"""Maldives mobile number normalisation.

Everything past the serializer layer deals in E.164 (`+960XXXXXXX`) so a
number is stored and looked up exactly one way.
"""

import re

from django.core.exceptions import ValidationError

COUNTRY_CODE = "960"
LOCAL_LENGTH = 7
# Maldives mobile prefixes are 7xx and 9xx.
LOCAL_RE = re.compile(r"^[79]\d{6}$")


def normalize_mobile(value: str) -> str:
    """Return `value` as +960XXXXXXX, or raise ValidationError."""
    digits = re.sub(r"[\s()-]", "", str(value or "")).lstrip("+")

    if digits.startswith("00" + COUNTRY_CODE):
        digits = digits[len("00" + COUNTRY_CODE) :]
    elif digits.startswith(COUNTRY_CODE) and len(digits) > LOCAL_LENGTH:
        digits = digits[len(COUNTRY_CODE) :]

    if not LOCAL_RE.match(digits):
        raise ValidationError("Enter a valid Maldives mobile number.")

    return f"+{COUNTRY_CODE}{digits}"