Add user via rest api

backend/api-docs.txt

@@ -24,7 +24,52 @@ Login:-
         403 Forbidden:-
             Content Type:- text/plain
             Note:- user_name or password is wrong, can display the response data to user.
-            Data:- What is wrong will be mentioned
+            Data:- What is wrong will be mentioned, text that can be displayed on the screen.
+
+    Example:-
+        formData = new FormData();
+        formData.append('name', 'John');
+        formData.append('password', 'John123');
+        fetch(
+            "/login",
+            {
+                body: formData,
+                method: "post"
+            }
+        );
+
+        This will give a response status 200 with no data if login is done.
+        This will return a 403 if the user gave wrong name or password.
+_____________________
+
+
+_____________________
+Add User:-
+    URL:- /add_user
+
+    Method:- POST
+
+    Data Type:- Form Data
+
+    Data content:- {
+            user_name: "<user name>",
+            password: "<password>"
+        }
+
+    Response:-
+        200 OK:-
+            Data:- No
+            Note:- Assume success.
+
+        400 Bad Request:-
+            Content Type:- text/plain
+            Note:- user_name or password not given a Form Data.
+            Data:- What is missing will be mentioned.
+
+        403 Forbidden:-
+            Content Type:- text/plain
+            Note:- user_name is exists, can display the response data to user.
+            Data:- Text that can be displayed on the screen.
 
     Example:-
         formData = new FormData();

backend/rest_api.py

@@ -68,3 +68,34 @@ class QueryHandler:
             )
 
         return Response(status=200)
+
+    @staticmethod
+    @app.post("/add_user")
+    def add_user() -> Response:
+        """
+        Adds a new user
+        """
+        data: ImmutableMultiDict[str, str] = request.form
+        if "user_name" not in data:
+            return Response(
+                    "user_name not given",
+                    400,
+                    content_type="text/plain"
+            )
+        if "password" not in data:
+            return Response(
+                    "password is not given",
+                    400,
+                    content_type="text/plain"
+            )
+
+        try:
+            DataHandler.create_user(data["user_name"], data["password"])
+        except ValueError as value_error:
+            return Response(
+                    str(value_error),
+                    403,
+                    content_type="text/plain"
+            )
+
+        return Response(status=200)