export function moveUp(buffer, cursor) {
  if (cursor.line > 0) cursor.line--;
  cursor.col = Math.min(cursor.col, buffer[cursor.line].length);
}

export function moveDown(buffer, cursor) {
  if (cursor.line < buffer.length - 1) cursor.line++;
  cursor.col = Math.min(cursor.col, buffer[cursor.line].length);
}

export function moveLeft(buffer, cursor) {
  if (cursor.col > 0) cursor.col--;
  else if (cursor.line > 0) {
    cursor.line--;
    cursor.col = buffer[cursor.line].length;
  }
}

export function moveRight(buffer, cursor) {
  if (cursor.col < buffer[cursor.line].length) cursor.col++;
  else if (cursor.line < buffer.length - 1) {
    cursor.line++;
    cursor.col = 0;
  }
}