import java.util.Random;
import java.util.Scanner;

public class Part1 {
    static Scanner sc = new Scanner(System.in);
    static int[][] Table; // the board game
    static int[][] copyTable; // the board game
    static int best = 0; // highest score
    static int score = 0; // the current score
    static boolean gameNotOver = true; // flag that keeps the game status
    static boolean gameIsWonButCont = false; // true if the game won but continued
    static int preScore; // score from last move
    static int prebest; // best score from last move
    static boolean canNotRevers = false; // true if player already used reverse option

    public static void main(String[] args) {
        initGameBoard();
        printTable();
        System.out.println("Welcome, would you like to start the game?");
        char input = inputUser();
        if (input == 'y') { // start the game
            startGame();
        } else if (input == 'n') // cancel the game
            endGame();
    }// main

    // initialize the game
    public static void startGame() {
        initVars();
        while (gameNotOver) {
            playerMove();
        }
        System.out.println("Game Over");
    }

    // initialize the game board and its variables and prints the created board
    public static void initVars() {
        initGameBoard();
        lottery();
        lottery();
        printTable();
        printInformation();
    }

    // ends the game
    public static void endGame() {
        System.out.println("game over!");
        initGameBoard();
    }

    // take the input from the user
    public static char inputUser() {
        char input = sc.next().charAt(0); // input variable
        return input;
    }

    // initialize the board and it's copied board
    public static void initGameBoard() {
        Table = new int[4][4];
        copyTable = new int[4][4];
        gameIsWonButCont = false;
        gameNotOver = true;
        score = 0;
    }

    // cast a random number - 2 or 4
    public static void lottery() {
        Random rand = new Random();
        boolean v = false;
        while (v == false) {
            int row = rand.nextInt(4);
            int column = rand.nextInt(4);
            if (Table[row][column] == 0) {
                if (Math.random() < 0.7) {
                    Table[row][column] = 2;
                    v = true;
                } else {
                    Table[row][column] = 4;
                    v = true;
                }
            }
        }
    }

    // prints the current board to the player
    public static void printTable() {
        for (int i = 0; i < 4; i++) { // loop to print the board
            System.out.print("        ");
            for (int j = 0; j < 4; j++) {
                System.out.print(Table[i][j] + "     ");
            }
            System.out.println();
        }
        System.out.println();
    }

    // prints the updated game information
    public static void printInformation() {
        System.out.println("w = up, s = down, a = left, d = right, r = return, e = exit, n = new game");
        System.out.println("score:" + score(0));
        System.out.println("best:" + best());
    }

    // initialize the board for the first time
    public static void initBoard() {
        initGameBoard();
        printInformation();
    }

    // updates the score after every move
    public static int score(int sum) {
        score = score + sum;
        return score;
    }

    // save the best score and updates it
    public static int best() {
        if (score > best) {
            best = score(0);
            return best;
        }
        return best;
    }

    // check if the player has won the game - if he reached 2048
    public static boolean checkIfWin() {
        for (int i = 0; i < 4; i++) {
            for (int j = 0; j < 4; j++) {
                if (Table[i][j] == 2048) {
                    printTable();
                    return true;
                }
            }
        }
        return false;
    }

    // check if the player has lost the game and ask to stay or leave
    public static boolean lose() {
        if (checkIfLose()) {
            System.out.println("Game over! your score is: " + score(0) + " For a new game press y, n if not");
            char choose = inputUser();
            if (choose == 'n') {
                endGame();
                return true;
            }
            if (choose == 'y') {
                score = 0;// מאפס את הניקוד
                startGame();// מתחיל משחק מחדש
                return false;
            }
        }
        return false;
    }

    // check if there is an option to continue the game. Returns false if the player can continue playing
    public static boolean checkIfLose() {
        for (int i = 0; i < 4; i++) {
            for (int j = 0; j < 3; j++) {
                if (Table[i][j] == 0 || Table[i][j + 1] == Table[i][j]) {
                    return false;
                }
            }
        }
        for (int j = 0; j < 4; j++) {
            for (int i = 0; i < 3; i++) {
                if (Table[i][j] == 0 || Table[i][j] == Table[i + 1][j]) {
                    return false;
                }
            }
        }
        return true;
    }

    // check if there is an option to move in the game. Returns true if the player can't move
    public static boolean canNotMove() {
        boolean error = true;
        for (int i = 0; i < 4; i++) {
            for (int j = 0; j < 4; j++) {
                if (Table[i][j] != copyTable[i][j]) {
                    error = false;
                    return error;
                }
            }
        }
        return error;
    }

    // move the cells up and adds their value if possible
    public static void moveUp() {
        for (int j = 0; j < 4; j++) {
            boolean sum = true; // flag that prevent double cell merge in the same column
            for (int i = 1; i < 4; i++) {
                int temp = i;
                if (Table[i][j] != 0) { // get in only if the cell has value
                    while (temp > 0) { // so the loop goes through all the way down
                        if (Table[temp - 1][j] == 0) { // if the upper cell is 0 merge the cells
                            Table[temp - 1][j] = (Table[temp - 1][j] + Table[temp][j]);
                            Table[temp][j] = 0;
                            temp = temp - 1;
                        } else if (Table[temp - 1][j] == Table[temp][j] && sum) {// if the upper cell and current cell are equals merge them to the upper cell
                            Table[temp - 1][j] = (Table[temp - 1][j] + Table[temp][j]);
                            score(Table[temp - 1][j]);
                            Table[temp][j] = 0;
                            temp = temp - 1;
                            if(temp ==1) {
                                sum = false;
                    }
                        } else { // to continue the loop
                            temp = temp - 1;
                        }
                    } // while
                }
            }
        }
        checkWrongStep();
        canNotRevers = false;
    }

