main.py

import logging
from fastapi import FastAPI, Depends, HTTPException, status
from fastapi.security import OAuth2PasswordBearer, OAuth2PasswordRequestForm
from pydantic import BaseModel
from sqlalchemy import create_engine, Column, Integer, String
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker
from passlib.context import CryptContext
from jose import JWTError, jwt
from datetime import datetime, timedelta
import os

logging.basicConfig(level=logging.INFO)
logger = logging.getLogger(__name__)

app = FastAPI()

from fastapi.responses import RedirectResponse
@app.get("/", include_in_schema=False)
def redirect_root_to_docs():
    return RedirectResponse(url="/docs")



# Database setup
SQLALCHEMY_DATABASE_URL = "sqlite:///./test.db"
engine = create_engine(SQLALCHEMY_DATABASE_URL)
SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
Base = declarative_base()

# Type alias for SessionLocal
from typing import Generator
DBSession = Generator[SessionLocal, None, None]

# User model
class User(Base):
    __tablename__ = "users"
    id = Column(Integer, primary_key=True, index=True)
    username = Column(String, unique=True, index=True)
    hashed_password = Column(String)

Base.metadata.create_all(bind=engine)

Base.metadata.create_all(bind=engine)


# Pydantic models
class UserCreate(BaseModel):
    username: str
    password: str

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

# Security
pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")
oauth2_scheme = OAuth2PasswordBearer(tokenUrl="token")

# TODO: Replace with a secure secret key
SECRET_KEY = "your-secret-key"
ALGORITHM = "HS256"
ACCESS_TOKEN_EXPIRE_MINUTES = 30

def get_db():
    db = SessionLocal()
    try:
        yield db
    finally:
        db.close()

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):
    return db.query(User).filter(User.username == username).first()

def authenticate_user(db, username: str, password: str):
    user = get_user(db, username)
    if not user or not verify_password(password, user.hashed_password):
        return False
    return user

def create_access_token(data: dict, expires_delta: 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

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
    except JWTError:
        raise credentials_exception
    user = get_user(SessionLocal(), username=username)
    if user is None:
        raise credentials_exception
    return user

@app.post("/register", response_model=Token)
def register(user: UserCreate, db: SessionLocal = Depends(get_db)):
    db_user = get_user(db, username=user.username)
    if db_user:
        raise HTTPException(status_code=400, detail="Username already registered")
    hashed_password = get_password_hash(user.password)
    new_user = User(username=user.username, hashed_password=hashed_password)
    db.add(new_user)
    db.commit()
    db.refresh(new_user)
    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"}

@app.post("/token", response_model=Token)
def login_for_access_token(form_data: OAuth2PasswordRequestForm = Depends(), db: SessionLocal = Depends(get_db)):
    user = authenticate_user(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"}

@app.get("/users/me")
async def read_users_me(current_user: User = Depends(get_current_user)):
    return {"username": current_user.username}

if __name__ == "__main__":
    import uvicorn
    uvicorn.run(app, host="0.0.0.0", port=8080, log_level="info")