OOP First four tasks

using System;
using System.Text;

/*1. Define a class that holds information about a mobile phone device:
 * model, manufacturer, price, owner, battery characteristics (model, hours idle and hours talk) and
 * display characteristics (size and number of colors).
 * Define 3 separate classes (class GSM holding instances of the classes Battery and Display).*/

/*2. Define several constructors for the defined classes that take different sets of arguments
 * (the full information for the class or part of it). Assume that model and manufacturer are mandatory
 * (the others are optional). All unknown data fill with null.*/

/*3. Add an enumeration BatteryType (Li-Ion, NiMH, NiCd, …) and use it as a new field for the batteries.*/

/*4. Add a method in the GSM class for displaying all information about it. Try to override ToString().*/

namespace MobilePhoneInformation
{
    class BaseClass
    {
        static void Main()
        {
            GSM newGSM = new GSM("Galaxy note 2", "Samsung", 1030, "Pesho Peshov");
            Console.WriteLine(newGSM.ToString());

            //newGSM.Model = "Galaxy note 2";
            //newGSM.Manufacturer = "Samsung";
            //newGSM.Price = 1030;
            //newGSM.Owner = "Pesho Peshov";

            Battery newBattery = new Battery("Li-Ion 3100 mAh", 980, 35, BatteryType.LiIon);
            //newBattery.Print();

            //newGSM.Battery.Model = "Li-Ion 3100 mAh battery";
            //newGSM.Battery.HoursIdle = 980;
            //newGSM.Battery.HoursTalk = 35;

            //Display newDisplay = new Display(5.55, 16000000);
            //newDisplay.Print();

            //newGSM.Display.Size = 5.55;
            //newGSM.Display.NumberOfColors = 16000000;

            //newGSM.Print();
            //newGSM.Battery.Print();
            ////newGSM.Display.Print();
        }
    }

    class GSM
    {
        private string model;
        private string manufacturer;
        private double? price;
        private string owner;

        public GSM(string model)
        {
            this.Model = model;
        }

        public GSM(string model, string manufacturer) : this(model)
        {
            this.Manufacturer = manufacturer;
        }

        public GSM(string model, string manufacturer, double price)
            : this(model, manufacturer)
        {
            this.Price = price;
        }

        public GSM(string model, string manufacturer, double price, string owner)
            : this(model, manufacturer, price)
        {
            this.Owner = owner;
        }

        public string Model
        {
            get { return model; }
            set { model = value; }
        }

        public string Manufacturer
        {
            get { return manufacturer; }
            set { manufacturer = value; }
        }

        public double? Price
        {
            get { return price; }
            set { price = value; }
        }

        public string Owner
        {
            get { return owner; }
            set { owner = value; }
        }

        Battery newBattery = new Battery("Li-Ion 3100 mAh", 980, 35, BatteryType.LiIon);
        Display newDisplay = new Display(5.55, 16000000);

        public void Print()
        {
            Console.WriteLine("===================");
            Console.WriteLine("GSM characteristics");
            Console.WriteLine("===================");
            Console.WriteLine("Model: {0}", this.Model);
            Console.WriteLine("-------------------");
            Console.WriteLine("Manufacturer: {0}", this.Manufacturer);
            Console.WriteLine("-------------------");
            Console.WriteLine("Price: {0} lv.", this.Price);
            Console.WriteLine("-------------------");
            Console.WriteLine("Owner: {0}", this.Owner);
            Console.WriteLine("===================");
        }

        public override string ToString()
        {
            StringBuilder sb = new StringBuilder();

            sb.AppendLine("Model: " + this.Model);
            sb.AppendLine("Manufacturer: " + this.Manufacturer);
            sb.AppendLine("Price: " + this.Price + "lv");
            sb.AppendLine("Owner: " + this.Owner);
            sb.AppendLine("Battery model: " + newBattery.Model);
            sb.AppendLine("Battery type: " + newBattery.Type);
            sb.AppendLine("Hours idle: " + newBattery.HoursIdle);
            sb.AppendLine("Hours talk: " + newBattery.HoursTalk);
            sb.AppendLine("Display size: " + newDisplay.Size);
            sb.AppendLine("Display colors: " + newDisplay.NumberOfColors);

            return sb.ToString();
        }
    }

    class Battery
    {
        private string model;
        private double hoursIdle;
        private double hoursTalk;
        private BatteryType type;


        public Battery(string model)
        {
            this.Model = model;
        }

        public Battery(string model, double hoursIdle, double hoursTalk)
            : this(model)
        {
            this.HoursIdle = hoursIdle;
            this.HoursTalk = hoursTalk;
        }

        public Battery(string model, double hoursIdle, double hoursTalk, BatteryType type)
            : this(model, hoursIdle, hoursTalk)
        {
            this.Type = type;
        }

        public string Model
        {
            get { return model; }
            set { model = value; }
        }

        public double HoursIdle
        {
            get { return hoursIdle; }
            set { hoursIdle = value; }
        }

        public double HoursTalk
        {
            get { return hoursTalk; }
            set { hoursTalk = value; }
        }

        public BatteryType Type
        {
            get { return type; }
            set { type = value; }
        }

        public void Print()
        {
            Console.WriteLine("=======================");
            Console.WriteLine("Battery characteristics");
            Console.WriteLine("=======================");
            Console.WriteLine("Model: {0}", this.Model);
            Console.WriteLine("-----------------------");
            Console.WriteLine("Hours idle: {0} h", this.HoursIdle);
            Console.WriteLine("-----------------------");
            Console.WriteLine("Hours talk: {0} h", this.HoursTalk);
            Console.WriteLine("-----------------------");
            Console.WriteLine("Battery type: {0}", this.Type);
            Console.WriteLine("========================");
        }
    }

    class Display
    {
        private double size;
        private int numberOfColors;

        public Display(double size)
        {
            this.Size = size;
        }

        public Display(double size, int numberOfColors)
            : this(size)
        {
            this.NumberOfColors = numberOfColors;
        }

        public double Size
        {
            get { return size; }
            set { size = value; }
        }

        public int NumberOfColors
        {
            get { return numberOfColors; }
            set { numberOfColors = value; }
        }

        public void Print()
        {
            Console.WriteLine("=======================");
            Console.WriteLine("Display characteristics");
            Console.WriteLine("=======================");
            Console.WriteLine("Size: {0}", this.Size);
            Console.WriteLine("-----------------------");
            Console.WriteLine("Number of colors: {0}", this.NumberOfColors);
            Console.WriteLine("========================");
        }
    }
}