Imago/app/services/exif_service.py

"""
Service d'extraction EXIF — Pillow + piexif
"""
import logging
from datetime import datetime
from pathlib import Path
from typing import Any

logger = logging.getLogger(__name__)

import piexif
from PIL import Image as PILImage
from PIL.ExifTags import TAGS, GPSTAGS


def _dms_to_decimal(dms: tuple, ref: str) -> float | None:
    """Convertit les coordonnées GPS DMS (degrés/minutes/secondes) en décimal."""
    try:
        degrees = dms[0][0] / dms[0][1]
        minutes = dms[1][0] / dms[1][1]
        seconds = dms[2][0] / dms[2][1]
        decimal = degrees + minutes / 60 + seconds / 3600
        if ref in ("S", "W"):
            decimal = -decimal
        return round(decimal, 7)
    except Exception:
        return None


def _parse_rational(value) -> str | None:
    """Convertit un rationnel EXIF en chaîne lisible."""
    try:
        if isinstance(value, tuple) and len(value) == 2:
            num, den = value
            if den == 0:
                return None
            return f"{num}/{den}"
        return str(value)
    except Exception:
        return None


def _safe_str(value: Any) -> str | None:
    """Décode les bytes en string si nécessaire."""
    if value is None:
        return None
    if isinstance(value, bytes):
        return value.decode("utf-8", errors="ignore").strip("\x00")
    return str(value)


def extract_exif(file_path: str) -> dict:
    """
    Extrait toutes les métadonnées EXIF d'une image.
    Retourne un dict structuré avec les données parsées.
    """
    result = {
        "raw": {},
        "make": None,
        "model": None,
        "lens": None,
        "taken_at": None,
        "gps_lat": None,
        "gps_lon": None,
        "altitude": None,
        "iso": None,
        "aperture": None,
        "shutter": None,
        "focal": None,
        "flash": None,
        "orientation": None,
        "software": None,
    }

    try:
        path = Path(file_path)
        if not path.exists():
            return result

        # ── Lecture EXIF brute via piexif ─────────────────────
        try:
            exif_data = piexif.load(str(path))
        except Exception:
            # JPEG sans EXIF, PNG, etc.
            return result

        raw_dict = {}

        # ── IFD 0 (Image principale) ──────────────────────────
        ifd0 = exif_data.get("0th", {})
        result["make"] = _safe_str(ifd0.get(piexif.ImageIFD.Make))
        result["model"] = _safe_str(ifd0.get(piexif.ImageIFD.Model))
        result["software"] = _safe_str(ifd0.get(piexif.ImageIFD.Software))
        result["orientation"] = ifd0.get(piexif.ImageIFD.Orientation)

        # ── EXIF IFD ──────────────────────────────────────────
        exif = exif_data.get("Exif", {})

        # Date de prise de vue
        taken_raw = _safe_str(exif.get(piexif.ExifIFD.DateTimeOriginal))
        if taken_raw:
            try:
                result["taken_at"] = datetime.strptime(taken_raw, "%Y:%m:%d %H:%M:%S")
            except ValueError:
                pass

        # Paramètres de prise de vue
        iso_val = exif.get(piexif.ExifIFD.ISOSpeedRatings)
        result["iso"] = int(iso_val) if iso_val else None

        aperture_val = exif.get(piexif.ExifIFD.FNumber)
        if aperture_val:
            try:
                f = aperture_val[0] / aperture_val[1]
                result["aperture"] = f"f/{f:.1f}"
            except Exception:
                pass

        shutter_val = exif.get(piexif.ExifIFD.ExposureTime)
        if shutter_val:
            result["shutter"] = _parse_rational(shutter_val)

        focal_val = exif.get(piexif.ExifIFD.FocalLength)
        if focal_val:
            try:
                f = focal_val[0] / focal_val[1]
                result["focal"] = f"{f:.0f}mm"
            except Exception:
                pass

        flash_val = exif.get(piexif.ExifIFD.Flash)
        result["flash"] = bool(flash_val & 1) if flash_val is not None else None

        lens_val = _safe_str(exif.get(piexif.ExifIFD.LensModel))
        result["lens"] = lens_val

        # ── GPS IFD ───────────────────────────────────────────
        gps = exif_data.get("GPS", {})
        if gps:
            lat_val = gps.get(piexif.GPSIFD.GPSLatitude)
            lat_ref = _safe_str(gps.get(piexif.GPSIFD.GPSLatitudeRef))
            lon_val = gps.get(piexif.GPSIFD.GPSLongitude)
            lon_ref = _safe_str(gps.get(piexif.GPSIFD.GPSLongitudeRef))

            if lat_val and lat_ref:
                result["gps_lat"] = _dms_to_decimal(lat_val, lat_ref)
            if lon_val and lon_ref:
                result["gps_lon"] = _dms_to_decimal(lon_val, lon_ref)

            alt_val = gps.get(piexif.GPSIFD.GPSAltitude)
            if alt_val:
                try:
                    result["altitude"] = round(alt_val[0] / alt_val[1], 2)
                except Exception:
                    pass

        # ── Dict brut lisible (TAGS humains) ──────────────────
        with PILImage.open(path) as img:
            raw_exif = img._getexif()
            if raw_exif:
                for tag_id, val in raw_exif.items():
                    tag = TAGS.get(tag_id, str(tag_id))
                    if isinstance(val, bytes):
                        val = val.decode("utf-8", errors="ignore")
                    elif isinstance(val, tuple):
                        val = list(val)
                    raw_dict[tag] = val
        result["raw"] = raw_dict

    except Exception as e:
        logger.error("exif.extraction_error", extra={"file": file_path, "error": str(e)})

    return result