const boardElement = document.getElementById('board');
const size = 7;

// -1 = invalid, 1 = marble, 0 = empty
const board = [
  [-1, -1,  1,  1,  1, -1, -1],
  [-1, -1,  1,  1,  1, -1, -1],
  [ 1,  1,  1,  1,  1,  1,  1],
  [ 1,  1,  1,  0,  1,  1,  1],
  [ 1,  1,  1,  1,  1,  1,  1],
  [-1, -1,  1,  1,  1, -1, -1],
  [-1, -1,  1,  1,  1, -1, -1]
];

let selectedCell = null;


function drawBoard() {
    boardElement.innerHTML = '';
    for (let row = 0; row < size; row++) {
        for (let col = 0; col < size; col++) {
            const cell = document.createElement('div');
            cell.classList.add('cell');
            
            if (board[row][col] === 1) {
                cell.classList.add('marble');
            } else if (board[row][col] === 0) {
                cell.classList.add('empty');
            } else {
                cell.classList.add('invalid');
            }

            if (selectedCell && selectedCell.row === row && selectedCell.col === col) {
                cell.classList.add('selected');
            }

            cell.dataset.row = row;
            cell.dataset.col = col;
            cell.addEventListener('click', () => handleClick(row, col));
            boardElement.appendChild(cell);
        }
    }
}

// Handle cell click
function handleClick(row, col) {
    if (selectedCell) {
        if (isValidMove(selectedCell.row, selectedCell.col, row, col)) {
            makeMove(selectedCell.row, selectedCell.col, row, col);
            selectedCell = null;
        } else {
            selectedCell = null; 
        }
    } else if (board[row][col] === 1) {
        selectedCell = { row, col };
    }
    drawBoard(); 
}

// Check if the move is valid
function isValidMove(fromRow, fromCol, toRow, toCol) {
    if (board[toRow][toCol] !== 0) return false; 

    const rowDiff = Math.abs(fromRow - toRow);
    const colDiff = Math.abs(fromCol - toCol);

    if ((rowDiff === 2 && colDiff === 0) || (rowDiff === 0 && colDiff === 2)) {
        const midRow = (fromRow + toRow) / 2;
        const midCol = (fromCol + toCol) / 2;
        return board[midRow][midCol] === 1; 
    }
    return false;
}

function makeMove(fromRow, fromCol, toRow, toCol) {
    const midRow = (fromRow + toRow) / 2;
    const midCol = (fromCol + toCol) / 2;

    board[fromRow][fromCol] = 0;
    board[midRow][midCol] = 0;
    board[toRow][toCol] = 1;

    drawBoard();
    checkWinCondition(); 
}

function checkWinCondition() {
    let marbleCount = 0;
    
    for (let row = 0; row < size; row++) {
        for (let col = 0; col < size; col++) {
            if (board[row][col] === 1) {
                marbleCount++;
            }
        }
    }

    if (marbleCount === 1) {
        alert("Congratulations! You've won the game!");
    }
}

drawBoard();