small modifications for custom SAFE support

src/hyp3_isce2/slc.py

@@ -4,6 +4,7 @@
 from subprocess import PIPE, run
 from zipfile import ZipFile
 
+import lxml.etree as ET
 from hyp3lib.fetch import download_file
 from hyp3lib.scene import get_download_url
 from shapely import geometry
@@ -19,6 +20,10 @@ def get_granule(granule: str) -> Path:
     Returns:
         The path to the unzipped granule
     """
+    if Path(f'{granule}.SAFE').exists():
+        print('SAFE file already exists, skipping download.')
+        return Path.cwd() / f'{granule}.SAFE'
+
     download_url = get_download_url(granule)
     zip_file = download_file(download_url, chunk_size=10485760)
     safe_dir = unzip_granule(zip_file, remove=True)
@@ -41,6 +46,16 @@ def get_geometry_from_kml(kml_file: str) -> Polygon:
     return geometry.shape(geojson)
 
 
+def get_geometry_from_manifest(manifest_path: Path):
+    manifest = ET.parse(manifest_path).getroot()
+    frame_element = [x for x in manifest.findall('.//metadataObject') if x.get('ID') == 'measurementFrameSet'][0]
+    frame_string = frame_element.find('.//{http://www.opengis.net/gml}coordinates').text
+    coord_strings = [pair.split(',') for pair in frame_string.split(' ')]
+    coords = [(float(lon), float(lat)) for lat, lon in coord_strings]
+    footprint = Polygon(coords)
+    return footprint
+
+
 def get_dem_bounds(reference_granule: Path, secondary_granule: Path) -> tuple:
     """Get the bounds of the DEM to use in processing from SAFE KML files
 
@@ -53,7 +68,7 @@ def get_dem_bounds(reference_granule: Path, secondary_granule: Path) -> tuple:
     """
     bboxs = []
     for granule in (reference_granule, secondary_granule):
-        footprint = get_geometry_from_kml(str(granule / 'preview' / 'map-overlay.kml'))
+        footprint = get_geometry_from_manifest(granule / 'manifest.safe')
         bbox = geometry.box(*footprint.bounds)
         bboxs.append(bbox)