"""
Security utilities: password hashing and JWT token management.

This module provides pure functions for:
- Hashing and verifying passwords using bcrypt via passlib.
- Creating JWT access tokens using python-jose.
- Managing a Redis-backed token blacklist for revocation.

No endpoints are defined here.
"""

import logging
import uuid as _uuid
from datetime import datetime, timedelta, timezone

from jose import jwt
from passlib.context import CryptContext

from app.config import settings

logger = logging.getLogger(__name__)

# ---------------------------------------------------------------------------
# Password hashing
# ---------------------------------------------------------------------------

pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")


def hash_password(password: str) -> str:
    """Return a bcrypt hash of *password*."""
    return pwd_context.hash(password)


def verify_password(plain: str, hashed: str) -> bool:
    """Return ``True`` if *plain* matches the bcrypt *hashed* value."""
    return pwd_context.verify(plain, hashed)


# ---------------------------------------------------------------------------
# JWT tokens
# ---------------------------------------------------------------------------


def create_access_token(data: dict) -> str:
    """Create a signed JWT containing *data* plus ``exp`` and ``jti`` claims.

    - ``jti`` (JWT ID): unique identifier that enables token revocation.
    - ``exp``: expiration timestamp based on ``ACCESS_TOKEN_EXPIRE_MINUTES``.
    """
    to_encode = data.copy()
    expire = datetime.now(timezone.utc) + timedelta(
        minutes=settings.ACCESS_TOKEN_EXPIRE_MINUTES,
    )
    to_encode.update({
        "exp": expire,
        "jti": str(_uuid.uuid4()),
    })
    return jwt.encode(to_encode, settings.SECRET_KEY, algorithm=settings.ALGORITHM)


# ---------------------------------------------------------------------------
# Token blacklist (Redis-backed)
# ---------------------------------------------------------------------------
# Each revoked token's ``jti`` is stored in Redis with a TTL equal to the
# token's remaining lifetime.  This means entries auto-expire exactly when
# the token would have become invalid anyway — no manual cleanup needed.
#
# Redis survives backend restarts, so blacklisted tokens stay revoked
# across deploys and multi-worker setups.
# ---------------------------------------------------------------------------

_BLACKLIST_PREFIX = "blacklist:"


def blacklist_token(jti: str, exp: float) -> None:
    """Add *jti* to the Redis blacklist with a TTL derived from *exp*.

    *exp* is the token's ``exp`` claim (epoch timestamp).  The TTL is set
    to ``exp - now`` so the key vanishes when the token would have expired
    naturally.
    """
    from app.infrastructure.redis_client import get_redis_blacklist

    ttl = max(int(exp - datetime.now(timezone.utc).timestamp()), 1)
    try:
        r = get_redis_blacklist()
        r.setex(f"{_BLACKLIST_PREFIX}{jti}", ttl, "1")
    except Exception:
        logger.warning("Failed to blacklist token %s in Redis", jti, exc_info=True)


def is_token_blacklisted(jti: str) -> bool:
    """Return ``True`` if *jti* has been revoked (exists in Redis)."""
    from app.infrastructure.redis_client import get_redis_blacklist

    try:
        r = get_redis_blacklist()
        return r.exists(f"{_BLACKLIST_PREFIX}{jti}") > 0
    except Exception:
        logger.warning("Failed to check blacklist for %s in Redis", jti, exc_info=True)
        return False
