From 81eecfad9343768dd4f3050b977e391064eda700 Mon Sep 17 00:00:00 2001
From: darshan2006-op <darshanpanzade2006@gmail.com>
Date: Thu, 11 Dec 2025 16:50:05 +0530
Subject: [PATCH] added data persistence

---
 .gitignore         |  1 +
 main.py            |  7 ++++++-
 student_manager.py | 50 +++++++++++++++++++++++++++++++++++++++++++++-
 utils.py           | 49 +++++++++++++++++++++++++++++++++++++++++----
 4 files changed, 101 insertions(+), 6 deletions(-)

diff --git a/.gitignore b/.gitignore
index 414bdd2..0d7ef7e 100644
--- a/.gitignore
+++ b/.gitignore
@@ -39,3 +39,4 @@ htmlcov/
 data.json
 *.csv
 *.log
+
diff --git a/main.py b/main.py
index b183d2f..f91f902 100644
--- a/main.py
+++ b/main.py
@@ -24,7 +24,10 @@ def main():
 
     args = parser.parse_args()
 
-    manager = StudentManager()
+    manager, status = StudentManager.load_manager()
+
+    if status == 2:
+        print("Error: Corrupted persistence file detected and removed. Starting with fresh data.")
 
     if args.command == 'add-assignment':
         if not args.value or not args.deadline:
@@ -71,5 +74,7 @@ def main():
         )
         timer.start(interactive=True)
 
+    manager.dump_manager()
+
 if __name__ == '__main__':
     main()
\ No newline at end of file
diff --git a/student_manager.py b/student_manager.py
index 452ed31..45c3ffb 100644
--- a/student_manager.py
+++ b/student_manager.py
@@ -3,10 +3,11 @@
 """
 
 from datetime import datetime
-from utils import calculate_days_remaining, validate_grade, get_priority_level
+from utils import calculate_days_remaining, validate_grade, get_priority_level, save_to_json, load_from_json
 
 
 class StudentManager:
+    PERSISTENCE_FILE_NAME = "data.json"
     def __init__(self):
         self.assignments = []
         self.grades = []
@@ -73,6 +74,28 @@ def get_upcoming_deadlines(self, days=7):
 
         return sorted(upcoming, key=lambda x: x['days_remaining'])
 
+    def dump_manager(self):
+        """Dumps data into json file for persistence"""
+        data = self._ser_object()
+        save_to_json(data, self.PERSISTENCE_FILE_NAME)
+
+    @classmethod
+    def load_manager(cls):
+        """
+        Load data into the program from persistence file
+
+        Returns: 
+            int: status of loading data from file
+            0 - success
+            1 - persistence file not found
+            2 - corrupted persistence file
+        """
+        res = load_from_json(cls.PERSISTENCE_FILE_NAME)
+        if res["status"] != 0:
+            status = res.get("status")
+            return cls(), status
+        return cls._deser_object(res.get("data")), 0
+
     def get_statistics(self):
         """Get student statistics"""
         total_assignments = len(self.assignments)
@@ -84,3 +107,28 @@ def get_statistics(self):
             'pending': total_assignments - completed,
             'gpa': self.calculate_gpa()
         }
+
+    def _ser_object(self):
+        """
+        Protected method to aggrigate data
+
+        Returns: 
+            dict: final data
+        """
+        return {
+            "Assignments": self.assignments,
+            "Grades": self.grades
+        }
+    
+    @classmethod
+    def _deser_object(cls, data):
+        """
+        Protected method to load aggregate data
+        
+        Args:
+            data: dict - data to be deserialized
+        """
+        manager = cls()
+        manager.assignments = data.get("Assignments", [])
+        manager.grades = data.get("Grades", [])
+        return manager
\ No newline at end of file
diff --git a/utils.py b/utils.py
index 8197631..b8e8e53 100644
--- a/utils.py
+++ b/utils.py
@@ -4,7 +4,35 @@
 
 from datetime import datetime
 import json
+import os
 
+class DateTimeEncoder(json.JSONEncoder):
+    def default(self, obj):
+        """Handles special case of date serialization"""
+        if isinstance(obj, datetime):
+            return obj.isoformat()
+        return super().default(obj)
+    
+class DateTimeDecoder(json.JSONDecoder):
+    def __init__(self, *args, **kwargs):
+        super().__init__(object_hook=self.object_hook, *args, **kwargs)
+
+    def object_hook(self, obj):
+        """Handles special case of date deserialization, including nested structures"""
+        return self._decode_dates(obj)
+    
+    def _decode_dates(self, value):
+        if isinstance(value, dict):
+            return {k: self._decode_dates(v) for k, v in value.items()}
+        elif isinstance(value, list):
+            return [self._decode_dates(item) for item in value]
+        elif isinstance(value, str):
+            try:
+                return datetime.fromisoformat(value)
+            except ValueError:
+                return value
+        else:
+            return value
 
 def format_date(date_string):
     """Convert date string to datetime object"""
@@ -33,16 +61,29 @@ def validate_grade(grade):
 def save_to_json(data, filename):
     """Save data to JSON file"""
     with open(filename, 'w') as f:
-        json.dump(data, f, indent=4)
-
+        # NOTE: Edit DateTimeEncoder accordingly if StudentManager contains other non serializable types
+        json.dump(data, f, indent=4, cls=DateTimeEncoder)
 
 def load_from_json(filename):
     """Load data from JSON file"""
     try:
         with open(filename, 'r') as f:
-            return json.load(f)
+            # NOTE: Edit DateTimeDecoder accordingly if StudentManager contains other non serializable types
+            return {
+                "data": json.load(f, cls=DateTimeDecoder),
+                "status": 0
+            }
     except FileNotFoundError:
-        return {}
+        return {
+            "data" : None,
+            "status": 1
+        }
+    except json.JSONDecodeError as e:
+        os.remove(filename)
+        return {
+            "data" : None,
+            "status": 2
+        }
 
 
 def get_priority_level(days_remaining):