from datetime import datetime, timedelta
from typing import Annotated

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


fake_users = [
    # password foo
    {'id': 1, 'username': 'admin', 'password': '$2b$12$N.i74Kle18n5Toxhas.rVOjZreVC2WM34fCidNDyhSNgxVlbKwX7i',
     'permissions': ['items:read', 'items:write', 'users:read', 'users:write']
    },
    # password bar
    {'id': 2, 'username': 'client', 'password': '$2b$12$KUgpw1m0LF/s9NS1ZB5rRO2cA5D13MqRm56ab7ik2ixftXW/aqEyq',
     'permissions': ['items:read']}
]

SECRET_KEY = "09d25e094faa6ca2556c818166b7a9563b93f7099f6f0f4caa6cf63b88e8d3e7"
ALGORITHM = "HS256"
ACCESS_TOKEN_EXPIRE_MINUTES = 30

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

oauth2_scheme = OAuth2PasswordBearer(tokenUrl="token")

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 get_user(db, username: str):
    for user in db:
        if username == user.username:
            return UserInDB(**user)

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.password):
        return False
    return user

def create_access_token(data: dict, expires_delta: timedelta | None = 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

async def get_current_user(token: Annotated[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, username=token_data.username)
    if user is None:
        raise credentials_exception
    return user