start introducing modules

zfs_backup/time.py

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+from __future__ import annotations
+
+from datetime import datetime
+
+
+class Time:
+    @staticmethod
+    def _get_date_format() -> str:
+        """date format as used by zpool status
+
+        %a: day of week, short version
+        %b: month, short version
+        %d: day of month, zero-padded
+        %H, %M, %S: hour, minute, second, zero-padded
+        %Y: year
+        """
+        return "%a %b %d %H:%M:%S %Y"
+
+    @classmethod
+    def _extract_datetime_segment(cls, line_with_datetime: str) -> str:
+        """From the line in `zpool status` that includes the date and time, extract only the part with date and time."""
+        return line_with_datetime.split(" errors on ")[-1]
+
+    @classmethod
+    def _get_line_with_datetime_from_status_output(cls, output: str) -> str:
+        """From `zpool status`, extract the line that contains the date and time of the last scrub."""
+        lines = output.split("\n")
+        for line in lines:
+            if line.startswith("  scan: scrub repaired"):
+                return line.strip()
+        else:
+            raise ValueError("Could not find the correct line")
+
+    @classmethod
+    def get_last_scrub_from_status_output(cls, output: str) -> datetime:
+        """Given the output of `zfs status`, return the `datetime` object of the last scrub."""
+        line_with_datetime = cls._get_line_with_datetime_from_status_output(output)
+        date_str = cls._extract_datetime_segment(line_with_datetime)
+        return datetime.strptime(date_str, cls._get_date_format())