using System;

using System.Collections.Generic;

using System.Security.Cryptography;

using System.Text;

​

namespace StudentManagementSystem

{

    class Program

    {

        // In-memory "database" of users

        private static Dictionary<string, (string PasswordHash, string Salt, string Role)> users = new Dictionary<string, (string, string, string)>

        {

            { "admin", HashPasswordWithSalt("admin123", "Admin") },

            { "student", HashPasswordWithSalt("student123", "Student") }

        };

​

        // In-memory "database" of students

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

​

        static void Main(string[] args)

        {

            Console.WriteLine("Welcome to Student Management System");

​

            // Simulate login form in console

            Console.Write("Username: ");

            string username = Console.ReadLine();

            Console.Write("Password: ");

            string password = Console.ReadLine();

​

            if (string.IsNullOrEmpty(username) || string.IsNullOrEmpty(password))

            {

                Console.WriteLine("Please enter both username and password.");

                return;

            }

​

            if (AuthenticateUser(username, password, out string role))

            {

                Console.WriteLine("Login Successful!");

                Console.WriteLine($"Logged in as: {role}");

                ShowDashboard(role);

            }

            else

            {

                Console.WriteLine("Invalid username or password.");

            }

        }

​

        private static bool AuthenticateUser(string username, string password, out string role)

        {

            role = null;

            if (users.ContainsKey(username))

            {

                var user = users[username];

                string storedHash = user.PasswordHash;

                string salt = user.Salt; // Retrieve the salt

                role = user.Role;

                return VerifyPasswordWithSalt(password, storedHash, salt); // Use the salt in verification

            }

            return false;

        }

​

        private static string GenerateSalt()

        {

            byte[] salt = new byte[16]; // 128-bit salt

            using (var rng = RandomNumberGenerator.Create())

            {

                rng.GetBytes(salt);

            }

            return Convert.ToBase64String(salt);

        }

​

        private static (string PasswordHash, string Salt, string Role) HashPasswordWithSalt(string password, string role)

        {

            string salt = GenerateSalt();

            string passwordHash = HashPassword(password, salt);

            return (passwordHash, salt, role);

        }

​

        private static string HashPassword(string password, string salt)

        {

            string saltedPassword = salt + password;

​

            using (SHA256 sha256 = SHA256.Create())

            {

                byte[] bytes = sha256.ComputeHash(Encoding.UTF8.GetBytes(saltedPassword));

                StringBuilder builder = new StringBuilder();

                foreach (byte b in bytes)

                {

                    builder.Append(b.ToString("x2"));

                }

                return builder.ToString();

            }

        }

​

        private static bool VerifyPasswordWithSalt(string enteredPassword, string storedHash, string salt)

        {

            string enteredHash = HashPassword(enteredPassword, salt);

            return enteredHash.Equals(storedHash, StringComparison.OrdinalIgnoreCase);

        }

​

        private static void ShowDashboard(string role)

        {

            while (true)

            {

                Console.WriteLine("\n--- Dashboard ---");

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

                Console.WriteLine("2. View/Search Students");

                Console.WriteLine("3. Logout");

                Console.Write("Enter your choice: ");

                string choice = Console.ReadLine();

​

                switch (choice)

                {

                    case "1":

                        AddStudent();

                        break;

                    case "2":

                        ViewSearchStudents();

                        break;

                    case "3":

                        Console.WriteLine("Logging out...");

                        return; // Exit the dashboard loop

                    default:

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

                        break;

                }

            }

        }

​

        private static void AddStudent()

        {

            Console.WriteLine("\n--- Add Student ---");

            Console.Write("Enter Student ID: ");

            string studentId = Console.ReadLine();

​

            if (students.Exists(s => s.StudentID == studentId))

            {

                Console.WriteLine("A student with this ID already exists.");

                return;

            }

​

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

            string name = Console.ReadLine();

​

            Console.Write("Enter Student Age: ");

            if (!int.TryParse(Console.ReadLine(), out int age))

            {

                Console.WriteLine("Invalid age. Please enter a valid number.");

                return;

            }

​

            students.Add(new Student { StudentID = studentId, Name = name, Age = age });

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

        }

​

        private static void ViewSearchStudents()

        {

            Console.WriteLine("\n--- View/Search Students ---");

​

            if (students.Count == 0)

            {

                Console.WriteLine("No students found.");

                return;

            }

​

            Console.Write("Enter search term (name or ID) or leave blank to view all: ");

            string searchTerm = Console.ReadLine().ToLower();

​

            Console.WriteLine("\n--- Student List ---");

            foreach (var student in students)

            {

                if (string.IsNullOrEmpty(searchTerm) ||

                    student.Name.ToLower().Contains(searchTerm) ||

                    student.StudentID.ToLower().Contains(searchTerm))

                {

                    Console.WriteLine($"ID: {student.StudentID}, Name: {student.Name}, Age: {student.Age}");

                }

            }

        }

    }

​

    class Student

    {

        public string StudentID { get; set; }

        public string Name { get; set; }

        public int Age { get; set; }

    }

}

​