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package org.psjava.ds.numbersystrem;

import java.util.Comparator;

import org.psjava.algo.math.numbertheory.GCD;

public class FractionNumberSystem implements DivisableNumberSystem>, Comparator> {

	public static  FractionNumberSystem newInstance(IntegerDivisableNumberSystem subSystem) {
		return new FractionNumberSystem(subSystem);
	}

	private final IntegerDivisableNumberSystem ns;

	private FractionNumberSystem(IntegerDivisableNumberSystem subSystem) {
		this.ns = subSystem;
	}

	@Override
	public Fraction getOne() {
		return Fraction.valueOf(ns.getOne(), ns.getOne());
	}

	@Override
	public Fraction getZero() {
		return Fraction.valueOf(ns.getZero(), ns.getOne());
	}

	@Override
	public Fraction getByInt(int v) {
		return Fraction.valueOf(ns.getByInt(v), ns.getOne());
	}

	@Override
	public Fraction add(Fraction v1, Fraction v2) {
		T num = ns.add(ns.multiply(v1.numerator, v2.denominator), ns.multiply(v2.numerator, v1.denominator));
		T denom = ns.multiply(v1.denominator, v2.denominator);
		return reduce(num, denom);
	}

	@Override
	public Fraction subtract(Fraction minuend, Fraction subtrahend) {
		T num = ns.subtract(ns.multiply(minuend.numerator, subtrahend.denominator), ns.multiply(subtrahend.numerator, minuend.denominator));
		T denom = ns.multiply(minuend.denominator, subtrahend.denominator);
		return reduce(num, denom);
	}

	@Override
	public Fraction multiply(Fraction v1, Fraction v2) {
		T num = ns.multiply(v1.numerator, v2.numerator);
		T denom = ns.multiply(v1.denominator, v2.denominator);
		return reduce(num, denom);
	}

	@Override
	public boolean areEqual(Fraction o1, Fraction o2) {
		T t1 = ns.multiply(o1.numerator, o2.denominator);
		T t2 = ns.multiply(o2.numerator, o1.denominator);
		return ns.areEqual(t1, t2);
	}

	@Override
	public Fraction divide(Fraction dividend, Fraction divisor) {
		T num = ns.multiply(dividend.numerator, divisor.denominator);
		T denom = ns.multiply(dividend.denominator, divisor.numerator);
		return reduce(num, denom);
	}

	@Override
	public int getSign(Fraction v) {
		return ns.getSign(v.numerator) * ns.getSign(v.denominator);
	}

	@Override
	public boolean isNegative(Fraction v) {
		return getSign(v) < 0;
	}

	@Override
	public boolean isOne(Fraction v) {
		return ns.areEqual(v.numerator, v.denominator);
	}

	@Override
	public boolean isPositive(Fraction v) {
		return getSign(v) > 0;
	}

	@Override
	public boolean isZero(Fraction v) {
		return ns.isZero(v.numerator);
	}

	@Override
	public int compare(Fraction o1, Fraction o2) {
		o1 = reduce(o1);
		o2 = reduce(o2);
		T v1 = ns.multiply(o1.numerator, o2.denominator);
		T v2 = ns.multiply(o2.numerator, o1.denominator);
		return ns.compare(v1, v2);
	}

	public Fraction reduce(Fraction v) {
		return reduce(v.numerator, v.denominator);
	}

	private Fraction reduce(T num, T denom) {
		if (ns.isNegative(denom)) {
			num = AddInvert.calc(ns, num);
			denom = AddInvert.calc(ns, denom);
		}
		T gcd = GCD.gcd(ns, num, denom);
		num = ns.integerDivide(num, gcd);
		denom = ns.integerDivide(denom, gcd);
		return Fraction.valueOf(num, denom);
	}

}