Assignment06

# ------------------------------------------------------------------------------------------ #
# Title: Assignment06
# Desc: This assignment demonstrates using functions with structured error handling
# Change Log: (Who, When, What)
#   RRoot,1/1/2030,Created Script
#   Julianne Tillmann, 11/18/2024, Added functions and error handling.
# ------------------------------------------------------------------------------------------ #

import json  # Enables work with JSON files

# Define the Data Constants
MENU: str = '''
---- Course Registration Program ----
  Select from the following menu:  
    1. Register a Student for a Course
    2. Show current data  
    3. Save data to a file
    4. Exit the program
----------------------------------------- 
'''
FILE_NAME: str = "Enrollments.json"
students: list = []  # A table of student data


# Class Definitions
class FileProcessor:
    """Handles file read/write operations"""

    @staticmethod
    def read_data_from_file(file_name: str, student_data: list) -> None:
        """Reads data from a file into a list of dictionaries"""
        try:
            with open(file_name, "r") as file:
                student_data.extend(json.load(file))
            print(f"Data loaded successfully from {file_name}.")
        except FileNotFoundError:
            print(f"{file_name} was not found. A new file will be created.")
        except json.JSONDecodeError:
            print(f"Error decoding JSON data in {file_name}.")
        except Exception as e:
            print(f"An unexpected error occurred: {e}")

    @staticmethod
    def write_data_to_file(file_name: str, student_data: list) -> None:
        """Writes data from a list of dictionaries to a file"""
        try:
            with open(file_name, "w") as file:
                json.dump(student_data, file)
            print(f"Data saved successfully to {file_name}.")
        except Exception as e:
            print(f"An unexpected error occurred while saving data: {e}")


class IO:
    """Handles input and output operations"""

    @staticmethod
    def output_menu(menu: str) -> None:
        """Displays a menu of choices to the user"""
        print(menu)

    @staticmethod
    def input_menu_choice() -> str:
        """Gets the user's menu choice"""
        return input("What would you like to do? ")

    @staticmethod
    def input_student_data(student_data: list) -> None:
        """Gets student data from the user and adds it to the list"""
        try:
            student_first_name = input("Enter the student's first name: ")
            if not student_first_name.isalpha():
                raise ValueError("First name must only contain letters.")

            student_last_name = input("Enter the student's last name: ")
            if not student_last_name.isalpha():
                raise ValueError("Last name must only contain letters.")

            course_name = input("Enter the course name: ")

            # Create a new dictionary and append it to the list
            new_student = {
                "FirstName": student_first_name,
                "LastName": student_last_name,
                "CourseName": course_name
            }
            student_data.append(new_student)
            print(f"Student {student_first_name} {student_last_name} registered for {course_name}.")
        except ValueError as e:
            print(f"Input error: {e}")
        except Exception as e:
            print(f"An unexpected error occurred: {e}")

    @staticmethod
    def output_student_courses(student_data: list) -> None:
        """Displays all students and their courses"""
        print("\nCurrent Enrollments:")
        if student_data:
            for student in student_data:
                try:
                    print(f"{student['FirstName']} {student['LastName']} - {student['CourseName']}")
                except KeyError as e:
                    print(f"Error: Missing {e} in student record {student}")
        else:
            print("No data available.")


# Main Body
if __name__ == "__main__":
    # Load existing data from the file
    FileProcessor.read_data_from_file(FILE_NAME, students)

    while True:
        # Display menu and get user choice
        IO.output_menu(MENU)
        choice = IO.input_menu_choice()

        # Process user choice
        if choice == "1":
            IO.input_student_data(students)
        elif choice == "2":
            IO.output_student_courses(students)
        elif choice == "3":
            FileProcessor.write_data_to_file(FILE_NAME, students)
        elif choice == "4":
            print("Exiting the program.")
            break
        else:
            print("Invalid choice. Please select a valid option.")