From f7f29d33d8ac0b57a8fec911a12d4ebb167dc9de Mon Sep 17 00:00:00 2001
From: "Huang, Huan (PG/T - Comp Sci & Elec Eng)" <ch01402@surrey.ac.uk>
Date: Thu, 2 May 2024 19:37:40 +0000
Subject: [PATCH] auth.py is for later database.

---
 auth.py | 57 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 57 insertions(+)
 create mode 100644 auth.py

diff --git a/auth.py b/auth.py
new file mode 100644
index 0000000..c201585
--- /dev/null
+++ b/auth.py
@@ -0,0 +1,57 @@
+# auth.py
+# pip install fastapi uvicorn jose[cryptography] passlib[bcrypt]
+from datetime import datetime, timedelta
+from typing import Optional
+
+from fastapi import HTTPException, Depends, status
+from fastapi.security import OAuth2PasswordBearer, OAuth2PasswordRequestForm
+from jose import JWTError, jwt
+from passlib.context import CryptContext
+
+from db import get_user_by_username
+
+# Configuration
+SECRET_KEY = "your_secret_key"
+ALGORITHM = "HS256"
+ACCESS_TOKEN_EXPIRE_MINUTES = 30
+
+# OAuth2PasswordBearer defines the token URL
+oauth2_scheme = OAuth2PasswordBearer(tokenUrl="token")
+
+# Password hashing context
+pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")
+
+# Helper Functions
+def verify_password(plain_password: str, hashed_password: str) -> bool:
+    return pwd_context.verify(plain_password, hashed_password)
+
+def get_password_hash(password: str) -> str:
+    return pwd_context.hash(password)
+
+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=ACCESS_TOKEN_EXPIRE_MINUTES)
+    to_encode.update({"exp": expire})
+    return jwt.encode(to_encode, SECRET_KEY, ALGORITHM)
+
+def authenticate_user(username: str, password: str):
+    user = get_user_by_username(username)
+    if not user or not verify_password(password, user["password"]):
+        return None
+    return user
+
+def get_current_user(token: str = Depends(oauth2_scheme)):
+    try:
+        payload = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM])
+        username = payload.get("sub")
+        if not username:
+            raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="Invalid token")
+        user = get_user_by_username(username)
+        if not user:
+            raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="User not found")
+    except JWTError:
+        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="Invalid token")
+    return user
-- 
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