Generate fallback URLs for web archive links (#804)

* generate fallback web archive URL if none exists

* remove fallback web archive snapshot creation

* fix test

bookmarks/services/wayback.py

@@ -1,42 +1,20 @@
-import time
-from typing import Dict
+import datetime
 
-import waybackpy
-import waybackpy.utils
-from waybackpy.exceptions import NoCDXRecordFound
+from django.utils import timezone
 
 
-class CustomWaybackMachineCDXServerAPI(waybackpy.WaybackMachineCDXServerAPI):
+def generate_fallback_webarchive_url(
+    url: str, timestamp: datetime.datetime
+) -> str | None:
     """
-    Customized WaybackMachineCDXServerAPI to work around some issues with retrieving the newest snapshot.
-    See https://github.com/akamhy/waybackpy/issues/176
+    Generate a URL to the web archive for the given URL and timestamp.
+    A snapshot for the specific timestamp might not exist, in which case the
+    web archive will show the closest snapshot to the given timestamp.
+    If there is no snapshot at all the URL will be invalid.
     """
+    if not url:
+        return None
+    if not timestamp:
+        timestamp = timezone.now()
 
-    def newest(self):
-        unix_timestamp = int(time.time())
-        self.closest = waybackpy.utils.unix_timestamp_to_wayback_timestamp(
-            unix_timestamp
-        )
-        self.sort = "closest"
-        self.limit = -5
-
-        newest_snapshot = None
-        for snapshot in self.snapshots():
-            newest_snapshot = snapshot
-            break
-
-        if not newest_snapshot:
-            raise NoCDXRecordFound(
-                "Wayback Machine's CDX server did not return any records "
-                + "for the query. The URL may not have any archives "
-                + " on the Wayback Machine or the URL may have been recently "
-                + "archived and is still not available on the CDX server."
-            )
-
-        return newest_snapshot
-
-    def add_payload(self, payload: Dict[str, str]) -> None:
-        super().add_payload(payload)
-        # Set fastLatest query param, as we are only using this API to get the latest snapshot and using fastLatest
-        # makes searching for latest snapshots faster
-        payload["fastLatest"] = "true"
+    return f"https://web.archive.org/web/{timestamp.strftime('%Y%m%d%H%M%S')}/{url}"