sofars 0.6.0

use crate::erst::era00;
use crate::pnp::sp00;
use crate::ts::{taitt, utctai, utcut1};

use super::{IauAstrom, apio, refco};

///  Prepare for CIRS <−> observed, terrestrial
///
///  For a terrestrial observer, prepare star-independent astrometry
///  parameters for transformations between CIRS and observed
///  coordinates.  The caller supplies UTC, site coordinates, ambient air
///  conditions and observing wavelength.
///
///  This function is part of the International Astronomical Union's
///  SOFA (Standards of Fundamental Astronomy) software collection.
///
///  Status:  support function.
///
///  Given:
///  ```
///     utc1   double      UTC as a 2-part...
///     utc2   double      ...quasi Julian Date (Notes 1,2)
///     dut1   double      UT1-UTC (seconds)
///     elong  double      longitude (radians, east +ve, Note 3)
///     phi    double      geodetic latitude (radians, Note 3)
///     hm     double      height above ellipsoid (m, geodetic Notes 4,6)
///     xp,yp  double      polar motion coordinates (radians, Note 5)
///     phpa   double      pressure at the observer (hPa = mB, Note 6)
///     tc     double      ambient temperature at the observer (deg C)
///     rh     double      relative humidity at the observer (range 0-1)
///     wl     double      wavelength (micrometers, Note 7)
///  ```
///  Returned:
///  ```
///     astrom iauASTROM*  star-independent astrometry parameters:
///      pmt    double       unchanged
///      eb     double[3]    unchanged
///      eh     double[3]    unchanged
///      em     double       unchanged
///      v      double[3]    unchanged
///      bm1    double       unchanged
///      bpn    double[3][3] unchanged
///      along  double       longitude + s' (radians)
///      xpl    double       polar motion xp wrt local meridian (radians)
///      ypl    double       polar motion yp wrt local meridian (radians)
///      sphi   double       sine of geodetic latitude
///      cphi   double       cosine of geodetic latitude
///      diurab double       magnitude of diurnal aberration vector
///      eral   double       "local" Earth rotation angle (radians)
///      refa   double       refraction constant A (radians)
///      refb   double       refraction constant B (radians)
///  ```
///  Returned (function value):
///  ```
///            int         status: +1 = dubious year (Note 2)
///                                 0 = OK
///                                -1 = unacceptable date
///  ```
///  Notes:
///
///  1)  utc1+utc2 is quasi Julian Date (see Note 2), apportioned in any
///      convenient way between the two arguments, for example where utc1
///      is the Julian Day Number and utc2 is the fraction of a day.
///
///      However, JD cannot unambiguously represent UTC during a leap
///      second unless special measures are taken.  The convention in the
///      present function is that the JD day represents UTC days whether
///      the length is 86399, 86400 or 86401 SI seconds.
///
///      Applications should use the function iauDtf2d to convert from
///      calendar date and time of day into 2-part quasi Julian Date, as
///      it implements the leap-second-ambiguity convention just
///      described.
///
///  2)  The warning status "dubious year" flags UTCs that predate the
///      introduction of the time scale or that are too far in the future
///      to be trusted.  See iauDat for further details.
///
///  3)  UT1-UTC is tabulated in IERS bulletins.  It increases by exactly
///      one second at the end of each positive UTC leap second,
///      introduced in order to keep UT1-UTC within +/- 0.9s.  n.b. This
///      practice is under review, and in the future UT1-UTC may grow
///      essentially without limit.
///
///  4)  The geographical coordinates are with respect to the WGS84
///      reference ellipsoid.  TAKE CARE WITH THE LONGITUDE SIGN:  the
///      longitude required by the present function is east-positive
///      (i.e. right-handed), in accordance with geographical convention.
///
///  5)  The polar motion xp,yp can be obtained from IERS bulletins.  The
///      values are the coordinates (in radians) of the Celestial
///      Intermediate Pole with respect to the International Terrestrial
///      Reference System (see IERS Conventions 2003), measured along the
