#!/usr/bin/python3
# -*- coding:utf-8 -*-
# __author__ = '__Jack__'

from datetime import datetime, timedelta
from typing import Optional

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

app06 = APIRouter()

"""OAuth2 密码模式和 FastAPI 的 OAuth2PasswordBearer"""

"""
OAuth2PasswordBearer是接收URL作为参数的一个类：客户端会向该URL发送username和password参数，然后得到一个Token值
OAuth2PasswordBearer并不会创建相应的URL路径操作，只是指明客户端用来请求Token的URL地址
当请求到来的时候，FastAPI会检查请求的Authorization头信息，如果没有找到Authorization头信息，或者头信息的内容不是Bearer token，它会返回401状态码(UNAUTHORIZED)
"""

oauth2_schema = OAuth2PasswordBearer(tokenUrl="/chapter06/token")  # 请求Token的URL地址 http://127.0.0.1:8000/chapter06/token


@app06.get("/oauth2_password_bearer")
async def oauth2_password_bearer(token: str = Depends(oauth2_schema)):
    return {"token": token}


"""基于 Password 和 Bearer token 的 OAuth2 认证"""

fake_users_db = {
    "john snow": {
        "username": "john snow",
        "full_name": "John Snow",
        "email": "johnsnow@example.com",
        "hashed_password": "fakehashedsecret",
        "disabled": False,
    },
    "alice": {
        "username": "alice",
        "full_name": "Alice Wonderson",
        "email": "alice@example.com",
        "hashed_password": "fakehashedsecret2",
        "disabled": True,
    },
}


def fake_hash_password(password: str):
    return "fakehashed" + password


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


class UserInDB(User):
    hashed_password: str


@app06.post("/token")
async def login(form_data: OAuth2PasswordRequestForm = Depends()):
    user_dict = fake_users_db.get(form_data.username)
    if not user_dict:
        raise HTTPException(status_code=status.HTTP_400_BAD_REQUEST, detail="Incorrect username or password")
    user = UserInDB(**user_dict)
    hashed_password = fake_hash_password(form_data.password)
    if not hashed_password == user.hashed_password:
        raise HTTPException(status_code=status.HTTP_400_BAD_REQUEST, detail="Incorrect username or password")
    return {"access_token": user.username, "token_type": "bearer"}


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


def fake_decode_token(token: str):
    user = get_user(fake_users_db, token)
    return user


async def get_current_user(token: str = Depends(oauth2_schema)):
    user = fake_decode_token(token)
    if not user:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Invalid authentication credentials",
            headers={"WWW-Authenticate": "Bearer"},  # OAuth2的规范，如果认证失败，请求头中返回“WWW-Authenticate”
        )
    return user


async def get_current_active_user(current_user: User = Depends(get_current_user)):
    if current_user.disabled:
        raise HTTPException(status_code=status.HTTP_400_BAD_REQUEST, detail="Inactive user")
    return current_user


@app06.get("/users/me")
async def read_users_me(current_user: User = Depends(get_current_active_user)):
    return current_user


"""OAuth2 with Password (and hashing), Bearer with JWT tokens 开发基于JSON Web Tokens的认证"""

fake_users_db.update({
    "john snow": {
        "username": "john snow",
        "full_name": "John Snow",
        "email": "johnsnow@example.com",
        "hashed_password": "$2b$12$EixZaYVK1fsbw1ZfbX3OXePaWxn96p36WQoeG6Lruj3vjPGga31lW",
        "disabled": False,
    }
})

SECRET_KEY = "09d25e094faa6ca2556c818166b7a9563b93f7099f6f0f4caa6cf63b88e8d3e7"  # 生成密钥 openssl rand -hex 32
ALGORITHM = "HS256"  # 算法
ACCESS_TOKEN_EXPIRE_MINUTES = 30  # 访问令牌过期分钟


class Token(BaseModel):
    """返回给用户的Token"""
    access_token: str
    token_type: str


pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")

oauth2_schema = OAuth2PasswordBearer(tokenUrl="/chapter06/jwt/token")


def verity_password(plain_password: str, hashed_password: str):
    """对密码进行校验"""
    return pwd_context.verify(plain_password, hashed_password)


def jwt_get_user(db, username: str):
    if username in db:
        user_dict = db[username]
        return UserInDB(**user_dict)


def jwt_authenticate_user(db, username: str, password: str):
    user = jwt_get_user(db=db, username=username)
    if not user:
        return False
    if not verity_password(plain_password=password, hashed_password=user.hashed_password):
        return False
    return user


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(claims=to_encode, key=SECRET_KEY, algorithm=ALGORITHM)
    return encoded_jwt


@app06.post("/jwt/token", response_model=Token)
async def login_for_access_token(form_data: OAuth2PasswordRequestForm = Depends()):
    user = jwt_authenticate_user(db=fake_users_db, username=form_data.username, password=form_data.password)
    if not user:
        raise HTTPException(
            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"}


async def jwt_get_current_user(token: str = Depends(oauth2_schema)):
    credentials_exception = HTTPException(
        status.HTTP_401_UNAUTHORIZED,
        detail="Could not validate credentials",
        headers={"WWW-Authenticate": "Bearer"},
    )
    try:
        payload = jwt.decode(token=token, key=SECRET_KEY, algorithms=[ALGORITHM])
        username = payload.get("sub")
        if username is None:
            raise credentials_exception
    except JWTError:
        raise credentials_exception
    user = jwt_get_user(db=fake_users_db, username=username)
    if user is None:
        raise credentials_exception
    return user


async def jwt_get_current_active_user(current_user: User = Depends(jwt_get_current_user)):
    if current_user.disabled:
        raise HTTPException(status_code=status.HTTP_400_BAD_REQUEST, detail="Inactive user")
    return current_user


@app06.get("/jwt/users/me")
async def jwt_read_users_me(current_user: User = Depends(jwt_get_current_active_user)):
    return current_user