//Name: Matthew Nguyen
//Date: 11/18/19
//Purpose: Do stuff with fractions like add, sub, multiply or divide them

public class Fraction
{
    private int num; //Makes instance variable num
    private int denom;//Makes instance variable denom
    private Fraction answer; //Makes instance variable answer

    public Fraction(int n, int d)
    {
      num = n; //Sets n equal to num
      denom = d;//Sets d equal to denom

    }

    public String toString() //toString to print out the objects

    {
        String fraction;
        if(denom == 0)//Undefined checker
        {
            fraction = "undefined";
        }
        else if(num == 0)//Checks if numerator is 0
        {
            fraction = "0";
        }
        else if(denom == 1)//Checks if denominator is 1
        {
            fraction = ""+num;
        }
        else if(denom == -1 && num<0){
            fraction = ""+(-1*num);
        }
        else if(num < 0 && denom < 0)//check if both parts of fraction are negative
        {
            fraction = ""+(-1*num)+"/"+(-1*denom);
        }
        else
        {
            fraction = ""+num+"/"+denom;
        }
        return fraction;
    }



    public int getNum()
    {
        return num;//returns int num when called
    }



    public int getDen()
    {
        return denom;//returns int denom when called
    }



   public boolean equals(Object other)
   {

            Fraction temp = (Fraction) other; //Temp fraction to test if the things are equal
            int otherNum = temp.getNum(); //temp num and denominator to testif they are equal
            int otherDenom = temp.getDen();
            if((num*otherDenom) == (otherNum*denom))//cross multiply and if both sides are equal, then the fractions are equal
            {
                return true;
            }
            else//if they are not equal, a false is returned
            {
             return false;
            }

        }


    private Fraction reduce()

    {
        int answerNum;
        int answerDenom;
        int gcf = 1;
        for(int i = 1;i<=Math.min(Math.abs(num),Math.abs(denom));i++)
        {
            if((num%i==0) && (denom%i==0))
            {
                gcf = i;
            }
        }
        answerNum = getNum()/gcf;
        answerDenom= getDen()/gcf;
        Fraction reduced = new Fraction(answerNum, answerDenom);
        return reduced;
    }

    public static Fraction reduced(Fraction reduced)
    {
        return reduced.reduce();
    }



    public Fraction add(Fraction other)//method to add fractions
    {
        Fraction answer;
        int n = this.getNum()*other.getDen()+other.getNum()*this.getDen();//Function to produce numerator in instance of addition
        int d = this.getDen()*other.getDen(); //Function to produce denominator
        answer = new Fraction(n,d); //Creates a fraction with the new numerator and denominator when two fracs are added


        return reduced(answer); //Returns new fraction


    }

    public Fraction sub(Fraction other)//method to subtract fractions
    {
        Fraction answer;
        int n = this.getNum()*other.getDen()-other.getNum()*this.getDen(); //Function to produce numerator in instance of subtraction
        int d = this.getDen()*other.getDen(); //Function to produce denominator
        answer = new Fraction(n,d); //Creates a fraction with the new numerator and denominator when two fracs are subtracted

        return reduced(answer); //Returns new fraction

    }

    public Fraction mult(Fraction other)//method to multiply fractions
    {
        Fraction answer;
        int n = this.getNum()*other.getNum();
        int d = this.getDen()*other.getDen();
        answer = new Fraction (n,d);

        return reduced(answer); //Returns new fraction
    }

    public Fraction div(Fraction other)//method to divide fractions
    {
        int n = this.getNum()*other.getDen();
        int d = this.getDen()*other.getNum();
        Fraction answer;
        answer = new Fraction (n,d);
        Fraction undefined;
        undefined = new Fraction (0,0);

        if(d==0)
        {
        return undefined;
        }
        else
        {
        return reduced(answer); //Returns new fraction
        }
    }
}