104 lines
2.9 KiB
Python
104 lines
2.9 KiB
Python
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"""
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EXIF-Aufnahmedatum/-zeit aus Bildbytes (JPEG, PNG mit EXIF, …).
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EXIF enthält keine Zeitzone; wir interpretieren die Wandzeit in PHOTO_EXIF_TIMEZONE
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(Standard Europe/Berlin) und speichern als TIMESTAMPTZ (UTC in PostgreSQL).
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"""
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from __future__ import annotations
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import os
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from datetime import datetime, timezone
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from io import BytesIO
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from typing import Optional
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from zoneinfo import ZoneInfo
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from PIL import Image
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EXIF_DATETIME_FMT = "%Y:%m:%d %H:%M:%S"
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_EXIF_IFD = 0x8769
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_EXIF_DATETIME_TAGS = (36867, 36868) # DateTimeOriginal, DateTimeDigitized
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_TAG_DATETIME_MAIN = 306
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def extract_taken_at_from_image_bytes(raw: bytes) -> Optional[datetime]:
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"""
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Liest DateTimeOriginal (o. ä.) aus EXIF und gibt ein timezone-aware datetime zurück,
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oder None wenn nicht ermittelbar.
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"""
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try:
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img = Image.open(BytesIO(raw))
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except Exception:
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return None
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try:
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naive = _extract_exif_naive_datetime(img)
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finally:
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try:
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img.close()
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except Exception:
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pass
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if naive is None:
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return None
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tz_name = os.getenv("PHOTO_EXIF_TIMEZONE", "Europe/Berlin")
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try:
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tz = ZoneInfo(tz_name)
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except Exception:
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tz = ZoneInfo("Europe/Berlin")
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return naive.replace(tzinfo=tz)
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def _extract_exif_naive_datetime(img: Image.Image) -> Optional[datetime]:
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exif = img.getexif()
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if not exif:
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return None
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strings: list[str] = []
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try:
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exif_ifd = exif.get_ifd(_EXIF_IFD)
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except Exception:
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exif_ifd = None
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if exif_ifd:
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for tag in _EXIF_DATETIME_TAGS:
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v = exif_ifd.get(tag)
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if isinstance(v, str) and v.strip():
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strings.append(v)
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v = exif.get(_TAG_DATETIME_MAIN)
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if isinstance(v, str) and v.strip():
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strings.append(v)
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for s in strings:
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dt = _parse_exif_datetime_str(s)
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if dt:
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return dt
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return None
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def _parse_exif_datetime_str(s: str) -> Optional[datetime]:
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s = (s or "").strip()
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if not s:
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return None
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try:
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return datetime.strptime(s, EXIF_DATETIME_FMT)
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except ValueError:
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return None
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def taken_at_from_file_last_modified_ms(ms_raw: Optional[str]) -> Optional[datetime]:
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"""
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Browser sendet File.lastModified (ms seit UTC-Epoch), echte Dateirevision auf der Platte.
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Wird als echter Zeitpunkt interpretiert und nach PHOTO_EXIF_TIMEZONE für Anzeige gelegt
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(konsistent zu EXIF-Wandzeit).
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"""
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if not ms_raw or not str(ms_raw).strip():
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return None
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try:
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ms = int(str(ms_raw).strip())
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except ValueError:
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return None
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if ms <= 0:
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return None
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instant_utc = datetime.fromtimestamp(ms / 1000.0, tz=timezone.utc)
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tz_name = os.getenv("PHOTO_EXIF_TIMEZONE", "Europe/Berlin")
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try:
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tz = ZoneInfo(tz_name)
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except Exception:
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tz = ZoneInfo("Europe/Berlin")
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return instant_utc.astimezone(tz)
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