smaller for distant observers). */

    let mut em2 = em * em;

    if em2 < 1.0 {

        em2 = 1.0;

    }

    let dlim = 1e-6 / if em2 > 1.0 { em2 } else { 1.0 };

    /* Apply the deflection. */

    ld(1.0, p, p, e, em, dlim)

}