things kinda work

anaxi/checkpoint.py

@@ -0,0 +1,48 @@
+import datetime
+import pathlib
+from typing import Union
+
+from anaxi.file_persistence import read_yaml, write_yaml
+
+
+class CheckpointManager:
+
+    highest_synced_timestamp_field_key = "highest_synced_timestamp"
+
+    def __init__(
+        self,
+        file_path: pathlib.Path,
+        highest_synced_timestamp: Union[None, datetime.datetime],
+    ):
+        self.file_path = file_path
+        self.highest_synced_timestamp = highest_synced_timestamp
+        self.goal = None
+
+    @classmethod
+    def load_from_yml(cls, file_path: pathlib.Path) -> "CheckpointManager":
+        contents = read_yaml(file_path)
+
+        if CheckpointManager.highest_synced_timestamp_field_key not in contents.keys():
+            raise ValueError(f"Invalid checkpoint state contents in file: {file_path}.")
+
+        return CheckpointManager(
+            file_path=file_path,
+            highest_synced_timestamp=contents[
+                CheckpointManager.highest_synced_timestamp_field_key
+            ],
+        )
+
+    def update_yml(self):
+        write_yaml(
+            path=self.file_path,
+            data={
+                CheckpointManager.highest_synced_timestamp_field_key: self.highest_synced_timestamp
+            },
+        )
+
+    def set_new_goal(self, goal_timestamp: datetime.datetime) -> None:
+        self.goal = goal_timestamp
+
+    def commit_goal(self):
+        self.highest_synced_timestamp = self.goal
+        self.update_yml()