Add start of ASF s3 orbit fetching

Addresses #63

eof/_fetch_s3_bucket.py

@@ -0,0 +1,117 @@
+import logging
+from functools import cache
+from typing import Optional, Literal
+
+import requests
+import xml.etree.ElementTree as ET
+
+logging.basicConfig(level=logging.INFO)
+logger = logging.getLogger(__name__)
+
+ASF_BUCKET_NAME = "s1-orbits"
+
+
+@cache
+def list_public_bucket(bucket_name: str, prefix: str = "") -> list[str]:
+    """List all objects in a public S3 bucket.
+
+    Parameters
+    ----------
+    bucket_name : str
+        Name of the S3 bucket.
+    prefix : str, optional
+        Prefix to filter objects, by default "".
+
+    Returns
+    -------
+    list[str]
+        list of object keys in the bucket.
+
+    Raises
+    ------
+    requests.RequestException
+        If there's an error in the HTTP request.
+    """
+    endpoint = f"https://{bucket_name}.s3.amazonaws.com"
+    marker: Optional[str] = None
+    keys: list[str] = []
+
+    while True:
+        params = {"prefix": prefix}
+        if marker:
+            params["marker"] = marker
+
+        try:
+            response = requests.get(endpoint, params=params)
+            response.raise_for_status()
+        except requests.RequestException as e:
+            logger.error(f"Error fetching bucket contents: {e}")
+            raise
+
+        root = ET.fromstring(response.content)
+        for contents in root.findall(
+            "{http://s3.amazonaws.com/doc/2006-03-01/}Contents"
+        ):
+            key = contents.find("{http://s3.amazonaws.com/doc/2006-03-01/}Key")
+            if key:
+                keys.append(key.text or "")
+                logger.debug(f"Found key: {key}")
+
+        is_truncated = root.find("{http://s3.amazonaws.com/doc/2006-03-01/}IsTruncated")
+        if (
+            is_truncated is not None
+            and is_truncated.text
+            and is_truncated.text.lower() == "true"
+        ):
+            next_marker = root.find(
+                "{http://s3.amazonaws.com/doc/2006-03-01/}NextMarker"
+            )
+            if next_marker is not None:
+                marker = next_marker.text
+            else:
+                found_keys = root.findall(
+                    "{http://s3.amazonaws.com/doc/2006-03-01/}Contents/{http://s3.amazonaws.com/doc/2006-03-01/}Key"
+                )
+                if found_keys:
+                    marker = found_keys[-1].text
+                else:
+                    break
+        else:
+            break
+
+    return keys
+
+
+def get_orbit_files(orbit_type: Literal["precise", "restituted"]) -> list[str]:
+    """Get a list of precise or restituted orbit files.
+
+    Parameters
+    ----------
+    orbit_type : Literal["precise", "restituted"]
+        Type of orbit files to retrieve.
+
+    Returns
+    -------
+    list[str]
+        list of orbit file keys.
+
+    Raises
+    ------
+    ValueError
+        If an invalid orbit_type is provided.
+    """
+    prefix = (
+        "AUX_POEORB"
+        if orbit_type == "precise"
+        else "AUX_RESORB"
+        if orbit_type == "restituted"
+        else None
+    )
+    if prefix is None:
+        raise ValueError("orbit_type must be either 'precise' or 'restituted'")
+
+    all_keys = list_public_bucket(ASF_BUCKET_NAME)
+    orbit_files = [key for key in all_keys if key.startswith(prefix)]
+
+    logger.info(f"Found {len(orbit_files)} {orbit_type} orbit files")
+    return orbit_files

eof/tests/test_asf_s3.py

@@ -0,0 +1,20 @@
+import pytest
+from eof._fetch_s3_bucket import get_orbit_files
+
+
+@pytest.mark.vcr()
+def test_get_orbit_files():
+    """
+    Test the get_orbit_files function using pytest and vcr.
+    """
+    precise_orbits = get_orbit_files("precise")
+    restituted_orbits = get_orbit_files("restituted")
+
+    assert len(precise_orbits) > 0, "No precise orbit files found"
+    assert len(restituted_orbits) > 0, "No restituted orbit files found"
+    assert all(
+        orbit.startswith("AUX_POEORB") for orbit in precise_orbits
+    ), "Invalid precise orbit file name"
+    assert all(
+        orbit.startswith("AUX_RESORB") for orbit in restituted_orbits
+    ), "Invalid restituted orbit file name"