from datetime import datetime, timedelta
from typing import Optional

from fastapi import Depends, FastAPI, HTTPException, status
from fastapi.security import OAuth2PasswordBearer, OAuth2PasswordRequestForm
from jose import JWTError, jwt
from passlib.context import CryptContext
from pydantic import BaseModel

# 配置参数（应从环境变量读取）
SECRET_KEY = "your-secret-key-keep-it-secret!"
ALGORITHM = "HS256"
ACCESS_TOKEN_EXPIRE_MINUTES = 30

# 模拟用户数据库
fake_users_db = {
    "johndoe": {
        "username": "johndoe",
        "full_name": "John Doe",
        "email": "johndoe@example.com",
        # 哈希后的密码（明文是 secret）
        "hashed_password": "$2b$12$EixZaYVK1fsbY1eZIbOnjesN9NwG1s3Z6FDcjyH103a2.dJgD0L4q",
        "disabled": False,
    }
}

# Token 模型
class Token(BaseModel):
    access_token: str
    token_type: str

class TokenData(BaseModel):
    username: Optional[str] = None

# 用户模型
class User(BaseModel):
    username: str
    email: Optional[str] = None
    full_name: Optional[str] = None
    disabled: Optional[bool] = None

class UserInDB(User):
    hashed_password: str

# 密码哈希配置
pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")

# OAuth2 配置
oauth2_scheme = OAuth2PasswordBearer(tokenUrl="token")

app = FastAPI()

# 密码验证工具
def verify_password(plain_password: str, hashed_password: str):
    return pwd_context.verify(plain_password, hashed_password)

# 获取用户
def get_user(db, username: str):
    if username in db:
        user_dict = db[username]
        return UserInDB(**user_dict)

# 用户认证
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

# 创建访问令牌
def create_access_token(data: dict, expires_delta: Optional[timedelta] = None):
    to_encode = data.copy()
    if expires_delta:
        expire = datetime.utcnow() + expires_delta
    else:
        expire = datetime.utcnow() + timedelta(minutes=15)
    to_encode.update({"exp": expire})
    encoded_jwt = jwt.encode(to_encode, SECRET_KEY, algorithm=ALGORITHM)
    return encoded_jwt

# 获取当前用户（依赖注入）
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:
        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

# 登录路由
@app.post("/token", response_model=Token)
async def login_for_access_token(form_data: OAuth2PasswordRequestForm = Depends()):
    user = authenticate_user(fake_users_db, form_data.username, form_data.password)
    if not user:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Incorrect username or password",
            headers={"WWW-Authenticate": "Bearer"},
        )
    access_token_expires = timedelta(minutes=ACCESS_TOKEN_EXPIRE_MINUTES)
    access_token = create_access_token(
        data={"sub": user.username}, expires_delta=access_token_expires
    )
    return {"access_token": access_token, "token_type": "bearer"}

# 受保护路由
@app.get("/users/me/", response_model=User)
async def read_users_me(current_user: User = Depends(get_current_user)):
    return current_user