import static org.junit.jupiter.api.Assertions.*;

import org.junit.jupiter.api.DisplayName;
import org.junit.jupiter.api.RepeatedTest;
import org.junit.jupiter.api.Tag;
import org.junit.jupiter.api.Test;

import java.util.Random;
import java.util.ArrayList;


class SolutionTest {
	@Test
	@Tag("BasicTest")
	void BasicTest() {

		String[] reverseLeterHello = { "lello", "hollo", "hehlo", "heleo", "helll" };
		String[] reverseLeterBye = { "eye", "bbe", "byy" };

		String[] reverseLeterThanks = { "Thanks", "Thanks", "Thanks", "Thanks", "Thanks", "Thanks" };
    String[] reverseLetterHellowWorld = { "lello  world", "Hlllo  world", "Heolo  world", "Helwo  world",
				"Hello  world", "Hello  rorld", "Hello  wlrld", "Hello  wodld", "Hello  worHd", "Hello  worle" };
    String[] reverseLetterHellowWorldLong = {"   rello world  ","   hlllo world  ","   hedlo world  ","   helho world  ","   helle world  ","   hello lorld  ","   hello wlrld  ","   hello woold  ","   hello worwd  ","   hello worlo  "};
    
		assertArrayEquals(reverseLeterHello, Kata.replaceLetter("hello", 3));
		assertArrayEquals(reverseLeterThanks, Kata.replaceLetter("Thanks", 0));
    assertArrayEquals(reverseLetterHellowWorld, Kata.replaceLetter("Hello  world", 2));
    assertArrayEquals(reverseLetterHellowWorldLong, Kata.replaceLetter("   hello world  ", 7));
	}

	@Test
	@Tag("SpecialCase")
	void SpecialCase() {
		String[] reverseLeterVoid = {};
		assertArrayEquals(reverseLeterVoid, Kata.replaceLetter(" ", 2));
    assertArrayEquals(new String[] { "  a  " }, Kata.replaceLetter("  a  ", 1));
		assertArrayEquals(new String[] { "   bb   ", "   aa   " }, Kata.replaceLetter("   ab   ", 7));

	}
  

  @Tag("RandomTest")
	@RepeatedTest(10)
	@DisplayName("RandomWord")
	void RandomTest() {
		String word = generate(new Random().nextInt(15) + 1);
		int letterRandom = new Random().nextInt(word.length());
		assertArrayEquals(replaceLetter(word, letterRandom), Kata.replaceLetter(word, letterRandom));

	}
  
	public static String generate(int length) {

		String strChars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890     ^*¨_:;=?¿";
		StringBuilder sb = new StringBuilder();
    
		for (int i = 0; i < length; i++) {
			int nRandom = new Random().nextInt(strChars.length());
			sb.append(strChars.charAt(nRandom));
		}
		return sb.toString();
	}

  	public static String[] replaceLetter(String str, int n) {

		ArrayList<String> arr = new ArrayList<>();
		StringBuilder strFinal = new StringBuilder(str);
		int nextIndex = n - 1;
		int posSpaces = n;
		
		// Find first spaces
		for(int i =0; i<posSpaces; i++) if(str.charAt(i% str.length())==' ') {
			posSpaces++;
			nextIndex++;
		}
		
		// Iterate string 
		for (int i = 0; i < str.length(); i++) {
			nextIndex = (nextIndex + 1) % str.length();

			if (str.charAt(i) != ' ') {
				while (str.charAt(nextIndex) == ' ')  {
					nextIndex = (nextIndex + 1) % str.length();
				}

				// Replace letters
				strFinal.replace(i, i + 1, String.valueOf(str.charAt(nextIndex)));
				arr.add(strFinal.toString());
				// Reset string to add
				strFinal = new StringBuilder(str);
			} else{ // current index is white space
				nextIndex --;
			}

		}

		return arr.toArray(new String[arr.size()]);

	}
}

import static org.junit.jupiter.api.Assertions.*;

import org.junit.jupiter.api.DisplayName;
import org.junit.jupiter.api.RepeatedTest;
import org.junit.jupiter.api.Tag;
import org.junit.jupiter.api.Test;
import java.util.Random;
import java.util.ArrayList;

class SolutionTest {
  
	@Test
	@Tag("BasicTest")
	void BasicTest() {
    
    String[] reverseLetterHellowWorld = { "eello  world", "Hlllo  world", "Hello  world", "Heloo  world", "Hellw  world", "Hello  oorld", "Hello  wrrld", "Hello  wolld", "Hello  wordd", "Hello  worlH" };
    assertArrayEquals(reverseLetterHellowWorld, Kata.replaceLetter("Hello  world", 1));
    
