from __future__ import annotations

PLACEHOLDER_EMAIL_SUFFIX = "@noemail.local"


def normalize_email_identity(value: str | None) -> str | None:
    if value is None:
        return None
    normalized = value.strip().lower()
    return normalized or None


def normalize_mobile_number(value: str | None) -> str | None:
    if value is None:
        return None
    normalized = "".join(ch for ch in value if ch.isdigit())
    return normalized or None


def is_valid_mobile_number(value: str | None) -> bool:
    normalized = normalize_mobile_number(value)
    return bool(normalized and len(normalized) == 11 and normalized.startswith("09"))


def mask_mobile(value: str | None) -> str | None:
    if not value:
        return None
    if len(value) <= 4:
        return value
    return f"{value[:2]}{'*' * max(len(value) - 6, 1)}{value[-4:]}"


def is_placeholder_email(value: str | None) -> bool:
    normalized = normalize_email_identity(value)
    return bool(normalized and normalized.endswith(PLACEHOLDER_EMAIL_SUFFIX))