/*
 * Eric Liu
 * Mr. Peterson
 * APCS Period 3
 * 15 December 2017
 */

public class Fraction {
    private int denominator;
    private int numerator;
    public Fraction() {
        numerator = 1;
        denominator = 0;
    }
    public Fraction(String input) {
        int slash = 0;
        int neg = 1;
        String blah = "+-";

        if(input.charAt(0) == blah.charAt(0) ||input.charAt(0) == blah.charAt(1)) {
            if(input.charAt(0) == blah.charAt(1)) {
                neg = -1;
            }
            input = input.substring(1);
        }
        for(int i = 0; i <= input.length() - 1; i++) {
            if(input.charAt(i) == '/') {
                break;
            }
            slash++;
        }
        numerator = Integer.parseInt(input.substring(0, slash));
        denominator = Integer.parseInt(input.substring(slash + 1));
        numerator *= neg;

        reduce();
    }
    public Fraction(int num) {
        numerator = num;
        denominator = 1;
    }
    public Fraction(int num, int denom) {
        numerator = (denom < 0 ? -num : num);
        if(denominator == 0) {

        }
        denominator = (denom < 0 ? -denom : denom);
        reduce();
    }
    public void setNumerator(int num) {
        numerator = num;
        reduce();
    }
    public int getNumerator() {
        return numerator;
    }
    public void setDenominator(int denom) {
        if(denom > 0) {
            denominator = denom;
            reduce();
        }
        else if(denom < 0) {
            numerator = -numerator;
            denominator = -denom;
            reduce();
        }
    }
    public int getDenominator() {
        return denominator;
    }

    public Fraction add(Fraction f) {
        f.reduce();
        Fraction sum = new Fraction();
        sum.denominator = denominator * f.denominator;
        sum.numerator =  (numerator * f.denominator + denominator * f.numerator);
        sum.reduce();
        return sum;
    }
    public Fraction subtract(Fraction f) {
        f.reduce();
        Fraction result = new Fraction();
        result.numerator = numerator * f.denominator - f.numerator * denominator;
        result.denominator = denominator * f.denominator;
        result.reduce();
        return result;
    }
    public Fraction multiply(Fraction f) {
        f.reduce();
        Fraction result = new Fraction();
        result.numerator = numerator * f.numerator;
        result.denominator = denominator * f.denominator;
        result.reduce();
        return result;
    }
    public Fraction divide(Fraction f) {
        f.reduce();
        Fraction result = new Fraction();
        if(f.numerator == 0) {
            throw new IllegalArgumentException("Cannot divide by 0");
        }
        result.numerator = numerator * f.denominator;
        result.denominator = denominator * f.numerator;
        result.reduce();
        if(result.denominator < 0 && result.numerator < 0) {
            result.denominator *= -1;
            result.numerator *= -1;
        }
        return result;
    }
    public String toString() {
        if(numerator == 0) {
            return "0";
        }
        else if(denominator == 1) {
            return "" + numerator;
        }
        return numerator + "/" + denominator;
    }
    public String toMixedNumberString() {
        int wholeNum = 0;
        if(numerator > denominator) {
            wholeNum = numerator / denominator;
            numerator -= denominator * wholeNum;
            if(numerator == 0) {
                return "" + wholeNum;
            }
            return "" + wholeNum + "_" + numerator + "/" + denominator;
        }
        else if((numerator*-1) > denominator && numerator < 0) {
            numerator *= -1;
            if(denominator < 0) {
                denominator *= -1;
            }
            wholeNum = numerator / denominator;
            numerator -= denominator * wholeNum;
            if(numerator == 0) {
                return "-" + wholeNum;
            }
            return "-" + wholeNum + "_" + numerator + "/" + denominator;
        }
        if(denominator == 1)return numerator + "";
        return numerator + "/" + denominator;
    }
    public int compareTo(Fraction f) {
        int n = numerator * f.denominator;
        int newn = f.numerator * denominator;
        return n - newn;
    }
    private void reduce() {
        int n = numerator, d = denominator, largest;
        if(numerator < 0) {
            n = -numerator;
        }
        if(n > d) {
            largest = n;
        }
        else {
            largest = d;
        }
        int gcd = 0;
        for(int i = largest; i >= 2; i--) {
            if(numerator % i == 0 && denominator % i == 0) {
                gcd = i;
                break;
            }
        }
        if(gcd != 0) {
            numerator /= gcd;
            denominator /= gcd;
        }

        if(denominator < 0){
            denominator *= -1;
            numerator *= -1;
        }
    }
}