State Design Patterns in C#

State Design Patterns - Behavioral Patterns in  C#

State: Allows an object to change its behavior when its internal state changes.

class Program
    {
        static void Main(string[] args)
        {
            Account account = new Account("paramesh");
            account.Deposite(500.0);

            account.Deposite(500.0);
            account.Deposite(300.0);
            account.Deposite(550.0);
            account.PayInterest();
            account.Withdraw(2000.00);
            account.Withdraw(1100.00);

            // Wait for user
            Console.ReadKey();
        }
    }
    abstract class State
    {
        protected Account account;
        protected double balance;

        protected double interest;
        protected double lowerLimit;
        protected double upperLimit;

        public Account Account
        {
            get { return account; }
            set { account = value; }
        }
        public double Balance
        {
            get { return balance; }
            set { balance = value; }
        }

        public abstract void Deposit(double amount);
        public abstract void Withdraw(double amount);
        public abstract void PayInterest();
    }
    class RedState : State
    {
        private double _serviceFee;
        public RedState(State state)
        {
            this.balance = state.Balance;
            this.account = state.Account;
            Initialize();
        }

        private void Initialize()
        {
            interest = 0.0;
            lowerLimit = -100.0;
            upperLimit = 0.0;
            _serviceFee = 15.00;
        }
        public override void Deposit(double amount)
        {
            balance += amount;
            StateChageCheck();
        }

        private void StateChageCheck()
        {
            if (balance > upperLimit)
            {
                account.State = new SilverState(this);
            }
        }

        public override void Withdraw(double amount)
        {
            amount = amount - _serviceFee;
            Console.WriteLine("No funds available for withdrawal!");
        }

        public override void PayInterest()
        {
            //
        }
    }
    class SilverState : State
    {
        public SilverState(State state) : this(state.Balance, state.Account) { }
        public SilverState(double balance, Account account)
        {
            this.balance = balance;
            this.account = account;
            Initialize();
        }

        private void Initialize()
        {
            interest = 0.0;
            lowerLimit = 0.0;
            upperLimit = 1000.0;
        }
        public override void Deposit(double amount)
        {
            balance += amount;
            StateChangeCheck();
        }

        private void StateChangeCheck()
        {
            if (balance < lowerLimit)
                account.State = new RedState(this);
            else if (balance > upperLimit)
                account.State = new GoldState(this);
        }

        public override void Withdraw(double amount)
        {
            balance -= amount;
            StateChangeCheck();
        }

        public override void PayInterest()
        {
            balance += interest * balance;
            StateChangeCheck();
        }
    }
    class GoldState : State
    {
        public GoldState(State state) : this(state.Balance, state.Account) { }
        public GoldState(double balance, Account account)
        {
            this.balance = balance;
            this.account = account;
            Initialize();
        }

        private void Initialize()
        {
            interest = 0.05;
            lowerLimit = 1000.0;
            upperLimit = 1000000.0;
        }
        public override void Deposit(double amount)
        {
            balance += amount;
            StateChangeCheck();
        }

        private void StateChangeCheck()
        {
            if (balance < 0.0)
                account.State = new RedState(this);
            else if (balance < lowerLimit)
                account.State = new SilverState(this);
        }

        public override void Withdraw(double amount)
        {
            balance -= amount;
            StateChangeCheck();
        }

        public override void PayInterest()
        {
            balance += interest * balance;
            StateChangeCheck();
        }
    }



    class Account
    {
        private State _state;
        private string _owner;

        public Account(string owner)
        {
            this._owner = owner;
            this._state = new SilverState(0.0, this);
        }
        public double Balance
        {
            get { return _state.Balance; }
        }
        public State State
        {
            get { return _state; }
            set { _state = value; }
        }
        public void Deposite(double amount)
        {
            _state.Deposit(amount);
            Console.WriteLine("Deposited {0:C}", amount);
            Console.WriteLine("Balance={0:C}", this.Balance);
            Console.WriteLine("Status={0}", this.State.GetType().Name);
            Console.WriteLine("");
        }
        public void Withdraw(double amount)
        {
            _state.Withdraw(amount);
            Console.WriteLine("Withdres {0:C}", amount);
            Console.WriteLine("Balance={0:C}", this.Balance);
            Console.WriteLine("Status={0}\n", this.State.GetType().Name);
        }
        public void PayInterest()
        {
            _state.PayInterest();
            Console.WriteLine("Interest Paid..");
            Console.WriteLine("Balance ={0:C}", this.Balance);
            Console.WriteLine("State={0}\n", this.State.GetType().Name);

        }

    }