using System;

using System.Collections.Generic;

using System.Text.RegularExpressions;

​

// Base Class Person - Common Properties and Methods for all Users

public class Person

{

    public string Name { get; set; }

    public string PhoneNumber { get; set; }

    public string Email { get; set; }

    public string Role { get; set; }

​

    // Constructor for Person class

    public Person(string name, string phoneNumber, string email, string role)

    {

        Name = name;

        PhoneNumber = phoneNumber;

        Email = email;

        Role = role;

    }

​

    // Virtual method to display details (to be overridden by subclasses)

    public virtual void DisplayDetails()

    {

        Console.WriteLine($"Name: {Name}, Phone: {PhoneNumber}, Email: {Email}, Role: {Role}");

    }

​

    // Method for validating email format

    public static bool IsValidEmail(string email)

    {

        string pattern = @"^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$";

        return Regex.IsMatch(email, pattern);

    }

​

    // Method for validating phone number format

    public static bool IsValidPhoneNumber(string phoneNumber)

    {

        string pattern = @"^\d{10}$"; // Validates 10-digit phone number

        return Regex.IsMatch(phoneNumber, pattern);

    }

}

​

// Derived Class: Teacher

public class Teacher : Person

{

    public decimal Salary { get; set; }

    public List<string> Subjects { get; set; }

​

    // Constructor for Teacher class

    public Teacher(string name, string phoneNumber, string email, decimal salary, List<string> subjects)

        : base(name, phoneNumber, email, "Teacher")

    {

        Salary = salary;

        Subjects = subjects;

    }

​

    // Overriding method to display teacher details

    public override void DisplayDetails()

    {

        base.DisplayDetails();

        Console.WriteLine($"Salary: {Salary}, Subjects: {string.Join(", ", Subjects)}");

    }

}

​

// Derived Class: Admin

public class Admin : Person

{

    public decimal Salary { get; set; }

    public string EmploymentType { get; set; } // Full-time/Part-time

​

    // Constructor for Admin class

    public Admin(string name, string phoneNumber, string email, decimal salary, string employmentType)

        : base(name, phoneNumber, email, "Admin")

    {

        Salary = salary;

        EmploymentType = employmentType;

    }

​

    // Overriding method to display admin details

    public override void DisplayDetails()

    {

        base.DisplayDetails();

        Console.WriteLine($"Salary: {Salary}, Employment Type: {EmploymentType}");

    }

}

​

// Derived Class: Student

public class Student : Person

{

    public DateTime DateOfBirth { get; set; }

    public List<string> Subjects { get; set; }

​

    // Constructor for Student class

    public Student(string name, string phoneNumber, string email, DateTime dateOfBirth, List<string> subjects)

        : base(name, phoneNumber, email, "Student")

    {

        DateOfBirth = dateOfBirth;

        Subjects = subjects;

    }

​

    // Overriding method to display student details

    public override void DisplayDetails()

    {

        base.DisplayDetails();

        Console.WriteLine($"Date of Birth: {DateOfBirth.ToShortDateString()}, Subjects: {string.Join(", ", Subjects)}");

    }

}

​

// Main Application Class

public class DesktopInformationSystem

{

    // Lists to store different user roles

    private List<Teacher> teachers = new List<Teacher>();

    private List<Admin> admins = new List<Admin>();

    private List<Student> students = new List<Student>();

​

    // Method to add a teacher

    public void AddTeacher()

    {

        Console.WriteLine("Enter Teacher Name:");

        string name = Console.ReadLine();

​

        Console.WriteLine("Enter Teacher Phone Number (10 digits):");

        string phoneNumber = Console.ReadLine();

​

        Console.WriteLine("Enter Teacher Email:");

        string email = Console.ReadLine();

​

        Console.WriteLine("Enter Teacher Salary:");

        decimal salary = decimal.Parse(Console.ReadLine());

​

        Console.WriteLine("Enter Teacher Subjects (comma separated):");

        List<string> subjects = new List<string>(Console.ReadLine().Split(','));

​

        // Validate phone number and email

        if (!Person.IsValidPhoneNumber(phoneNumber) || !Person.IsValidEmail(email))

        {

            Console.WriteLine("Invalid phone number or email.");

            return;

        }

​

        teachers.Add(new Teacher(name, phoneNumber, email, salary, subjects));

        Console.WriteLine("Teacher added successfully.");

    }

​

    // Method to add an admin

    public void AddAdmin()

    {

        Console.WriteLine("Enter Admin Name:");

        string name = Console.ReadLine();

​

        Console.WriteLine("Enter Admin Phone Number (10 digits):");

        string phoneNumber = Console.ReadLine();

​

        Console.WriteLine("Enter Admin Email:");

        string email = Console.ReadLine();

