from datetime import datetime, timedelta
from typing import Optional
from jose import JWTError, jwt
from passlib.context import CryptContext
from fastapi import HTTPException, status
import os

# Configuración JWT con valores por defecto
SECRET_KEY = os.getenv("SECRET_KEY", "your-secret-key-change-in-production-123456789")
ALGORITHM = "HS256"
ACCESS_TOKEN_EXPIRE_MINUTES = 1440  # 24 horas

# Configuración para hashing de passwords
pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")

def verify_password(plain_password: str, hashed_password: str) -> bool:
    """Verificar password contra hash"""
    return pwd_context.verify(plain_password, hashed_password)

def get_password_hash(password: str) -> str:
    """Hashear password con bcrypt"""
    return pwd_context.hash(password)

def create_access_token(data: dict, expires_delta: Optional[timedelta] = None):
    """Crear JWT token con expiración"""
    to_encode = data.copy()
    
    if expires_delta:
        expire = datetime.utcnow() + expires_delta
    else:
        expire = datetime.utcnow() + timedelta(minutes=ACCESS_TOKEN_EXPIRE_MINUTES)
    
    to_encode.update({"exp": expire, "iat": datetime.utcnow()})
    encoded_jwt = jwt.encode(to_encode, SECRET_KEY, algorithm=ALGORITHM)
    return encoded_jwt

def verify_token(token: str) -> Optional[str]:
    """Verificar JWT token y devolver username"""
    try:
        payload = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM])
        username: str = payload.get("sub")
        if username is None:
            return None
        return username
    except JWTError:
        return None

def decode_token(token: str) -> dict:
    """Decodificar token completo para debugging"""
    try:
        payload = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM])
        return payload
    except JWTError as e:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail=f"Token invalid: {str(e)}",
            headers={"WWW-Authenticate": "Bearer"},
        )

def get_token_from_header(authorization: str) -> Optional[str]:
    """Extraer token del header Authorization"""
    if not authorization or not authorization.startswith("Bearer "):
        return None
    return authorization.split(" ")[1]

def validate_password_strength(password: str) -> bool:
    """Validar fortaleza de password (mínimo 6 caracteres para testing)"""
    if len(password) < 6:
        return False
    # Aquí se pueden agregar más validaciones (mayúsculas, números, etc.)
    return True