"""Fetch a published globular cluster catalogue for NGC 5128 (Centaurus A) from VizieR.

Primary catalogue: J/MNRAS/469/3444 table "gc" -- Taylor, Puzia, Ferrarez et al. 2017,
MNRAS 469, 3444, "Survey of Centaurus A's Baryonic Structures (SCABS) II":
3210 globular cluster candidates with ugriz photometry over ~1.55 deg^2 centred on Cen A.

Fallback: J/AJ/143/84 (Harris+ 2012, 833 new GC candidates).

Writes _cena_gc_ref.npz with keys:
  ra, dec  : degrees, J2000 (ICRS)
  vmag     : Johnson V estimated from SDSS g,r via Lupton (2005):
             V = g - 0.5784*(g-r) - 0.0038
  gmag,rmag: SDSS-like g and r from the source catalogue (NaN where missing)
  prob     : Taylor+ 2017 GC membership probability (0-1), higher = more likely a GC
"""
import numpy as np
from astroquery.vizier import Vizier
from astropy.coordinates import SkyCoord
import astropy.units as u

import layout

OUT = layout.path("_cena_gc_ref.npz")
RA0, DEC0 = 201.365, -43.019
# field half-widths in arcmin for a 43' x 29' frame
HW_RA, HW_DEC = 21.5, 14.5


def col(t, name):
    if name not in t.colnames:
        return None
    return np.ma.filled(np.ma.asarray(t[name]).astype(float), np.nan)


def report(ra, dec, label):
    dra = (ra - RA0) * np.cos(np.radians(dec)) * 60.0
    dde = (dec - DEC0) * 60.0
    sep = np.hypot(dra, dde)
    infield = (np.abs(dra) <= HW_RA) & (np.abs(dde) <= HW_DEC)
    print(f"  {label}: {len(ra)} rows")
    print(f"    RA  {ra.min():.4f} .. {ra.max():.4f}  "
          f"(span {(ra.max()-ra.min())*np.cos(np.radians(DEC0))*60:.1f}')")
    print(f"    Dec {dec.min():.4f} .. {dec.max():.4f}  "
          f"(span {(dec.max()-dec.min())*60:.1f}')")
    print(f"    sep from centre: median {np.median(sep):.1f}'  max {sep.max():.1f}'")
    print(f"    inside 43'x29' field: {infield.sum()}")
    return infield


def main():
    v = Vizier(row_limit=-1)
    cid, tname = "J/MNRAS/469/3444", "J/MNRAS/469/3444/gc"
    print(f"Fetching {tname} (Taylor+ 2017, SCABS II)")
    try:
        tabs = v.get_catalogs(cid)
        t = [x for x in tabs if x.meta.get("name") == tname][0]
    except Exception as e:
        print(f"  FAILED: {e}")
        return 1

    # RAJ2000/DEJ2000 are sexagesimal strings in this table
    sc = SkyCoord(np.asarray(t["RAJ2000"], str), np.asarray(t["DEJ2000"], str),
                  unit=(u.hourangle, u.deg))
    ra = sc.ra.deg
    dec = sc.dec.deg
    g = col(t, "gmag")
    r = col(t, "rmag")
    prob = col(t, "Prob")

    good = np.isfinite(ra) & np.isfinite(dec)
    ra, dec, g, r, prob = ra[good], dec[good], g[good], r[good], prob[good]

    # -1.0 is the catalogue's "no photometry" sentinel -> NaN
    g = np.where(g <= 0, np.nan, g)
    r = np.where(r <= 0, np.nan, r)

    # Lupton (2005) SDSS -> Johnson V
    vmag = g - 0.5784 * (g - r) - 0.0038

    report(ra, dec, tname)
    print(f"    vmag finite: {np.isfinite(vmag).sum()}  "
          f"range {np.nanmin(vmag):.2f} .. {np.nanmax(vmag):.2f}")
    print(f"    prob >=0.5: {(prob >= 0.5).sum()}   >=0.9: {(prob >= 0.9).sum()}")

    np.savez(OUT, ra=ra, dec=dec, vmag=vmag, gmag=g, rmag=r, prob=prob)
    print(f"WROTE {OUT}")
    return 0


if __name__ == "__main__":
    raise SystemExit(main())