Write metakernel to custom location and update KERNELS. Optionally, create symlink to Kernels location.

update_metakernel.py

# -*- coding: utf-8 -*-
"""This module contains code related to NAIF/SPICE.
"""
import pathlib 

def update_metakernel(metakernel_path=pathlib.Path,
                      metakernel_version=None,
                      KPATH=None,
                      outdir=None,
                      symlink=None,
                      loglevel=None):
    """Extract SKD_VERSION from input metakernel,
    update given metakernel relative path to absolute.
    Write the update metakernel to output with SKD_VERSION in 
    filename.
    Return both SKD_VERSION and updated metakernel pathlib.Path

    Parameters
    ----------
    metakernel_path: pathlib.Path or str
           input  metakernel path.

    metakernel_version: str, default None.
            Version string for the output metakernel.
            If not defined and SKD_VERSION not found in metakernel,
            strftime("%Y-%M-%dT%H:%M:%S") is used.

    KPATH: pathlib.Path or str, default None
            SPICE kernels location path. Default
            points to metakernel_path.parent.parent.

    outdir: pathlib.Path or str, default None
            output directory to write the metakernel to.
            Default points to metakernel_path.parent.

    symlink: pathlib.Path or str, default None
            If defined, symlink KPATH to it. Useful to create 
            a shorter KPATH i.e. /tmp/symlink . 

    loglevel: str, default None
            if defined, set logging level.

    Returns
    -------
    meta_mdf : pathlib.Path
            updated metakernel pathlib.Path

    SKD_VERSION: str
            version of the kernel data set used.
    """
    import logging
    if loglevel is not None :
        logging.getLogger().setLevel(loglevel.upper())

    SKD_VERSION=None

    # check if inputs are defined (!= None) and are pathlib.Path class
    metakernel_path=pathlib.Path(metakernel_path)
    if KPATH is not None and not isinstance(KPATH,pathlib.Path):
        KPATH = pathlib.Path(KPATH)
    if outdir is not None and not isinstance(outdir,pathlib.Path):
        outdir = pathlib.Path(outdir)
    if symlink is not None and not isinstance(symlink,pathlib.Path):
        symlink = pathlib.Path(symlink)

    if KPATH is None :
        KPATH = metakernel_path.parent.parent
    if outdir is None :
        outdir = metakernel_path.parent

    # try to read metakernel
    mylines = []
    try:
        with open(metakernel_path, 'r') as f:
            for lines in f:
                mylines.append(lines)
                if not metakernel_version:
                    if lines.find('SKD_VERSION') != -1:
                        SKD_VERSION = (str.split(lines, "'"))[1]
        logging.info(f'Reading SPICE Metakernel {metakernel_path}') 
    except FileNotFoundError:
        logging.error(f'SPICE Metakernel {metakernel_path} could not be opened.') 
        sys.exit(1)

    if metakernel_version: 
        logging.info('SKD_VERSION : using user input')
        SKD_VERSION = metakernel_version

    if not SKD_VERSION: 
        logging.warning('NOT FOUND: SPICE Kernel Dataset Version variable SKD_VERSION - use current time')
        from time import strftime,localtime
        SKD_VERSION = strftime("%Y-%M-%dT%H:%M:%S", localtime())


    # create fake spice kernels directory
    if symlink:
        try:
            symlink.symlink_to(KPATH, target_is_directory=True)
            logging.info(f'Create symlink {symlink} to {KPATH}')
        except FileExistsError as e:
            logging.info(e)

    # write temporary metakernel with modified paths
    meta_mdf = outdir / f"{metakernel_path.stem}_updated-{SKD_VERSION}.tm"
    try:
        with open(meta_mdf, 'w') as f:
            for lines in mylines:
                if lines.find("PATH_VALUES") != -1:
                    splitted = lines.split("'")
                    if symlink:
                        lines = f"{splitted[0]}'{symlink}'{splitted[-1]}"
                    else:
                        lines = f"{splitted[0]}'{KPATH}'{splitted[-1]}"
                # #TODO adapt Replacing path separator and convert line terminators to non *NIX systems
                # if lines.find("$KERNELS") != 0:
                #     lines = lines.replace("/", os.sep)
                f.write(lines)
        logging.info(f'Metakernel with updated paths created and moved to {outdir}')
    except FileNotFoundError:
        logging.error(f'SPICE Metakernel {metakernel_path} could not be write.') 

    logging.debug(f'{metakernel_path=}')
    logging.debug(f'{metakernel_version=}')
    logging.debug(f'{KPATH=}')
    logging.debug(f'{meta_mdf=}')
    logging.debug(f'{SKD_VERSION=}')
    logging.debug(f'{outdir=}')
    logging.debug(f'{symlink=}')

    return {'kernels_updated_version':SKD_VERSION,'metakernel_path':meta_mdf}