Added endpoint to add a user using a join code (#218)

* Fix #71

* added course join endpoint

* internal server error is 500

* fixed code docs

backend/project/endpoints/courses/courses_config.py

@@ -15,6 +15,7 @@
 from  project.endpoints.courses.course_details import CourseByCourseId
 from  project.endpoints.courses.course_admin_relation import CourseForAdmins
 from  project.endpoints.courses.course_student_relation import CourseToAddStudents
+from  project.endpoints.courses.join import CourseJoin
 
 courses_bp = Blueprint("courses", __name__)
 courses_api = Api(courses_bp)
@@ -30,3 +31,5 @@
 
 courses_bp.add_url_rule("/courses/<int:course_id>/students",
                         view_func=CourseToAddStudents.as_view('course_students'))
+
+courses_bp.add_url_rule("/courses/join", view_func=CourseJoin.as_view('course_join'))

backend/project/endpoints/courses/join.py

@@ -0,0 +1,78 @@
+"""
+This file contains the endpoint to join a course using a join code
+"""
+
+
+from os import getenv
+from datetime import datetime
+from zoneinfo import ZoneInfo
+
+from flask import request
+from flask_restful import Resource
+
+from sqlalchemy.exc import SQLAlchemyError
+
+from project.models.course_share_code import CourseShareCode
+from project.models.course_relation import CourseStudent, CourseAdmin
+
+
+TIMEZONE = getenv("TIMEZONE", "GMT")
+API_URL = getenv("API_HOST")
+
+class CourseJoin(Resource):
+    """
+    Class that will respond to the /courses/join link
+    students or admins with a join code can join a course
+    """
+
+    def post(self, uid=None): # pylint: disable=too-many-return-statements
+        """
+        Post function for /courses/join
+        students or admins with a join code can join a course
+        """
+
+        response = {
+            "url": f"{API_URL}/courses/join"
+        }
+
+        data = request.get_json()
+        if not "join_code" in data:
+            return {"message": "join_code is required"}, 400
+
+        join_code = data["join_code"]
+        share_code = CourseShareCode.query.filter_by(join_code=join_code).first()
+
+        if not share_code:
+            response["message"] = "Invalid join code"
+            return response, 400
+
+        if share_code.expiry_time and share_code.expiry_time < datetime.now(ZoneInfo(TIMEZONE)):
+            response["message"] = "Join code has expired"
+            return response, 400
+
+
+        course_id = share_code.course_id
+        is_for_admins = share_code.for_admins
+
+        course_relation = CourseStudent
+        if is_for_admins:
+            course_relation = CourseAdmin
+
+        try:
+            relation = course_relation.query.filter_by(course_id=course_id, uid=uid).first()
+            if relation:
+                response["message"] = "User already in course"
+                return response, 400
+        except SQLAlchemyError:
+            response["message"] = "Internal server error"
+            return response, 500
+
+        course_relation = course_relation(course_id=course_id, uid=uid)
+
+        try:
+            course_relation.insert()
+            response["message"] = "User added to course"
+            return response, 201
+        except SQLAlchemyError:
+            response["message"] = "Internal server error"
+            return response, 500