import logging

logger = logging.getLogger(__name__)

_mrz = None


def _get_mrz():
    """Lazy-initialize FastMRZ. First call loads ONNX model."""
    global _mrz
    if _mrz is None:
        logger.info("Initializing FastMRZ...")
        from fastmrz import FastMRZ
        _mrz = FastMRZ()
        logger.info("FastMRZ initialized")
    return _mrz


def read_mrz(image_path: str) -> dict | None:
    """Read MRZ (Machine Readable Zone) from a passport image.

    Returns dict with extracted fields, or None if MRZ not found/readable.

    Fields returned:
        passport_number, surname, given_names, nationality,
        date_of_birth, sex, expiry_date, issuing_country,
        mrz_valid (bool — check digits passed)
    """
    try:
        mrz = _get_mrz()
        mrz_data = mrz.get_mrz(image_path)

        if not mrz_data:
            logger.info("No MRZ found in image")
            return None

        # FastMRZ returns a dict with standardized field names
        result = {
            "source": "mrz",
            "passport_number": mrz_data.get("document_number", "").replace("<", "").strip() or None,
            "surname": mrz_data.get("surname", "").replace("<", " ").strip() or None,
            "given_names": mrz_data.get("given_name", "").replace("<", " ").strip() or None,
            "nationality": mrz_data.get("nationality", "").strip() or None,
            "date_of_birth": _format_mrz_date(mrz_data.get("birth_date", "")),
            "sex": _normalize_sex(mrz_data.get("sex", "")),
            "expiry_date": _format_mrz_date(mrz_data.get("expiry_date", "")),
            "issuing_country": mrz_data.get("country", "").strip() or None,
            "mrz_valid": mrz_data.get("valid_score", False),
        }

        # Clean up names
        if result["surname"]:
            result["surname"] = result["surname"].title()
        if result["given_names"]:
            result["given_names"] = result["given_names"].title()

        logger.info(
            "MRZ extracted: nationality=%s passport=%s valid=%s",
            result["nationality"],
            result["passport_number"],
            result["mrz_valid"],
        )
        return result

    except Exception as e:
        logger.warning("MRZ reading failed: %s", e)
        return None


def _format_mrz_date(date_str: str) -> str | None:
    """Convert MRZ date (YYMMDD) to ISO format (YYYY-MM-DD)."""
    if not date_str or len(date_str) < 6:
        return None

    date_str = date_str.strip().replace("-", "").replace("/", "")
    if len(date_str) < 6:
        return None

    try:
        yy = int(date_str[:2])
        mm = int(date_str[2:4])
        dd = int(date_str[4:6])

        # Century heuristic: same as SA ID parser
        from datetime import datetime
        current_yy = datetime.now().year % 100
        year = 1900 + yy if yy > current_yy else 2000 + yy

        from datetime import date
        d = date(year, mm, dd)
        return d.isoformat()
    except (ValueError, IndexError):
        return None


def _normalize_sex(sex_str: str) -> str | None:
    """Normalize MRZ sex field to 'Male' or 'Female'."""
    s = sex_str.strip().upper()
    if s in ("M", "MALE"):
        return "Male"
    if s in ("F", "FEMALE"):
        return "Female"
    return None


def warm_mrz() -> bool:
    """Pre-load FastMRZ model. Returns True if successful."""
    try:
        _get_mrz()
        return True
    except Exception as e:
        logger.warning("FastMRZ warm-up failed: %s", e)
        return False