// DOM Variables

var buttons = document.getElementsByClassName("btn");
var reset = document.getElementById("reset-btn");
var playerType = document.getElementById("player-type");

// Game Flow Variables

var playerNumber = 1; // Initially player - 1 gets to start his/her turn

var filledGrid = []; // Player board

var filledCells = 0; // No. of cells that has been filled

for (var i = 0; i < 6; i++) {
  var arr = [-1, -1, -1, -1, -1, -1, -1]; // Board is initialised with -1
  filledGrid.push(arr);
}

// Event Listener for Buttons

reset.addEventListener("click", function () {
  resetBoard();
});

for (var i = 0; i < buttons.length; i++) {
  // Handing the Event when button was clicked

  buttons[i].addEventListener("click", function () {
    // Make move and disable the button to avoid furthur clicking it again

    var buttonNo = this.classList[1];
    makeMove(this, buttonNo.slice(4));
  });
}

// Function to Make Move on the passed button and disable it
function makeMove(button, buttonNo) {
  var row =
    buttonNo % 7 === 0
      ? Math.floor(buttonNo / 7) - 1
      : Math.floor(buttonNo / 7);
  var col = buttonNo % 7 === 0 ? 6 : (buttonNo % 7) - 1;

  if (playerNumber === 1) {
    button.classList.add("btn-player-1");

    filledGrid[row][col] = 1;
    filledCells++;

    if (playerWon(row, col, 1) === true) {
      setTimeout(function () {
        alert("Game Over: Green Wins");
        resetBoard();
      }, 200);
    }

    // Update the player
    playerNumber = 2;
    playerType.textContent = "Player - 2";
  } else {
    button.classList.add("btn-player-2");

    filledGrid[row][col] = 2;
    filledCells++;

    if (playerWon(row, col, 2) === true) {
      setTimeout(function () {
        alert("Game Over : Red Wins");
        resetBoard();
      }, 200);
    }

    // Update the player
    playerNumber = 1;
    playerType.textContent = "Player - 1";
  }

  // If all the cells has been filled

  if (filledCells === 42) {
    setTimeout(function () {
      alert("Game Draw");
      resetBoard();
    }, 200);
    return;
  }

  // Disable the button is the move is made
  setTimeout(function () {
    button.disabled = true;
  }, 10);
}

function playerWon(row, col, player) {
  var count = 0;

  // Check for columns

  for (var i = 0; i < 7; i++) {
    if (filledGrid[row][i] === player) {
      count++;
      if (count === 4) return true;
    } else {
      count = 0;
    }
  }

  count = 0;

  // Check for Rows

  for (var i = 0; i < 6; i++) {
    if (filledGrid[i][col] === player) {
      count++;
      if (count === 4) return true;
    } else {
      count = 0;
    }
  }

  count = 0;

  // Check for primary diagonal

  if (row >= col) {
    var i = row - col;
    var j = 0;

    for (; i <= 5; i++, j++) {
      if (filledGrid[i][j] === player) {
        count++;
        if (count == 4) return true;
      } else {
        count = 0;
      }
    }
  } else {
    var i = 0;
    var j = col - row;

    for (; j <= 6; i++, j++) {
      if (filledGrid[i][j] === player) {
        count++;
        if (count == 4) return true;
      } else {
        count = 0;
      }
    }
  }

  count = 0;

  // Check for secondary diagonal

  if (row + col <= 5) {
    var i = row + col;
    var j = 0;

    for (; i >= 0 && j <= row + col; i--, j++) {
      if (filledGrid[i][j] === player) {
        count++;
        if (count == 4) return true;
      } else {
        count = 0;
      }
    }
  } else {
    var i = 5;
    var j = row + col - 5;

    for (; j <= 6; j++, i--) {
      if (filledGrid[i][j] === player) {
        count++;
        if (count == 4) return true;
      } else {
        count = 0;
      }
    }
  }
  return false;
}

// Function to reset the Board completely
function resetBoard() {
  // Remove all the disabled buttons and the styles

  for (var i = 0; i < buttons.length; i++) {
    buttons[i].disabled = false;
    buttons[i].classList.remove("btn-player-1");
    buttons[i].classList.remove("btn-player-2");
  }

  // Player Number is changed to 1

  playerNumber = 1;
  playerType.textContent = "Player - 1";

  // Filled Cells is changed to 0

  filledCells = 0;

  // Filling the Board with -1

  for (var i = 0; i < 6; i++) {
    for (var j = 0; j < 7; j++) {
      filledGrid[i][j] = -1;
    }
  }
}