package de.janchristiangruenhage.math.multiplication;

import java.util.LinkedList;

/**
 * The class <tt>LongMultiplication</tt> represents a Multiplication of two factors,
 * one very very large one (basically limitless)
 * and a relatively large one (more than about 25 digits make the calculation pretty confusing)
 */
public class LongMultiplication {
    private String factorOne;
    private String factorTwo;
    private int splitInLine;
    private int splitLines;

    /**
     * @param factorOne   First Factor
     * @param factorTwo   Second Factor
     * @param splitInLine How many digits of the first Factor will be used per multiplication
     * @param splitLines  How many lines of the multiplication will be added in one addition,
     *                    If != 0 and smaller than the number of digits in the second factor,
     *                    there will be multiple Additions per Multiplication.
     */
    public LongMultiplication(String factorOne, String factorTwo, int splitInLine, int splitLines) {
        this.factorOne = factorOne;
        this.factorTwo = factorTwo;
        this.splitInLine = splitInLine;
        this.splitLines = splitLines;
    }

    /**
     * Creates and easily readable Multiplication and returns it.
     *
     * @return String representation of the Calculation
     */
    public String printCalculation() {
        LinkedList<Multiplication> multiplications = new LinkedList<>();
        //Constructing new List for Multiplications
        while (factorOne.length() > splitInLine && splitInLine != 0) {
            String splitFactorString = factorOne.substring(factorOne.length() - splitInLine);
            factorOne = factorOne.substring(0, factorOne.length() - splitInLine);
            //Cutting String for Multiplication Parts
            multiplications.add(new Multiplication(splitFactorString, factorTwo, splitLines, false));
            //Constructing new Multiplication and adding it to the List
        }
        multiplications.add(new Multiplication(factorOne, factorTwo, splitLines, true));
        //Constructing last new Multiplication and adding i to the List
        String retVal = "";
        //Initialising the retVal String, which will be returned
        for (int i = 0; i < multiplications.size(); i++) {
            retVal = multiplications.get(i).printCalculation() + retVal;
            //"Printing" the Multiplication, adding it to the retVal String
            if (i < multiplications.size() - 1) {
                //This is needed to avoid a index out of bounds exception since the next line always uses the following multiplication too
                multiplications.get(i + 1).setCarry(multiplications.get(i).getResultCarry());
                //Calculating the Carry for the following Multiplication
            }
        }
        return retVal;
    }


}