Source code for gdt.missions.gifts.tcat

#
# Copyright 2026 by University College Dublin. All rights reserved.
#
# Developed by: Derek O'Callaghan
#               University College Dublin
#               https://www.ucd.ie/
#
# Builds on:
#               Gamma-ray Data Tools - Core Components (https://github.com/USRA-STI/gdt-core)
#               Gamma-ray Data Tools - Fermi mission components (https://github.com/USRA-STI/gdt-fermi/)
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
# in compliance with the License. You may obtain a copy of the License at
#
#    http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software distributed under the License
# is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
# implied. See the License for the specific language governing permissions and limitations under the
# License.
#
import astropy.io.fits as fits
from astropy.coordinates import Latitude, Longitude
from gdt.core.file import FitsFileContextManager
from gdt.missions.fermi.gbm.tcat import Tcat as GbmTcat
from .headers import TcatHeaders

__all__ = ['Tcat']



class Tcat(GbmTcat):
    """TCAT (Trigger CATalog) file class.
    """

    @property
    def gifts_location(self):
        """(astropy.coordinates.Longitude, astropy.coordinates.Latitude): GIFT's 
        orbital longitude and latitude"""
        return self.fermi_location
        


    @classmethod
    def open(cls, file_path, **kwargs):
        """Open a TCAT FITS file and return the Tcat object
        
        Args:
            file_path (str): The file path of the FITS file
        
        Returns:        
            (:class:`Tcat`)
        """
        # Currently impossible to access the FITS HDUs without opening twice, not ideal
        # This could be avoided if the original HDUs were retained during opening, but
        # they're rebuilt by each FITS subclass that uses its own headers
        obj = FitsFileContextManager.open(file_path, **kwargs)
        hdrs = [hdu.header for hdu in obj.hdulist]
        # This is the reason why GbmTcat.open() can't solely be used, 
        # need to explicitly specify the header classes
        tcat_headers = TcatHeaders.from_headers(hdrs)        
        obj.close()

        tcat = super().open(file_path, **kwargs)
        tcat._headers = tcat_headers
        return tcat

    
    def _build_hdulist(self):
        """
        Fixes bug in GbmTcat._build_hdulist()
        """
        hdulist = fits.HDUList()
        # Bug fix: self['PRIMARY'] -> self.headers['PRIMARY']
        primary_header = self.headers["PRIMARY"]
        primary_hdu = fits.PrimaryHDU(header=primary_header)
        hflag = 0
        # Bug fix: self['PRIMARY'] -> self.headers['PRIMARY']
        for key, val in primary_header.items():
            if key == 'HISTORY':
                primary_hdu.header['HISTORY'][hflag] = val
                hflag += 1
            else:
                primary_hdu.header[key] = val
        hdulist.append(primary_hdu)
        return hdulist