import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class HomeAssignment {

    private char[] inputArray;
    private boolean isWinnerX = false;
    private boolean isWinnerO = false;
    private int xCounter = 0;
    private int oCounter = 0;
    private boolean isFinished = false;

    private void ticTacToe(String input) {

        validateInput(input);
        if (!isFinished) {
            validateState(inputArray);
        }
        if (!isFinished) {
            isWinnerX = findWinner(inputArray, 'X');
            isWinnerO = findWinner(inputArray, 'O');
        }
        if (!isFinished) {
            validateWinner();
        }
        if (!isFinished) {
            whoseTurnToPlay();
        }
        resetResults();

    }

    /**
     * Description: Validation of input string allowed symbols: X O - allowed length 9.
     *
     * @param input string
     */
    private void validateInput(String input) {
        Pattern pattern = Pattern.compile("^[\\-XO]{9}$");
        Matcher matcher = pattern.matcher(input);

        if (matcher.matches()) {
            inputArray = input.toCharArray();
        } else {
            System.out.println("Invalid input");
            isFinished = true;
        }
    }

    /**
     * Description: Validation of the state. X counter must be equal or higher +1 then O counter.
     *
     * @param array input string converted to array
     */
    private void validateState(char[] array) {
        for (char element : array) {
            if (element == 'X') xCounter++;
            if (element == 'O') oCounter++;
        }
        if (!(xCounter == oCounter || xCounter == oCounter + 1)) {
            System.out.println("Invalid state");
            isFinished = true;
        }
    }

    /**
     * Description: Check all states to find a winner.
     *
     * @param array input string parsed to array.
     * @param tic   X or O
     * @return true if winner is found
     */
    private boolean findWinner(char[] array, char tic) {
        boolean winner = false;
        if (array[0] == tic && array[1] == tic && array[2] == tic ||
                array[3] == tic && array[4] == tic && array[5] == tic ||
                array[6] == tic && array[7] == tic && array[8] == tic ||
                array[0] == tic && array[3] == tic && array[6] == tic ||
                array[1] == tic && array[4] == tic && array[7] == tic ||
                array[2] == tic && array[5] == tic && array[8] == tic ||
                array[0] == tic && array[4] == tic && array[8] == tic ||
                array[2] == tic && array[4] == tic && array[6] == tic) {
            winner = true;
        }
        return winner;
    }

    /**
     * Description: Check if there is tiy or possibility for 2 winners.
     */
    private void validateWinner() {
        // if there is no winner and all moves are done it is tie
        if (!isWinnerX && !isWinnerO && xCounter == 5 && oCounter == 4) {
            System.out.println("Valid state, game is over, result is a tie");
            isFinished = true;
        }
        // if there are 2 winners it is invalid state.
        if (isWinnerX && isWinnerO) {
            System.out.println("invalid state. There is can be only one winner");
            isFinished = true;
        }
        // if X is winner and game still not finished X win.
        if (isWinnerX && !isFinished) {
            System.out.println("Valid state, game is over, “X” won");
            isFinished = true;
        } else if (isWinnerO && !isFinished) {
            System.out.println("Valid state, game is over, “O” won");
            isFinished = true;
        }
    }

    private void whoseTurnToPlay() {
        if (xCounter < 5) {
            if (xCounter == oCounter) {
                System.out.println("Valid state, game is still going, “X” to play");
            } else System.out.println("Valid state, game is still going, “O” to play");
        }
    }

    // reset all fields to default values.
    private void resetResults() {
        isFinished = false;
        isWinnerX = false;
        isWinnerO = false;
        xCounter = 0;
        oCounter = 0;
        inputArray = null;
    }

    public static void main(String[] args) {
        HomeAssignment result = new HomeAssignment();

        System.out.println("----------Invalid input testing---------");
        result.ticTacToe("XPLXX"); // invalid symbol
        result.ticTacToe("XOXOXOXO"); // 8 symbols
        result.ticTacToe("XOXOXOXOXO"); // 10 symbols
        result.ticTacToe(""); // empty input
        result.ticTacToe("xO-------"); // case sensitive
        result.ticTacToe("О--------"); // different language letter

        System.out.println();
        System.out.println("----------Invalid state testing---------");
        result.ticTacToe("O--------"); // invalid state X should start first
        result.ticTacToe("OOOXX----"); // invalid state X should be more than O
        result.ticTacToe("OOXXXX---"); // invalid state too many X
        result.ticTacToe("OOOXXX---"); // invalid state 2 winners at the same time.

        System.out.println();
        System.out.println("----------Tie---------");
        result.ticTacToe("XOXOOXXXO");
        result.ticTacToe("OXOXOXXOX");

        System.out.println();
        System.out.println("----------X won---------");
        result.ticTacToe("XXXOO-O--"); // 012
        result.ticTacToe("OO-XXXOOX"); // 345
        result.ticTacToe("OOXOXOXXX"); // 678
        result.ticTacToe("XOOXOXXXO"); // 036

        System.out.println();
        System.out.println("----------O won---------");
        result.ticTacToe("XOXXO--OX"); // 147
        result.ticTacToe("XXOXOO-XO"); // 258
        result.ticTacToe("OXXXOOXXO"); // 048
        result.ticTacToe("XXOXOXO--"); // 246

        System.out.println();
        System.out.println("----------X to play---------");
        result.ticTacToe("XO-------");
        result.ticTacToe("XOXO-----");
        result.ticTacToe("XOXOXO---");
        result.ticTacToe("XOXOXOOX-");
        result.ticTacToe("XOXOXO-XO");

        System.out.println();
        System.out.println("----------O to play---------");
        result.ticTacToe("X--------");
        result.ticTacToe("XO------X");
        result.ticTacToe("XO----XOX");
        result.ticTacToe("--XXOXOXO");
    }
}