package edu.neu.ccs.satsolver;

import java.util.*;
import java.io.*;

public class SATSolverUtil 
{

	public static OutputI calculateBias(InputInitialI ii)
	{

		// Return something
		// getInitialCalc( ii.getPairs() );
		return getInitialCalc( ii.getPairs() );
		
	}	
	public static OutputI updateBias(InputUpdateI ui)
	{
		// Return Something
		return getUpdateCalc(ui);
	}

	/* getInitialCalc : takes in a Set of pairs from the Input Object
	 * 		    created by the Undergraduates and returns
	 * 		    Output object with the MaxBias and Polynomial
	 */
	private static OutputI getInitialCalc(java.util.Set pairs)
	{
		// make the set into an array so we can iterate over it
		Object[] ps = pairs.toArray();

		// create a polynomial object with zero values for 
		// all of its coefficients
		double[] baseValues = {0,0,0,0};
		Polynomial appmean_x = new Polynomial(baseValues);
	       
		// iterate through all of the pairs given 
		// For each pair : 1. get its polynomial (tempP) 
		// 		   2. multiply tempP by the pair's fractional weight
		// 		   3. add the tempP to appmean_x
		for(int i = 0; i < ps.length; i++)
		{
			PairI p = (PairI)ps[i];
			Polynomial tempP = appSat.getPolynomial(p.getRelationNumber());
			appmean_x  = appmean_x.addPolynomials(tempP.multiplyBy(p.getFraction()));
		}
		
		// Take the derivative of the appmean_x(S) polynomial
		double max = appmean_x.findMax();

		return new Output(max, appmean_x);
	}	

	/* getUpdateCalc : takes in an inputUpdate object and returns the new max from
	 * 		   the added and subtracted polynomials.
	 */
	private static OutputI getUpdateCalc( InputUpdateI iu )
	{
		// Pull out all the data structures hidden in the
		// InputUpdate Object
		PolynomialI oldPoly = (PolynomialI)iu.getPolynomialBefore();
		double[] oldCoeffs = { oldPoly.getCoefficient(0), oldPoly.getCoefficient(1), oldPoly.getCoefficient(2), oldPoly.getCoefficient(3) };

		Object[] aps = iu.getAddedPairs().toArray();
		Object[] sps = iu.getSubtractedPairs().toArray();
		
		// create a polynomial object with zero values for 
		// all of its coefficients
		Polynomial appmean_x = new Polynomial(oldCoeffs);
		
		// iterate through all of the pairs given 
		// For each pair : 1. get its polynomial (tempP) 
		// 		   2. multiply tempP by the pair's fractional weight
		// 		   3. add the tempP to appmean_x
		for(int i = 0; i < aps.length; i++)
		{
			PairI p = (PairI)aps[i];
			Polynomial tempP = appSat.getPolynomial(p.getRelationNumber());
			appmean_x  = appmean_x.addPolynomials(tempP.multiplyBy(p.getFraction()));
		}
		
		// iterate through all of the pairs given 
		// For each pair : 1. get its polynomial (tempP) 
		// 		   2. multiply tempP by the pair's fractional weight
		// 		   3. subtract the tempP to appmean_x
		for(int i = 0; i < sps.length; i++)
		{
			PairI p = (PairI)sps[i];
			Polynomial tempP = appSat.getPolynomial(p.getRelationNumber());
			appmean_x  = appmean_x.subtractPolynomials(tempP.multiplyBy(p.getFraction()));
		}
			
		// Take the derivative of the appmean_x(S) polynomial
		double max = appmean_x.findMax();

		return new Output(max, appmean_x);
		
	}

	

}