Remove pystac (#690)

* remove pystac

* update, fix changelog

* fix link

* Update stac_fastapi/types/stac_fastapi/types/rfc3339.py

Co-authored-by: Pete Gadomski <pete.gadomski@gmail.com>

---------

Co-authored-by: Pete Gadomski <pete.gadomski@gmail.com>

Author: jonhealy1

CHANGES.md

@@ -1,11 +1,15 @@
 # Changelog
 
-[Unreleased] - TBD
+## [Unreleased] - TBD
 
-## Changed
+### Changed
+
+* switch from `fastapi` to `fastapi-slim` to avoid installing unwanted dependencies. ([#687](https://github.com/stac-utils/stac-fastapi/pull/687))
+* replace Enum with `Literal` for `FilterLang`. ([#686](https://github.com/stac-utils/stac-fastapi/pull/686))
+
+### Removed
 
-* switch from `fastapi` to `fastapi-slim` to avoid installing unwanted dependencies
-* replace Enum with `Literal` for `FilterLang`
+* Pystac as it was just used for a datetime to string function. ([#690](https://github.com/stac-utils/stac-fastapi/pull/690))
 
 ## [3.0.0a0] - 2024-05-06
 

stac_fastapi/api/setup.py

@@ -18,7 +18,6 @@
         "pytest-asyncio",
         "pre-commit",
         "requests",
-        "pystac[validation]==1.*",
     ],
     "benchmark": [
         "pytest-benchmark",

stac_fastapi/types/setup.py

@@ -10,7 +10,6 @@
     "attrs>=23.2.0",
     "pydantic-settings>=2",
     "stac_pydantic>=3",
-    "pystac==1.*",
     "iso8601>=1.0.2,<2.2.0",
 ]
 

stac_fastapi/types/stac_fastapi/types/rfc3339.py

@@ -6,7 +6,6 @@
 
 import iso8601
 from fastapi import HTTPException
-from pystac.utils import datetime_to_str
 
 RFC33339_PATTERN = (
     r"^(\d\d\d\d)\-(\d\d)\-(\d\d)(T|t)(\d\d):(\d\d):(\d\d)([.]\d+)?"
@@ -21,6 +20,34 @@
 ]
 
 
+# Borrowed from pystac - https://github.com/stac-utils/pystac/blob/f5e4cf4a29b62e9ef675d4a4dac7977b09f53c8f/pystac/utils.py#L370-L394
+def datetime_to_str(dt: datetime, timespec: str = "auto") -> str:
+    """Converts a :class:`datetime.datetime` instance to an ISO8601 string in the
+    `RFC 3339, section 5.6
+    <https://datatracker.ietf.org/doc/html/rfc3339#section-5.6>`__ format required by
+    the :stac-spec:`STAC Spec <master/item-spec/common-metadata.md#date-and-time>`.
+
+    Args:
+        dt : The datetime to convert.
+        timespec: An optional argument that specifies the number of additional
+            terms of the time to include. Valid options are 'auto', 'hours',
+            'minutes', 'seconds', 'milliseconds' and 'microseconds'. The default value
+            is 'auto'.
+
+    Returns:
+        str: The ISO8601 (RFC 3339) formatted string representing the datetime.
+    """
+    if dt.tzinfo is None:
+        dt = dt.replace(tzinfo=timezone.utc)
+
+    timestamp = dt.isoformat(timespec=timespec)
+    zulu = "+00:00"
+    if timestamp.endswith(zulu):
+        timestamp = f"{timestamp[: -len(zulu)]}Z"
+
+    return timestamp
+
+
 def rfc3339_str_to_datetime(s: str) -> datetime:
     """Convert a string conforming to RFC 3339 to a :class:`datetime.datetime`.