#!/usr/bin/env python
# Version: 2019-02-13

import sys
import math
from pyvo.dal import tap

from astropy.coordinates import SkyCoord
from astropy.units import Quantity
 
ESO_TAP_OBS = "http://archive.eso.org/tap_obs"
tapobs = tap.TAPService(ESO_TAP_OBS)
 
 
target = "eta car"
radius = 0.5 # degrees

print()
print("Looking for public SCIENCE FORS2 frames around target %s in a cone of radius %f deg."   %(target, radius))
print("Querying the ESO TAP service at %s" %(ESO_TAP_OBS))

# --------------------------------------------------
# The actual position of the selected target
# is queried by the from_name() function,
# which queries the CDS SESAME service
# (http://cdsweb.u-strasbg.fr/cgi-bin/Sesame).
# --------------------------------------------------

print("The provided target is being resolved by SESAME...")
pos = SkyCoord.from_name(target)

print("SESAME coordinates for %s: %s" % (target, pos.to_string()))

cosd = math.cos( pos.dec.to_value() * math.pi/180. )
if ( math.fabs( pos.dec.to_value() - 90 ) < radius ):
    cosd = 1;

ra_min = pos.ra.to_value() - radius * cosd 
ra_max = pos.ra.to_value() + radius * cosd 
dec_min = pos.dec.to_value() - radius
dec_max = pos.dec.to_value() + radius

top = "TOP %d" % (3)

query="""SELECT %s object, ra, dec, tpl_start, prog_id, filter_path, dp_id
from dbo.raw
where ra  between %f and %f
  and dec between %f and %f
  and instrument='FORS2'
  and release_date < getdate()
  and dp_cat='SCIENCE' """ % ( top, ra_min, ra_max, dec_min, dec_max );

print(query)
 
res = tapobs.search(query=query)
print(res.to_table())

# --------------------------------------------------
import urllib
prompt = "Shall I download those %d files, [y|n]:" % (len(res.to_table()))
shall_I = input(prompt) # Python 3

if shall_I != "y":
    print("Stopping here, without downloading any file")
    sys.exit(0)

print("Downloading the non-proprietary files (%d files)" % (len(res.to_table())))

nfiles = 0
for row in res:
    nfiles += 1
    # Change from previous version: the access_url points to the datalink and not directly to the file download.
    # Given a dp_id of a public file, the link to download it is constructed as follows:
    download_url = "http://archive.eso.org/datalink/links?ID=ivo://eso.org/ID?%s&eso_download=file" % row["dp_id"].decode()

    urllib.request.urlretrieve(download_url, row["dp_id"].decode())

    # informing user:
    print("%4d/%d dp_id: %s downloaded"  % (nfiles, len(res.to_table()), row["dp_id"].decode()))