		String[] reverseLeterHello = { "lello", "hollo", "hehlo", "heleo", "helll" };
    assertArrayEquals(reverseLeterHello, Kata.replaceLetter("hello", 3));
    
		String[] reverseLeterBye = { "eye", "bbe", "byy" };
    assertArrayEquals(reverseLeterBye, Kata.replaceLetter("bye", 2));
    

		String[] reverseLeterThanks = { "Thanks", "Thanks", "Thanks", "Thanks", "Thanks", "Thanks" };
    assertArrayEquals(reverseLeterThanks, Kata.replaceLetter("Thanks", 0));
    
    String[] reverseLetterWhiteSpaceFinal = { "SSs " , "Mss " , "MSM " };
    assertArrayEquals(reverseLetterWhiteSpaceFinal, Kata.replaceLetter("MSs ", 1));

	}

	@Test
	@Tag("SpecialCase")
	void SpecialCase() {
		String[] reverseLeterVoid = {};
		assertArrayEquals(reverseLeterVoid, Kata.replaceLetter("", 2));
		assertArrayEquals(reverseLeterVoid, Kata.replaceLetter(" ", 2));
		assertArrayEquals(reverseLeterVoid, Kata.replaceLetter(" ", 0));

	}
  

  @Tag("RandomTest")
	@RepeatedTest(10)
	@DisplayName("RandomWord")
	void RandomTest() {
		String word = generate(new Random().nextInt(15) + 1);
		int letterRandom = new Random().nextInt(word.length());
		assertArrayEquals(replaceLetter(word, letterRandom), Kata.replaceLetter(word, letterRandom));

	}
  
	public static String generate(int length) {

		String strChars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890     ^*¨_:;=?¿";
		StringBuilder sb = new StringBuilder();
    
		for (int i = 0; i < length; i++) {
			int nRandom = new Random().nextInt(strChars.length());
			sb.append(strChars.charAt(nRandom));
		}
		return sb.toString();
	}

		private static String[] replaceLetter(String str, int n) {

		ArrayList<String> arr = new ArrayList<>();
		StringBuilder strFinal = new StringBuilder(str);

		for (int i = 0; i < str.length(); i++) {
			int nextIndex = (i + n) % str.length();
			if (str.charAt(i) != ' ') {

				if (str.charAt(nextIndex) != ' ') {

					strFinal.replace(i, i + 1, String.valueOf(str.charAt(nextIndex)));
					arr.add(strFinal.toString());
					strFinal.replace(0, str.length(), str);

				} else {
					while (str.charAt(nextIndex) == ' ') {

						if (nextIndex == str.length() - 1) {
							nextIndex = 0;
						} else {
							nextIndex++;
						}
					}
					strFinal.replace(i, i + 1, String.valueOf(str.charAt(nextIndex)));
					arr.add(strFinal.toString());
					strFinal.replace(0, str.length(), str);

				}
			}

		}

		return arr.toArray(new String[arr.size()]);
	}
}

import static org.junit.jupiter.api.Assertions.*;

import org.junit.jupiter.api.DisplayName;
import org.junit.jupiter.api.RepeatedTest;
import org.junit.jupiter.api.Tag;
import org.junit.jupiter.api.Test;
import java.util.Random;
import java.util.ArrayList;

class SolutionTest {
  
	@Test
	@Tag("BasicTest")
	void BasicTest() {
    
    String[] reverseLetterHellowWorld = { "eello  world", "Hlllo  world", "Hello  world", "Heloo  world", "Hellw  world", "Hello  oorld", "Hello  wrrld", "Hello  wolld", "Hello  wordd", "Hello  worlH" };
    assertArrayEquals(reverseLetterHellowWorld, Kata.replaceLetter("Hello  world", 1));
    
		String[] reverseLeterHello = { "lello", "hollo", "hehlo", "heleo", "helll" };
    assertArrayEquals(reverseLeterHello, Kata.replaceLetter("hello", 3));
    
		String[] reverseLeterBye = { "eye", "bbe", "byy" };
    assertArrayEquals(reverseLeterBye, Kata.replaceLetter("bye", 2));
    

		String[] reverseLeterThanks = { "Thanks", "Thanks", "Thanks", "Thanks", "Thanks", "Thanks" };
    assertArrayEquals(reverseLeterThanks, Kata.replaceLetter("Thanks", 0));
    
