//
//	bank teller simulation routine
//
//	Described in Chapter 10 of
//	Data Structures in C++ using the STL
//	Published by Addison-Wesley, 1997
//	Written by Tim Budd, budd@cs.orst.edu
//	Oregon State University
//

# include <list.h>
# include <vector.h>
# include <stack.h>
# include <string>

//
//	class Customer
//		a single customer waiting in the bank teller line

class randomInteger {
	public:
		unsigned int operator () (unsigned int);
};

unsigned int randomInteger::operator () (unsigned int max)
{
		// rand return random integer
		// convert to unsigned to make positive
		// take remainder to put in range
	unsigned int rval = rand();
	return rval % max;
}

randomInteger randomizer;

class Customer {
public:
		// constructors
	Customer (int at) : arrivalTime(at), 
			processTime(2 + randomizer(6)) {}
	Customer () : arrivalTime(0), processTime(0) { }
	
		// operations
	bool done    () { return --processTime < 0; }
	int  arrival () { return arrivalTime; }

	operator < (Customer & c)	// order by arrival time
		{ return arrivalTime < c.arrivalTime; }
		
	operator == (Customer & c)	// no two customers are alike
		{ return false; }
		
protected:
	unsigned int arrivalTime;
	unsigned int processTime;
};

//
//	class Teller
//		a teller servicing customers in a bank teller line

class Teller {
public:
	Teller() { free = true; }
	
	bool isFree()	// see if teller is free to work
	{ 
		if (free) return true;
		if (customer.done())
		  	free = true;
		  return free;
	}

	void addCustomer(Customer & c) // start servicing customer
	{
		customer = c;
		free = false;
	}

protected:
	bool free;
	Customer customer;
};

void main() {
	int numberOfTellers = 5;
	int numberOfMinutes = 60;
	double totalWait = 0;
	int numberOfCustomers = 0;
	vector < Teller > teller(numberOfTellers);
	queue < list< Customer > > line;
	
	for (int time = 0; time < numberOfMinutes; time++) {
		if (randomizer(10) < 9) {
			Customer newCustomer(time);
			line.push(newCustomer);
			}
		for (int i = 0; i < numberOfTellers; i++) {
			if (teller[i].isFree() & ! line.empty()) {
				Customer frontCustomer = line.front();
				numberOfCustomers++;
				totalWait += (time - frontCustomer.arrival());
				teller[i].addCustomer(frontCustomer);
				line.pop();
				}
			}
		}
	cout << "average wait:" <<   (totalWait / numberOfCustomers) << endl;
}