Refactor photo metadata workflow

tools/media_metadata.py

@@ -0,0 +1,63 @@
+"""Small, shared helpers for values returned by ExifTool."""
+
+from __future__ import annotations
+
+import math
+import re
+from collections.abc import Iterable, Mapping
+from datetime import datetime, timedelta, timezone
+
+
+DATETIME_RE = re.compile(
+    r"(?P<Y>\d{4})[:\-]?(?P<M>\d{2})[:\-]?(?P<D>\d{2})"
+    r"(?:[ T_])?"
+    r"(?P<h>\d{2}):?(?P<m>\d{2}):?(?P<s>\d{2})"
+    r"(?:[.,](?P<sub>\d+))?"
+    r"(?:\s*(?P<tz>Z|[+-]\d{2}:?\d{2}))?"
+)
+
+
+def first_tag(metadata: Mapping[str, object], tags: Iterable[str]) -> object | None:
+    for tag in tags:
+        if tag in metadata:
+            return metadata[tag]
+    return None
+
+
+def tag_value(metadata: Mapping[str, object], tag: str) -> str | None:
+    value = metadata.get(tag)
+    return None if value is None else str(value)
+
+
+def parse_exif_datetime(value: object, assume_utc: bool = False) -> datetime | None:
+    if value is None:
+        return None
+    match = DATETIME_RE.search(str(value).strip())
+    if not match:
+        return None
+    try:
+        tz_text = match.group("tz")
+        if tz_text == "Z":
+            tzinfo = timezone.utc
+        elif tz_text:
+            sign = 1 if tz_text[0] == "+" else -1
+            digits = tz_text[1:].replace(":", "")
+            tzinfo = timezone(sign * timedelta(hours=int(digits[:2]), minutes=int(digits[2:])))
+        else:
+            tzinfo = None
+        parsed = datetime(
+            int(match.group("Y")),
+            int(match.group("M")),
+            int(match.group("D")),
+            int(match.group("h")),
+            int(match.group("m")),
+            int(match.group("s")),
+            tzinfo=tzinfo,
+        )
+        return parsed.replace(tzinfo=timezone.utc) if assume_utc and tzinfo is None else parsed
+    except ValueError:
+        return None
+
+
+def round_half_up(value: float) -> int:
+    return math.floor(value + 0.5)