"""从图片 EXIF 提取拍摄时间与 GPS 地点标签。"""
from __future__ import annotations

from datetime import datetime
from fractions import Fraction
from pathlib import Path
from typing import Optional

from PIL import ExifTags, Image

from app.core.logger import get_logger


logger = get_logger(__name__)

# EXIF 地点类标签前缀，重分析时保留不被 AI 覆盖
EXIF_TAG_PREFIX = "地点:"


def _ratio_to_float(value) -> float:
    """EXIF 有理数 → float。"""
    if isinstance(value, tuple) and len(value) == 2:
        num, den = value
        return float(num) / float(den) if den else 0.0
    if isinstance(value, Fraction):
        return float(value)
    return float(value)


def _dms_to_decimal(dms: tuple, ref: str) -> Optional[float]:
    """度分秒 → 十进制度。"""
    try:
        deg, minutes, seconds = dms
        decimal = _ratio_to_float(deg) + _ratio_to_float(minutes) / 60 + _ratio_to_float(seconds) / 3600
        if ref in ("S", "W"):
            decimal = -decimal
        return round(decimal, 6)
    except (TypeError, ValueError, ZeroDivisionError):
        return None


def extract_image_metadata(path: Path) -> tuple[Optional[datetime], list[str]]:
    """读取 EXIF，返回 (拍摄时间, 地点标签列表)。"""
    captured: Optional[datetime] = None
    location_tags: list[str] = []

    try:
        with Image.open(path) as img:
            exif = img.getexif()
            if not exif:
                return None, []

            # 拍摄时间：优先 DateTimeOriginal
            for key in (36867, 36868, 306):  # DateTimeOriginal / DateTimeDigitized / DateTime
                raw = exif.get(key)
                if raw:
                    captured = _parse_exif_datetime(str(raw))
                    if captured:
                        break

            # GPS → 地点标签
            gps_ifd = exif.get_ifd(ExifTags.IFD.GPSInfo) if hasattr(exif, "get_ifd") else None
            if gps_ifd:
                lat = _dms_to_decimal(
                    gps_ifd.get(2),
                    gps_ifd.get(1, "N"),
                )
                lon = _dms_to_decimal(
                    gps_ifd.get(4),
                    gps_ifd.get(3, "E"),
                )
                if lat is not None and lon is not None:
                    location_tags.append(f"{EXIF_TAG_PREFIX}{lat},{lon}")

            # 部分设备写入可读地名（XP Keywords / ImageDescription 等）
            for key, val in exif.items():
                tag_name = ExifTags.TAGS.get(key, "")
                if tag_name in ("ImageDescription", "XPComment") and val:
                    text = str(val).strip()[:64]
                    if text and _looks_like_place(text):
                        location_tags.append(f"{EXIF_TAG_PREFIX}{text}")

    except Exception as exc:  # noqa: BLE001
        logger.debug("读取 EXIF 失败 %s: %s", path.name, exc)

    return captured, location_tags


def _parse_exif_datetime(raw: str) -> Optional[datetime]:
    """解析 EXIF 时间字符串。"""
    for fmt in ("%Y:%m:%d %H:%M:%S", "%Y-%m-%d %H:%M:%S"):
        try:
            return datetime.strptime(raw.strip(), fmt)
        except ValueError:
            continue
    return None


def _looks_like_place(text: str) -> bool:
    """粗判字符串是否像地名（含中文或常见地址关键词）。"""
    keywords = ("市", "省", "区", "县", "镇", "村", "路", "街", "国", "GPS")
    return any(k in text for k in keywords) or any("\u4e00" <= c <= "\u9fff" for c in text)


def is_exif_location_tag(name: str) -> bool:
    """是否为 EXIF 自动写入的地点标签。"""
    return name.startswith(EXIF_TAG_PREFIX)