"""
Contact-detail masking.

The dataset contains real personal data (e-mail addresses, mobile numbers,
street addresses).  Exposing it to every authenticated user would be both a
privacy and a compliance problem, so contact details are masked unless the
caller holds a role that is explicitly allowed to see them
(:pyattr:`apps.accounts.models.User.can_view_pii`).

Masking happens in the serialisation layer - the raw values never leave the
database for an unprivileged caller, and the search index stores them in a
non-searchable field so a keyword query can never be used to confirm an e-mail
address by brute force.
"""

from __future__ import annotations

import re

_EMAIL_RE = re.compile(r"^([^@]+)@(.+)$")


def mask_email(address: str) -> str:
    """``joseph.holland@garver.com`` -> ``jo************@garver.com``."""
    match = _EMAIL_RE.match(address or "")
    if not match:
        return "***"
    local, domain = match.groups()
    keep = min(2, max(len(local) - 1, 0))
    return f"{local[:keep]}{'*' * max(len(local) - keep, 1)}@{domain}"


def mask_phone(number: str) -> str:
    """``+19402058928`` -> ``+1940*****28``."""
    digits = (number or "").strip()
    if len(digits) < 6:
        return "***"
    return f"{digits[:5]}{'*' * (len(digits) - 7)}{digits[-2:]}"


def mask_emails(emails: list[dict[str, str]]) -> list[dict[str, str]]:
    return [{**item, "address": mask_email(item.get("address", ""))} for item in emails or []]


def mask_phones(numbers: list[str]) -> list[str]:
    return [mask_phone(number) for number in numbers or []]