from __future__ import annotations

import hashlib
import hmac
import secrets


def verify_nextcloud_talk_signature(
    signature: str,
    random: str,
    body: str,
    secret: str,
) -> bool:
    expected = hmac.new(
        secret.encode("utf-8"),
        (random + body).encode("utf-8"),
        hashlib.sha256,
    ).hexdigest()
    return hmac.compare_digest(expected, signature)


def generate_nextcloud_talk_signature(
    body: str,
    secret: str,
) -> tuple[str, str]:
    random = secrets.token_hex(32)
    signature = hmac.new(
        secret.encode("utf-8"),
        (random + body).encode("utf-8"),
        hashlib.sha256,
    ).hexdigest()
    return random, signature


def extract_nextcloud_talk_headers(
    headers: dict,
) -> dict | None:
    signature = headers.get("X-Nextcloud-Talk-Signature")
    random = headers.get("X-Nextcloud-Talk-Random")
    backend = headers.get("X-Nextcloud-Talk-Backend")

    if not all([signature, random, backend]):
        return None

    return {
        "signature": signature,
        "random": random,
        "backend": backend,
    }