handle already existing users

database.py

@@ -2,8 +2,6 @@ from models import User
 from settings import settings
 from fastapi import HTTPException, status, Request
 import sqlite3
-import jwt
-import datetime
 import security
 
 
@@ -51,27 +49,30 @@ def close() -> None:
 
 def register(user: User) -> None:
     """Registers a new user in the database."""
-    cursor.execute(
-        "INSERT INTO users (name, password) VALUES (?, ?)",
-        (user.name,
-         security.hash_password(user.password)))
-    connection.commit()
+    try:
+        cursor.execute(
+            "INSERT INTO users (name, password) VALUES (?, ?)",
+            (user.name,
+             security.hash_password(user.password)))
+        connection.commit()
+    except sqlite3.IntegrityError:
+        raise HTTPException(
+            status_code=status.HTTP_400_BAD_REQUEST,
+            detail="User already exists"
+        )
 
 
 def get_user_by_token(request: Request) -> User:
     """Retrieves a user from the database using a JWT token."""
-    token = request.headers.get("Authorization")
-    if not token or not token.startswith("Bearer "):
+
+    payload = security.decode_jwt(
+        request.headers.get("Authorization"))
+
+    if not payload:
         raise HTTPException(
             status_code=status.HTTP_401_UNAUTHORIZED,
             detail="Not authenticated"
         )
-    token = token.split(" ")[1]
-    payload = jwt.decode(
-        token,
-        key=settings.jwt_secret,
-        algorithms=[
-            settings.jwt_algorithm])
 
     connection, cursor = connect()
     cursor.execute(
@@ -100,14 +101,4 @@ def login(user: User) -> str:
             detail="Invalid credentials"
         )
 
-    exp = datetime.datetime.now(
-        datetime.timezone.utc) + datetime.timedelta(hours=1)
-    payload = {
-        "id": row["id"],
-        "exp": exp
-    }
-
-    return jwt.encode(
-        payload=payload,
-        key=settings.jwt_secret,
-        algorithm=settings.jwt_algorithm)
+    return security.sign_jwt(row)

main.py

@@ -2,6 +2,13 @@ from fastapi import FastAPI, Depends
 from contextlib import asynccontextmanager
 import database
 import models
+import logging
+
+logging.basicConfig(
+    level=logging.INFO,
+    format="%(asctime)s - %(name)s - %(levelname)s - %(message)s",
+    datefmt="%Y-%m-%d %H:%M:%S",
+)
 
 
 @asynccontextmanager

security.py

@@ -1,6 +1,11 @@
 from passlib.context import CryptContext
+from settings import settings
+import jwt
+import datetime
+import logging
 
 password_context = CryptContext(schemes=["sha256_crypt"], deprecated="auto")
+logger = logging.getLogger(__name__)
 
 
 def hash_password(password: str) -> str:
@@ -11,3 +16,46 @@ def hash_password(password: str) -> str:
 def verify_password(plain_password: str, hashed_password: str) -> bool:
     """Verifies a plain text password against a hashed password."""
     return password_context.verify(plain_password, hashed_password)
+
+
+def sign_jwt(row: dict) -> str:
+    """Signs a JWT token with the given payload."""
+    exp = datetime.datetime.now(
+        datetime.timezone.utc) + datetime.timedelta(hours=1)
+
+    payload = {
+        "id": row["id"],
+        "exp": exp
+    }
+
+    return jwt.encode(
+        payload,
+        key=settings.jwt_secret,
+        algorithm=settings.jwt_algorithm
+    )
+
+
+def decode_jwt(token: str | None) -> dict | None:
+    """Decodes a JWT token and returns the payload."""
+    if not token or not token.startswith("Bearer "):
+        logger.warning(
+            "No token provided or token does not start with 'Bearer '")
+        return None
+
+    try:
+        payload = jwt.decode(
+            token.replace("Bearer ", ""),
+            key=settings.jwt_secret,
+            algorithms=[settings.jwt_algorithm]
+        )
+
+        return payload
+    except jwt.ExpiredSignatureError:
+        logger.warning("Token has expired")
+        return None
+    except jwt.InvalidTokenError:
+        logger.warning("Invalid token")
+        return None
+
+    logger.warning("Unexpected error in token decoding")
+    return None