///      meridians 0 and 90 deg west respectively.  For many applications,
///      xp and yp can be set to zero.
///
///      Internally, the polar motion is stored in a form rotated onto
///      the local meridian.
///
///  6)  If hm, the height above the ellipsoid of the observing station
///      in meters, is not known but phpa, the pressure in hPa (=mB), is
///      available, an adequate estimate of hm can be obtained from the
///      expression
///
///            hm = -29.3 * tsl * log ( phpa / 1013.25 );
///
///      where tsl is the approximate sea-level air temperature in K
///      (See Astrophysical Quantities, C.W.Allen, 3rd edition, section
///      52).  Similarly, if the pressure phpa is not known, it can be
///      estimated from the height of the observing station, hm, as
///      follows:
///
///            phpa = 1013.25 * exp ( -hm / ( 29.3 * tsl ) );
///
///      Note, however, that the refraction is nearly proportional to the
///      pressure and that an accurate phpa value is important for
///      precise work.
///
///  7)  The argument wl specifies the observing wavelength in
///      micrometers.  The transition from optical to radio is assumed to
///      occur at 100 micrometers (about 3000 GHz).
///
///  8)  It is advisable to take great care with units, as even unlikely
///      values of the input parameters are accepted and processed in
///      accordance with the models used.
///
///  9)  In cases where the caller wishes to supply his own Earth
///      rotation information and refraction constants, the function
///      iauApc can be used instead of the present function.
///
///  10) This is one of several functions that inserts into the astrom
///      structure star-independent parameters needed for the chain of
///      astrometric transformations ICRS <-> GCRS <-> CIRS <-> observed.
///
///      The various functions support different classes of observer and
///      portions of the transformation chain:
///  ```
///          functions         observer        transformation
///
///       iauApcg iauApcg13    geocentric      ICRS <-> GCRS
///       iauApci iauApci13    terrestrial     ICRS <-> CIRS
///       iauApco iauApco13    terrestrial     ICRS <-> observed
///       iauApcs iauApcs13    space           ICRS <-> GCRS
///       iauAper iauAper13    terrestrial     update Earth rotation
///       iauApio iauApio13    terrestrial     CIRS <-> observed
///  ```
///      Those with names ending in "13" use contemporary SOFA models to
///      compute the various ephemerides.  The others accept ephemerides
///      supplied by the caller.
///
///      The transformation from ICRS to GCRS covers space motion,
///      parallax, light deflection, and aberration.  From GCRS to CIRS
///      comprises frame bias and precession-nutation.  From CIRS to
///      observed takes account of Earth rotation, polar motion, diurnal
///      aberration and parallax (unless subsumed into the ICRS <-> GCRS
///      transformation), and atmospheric refraction.
///
///  11) The context structure astrom produced by this function is used
///      by iauAtioq and iauAtoiq.
///
///  Called:
///  ```
///     iauUtctai    UTC to TAI
///     iauTaitt     TAI to TT
///     iauUtcut1    UTC to UT1
///     iauSp00      the TIO locator s', IERS 2000
///     iauEra00     Earth rotation angle, IAU 2000
///     iauRefco     refraction constants for given ambient conditions
///     iauApio      astrometry parameters, CIRS-observed
///  ```
pub fn apio13(
    utc1: f64,
    utc2: f64,
    dut1: f64,
    elong: f64,
    phi: f64,
    hm: f64,
    xp: f64,
    yp: f64,
    phpa: f64,
    tc: f64,
    rh: f64,
    wl: f64,
    astrom: &mut IauAstrom,
) -> Result<(), i32> {
    let (tai1, tai2) = match utctai(utc1, utc2) {
        Ok(v) => v,
        Err(j) => return Err(j),
    };

    let (tt1, tt2) = match taitt(tai1, tai2) {
        Ok(v) => v,
        Err(j) => return Err(j),
    };

    let (ut11, ut12) = match utcut1(utc1, utc2, dut1) {
        Ok(v) => v,
        Err(j) => return Err(j),
    };

    /* TIO locator s'. */
    let sp = sp00(tt1, tt2);

    /* Earth rotation angle. */
    let theta = era00(ut11, ut12);

    /* Refraction constants. */
    let (refa, refb) = refco(phpa, tc, rh, wl);

    /* CIRS <-> observed astrometry parameters. */
    apio(sp, theta, elong, phi, hm, xp, yp, refa, refb, astrom);

    Ok(())
}