    public static void moveDown() {
        for (int j = 0; j < 4; j++) {
            boolean sum = true;
            for (int i = 2; i >= 0; i--) {
                int temp = i;
                if (Table[i][j] != 0) {// אם אני לא אפס
                    while (temp < 3) {
                        if (Table[temp + 1][j] == 0) {// אם מי שמתחתיי שווה לאפס
                            Table[temp + 1][j] = (Table[temp + 1][j] + Table[temp][j]);
                            Table[temp][j] = 0;
                            temp = temp + 1;
                        } else if (Table[temp + 1][j] == Table[temp][j] && sum) {// אם מי שמתחתיי שווה לי
                            Table[temp + 1][j] = (Table[temp + 1][j] + Table[temp][j]);
                            score(Table[temp + 1][j]);
                            Table[temp][j] = 0;
                            temp = temp + 1;
                            if(temp ==2) {
                                sum = false;
                    }
                        } else {
                            temp = temp + 1;
                        }
                    } // while
                }
            }
        }
        checkWrongStep();
        canNotRevers = false;
    }

    public static void moveLeft() {
        for (int i = 0; i < 4; i++) {
            boolean sum = true;
            for (int j = 1; j < 4; j++) {
                int temp = j;
                if (Table[i][j] != 0) {// אם אני לא אפס
                    while (temp > 0) {
                        if (Table[i][temp - 1] == 0) {// אם מי שמשמאלי שווה לאפס
                            Table[i][temp - 1] = (Table[i][temp - 1] + Table[i][temp]);
                            Table[i][temp] = 0;
                            temp = temp - 1;
                        } else if (Table[i][temp - 1] == Table[i][temp] && sum) {// אם מי שמשמאלי שווה לי
                            Table[i][temp - 1] = (Table[i][temp - 1] + Table[i][temp]);
                            score(Table[i][temp - 1]);
                            Table[i][temp] = 0;
                            temp = temp - 1;
                            if(temp ==1) {
                                    sum = false;
                        }
                        } else {
                            temp = temp - 1;
                        }
                    } // while
                }
            }
        }
        checkWrongStep();
        canNotRevers = false;
    }

    public static void moveRight() {
        for (int i = 0; i < 4; i++) {
            boolean sum = true;
            for (int j = 2; j >= 0; j--) {
                int temp = j;
                if (Table[i][j] != 0) {// אם אני לא אפס
                    while (temp < 3) {
                        if (Table[i][temp + 1] == 0) {// אם מי שמימיני שווה לאפס
                            Table[i][temp + 1] = (Table[i][temp + 1] + Table[i][temp]);
                            Table[i][temp] = 0;
                            temp = temp + 1;
                        } else if (Table[i][temp + 1] == Table[i][temp] && sum) {// אם מי שמתחתיי שווה לי
                            Table[i][temp + 1] = (Table[i][temp + 1] + Table[i][temp]);
                            score(Table[i][temp + 1]);
                            Table[i][temp] = 0;
                            temp = temp + 1;
                            if(temp ==2) {
                                sum = false;
                    }
                        } else {
                            temp = temp + 1;
                        }
                    } // while
                }
            }
        }
        checkWrongStep();
        canNotRevers = false;
    }
    public static void checkWrongStep() {
        if (canNotMove()) {
            System.out.println("eror!!!! Please select another option:");
            printTable();
            printInformation();
        }
    }

    public static void revers() {
        for (int i = 0; i < 4; i++) {
            for (int j = 0; j < 4; j++) {
                Table[i][j] = copyTable[i][j];
            }
        }
        canNotRevers = true;
        score = preScore;
        best = prebest;
    }

    public static void copyTheBoard() {
        preScore = score;
        prebest = best;
        for (int i = 0; i < 4; i++) {
            for (int j = 0; j < 4; j++) {
                copyTable[i][j] = Table[i][j];
            }
        }
    }

    public static boolean checkIfGameIsOver() {
        if (!gameIsWonButCont && checkIfWin()) {
            System.out.println("You won! 2048! would you like to continue? Press y if yes, n if not");
            char choose = inputUser();
            if (choose == 'n') {
                endGame();
                return true;
            }
            if (choose == 'y') {
                gameIsWonButCont = true;
                startGame();
                return false;
            }
        }
        if (lose()) {
            return true;
        }
        return false;
    }

    public static void playerMove() {
        char choose = inputUser();
        if (choose == 'w' || choose == 'a' || choose == 's' || choose == 'd') {

            makeMovmentKeys(choose);
            if (!checkIfGameIsOver() && !canNotMove()) {
                lottery();
                printTable();
                printInformation();
            }
        } else if (choose == 'e') {
            endGame();
        } else if (choose == 'r') {
            if (!canNotRevers) {
                revers();
                lottery();
                printTable();
                printInformation();
            } else {
                System.out.println("You can not do return. Please select another option:");
                System.out.println();
                printTable();
                printInformation();
            }
        } else if (choose == 'n') {
            score = 0;// מאפס את הניקוד
            initVars();// מתחיל משחק מחדש
        }
    }

    public static void makeMovmentKeys(char choose) {
        copyTheBoard();
        if (choose == 'w') { // move up
            moveUp();
        } else if (choose == 's') { // ...
            moveDown();
        } else if (choose == 'a') {
            moveLeft();
        } else if (choose == 'd') {
            moveRight();
        }
    }
}// class