Initial LinkLog implementation

backend/app/api/dependencies.py

@@ -0,0 +1,41 @@
+from fastapi import Depends, HTTPException, status
+from fastapi.security import HTTPAuthorizationCredentials, HTTPBearer
+
+from backend.app.database import get_connection
+from backend.app.services.token_service import validate_token
+
+bearer_scheme = HTTPBearer(auto_error=False)
+
+
+def get_current_user(
+    credentials: HTTPAuthorizationCredentials | None = Depends(bearer_scheme),
+):
+    if credentials is None or credentials.scheme.lower() != 'bearer':
+        raise HTTPException(
+            status_code=status.HTTP_401_UNAUTHORIZED,
+            detail='Authentication required',
+            headers={'WWW-Authenticate': 'Bearer'},
+        )
+
+    token_data = validate_token(credentials.credentials)
+    if token_data is None:
+        raise HTTPException(
+            status_code=status.HTTP_401_UNAUTHORIZED,
+            detail='Token expired or invalid',
+            headers={'WWW-Authenticate': 'Bearer'},
+        )
+
+    with get_connection() as conn:
+        user = conn.execute(
+            'SELECT * FROM users WHERE id = ?',
+            (token_data['user_id'],),
+        ).fetchone()
+    if user is None:
+        raise HTTPException(status_code=404, detail='User not found')
+    return dict(user)
+
+
+def require_admin(user: dict = Depends(get_current_user)):
+    if not user['is_admin']:
+        raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail='Administrator access required')
+    return user