/*
 * (c) Copyright Christian P. Fries, Germany. All rights reserved. Contact: email@christianfries.com.
 *
 * Created on 14.06.2013
 */

package net.finmath.montecarlo.interestrate.products;

import net.finmath.exception.CalculationException;
import net.finmath.montecarlo.RandomVariable;
import net.finmath.montecarlo.interestrate.LIBORModelMonteCarloSimulationInterface;
import net.finmath.stochastic.RandomVariableInterface;

/**
 * Implements the valuation of a money market account. The money market account
 * is characterized by its inception time t0 and its accrual period
 * Δ t. 

 * 
 * With ti := t0 + i Δ t
 * the money market account value N(t0) = 1 and
 * N(t) = N(ti) (1 + L(ti,ti+1;ti) (t - ti)).
 * for ti < t < ti+1. 

 * 
 * The value of the account at inception is 1.0. The value of the account prior to inception is zero.
 * 
 * @author Christian Fries
 */
public class MoneyMarketAccount extends AbstractLIBORMonteCarloProduct {

	private double inceptionTime	= 0.0;
	private double initialValue		= 1.0;
	private double accrualPeriod	= -1.0;		// Accrual period, if this period is < 0, then the finest model LIBOR period discretization is used

	/**
	 * Create a money market account.
	 * 
	 * @param inceptionTime The inception time. The value of the account at inception is 1.0. The value of the account prior to inception is zero.
	 * @param initialValue The initial value, i.e., the value at inception time.
	 * @param accrualPeriod The accrual period. If this period is < 0, then the finest model LIBOR period discretization is used
	 */
	public MoneyMarketAccount(double inceptionTime, double initialValue, double accrualPeriod) {
		super();
		this.inceptionTime	= inceptionTime;
		this.initialValue	= initialValue;
		this.accrualPeriod	= accrualPeriod;
	}

	/**
	 * Create a money market account.
	 * 
	 * @param inceptionTime The inception time. The value of the account at inception is 1.0. The value of the account prior to inception is zero.
	 * @param accrualPeriod The accrual period. If this period is < 0, then the finest model LIBOR period discretization is used
	 */
	public MoneyMarketAccount(double inceptionTime, double accrualPeriod) {
		this(inceptionTime, 1.0, accrualPeriod);
	}
	
	/**
	 * Create a default money market account. The money market account will use the
	 * models tenor discretization as the accrual period and its inception time is 0.
	 */
	public MoneyMarketAccount() {
		this(0.0, 1.0, -1.0);
	}

	/* (non-Javadoc)
	 * @see net.finmath.montecarlo.interestrate.products.AbstractLIBORMonteCarloProduct#getValue(double, net.finmath.montecarlo.interestrate.LIBORModelMonteCarloSimulationInterface)
	 */
	@Override
	public RandomVariableInterface getValue(double evaluationTime, LIBORModelMonteCarloSimulationInterface model) throws CalculationException {

		if(inceptionTime > evaluationTime) return new RandomVariable(0.0);
		if(accrualPeriod <= 0) return new RandomVariable(Double.MAX_VALUE);
		
		// Initialize the value of the account to 1.0
		RandomVariableInterface value = new RandomVariable(initialValue);

		// Loop over accrual periods
		for(double time=inceptionTime; time