P8_AnonymousThreat*_Lists_Ex

package feb20_Lists_Exercises;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Scanner;
import java.util.stream.Collectors;

public class P8_AnonymousThreat {
    public static void main(String[] args) {
        @SuppressWarnings("resource")

        Scanner sc = new Scanner(System.in);

        List<String> elements = Arrays.stream(sc.nextLine().split("\\s+")).collect(Collectors.toList());

        String input = "";

        while (!"3:1".equals(input = sc.nextLine())) {
            String[] data = input.split("\\s+");
            String command = data[0];

            switch (command) {
            case "merge":
                int startIndex = Integer.parseInt(data[1]);
                int endIndex = Integer.parseInt(data[2]);
                startIndex = validateIndex(startIndex, elements.size());
                endIndex = validateIndex(endIndex, elements.size());
                String concatElements = String.join("", elements.subList(startIndex, endIndex + 1));
                elements.subList(startIndex, endIndex + 1).clear();
                elements.add(startIndex, concatElements);
                break;
            case "divide":
                int index = Integer.parseInt(data[1]);
                int partitions = Integer.parseInt(data[2]);

                List<String> result = dividedEquality(elements.get(index), partitions);
                elements.remove(index);
                elements.addAll(index, result);
                break;
            }
        }

        System.out.println(String.join(" ", elements));
    }

    private static List<String> dividedEquality(String element, int partitions) {
        int part = element.length() / partitions;
        List<String> result = new ArrayList<>();

        while (element.length() >= part) {
            result.add(element.substring(0, part));
            element = element.substring(part);
        }

        if (result.size() == partitions) {
            return result;
        } else {
            String concatLastTwoElements = result.get(result.size() - 2).concat(result.get(result.size() - 1));
            result.subList(result.size() - 2, (result.size())).clear();;
            result.add(concatLastTwoElements);
            return result;
        }
    }

    public static int validateIndex(int index, int lenght) {
        if (index < 0) {
            index = 0;
        } else if (index > lenght - 1) {
            index = lenght - 1;
        }
        return index;
    }
}