feat: User Authentication using Oauth

Author: Nishthajain7

.env.example

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+DATABASE_URL=
+GOOGLE_CLIENT_ID=
+ENV=

.gitignore

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+venv/
+*.db
+.env
+__pycache__/

app/__init__.py

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+from sqlalchemy.orm import Session
+from app import models
+from app.enums import Grade
+from app.utils.hashing import hash_password, verify_password
+
+def get_user(db: Session, google_id: str):
+    return db.query(models.User).filter(models.User.google_id == google_id).first()
+
+def get_user_by_id(db: Session, user_id: int):
+    return db.query(models.User).filter(models.User.id == user_id).first()
+
+def authenticate_user(db: Session, username: str, password: str):
+    user = db.query(models.User).filter(models.User.username == username).first()
+    if not user:
+        return None
+    if not verify_password(password, user.password):
+        return None
+    return user
+
+def create_google_user(
+    db: Session,
+    google_id: str,
+    email: str,
+    name: str,
+    username: str,
+    password: str,
+    grade: Grade,
+    institute: str,
+    city: str,
+    marketing: str):
+    user = models.User(
+        google_id=google_id,
+        email=email,
+        name=name,
+        username=username,
+        password=hash_password(password),
+        grade=grade,
+        institute=institute,
+        city=city,
+        marketing=marketing,
+    )
+    db.add(user)
+    db.commit()
+    db.refresh(user)
+    return user
+

app/crud.py

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+from sqlalchemy import create_engine
+from sqlalchemy.orm import sessionmaker, declarative_base
+from dotenv import load_dotenv
+import os
+
+load_dotenv()
+DATABASE_URL = os.getenv("DATABASE_URL")
+if not DATABASE_URL:
+    raise RuntimeError("DATABASE_URL environment variable is not set")
+engine = create_engine(DATABASE_URL,connect_args={"check_same_thread": False})
+SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
+Base = declarative_base()

app/database.py

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+from .database import SessionLocal
+
+def get_db():
+    db = SessionLocal()
+    try:
+        yield db
+    finally:
+        db.close()

app/dependencies.py

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+from enum import Enum
+
+class Grade(str, Enum):
+    grade_11 = "11"
+    grade_12 = "12"
+    repeater = "Repeater"

app/enums.py

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+from fastapi import FastAPI
+from app.database import Base, engine
+from app.routers import auth
+from fastapi.middleware.cors import CORSMiddleware
+
+app = FastAPI()
+app.add_middleware(
+    CORSMiddleware,
+    allow_origins=["http://localhost:3000"],
+    allow_credentials=True,
+    allow_methods=["*"],
+    allow_headers=["*"],
+)
+Base.metadata.create_all(bind=engine)
+
+app.include_router(auth.router)
+
+@app.get("/")
+def root():
+    return {"status": "running"}

app/main.py

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+from datetime import datetime, timezone
+from sqlalchemy import Column, DateTime, Enum, ForeignKey, Integer, String
+from .database import Base
+from .enums import Grade
+
+
+class User(Base):
+    __tablename__ = "users"
+
+    id = Column(Integer, primary_key=True, index=True)
+    google_id = Column(String, unique=True, index=True, nullable=True)
+    username = Column(String, unique=True, index=True, nullable=False)
+    password = Column(String, nullable=False)
+    email = Column(String, unique=True, index=True)
+    name = Column(String, nullable=False)
+    grade = Column(Enum(Grade), nullable=False)
+    institute = Column(String, nullable=False)
+    city = Column(String, nullable=False)
+    marketing = Column(String, nullable=False)
+    
+class Session(Base):
+    __tablename__ = "sessions"
+
+    id = Column(String, primary_key=True, index=True)
+    user_id = Column(Integer, ForeignKey("users.id", ondelete="CASCADE"), nullable=False)
+    expires_at = Column(DateTime, nullable=False)
+    created_at = Column(DateTime, default=datetime.now(timezone.utc))