"""
BAN YARO — Auth
JWT + Bcrypt. Einmal gebaut, von allen Routes genutzt.
"""

import os
import uuid
import jwt
import bcrypt
import logging
from datetime import datetime, timedelta, timezone
from fastapi import Depends, HTTPException, status, Request, Response
from fastapi.security import HTTPBearer, HTTPAuthorizationCredentials

from database import db

logger     = logging.getLogger(__name__)
JWT_SECRET = os.getenv("JWT_SECRET", "change-me-in-production")
JWT_ALGO   = "HS256"
# Default 7 Tage (vorher 30) — sensible Hundedaten brauchen kürzere Sessions.
JWT_EXPIRY = int(os.getenv("JWT_EXPIRY_DAYS", "7"))
# Wenn das Token älter als (JWT_EXPIRY / JWT_REFRESH_FRACTION) Tage ist,
# wird das Cookie bei einer authentifizierten Anfrage neu gesetzt (Sliding Session).
# Standard 2 → Refresh wenn mehr als die Hälfte der Laufzeit weg ist.
JWT_REFRESH_FRACTION = int(os.getenv("JWT_REFRESH_FRACTION", "2"))

if JWT_SECRET == "change-me-in-production" and os.getenv("ENV") == "production":
    raise RuntimeError(
        "SICHERHEITSFEHLER: JWT_SECRET ist nicht gesetzt. "
        "Bitte JWT_SECRET in .env setzen und Container neu starten."
    )

security   = HTTPBearer(auto_error=False)


# ------------------------------------------------------------------
# JWT-Blacklist (Logout invalidiert Token serverseitig)
# ------------------------------------------------------------------
def _is_jti_blacklisted(jti: str) -> bool:
    if not jti:
        return False
    with db() as conn:
        row = conn.execute(
            "SELECT 1 FROM jwt_blacklist WHERE jti=?", (jti,)
        ).fetchone()
    return bool(row)


def blacklist_jti(jti: str, expires_at_iso: str):
    """Token-ID auf die Blacklist setzen. expires_at_iso entspricht dem urspr. exp."""
    if not jti or not expires_at_iso:
        return
    with db() as conn:
        conn.execute(
            "INSERT OR IGNORE INTO jwt_blacklist (jti, expires_at) VALUES (?,?)",
            (jti, expires_at_iso)
        )


def _purge_expired_jwt() -> int:
    """Entfernt abgelaufene Blacklist-Einträge. Gibt Anzahl gelöschter Zeilen zurück.
    Kann später aus dem Scheduler aufgerufen werden."""
    now = datetime.now(timezone.utc).isoformat()
    with db() as conn:
        cur = conn.execute(
            "DELETE FROM jwt_blacklist WHERE expires_at < ?", (now,)
        )
        deleted = cur.rowcount or 0
    if deleted:
        logger.info("JWT-Blacklist Cleanup: %d abgelaufene Einträge entfernt.", deleted)
    return deleted


# ------------------------------------------------------------------
# Passwort
# ------------------------------------------------------------------
def hash_password(password: str) -> str:
    return bcrypt.hashpw(password.encode(), bcrypt.gensalt()).decode()


def verify_password(password: str, hashed: str) -> bool:
    return bcrypt.checkpw(password.encode(), hashed.encode())


# ------------------------------------------------------------------
# JWT
# ------------------------------------------------------------------
def create_token(user_id: int, rolle: str) -> str:
    now = datetime.now(timezone.utc)
    payload = {
        "sub":   str(user_id),
        "rolle": rolle,
        "exp":   now + timedelta(days=JWT_EXPIRY),
        "iat":   now,
        "jti":   uuid.uuid4().hex,
    }
    return jwt.encode(payload, JWT_SECRET, algorithm=JWT_ALGO)


def decode_token(token: str) -> dict:
    """Dekodiert + prüft Signatur, Ablauf und Blacklist.
    Wirft jwt.InvalidTokenError wenn Token auf der Blacklist steht."""
    payload = jwt.decode(token, JWT_SECRET, algorithms=[JWT_ALGO])
    jti = payload.get("jti")
    if jti and _is_jti_blacklisted(jti):
        raise jwt.InvalidTokenError("Token wurde invalidiert (Logout).")
    return payload


