using System;
using System.Collections.Generic;
using System.Collections;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Collections
{
    class Program
    {
        static void Main(string[] args)
        {
            Student may = new Student("May", "flower", new DateTime(1980, 2, 15));
            Student john = new Student("John", "Doe", new DateTime(1995, 11, 2));
            Student liv = new Student("Liv", "Boeree", new DateTime(1987, 8, 25));

            Course course = new Course("Electronics 101");
            course.Students.Add(may);
            course.Students.Add(john);
            course.Students.Add(liv);

            AddGrades(course);
            course.ListStudents();

        }

        static void AddGrades(Course course)
        {
            Random random = new Random();
            foreach (Student student in course.Students)
            {
                for (int i = 0; i < 5; i++)
                {
                    student.Grades.Push(random.Next(101)); //between 0 and 100
                }
            }
        }

    }

    class Person
    {
        public string FirstName { get; set; }
        public string LastName { get; set; }

        public Person(string firstName, string lastName)
        {
            FirstName = firstName;
            LastName = lastName;
        }

    }

    class Student : Person
    {
        public DateTime BirthDate { get; set; }
        public static int StudentsEnrolled;
        public Stack<int> Grades { get; set; }

        public Student(string firstName, string lastName, DateTime birthDate)
            : base(firstName, lastName)
        {
            BirthDate = birthDate;
            StudentsEnrolled++;
            Grades = new Stack<int>();
        }

        public void TakeTest()
        {
            Console.WriteLine("{0} {1} is taking a test", FirstName, LastName);
        }

        public double MeanGrade()
        {
            double meanGrade = 0;
            if (Grades.Count > 0)
            {
                foreach (int grade in Grades)
                {
                    meanGrade += grade;
                }
                meanGrade = meanGrade / Grades.Count;
            }
            return meanGrade;
        }
    }

    class Teacher : Person
    {
        public string FieldOfExpertice { get; set; }

        public Teacher(string firstName, string lastName, string fieldOfExpertice)
            : base(firstName, lastName)
        {
            FieldOfExpertice = fieldOfExpertice;
        }

        public void GradeTest()
        {
            Console.WriteLine("{0} {1} is grading a test.", FirstName, LastName);
        }
    }

    class Course
    {
        public string Name { get; set; }
        public ArrayList Students { get; set; }
        public Teacher HeadTeacher { get; set; }

        public Course(string name)
        {
            Name = name;
            Students = new ArrayList();
        }

        public void ListStudents()
        {
            Console.WriteLine("The course {0} contains {1} student{2}:\n", Name, Students.Count, Students.Count == 1 ? "" : "s");
            foreach (Student student in Students)
            {
                Console.WriteLine("{0} {1}, Average grade: {2} ", student.FirstName, student.LastName, student.MeanGrade());
            }
        }

    }

    class Degree
    {
        public string Name { get; set; }
        public string DegreeLevel { get; set; }
        public ArrayList CourseList { get; set; }

        public Degree(string name, string degreeLevel)
        {
            Name = name;
            DegreeLevel = degreeLevel;
            CourseList = new ArrayList();
        }
    }

    class UProgram
    {
        public string Name { get; set; }
        public ArrayList DegreeList { get; set; }

        public UProgram(string name)
        {
            Name = name;
            DegreeList = new ArrayList();
        }
    }
}