​

        Console.WriteLine("Enter Admin Salary:");

        decimal salary = decimal.Parse(Console.ReadLine());

​

        Console.WriteLine("Enter Admin Employment Type (Full-time/Part-time):");

        string employmentType = Console.ReadLine();

​

        // Validate phone number and email

        if (!Person.IsValidPhoneNumber(phoneNumber) || !Person.IsValidEmail(email))

        {

            Console.WriteLine("Invalid phone number or email.");

            return;

        }

​

        admins.Add(new Admin(name, phoneNumber, email, salary, employmentType));

        Console.WriteLine("Admin added successfully.");

    }

​

    // Method to add a student

    public void AddStudent()

    {

        Console.WriteLine("Enter Student Name:");

        string name = Console.ReadLine();

​

        Console.WriteLine("Enter Student Phone Number (10 digits):");

        string phoneNumber = Console.ReadLine();

​

        Console.WriteLine("Enter Student Email:");

        string email = Console.ReadLine();

​

        Console.WriteLine("Enter Student Date of Birth (yyyy-mm-dd):");

        DateTime dob = DateTime.Parse(Console.ReadLine());

​

        Console.WriteLine("Enter Student Subjects (comma separated):");

        List<string> subjects = new List<string>(Console.ReadLine().Split(','));

​

        // Validate phone number and email

        if (!Person.IsValidPhoneNumber(phoneNumber) || !Person.IsValidEmail(email))

        {

            Console.WriteLine("Invalid phone number or email.");

            return;

        }

​

        students.Add(new Student(name, phoneNumber, email, dob, subjects));

        Console.WriteLine("Student added successfully.");

    }

​

    // Method to display all data

    public void ViewAllData()

    {

        Console.WriteLine("Displaying all data...");

​

        foreach (var teacher in teachers) teacher.DisplayDetails();

        foreach (var admin in admins) admin.DisplayDetails();

        foreach (var student in students) student.DisplayDetails();

    }

​

    // Method to view data by role

    public void ViewByRole()

    {

        Console.WriteLine("Enter Role (Teacher/Admin/Student):");

        string role = Console.ReadLine();

​

        if (role.Equals("Teacher", StringComparison.OrdinalIgnoreCase))

        {

            foreach (var teacher in teachers) teacher.DisplayDetails();

        }

        else if (role.Equals("Admin", StringComparison.OrdinalIgnoreCase))

        {

            foreach (var admin in admins) admin.DisplayDetails();

        }

        else if (role.Equals("Student", StringComparison.OrdinalIgnoreCase))

        {

            foreach (var student in students) student.DisplayDetails();

        }

        else

        {

            Console.WriteLine("Invalid role entered.");

        }

    }

​

    // Method to delete data by name

    public void DeleteData()

    {

        Console.WriteLine("Enter the Name of the person to delete:");

        string name = Console.ReadLine();

​

        var teacher = teachers.Find(t => t.Name.Equals(name, StringComparison.OrdinalIgnoreCase));

        if (teacher != null)

        {

            teachers.Remove(teacher);

            Console.WriteLine("Teacher deleted successfully.");

            return;

        }

​

        var admin = admins.Find(a => a.Name.Equals(name, StringComparison.OrdinalIgnoreCase));

        if (admin != null)

        {

            admins.Remove(admin);

            Console.WriteLine("Admin deleted successfully.");

            return;

        }

​

        var student = students.Find(s => s.Name.Equals(name, StringComparison.OrdinalIgnoreCase));

        if (student != null)

        {

            students.Remove(student);

            Console.WriteLine("Student deleted successfully.");

            return;

        }

​

        Console.WriteLine("No user found with that name.");

    }

​

    // Main Menu Method

    public void DisplayMenu()

    {

        bool running = true;

​

        while (running)

        {

            Console.WriteLine("\nDesktop Information System Menu:");

            Console.WriteLine("1. Add Teacher");

            Console.WriteLine("2. Add Admin");

            Console.WriteLine("3. Add Student");

            Console.WriteLine("4. View All Data");

            Console.WriteLine("5. View Data by Role");

            Console.WriteLine("6. Delete Data");

            Console.WriteLine("7. Exit");

​

            Console.Write("Choose an option: ");

            int choice = int.Parse(Console.ReadLine());

​

            switch (choice)

            {

                case 1: AddTeacher(); break;

                case 2: AddAdmin(); break;

                case 3: AddStudent(); break;

                case 4: ViewAllData(); break;

                case 5: ViewByRole(); break;

                case 6: DeleteData(); break;

                case 7: running = false; break;

                default: Console.WriteLine("Invalid choice. Please try again."); break;

            }

        }

    }

}

​

// Program Execution Class

public class Program

{

    public static void Main()

    {

        DesktopInformationSystem system = new DesktopInformationSystem();

        system.DisplayMenu();

    }

}