# ------------------------------------------------------------------
# FastAPI Dependencies
# ------------------------------------------------------------------
def _get_token_from_request(
    request: Request,
    credentials: HTTPAuthorizationCredentials = Depends(security),
) -> str | None:
    """Token aus Bearer-Header oder HttpOnly-Cookie."""
    if credentials:
        return credentials.credentials
    return request.cookies.get("by_token")


def _maybe_refresh_token(request: Request, payload: dict):
    """Sliding-Session: setzt das Cookie neu wenn das Token älter als JWT_EXPIRY/JWT_REFRESH_FRACTION ist.
    Nur wirksam wenn das Token aus dem Cookie kommt (nicht Bearer-Header).
    Hängt das neue Token an request.state.refresh_token, damit Middleware es ins Response-Cookie setzen kann."""
    try:
        # Nur refreshen wenn Token aus Cookie kam (Bearer-Clients verwalten Tokens selbst)
        if not request.cookies.get("by_token"):
            return
        iat = payload.get("iat")
        exp = payload.get("exp")
        if not iat or not exp:
            return
        # Wenn mehr als 1/JWT_REFRESH_FRACTION der Laufzeit vergangen ist → neues Token ausstellen
        now_ts = datetime.now(timezone.utc).timestamp()
        lifetime = exp - iat
        if lifetime <= 0 or JWT_REFRESH_FRACTION <= 0:
            return
        threshold = iat + (lifetime / JWT_REFRESH_FRACTION)
        if now_ts < threshold:
            return
        new_token = create_token(int(payload["sub"]), payload.get("rolle", "user"))
        request.state.refresh_token = new_token
    except Exception:
        # Refresh-Fehler dürfen die eigentliche Anfrage nie blockieren.
        logger.exception("Sliding-Token-Refresh fehlgeschlagen")


def get_current_user(
    request: Request,
    credentials: HTTPAuthorizationCredentials = Depends(security),
):
    """Dependency: gibt den eingeloggten User zurück oder wirft 401."""
    token = _get_token_from_request(request, credentials)
    if not token:
        raise HTTPException(status.HTTP_401_UNAUTHORIZED, "Nicht eingeloggt.")

    try:
        payload = decode_token(token)
    except jwt.ExpiredSignatureError:
        raise HTTPException(status.HTTP_401_UNAUTHORIZED, "Session abgelaufen.")
    except jwt.InvalidTokenError:
        raise HTTPException(status.HTTP_401_UNAUTHORIZED, "Ungültiges Token.")

    user_id = int(payload["sub"])
    with db() as conn:
        row = conn.execute(
            "SELECT id, email, name, rolle, is_premium, is_moderator, is_banned, ban_reason, is_social_media, notes_ki_enabled, gassi_stunde_push, breeder_status, is_founder, is_partner, founder_number, email_verified, luna_trial_until, subscription_tier FROM users WHERE id=?",
            (user_id,)
        ).fetchone()

    if not row:
        raise HTTPException(status.HTTP_401_UNAUTHORIZED, "User nicht gefunden.")

    user = dict(row)
    if user.get("is_banned"):
        reason = user.get("ban_reason") or "Kein Grund angegeben."
        raise HTTPException(status.HTTP_403_FORBIDDEN, f"Account gesperrt: {reason}")

    # Sliding-Session: ggf. neues Token vorbereiten (in Middleware ins Cookie schreiben).
    _maybe_refresh_token(request, payload)

    return user


def get_current_user_optional(
    request: Request,
    credentials: HTTPAuthorizationCredentials = Depends(security),
):
    """Dependency: gibt User zurück falls eingeloggt, sonst None."""
    try:
        return get_current_user(request, credentials)
    except HTTPException:
        return None


def require_premium(user=Depends(get_current_user)):
    """Dependency: nur für Premium-User."""
    if not user["is_premium"]:
        raise HTTPException(
            status.HTTP_402_PAYMENT_REQUIRED,
            "Dieses Feature erfordert Ban Yaro Premium."
        )
    return user


def require_admin(user=Depends(get_current_user)):
    """Dependency: nur für Admins."""
    if user["rolle"] != "admin":
        raise HTTPException(status.HTTP_403_FORBIDDEN, "Kein Zugriff.")
    return user


def has_pro_access(user: dict) -> bool:
    """True wenn User Pro-Features nutzen darf."""
    if not user:
        return False
    role = user.get("rolle", "user")
    tier = user.get("subscription_tier", "standard")
    if role in ("admin", "moderator"):
        return True
    if user.get("is_moderator") or user.get("is_social_media"):
        return True
    return tier in ("pro", "breeder", "pro_test", "breeder_test")


def has_breeder_access(user: dict) -> bool:
    """True wenn User Züchter-Features nutzen darf."""
    if not user:
        return False
    role = user.get("rolle", "user")
    tier = user.get("subscription_tier", "standard")
    if role in ("admin", "moderator"):
        return True
    if user.get("is_moderator") or user.get("is_social_media"):
        return True
    return tier in ("breeder", "breeder_test") or role == "breeder"


def require_social_media(user=Depends(get_current_user)):
    """Dependency: Social-Media-Manager, Luna-Probezugang oder Admin."""
    from datetime import datetime as _dt
    trial = user.get("luna_trial_until")
    trial_active = bool(trial and _dt.utcnow().isoformat() < trial)
    if not (user.get("is_social_media") or user["rolle"] == "admin" or trial_active):
        raise HTTPException(status.HTTP_403_FORBIDDEN, "Kein Zugriff.")
    return user