package rational;

import java.util.regex.*;

class RatNum {

	// Variabler.

	// Täljare.
	private int teljare;
	// Nämnare.
	private int nemnare;

	// Constructors
	public RatNum() {
		sätt(0);
	}

	public RatNum(int a) {
		sätt(a);
	}

	public RatNum(int a, int b) {
		sätt(a, b);
	}

	public RatNum(RatNum r) { // Kopieringskonstruktorn
		sätt(r);
	}

	public RatNum(String text) {
		/* Om text innehåller en text som på ett korrekt sätt beskriver ett rat numb
		 * ska det nya talet initieras, annars NumberFormatException.
		 * Använd parse metoden och kopieringskonstruktorn
		 */
	}


	public int getNumerator() {
		return teljare;
	}

	public int getDenominator() {
		return nemnare;
	}


	public void sätt(int a, int b) {

		if (b == 0) {

			throw new NumberFormatException("Nämnare = 0");

		}


		if (a == 0) {

			teljare = 0;

			nemnare = b;
		}

		else {



			int numerator, denominator;

			denominator = Math.abs(b);



			if (a > 0 && b > 0 || a < 0 && b < 0) {
				numerator = Math.abs(a);
			}

			else {
				numerator = a < 0 ? a : a * -1;
			}


			int divisor = sgd(Math.abs(a), Math.abs(b));

			if (divisor == 1) {

				teljare = numerator;

				nemnare = denominator;
			} else {

				teljare = numerator / divisor;

				nemnare = denominator / divisor;
			}
		}

	}


	public void sätt(int a) {

		teljare = a;

		nemnare = 1;
	}


	public void sätt(RatNum r) {

		this.teljare = r.getNumerator();

		this.nemnare = r.getDenominator();
	}


	public static int sgd(int one, int two) {

		int r, m, n;

		m = Math.abs(one);

		n = Math.abs(two);

		if(m == 0 || n == 0)
			throw new IllegalArgumentException();

		r = m % n;

		if (r == 0) {
			return n;
		} else {
			return sgd(n, r);
		}
	}

	public String toString() {

		return (Integer.toString(teljare) + "/" + Integer.toString(nemnare));

	}


	public static RatNum parse(String s) {

		Pattern p = Pattern.compile("^(-?\\d+)(\\/(-?[1-9]{1}\\d*))?$");

		Matcher m = p.matcher(s);

		while (m.find()) {

			int a, b = 1;

			a = Integer.valueOf(m.group(1));

			if (m.group(3) != null) {

				b = Integer.valueOf(m.group(3));
			}

			return new RatNum(a, b);
		}

		return null;
	}

	public Object clone() {

		RatNum rat = new RatNum(this.getNumerator(), this.getDenominator());

		return (Object) rat;
	}


	public boolean equals(RatNum r) {

		return r.toString().equals(this.toString());

	}

	public boolean lessThan(RatNum r) {

		int n1, n2;


		if (this.getDenominator() != r.getDenominator()) {

			n1 = this.getNumerator() * r.getDenominator();

			n2 = r.getNumerator() * this.getDenominator();

		} else {

			n1 = this.getNumerator();

			n2 = r.getNumerator();

		}

		return n1 < n2;

	}

	public RatNum add(RatNum r) {

		return new RatNum(this.getNumerator() * this.getDenominator() + r.getNumerator() * r.getDenominator(), r.getNumerator() * this.getDenominator());
	}

	public RatNum sub(RatNum r) {

		return new RatNum(this.getNumerator() * this.getDenominator() - r.getNumerator() * r.getDenominator(), r.getNumerator()	 * this.getDenominator());
	}

	public RatNum mul(RatNum r) {


		return new RatNum(this.getNumerator() * r.getNumerator(), r.getDenominator() * this.getDenominator());
	}

	public RatNum div(RatNum r) {

		return new RatNum(this.getNumerator() * this.getDenominator(), r.getDenominator() * r.getNumerator());
	}

	public double toDouble() {
		return (double) teljare / nemnare;
	}

}