feature(backups): return snapshot info from backup function

selfprivacy_api/backup/restic_backuper.py

@@ -1,5 +1,6 @@
 import subprocess
 import json
+import datetime
 
 from typing import List
 
@@ -63,6 +64,7 @@ class ResticBackuper(AbstractBackuper):
         backup_command = self.restic_command(
             repo_name,
             "backup",
+            "--json",
             folder,
         )
         with subprocess.Popen(
@@ -72,8 +74,27 @@ class ResticBackuper(AbstractBackuper):
             stderr=subprocess.STDOUT,
         ) as handle:
             output = handle.communicate()[0].decode("utf-8")
-            if "saved" not in output:
-                raise ValueError("could not create a new snapshot: " + output)
+            try:
+                messages = self.parse_json_output(output)
+                return ResticBackuper._snapshot_from_backup_messages(
+                    messages, repo_name
+                )
+            except ValueError as e:
+                raise ValueError("could not create a snapshot: ") from e
+
+    @staticmethod
+    def _snapshot_from_backup_messages(messages, repo_name) -> Snapshot:
+        for message in messages:
+            if message["message_type"] == "summary":
+                return ResticBackuper._snapshot_from_fresh_summary(message, repo_name)
+
+    @staticmethod
+    def _snapshot_from_fresh_summary(message: object, repo_name) -> Snapshot:
+        return Snapshot(
+            id=message["snapshot_id"],
+            created_at=datetime.datetime.now(datetime.timezone.utc),
+            service_name=repo_name,
+        )
 
     def init(self, repo_name):
         init_command = self.restic_command(
@@ -189,11 +210,17 @@ class ResticBackuper(AbstractBackuper):
         starting_index = self.json_start(output)
 
         if starting_index == -1:
-            raise ValueError(
-                "There is no json in the restic snapshot output : " + output
-            )
+            raise ValueError("There is no json in the restic output : " + output)
 
-        return json.loads(output[starting_index:])
+        truncated_output = output[starting_index:]
+        json_messages = truncated_output.splitlines()
+        if len(json_messages) == 1:
+            return json.loads(truncated_output)
+
+        result_array = []
+        for message in json_messages:
+            result_array.append(json.loads(message))
+        return result_array
 
     def json_start(self, output: str) -> int:
         indices = [