Separated download url computation

hda/api.py

@@ -269,19 +269,38 @@ def __getitem__(self, index):
     def _download(self, result, download_dir: str = "."):
         logger.debug(result)
         self.client.accept_tac(self.dataset)
+        download_id = self._get_download_id(result)
+        self.stream(
+            download_id,
+            result["properties"]["size"],
+            download_dir,
+        )
 
+    def _get_download_id(self, result):
         query = {
             "dataset_id": self.dataset,
             "product_id": result["id"],
             "location": result["properties"]["location"],
         }
-        download_id = DataOrderRequest(self.client).run(query)
+        return DataOrderRequest(self.client).run(query)
 
-        self.stream(
-            download_id,
-            result["properties"]["size"],
-            download_dir,
-        )
+    def get_download_urls(self, limit: int = None):
+        """Utility function to return the list of final download URLs.
+        Useful in the context of the Serverless Functions service.
+        If the list of results is long, it might take a long time.
+        In that case, either subset the results or set a value for `limit`.
+        """
+
+        def build_url(result):
+            download_id = self._get_download_id(result)
+            return self.client.full_url(*[f"dataaccess/download/{download_id}"])
+
+        if limit is not None:
+            results = self.results[:limit]
+        else:
+            results = self.results
+
+        return [build_url(r) for r in results]
 
     def download(self, download_dir: str = "."):
         """Downloads the results into the given download directory.