/***********************************************
 *  CS2510 Fall 2011 
 *  Lecture #18_1
 *  ArrayList, While Loops, Traversal, Static
 ***********************************************/


// Get the ArrayList from the java libraries
import java.util.ArrayList;
import tester.*;

// Represents a Checking account (A group of them actually)
class Checking{
    // Number of checking accounts we've created
    static int numaccounts = 0;
    // A list of the accounts we've created
    static ArrayList<Checking> accounts = new ArrayList<Checking>();
    // The balance for an account
    double balance;
    
    // Sets the balance and adds to our global counters
    Checking(double balance) {
        this.balance = balance;
        numaccounts = numaccounts + 1;
        accounts.add(this);
    }
    
    // Returns the total number of accounts created
    static int getNumAccounts() {
        return numaccounts;
    }
    
    // Gets the sum of the balances of all accounts in the bank
    static double getBankBalance() {
        Traversal<Checking> travis = new Traversal<Checking>(accounts);
        double total = 0;
        while (! travis.isEmpty()) {
            total = total + travis.first().balance;
            travis.rest();
        }
        return total;
    }
    
    // Gets the sum of the balances of all accounts in the bank
    /*
    static double getBankBalance() {
        double total = 0;
        int index = 0;
        while (index < accounts.size()) {
            total = total + accounts.get(index).balance;
            index = index + 1;
        }
        return total;
    }
    */
    
}

// A class to Traverse a list (make an arraylist look like a linked list)
class Traversal<X> {
    int index;
    ArrayList<X> list;
    Traversal(ArrayList<X> list) {
        this.list = list;
        index=0;
    }

    Traversal(ArrayList<X> list, int index) {
        this.list = list;
        this.index = index;
    }
    
    // Give me the element at this position in the traversal
    X first() {
        return list.get(index);
    }
    /*
    Traversal<X> rest() {
        return new Traversal<X>(list,index + 1);
    }
    */
    
    // Go to the next element
    void rest() {
        index = index + 1;
    }
    
    // Are we at the end of our list?
    boolean isEmpty() {
        return index >= list.size();
    }
}


// Some examples of checking accounts
class BankExamples {
    Checking c1 = new Checking(20.0);
    Checking c2 = new Checking(25.0);
    Checking c3 = new Checking(10.0);
    
    // Tests of our static methods
    void testChecking(Tester t) {
        t.checkExpect(Checking.numaccounts,3);
        t.checkExpect(Checking.getBankBalance(),55.0);
    }
}