from datetime import datetime, timedelta
from typing import Optional
from jose import JWTError, jwt
from passlib.context import CryptContext
from fastapi import HTTPException, Security, Depends
from fastapi.security import HTTPBearer, HTTPAuthorizationCredentials
import db

SECRET_KEY = "your-secret-key-change-in-production"
ALGORITHM = "HS256"
ACCESS_TOKEN_EXPIRE_MINUTES = 60 * 24

pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")
security = HTTPBearer()
optional_security = HTTPBearer(auto_error=False)

def verify_password(plain_password, hashed_password):
    return pwd_context.verify(plain_password, hashed_password)

def get_password_hash(password):
    return pwd_context.hash(password)

def create_access_token(data: dict):
    to_encode = data.copy()
    expire = datetime.utcnow() + timedelta(minutes=ACCESS_TOKEN_EXPIRE_MINUTES)
    to_encode.update({"exp": expire})
    encoded_jwt = jwt.encode(to_encode, SECRET_KEY, algorithm=ALGORITHM)
    return encoded_jwt

def get_current_user(credentials: HTTPAuthorizationCredentials = Depends(security)):
    token = credentials.credentials
    try:
        payload = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM])
        user_id: int = payload.get("id")
        if user_id is None:
            raise HTTPException(status_code=401, detail="无效的认证信息")
    except JWTError:
        raise HTTPException(status_code=403, detail="登录已过期，请重新登录")
    
    user = db.get_user_by_id(user_id)
    if user is None:
        raise HTTPException(status_code=404, detail="用户不存在")
    return user

def get_optional_user(credentials: Optional[HTTPAuthorizationCredentials] = Depends(optional_security)):
    if not credentials:
        return None
    try:
        payload = jwt.decode(credentials.credentials, SECRET_KEY, algorithms=[ALGORITHM])
        user_id = payload.get("id")
        if user_id:
            return db.get_user_by_id(user_id)
    except JWTError:
        return None
    return None