Add check for login refresh

src/imperial_doc_materials/auth.py

 import requests
+from typing import Tuple
 
 MATERIALS_API_LOGIN_URL = "https://api-materials.doc.ic.ac.uk/auth/login"
-MATERIALS_API_LOGOUT_URL = "https://api-materials.doc.ic.ac.uk/auth/logout"
+MATERIALS_API_REFRESH_URL = "https://api-materials.doc.ic.ac.uk/auth/refresh"
 
-def login(username: str, password: str) -> str:
+def login(username: str, password: str) -> Tuple[str, str]:
     """
-    Authenticates a user given their username and password. Returns an access_token to be used
-    for subsequent requests in the Authorization header.
+    Authenticates a user given their username and password. Returns an access_token and 
+    a refresh_token to be used for subsequent requests in the Authorization header.
     """
     headers = {
         "Content-Type": "application/json"
@@ -20,7 +21,19 @@ def login(username: str, password: str) -> str:
     resp = requests.post(MATERIALS_API_LOGIN_URL, json=body, headers=headers)
     data = resp.json()
 
-    return str(data["access_token"])
+    return str(data["access_token"]), str(data["refresh_token"])
+
+
+def refresh(refresh_token: str) -> str:
+    """
+    Returns a new access token given a refresh token.
+    """
 
-def logout():
-    pass
\ No newline at end of file
+    headers = {
+        "Authorization": f"Bearer {refresh_token}"
+    }
+
+    resp = requests.post(MATERIALS_API_REFRESH_URL, json={}, headers=headers)
+    data = resp.json()
+
+    return str(data["access_token"])

src/imperial_doc_materials/client.py

@@ -7,15 +7,17 @@ from .resources import Resources, Resource
 MATERIALS_API_STATUS_URL = "https://api-materials.doc.ic.ac.uk/status"
 
 class Materials:
-    def __init__(self, token: str):
-        self._access_token = token
+    def __init__(self, access_token: str, refresh_token: str = ""):
+        self._access_token = access_token
+        self._refresh_token = refresh_token
+        self._has_refreshed = False
 
     def get_as_dict(self) -> dict:
         return vars(self)
 
     @staticmethod
     def from_dict(client: dict):
-        return Materials(client["_access_token"])
+        return Materials(client["_access_token"], client["_refresh_token"])
 
     @staticmethod
     def _is_alive() -> bool:
@@ -23,6 +25,11 @@ class Materials:
         data = resp.json()
         return data["status"] == "alive"
 
+    def _refresh_client(self):
+        self._access_token = auth.refresh(self._refresh_token)
+        self._refresh_token = ""
+        self._has_refreshed = True
+
     @staticmethod
     def create_client(username: str, password: str):
         """
@@ -31,7 +38,13 @@ class Materials:
         if not Materials._is_alive():
             raise Exception("The Materials API is currently down.")
 
-        return Materials(auth.login(username, password))
+        return Materials(*auth.login(username, password))
+
+    def requires_new_login(self) -> bool:
+        """
+        Check whether you need to request for a new login, to keep the client alive.
+        """
+        return self._has_refreshed
 
     def get_courses_for_year(self, academic_year: str) -> List[Course]:
         """
@@ -39,7 +52,14 @@ class Materials:
         user during the given the academic_year string.
         (e.g. 2122 for the year 2021/2022).
         """
-        return Courses.get_for_year(self._access_token, academic_year)
+        try:
+            return Courses.get_for_year(self._access_token, academic_year)
+        except:
+            if not self._has_refreshed:
+                self._refresh_client()
+                return self.get_courses_for_year(academic_year)
+            else:
+                raise ValueError("The client access token has expired, please request a new login for the user")
 
     def get_resources_for_year(self, academic_year: str) -> List[Resource]:
         """
@@ -47,4 +67,11 @@ class Materials:
         user during the given the academic_year string.
         (e.g. 2122 for the year 2021/2022).
         """
-        return Resources.get_for_year(self._access_token, academic_year)
\ No newline at end of file
+        try:
+            return Resources.get_for_year(self._access_token, academic_year)
+        except:
+            if not self._has_refreshed:
+                self._refresh_client()
+                return self.get_courses_for_year(academic_year)
+            else:
+                raise ValueError("The client access token has expired, please request a new login for the user")

src/imperial_doc_materials/flask_utils.py

@@ -54,6 +54,8 @@ def using_materials(f):
         materials_client = None
         try:
             materials_client = Materials.from_dict(session[SESSION_KEY_NAME])
+            if materials_client.requires_new_login() and IMPERIAL_DOC_MATERIALS_REDIRECT_URL:
+                    return redirect(IMPERIAL_DOC_MATERIALS_URL_PREFIX + str(url_for(IMPERIAL_DOC_MATERIALS_REDIRECT_URL, next=request.url)))
         except:
             if IMPERIAL_DOC_MATERIALS_REDIRECT_URL:
                 return redirect(IMPERIAL_DOC_MATERIALS_URL_PREFIX + str(url_for(IMPERIAL_DOC_MATERIALS_REDIRECT_URL, next=request.url)))