    String[] reverseLetterWhiteSpaceFinal = { "SSs " , "Mss " , "MSM " };
    assertArrayEquals(reverseLetterWhiteSpaceFinal, Kata.replaceLetter("MSs ", 1));

	}

	@Test
	@Tag("SpecialCase")
	void SpecialCase() {
		String[] reverseLeterVoid = {};
		assertArrayEquals(reverseLeterVoid, Kata.replaceLetter("", 2));
		assertArrayEquals(reverseLeterVoid, Kata.replaceLetter(" ", 2));
		assertArrayEquals(reverseLeterVoid, Kata.replaceLetter(" ", 0));

	}
  

  @Tag("RandomTest")
	@RepeatedTest(10)
	@DisplayName("RandomWord")
	void RandomTest() {
		String word = generate(new Random().nextInt(15) + 1);
		int letterRandom = new Random().nextInt(word.length());
		assertArrayEquals(replaceLetter(word, letterRandom), Kata.replaceLetter(word, letterRandom));

	}
  
	public static String generate(int length) {

		String strChars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890     ^*¨_:;=?¿";
		StringBuilder sb = new StringBuilder();
    
		for (int i = 0; i < length; i++) {
			int nRandom = new Random().nextInt(strChars.length());
			sb.append(strChars.charAt(nRandom));
		}
		return sb.toString();
	}

		public static String[] replaceLetter(String str, int n) {

		ArrayList<String> arr = new ArrayList<>();
		StringBuilder strFinal = new StringBuilder(str);

		for (int i = 0; i < str.length(); i++) {
			int nextIndex = (i + n) % str.length();
			if (str.charAt(i) != ' ') {

				if (str.charAt(nextIndex) != ' ') {

					strFinal.replace(i, i + 1, String.valueOf(str.charAt(nextIndex)));
					arr.add(strFinal.toString());
					strFinal.replace(0, str.length(), str);

				} else {
					while (str.charAt(nextIndex) == ' ') {

						if (nextIndex == str.length() - 1) {
							nextIndex = 0;
						} else {
							nextIndex++;
						}
					}
					strFinal.replace(i, i + 1, String.valueOf(str.charAt(nextIndex)));
					arr.add(strFinal.toString());
					strFinal.replace(0, str.length(), str);

				}
			}

		}

		return arr.toArray(new String[arr.size()]);
	}
}

import static org.junit.jupiter.api.Assertions.*;

import org.junit.jupiter.api.DisplayName;
import org.junit.jupiter.api.RepeatedTest;
import org.junit.jupiter.api.Tag;
import org.junit.jupiter.api.Test;

import java.util.Random;
import java.util.ArrayList;


// TODO: Replace examples and use TDD by writing your own tests

class SolutionTest {
	@Test
	@Tag("BasicTest")
	void BasicTest() {

		String[] reverseLeterHello = { "lello", "hollo", "hehlo", "heleo", "helll" };
		String[] reverseLeterBye = { "eye", "bbe", "byy" };

		String[] reverseLeterThanks = { "Thanks", "Thanks", "Thanks", "Thanks", "Thanks", "Thanks" };
    String[] reverseLetterHellowWorld = { "eello  world", "Hlllo  world", "Hello  world", "Heloo  world", "Hellw  world", "Hello  oorld", "Hello  wrrld", "Hello  wolld", "Hello  wordd", "Hello  worlH" };
    
		assertArrayEquals(reverseLeterHello, Kata.replaceLetter("hello", 3));
		assertArrayEquals(reverseLeterBye, Kata.replaceLetter("bye", 2));
		assertArrayEquals(reverseLeterThanks, Kata.replaceLetter("Thanks", 0));
    assertArrayEquals(reverseLetterHellowWorld, Kata.replaceLetter("Hello  world", 1));

	}

	@Test
	@Tag("SpecialCase")
	void SpecialCase() {
		String[] reverseLeterVoid = {};
		assertArrayEquals(reverseLeterVoid, Kata.replaceLetter("", 2));
		assertArrayEquals(reverseLeterVoid, Kata.replaceLetter(" ", 2));
		assertArrayEquals(reverseLeterVoid, Kata.replaceLetter(" ", 0));

	}
  

  @Tag("RandomTest")
	@RepeatedTest(10)
	@DisplayName("RandomWord")
	void RandomTest() {
		String word = generate(new Random().nextInt(15) + 1);
		int letterRandom = new Random().nextInt(word.length());
		assertArrayEquals(replaceLetter(word, letterRandom), Kata.replaceLetter(word, letterRandom));

