import os
from datetime import datetime, timedelta
from typing import Union
from dotenv import load_dotenv
from fastapi import Depends, FastAPI, HTTPException, status
from fastapi.security import OAuth2PasswordBearer, OAuth2PasswordRequestForm
from jose import JWTError, jwt
from passlib.context import CryptContext
from models.model import UserInDB, TokenData, User, Token, fake_users_db

# 加载环境变量
load_dotenv()
SECRET_KEY = os.getenv("SECRET_KEY")
ALGORITHM = os.getenv("ALGORITHM")
ACCESS_TOKEN_EXPIRE_MINUTES = os.getenv("ACCESS_TOKEN_EXPIRE_MINUTES")
print(SECRET_KEY)

# schemes 加密方式，默认第一个
pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")

# 请求/token 返回一个令牌
oauth2_scheme = OAuth2PasswordBearer(tokenUrl="token")


# 比较哈希值是否一直，一直就返回True，否则返回False
def verify_password(plain_password, hashed_password):
    return pwd_context.verify(plain_password, hashed_password)


# 对用户输入的密码进行hash加密
def get_password_hash(password):
    return pwd_context.hash(password)


# 去数据库中寻找，用户是否在数据库中，能找到就返回用户的所有信息
def get_user(db, username: str):
    if username in db:
        user_dict = db[username]
        return UserInDB(**user_dict)


# 判断用户是否存在于数据库中，存在就比较hash密码，比对成功，返回用户信息
def authenticate_user(fake_db, username: str, password: str):
    user = get_user(fake_db, username)
    if not user:
        return False
    if not verify_password(password, user.hashed_password):
        return False
    return user


# data:{"sub":user.username} datetime.utcnow():2023-05-31 23:46:27.912774
# utcnow()用于记录当前时间，datetime模块中的timedelta返回的数据可与utcnow()相加
def create_access_token(data: dict, expires_delta: Union[timedelta, None] = None):
    to_encode = data.copy()
    if expires_delta:
        expire = datetime.utcnow() + expires_delta
    else:
        expire = datetime.utcnow() + timedelta(minutes=15)
    # update可以将过期时间加入到to_encode字典中 => to_encoded = {"sub":user.username,"exp":expire}
    to_encode.update({"exp": expire})
    # jwt.encode(加密数据,密钥,加密方式)
    encoded_jwt = jwt.encode(to_encode, SECRET_KEY, algorithm=ALGORITHM)
    # 最终返回被加密后的to_encoded
    return encoded_jwt


# 这个函数必须携带令牌才能执行，携带令牌获取用户，返回用户信息
async def get_current_user(token: str = Depends(oauth2_scheme)):
    credentials_exception = HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="Could not validate credentials",
        headers={"WWW-Authenticate": "Bearer"},
    )
    try:
        # 对token进行解码
        payload = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM])
        username: str = payload.get("sub")
        if username is None:
            raise credentials_exception
        token_data = TokenData(username=username)
    except JWTError:
        raise credentials_exception
    user = get_user(fake_users_db, username=token_data.username)
    if user is None:
        raise credentials_exception
    return user


# 这里接收用户信息，接收到了就返回用户信息，没接收到，就表示令牌过期了，或者是未登陆
async def get_current_active_user(current_user: User = Depends(get_current_user)):
    if current_user.disabled:
        raise HTTPException(status_code=400, detail="Inactive user")
    return current_user