Source code for registrar.utils

"""
utils.py
=========

Contains helper functions

"""


from datetime import datetime
import importlib


def isoformat(dt: datetime) -> str:
    """Formats a datetime object to an ISO string. Timezone naive datetimes are
        are treated as UTC Zulu. UTC Zulu is expressed with the proper "Z"
        ending and not with the "+00:00" offset declaration.

    Args:
        dt (datetime): datetime to encode

    Returns:
        str: iso formatted datetime
    """
    if not dt.utcoffset():
        dt = dt.replace(tzinfo=None)
        return dt.isoformat("T") + "Z"
    return dt.isoformat("T")


def import_by_path(path: str):
    """Imports the object from the referenced module.

    Args:
        path (str): the dotted Python path, where the last element is the
        object in the referenced module.

    """
    module_path, _, object_name = path.rpartition(".")
    return getattr(importlib.import_module(module_path), object_name)


def extract_footprint(env: dict, vsipath: str) -> str:
    """Extracts the footprint from the extent of file. This method is
    currently imprecise due to the extent being different from the actual
    footprint in cases of nodata, unless the geotiff has geometry stored
    as geojson in a metadata attribute `geometry`

    Args:
        env (dict): environment vars for gdal
        vsipath (str): vsi path to file

    Returns:
        str: WKT formatted footprint
    """
    from osgeo.osr import SpatialReference, CoordinateTransformation
    from django.contrib.gis.geos import Polygon, GEOSGeometry

    from eoxserver.contrib.gdal import open_with_env, get_extent

    f = open_with_env(vsipath, env)
    try:
        geojson_footprint = f.GetMetadata()["geometry"]
        footprint = GEOSGeometry(geojson_footprint)
    except KeyError:
        extent = get_extent(f)
        dscrs = f.GetProjection()

        dcrs = SpatialReference()
        dcrs.ImportFromWkt(dscrs)

        wgs84 = SpatialReference()
        wgs84.ImportFromEPSG(4326)

        dcrs2wgs84 = CoordinateTransformation(dcrs, wgs84)
        ll = dcrs2wgs84.TransformPoint(extent[0], extent[1])
        ur = dcrs2wgs84.TransformPoint(extent[2], extent[3])

        footprint = Polygon(
            (
                (ll[1], ll[0]),
                (ur[1], ll[0]),
                (ur[1], ur[0]),
                (ll[1], ur[0]),
                (ll[1], ll[0]),
            )
        )

    return footprint.wkt


def extract_metadata(env: dict, vsipath: str) -> dict:
    """Extracts metadata from file

    Args:
        env (dict): environment vars for
        vsipath (str): vsi path to file

    Returns:
        dict: metadata as key value pairs
    """
    from eoxserver.contrib.gdal import open_with_env
    f = open_with_env(vsipath, env)
    return f.GetMetadata()