	}
  
	public static String generate(int length) {

		String strChars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890     ^*¨_:;=?¿";
		StringBuilder sb = new StringBuilder();
    
		for (int i = 0; i < length; i++) {
			int nRandom = new Random().nextInt(strChars.length());
			sb.append(strChars.charAt(nRandom));
		}
		return sb.toString();
	}

		public static String[] replaceLetter(String str, int n) {

		ArrayList<String> arr = new ArrayList<>();
		StringBuilder strFinal = new StringBuilder(str);

		for (int i = 0; i < str.length(); i++) {
			int nextIndex = (i + n) % str.length();
			if (str.charAt(i) != ' ') {

				if (str.charAt(nextIndex) != ' ') {

					strFinal.replace(i, i + 1, String.valueOf(str.charAt(nextIndex)));
					arr.add(strFinal.toString());
					strFinal.replace(0, str.length(), str);

				} else {
					while (str.charAt(nextIndex) == ' ') {
						nextIndex++;
					}
					strFinal.replace(i, i + 1, String.valueOf(str.charAt(nextIndex)));
					arr.add(strFinal.toString());
					strFinal.replace(0, str.length(), str);

				}
			}

		}

		return arr.toArray(new String[arr.size()]);

	}
}

import static org.junit.jupiter.api.Assertions.*;

import org.junit.jupiter.api.DisplayName;
import org.junit.jupiter.api.RepeatedTest;
import org.junit.jupiter.api.Tag;
import org.junit.jupiter.api.Test;

import java.util.Random;
import java.util.ArrayList;


// TODO: Replace examples and use TDD by writing your own tests

class SolutionTest {
	@Test
	@Tag("BasicTest")
	void BasicTest() {

		String[] reverseLeterHello = { "lello", "hollo", "hehlo", "heleo", "helll" };
		String[] reverseLeterBye = { "eye", "bbe", "byy" };
		String[] reverseLeterCodewars = { "oello codewars", "hdllo codewars", "heelo codewars", "helwo codewars",

				"hella codewars", "hello sodewars", "hello chdewars", "hello coeewars", "hello codlwars",

				"hello codelars", "hello codewors", "hello codewarc" };
		String[] reverseLeterThanks = { "Thanks", "Thanks", "Thanks", "Thanks", "Thanks", "Thanks" };

		assertArrayEquals(reverseLeterHello, Kata.replaceLetter("hello", 3));
		assertArrayEquals(reverseLeterBye, Kata.replaceLetter("bye", 2));
		assertArrayEquals(reverseLeterCodewars, Kata.replaceLetter("hello codewars", 7));
		assertArrayEquals(reverseLeterThanks, Kata.replaceLetter("Thanks", 0));

	}

	@Test
	@Tag("SpecialCase")
	void SpecialCase() {
		String[] reverseLeterVoid = {};
		assertArrayEquals(reverseLeterVoid, Kata.replaceLetter("", 2));
		assertArrayEquals(reverseLeterVoid, Kata.replaceLetter(" ", 2));
	}
  
  	@Test
	  @Tag("UnitTest")
	  void parseExceptionFecha() {
	        assertThrows(NullPointerException.class, () -> {
	        	int nRandom =  new Random().nextInt(15)+1;
	        	Kata.replaceLetter(null, nRandom);
	        });
	}
  @Tag("RandomTest")
	@RepeatedTest(10)
	@DisplayName("RandomWord")
	void RandomTest() {
		String word = generate(new Random().nextInt(15) + 1);
		int letterRandom = new Random().nextInt(word.length());
		assertArrayEquals(replaceLetter(word, letterRandom), Kata.replaceLetter(word, letterRandom));

	}
  
	public static String generate(int length) {

		String strChars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890";
		StringBuilder sb = new StringBuilder();
    
		for (int i = 0; i < length; i++) {
			int nRandom = new Random().nextInt(strChars.length());
			sb.append(strChars.charAt(nRandom));
		}
		return sb.toString();
	}

	public static String[] replaceLetter(String str, int n) {

		ArrayList<String> arr = new ArrayList<>();
		StringBuilder strFinal = new StringBuilder(str);

		for (int i = 0; i < str.length(); i++) {
			int nextIndex = (i + n) % str.length();

			if (str.charAt(i) != ' ' && str.charAt(nextIndex) != ' ') {
				nextIndex = (i + n) % str.length();
				strFinal.replace(i, i + 1, String.valueOf(str.charAt(nextIndex)));
				arr.add(strFinal.toString());
				strFinal.replace(0, str.length(), str);
			}

		}
		String[] array = arr.toArray(new String[arr.size()]);
		return array;
	}
}