from datetime import datetime, timedelta
from typing import Optional
from jose import JWTError, jwt
from passlib.context import CryptContext
from .config import settings
import hashlib

# 密码加密上下文 - 禁用bcrypt的wrap bug检测以避免72字节限制错误
pwd_context = CryptContext(
    schemes=["bcrypt"],
    deprecated="auto",
    bcrypt__ident="2b",  # 使用2b版本，跳过wrap bug检测
)

def _truncate_password(password: str) -> str:
    """
    截断密码以适应bcrypt的72字节限制
    对于超长密码，使用SHA256哈希确保唯一性
    """
    password_bytes = password.encode('utf-8')
    if len(password_bytes) <= 72:
        return password
    # 对超长密码进行hash，确保唯一性且在72字节以内
    return hashlib.sha256(password_bytes).hexdigest()

def verify_password(plain_password: str, hashed_password: str) -> bool:
    """验证密码"""
    safe_password = _truncate_password(plain_password)
    return pwd_context.verify(safe_password, hashed_password)

def get_password_hash(password: str) -> str:
    """加密密码（bcrypt限制最多72字节）"""
    safe_password = _truncate_password(password)
    return pwd_context.hash(safe_password)

def create_access_token(data: dict, expires_delta: Optional[timedelta] = None) -> str:
    """创建 JWT Token"""
    to_encode = data.copy()
    if expires_delta:
        expire = datetime.utcnow() + expires_delta
    else:
        expire = datetime.utcnow() + timedelta(minutes=settings.ACCESS_TOKEN_EXPIRE_MINUTES)
    
    to_encode.update({"exp": expire})
    encoded_jwt = jwt.encode(to_encode, settings.SECRET_KEY, algorithm=settings.ALGORITHM)
    return encoded_jwt

def decode_access_token(token: str) -> Optional[dict]:
    """解析 JWT Token"""
    try:
        payload = jwt.decode(token, settings.SECRET_KEY, algorithms=[settings.ALGORITHM])
        return payload
    except JWTError:
        return None