def main():
    args = parse_arguments()

    exchange = ExchangeConnection(args=args)

    # Store and print the "hello" message received from the exchange. This
    # contains useful information about your positions. Normally you start with
    # all positions at zero, but if you reconnect during a round, you might
    # have already bought/sold symbols and have non-zero positions.
    hello_message = exchange.read_message()
    print("First message from exchange:", hello_message)

    # Send an order for BOND at a good price, but it is low enough that it is
    # unlikely it will be traded against. Maybe there is a better price to
    # pick? Also, you will need to send more orders over time.
    # --- BOND 마켓 메이킹 설정 ---
    FAIR_VALUE = 1000       # BOND fair value (고정)
    ORDER_SIZE = 100        # 한 번에 최대한 많이 (포지션 한도 = 100)
    MAX_POSITION = 100      # 최대 포지션 한도
    REFRESH_INTERVAL = 5.0  # 주문 갱신 주기 (초)

    position = 0            # 현재 BOND 포지션
    order_id = 0            # 단조 증가하는 주문 ID
    active_orders = {}      # {order_id: {"dir": ..., "price": ...}}
    market_open = False     # 시장 open 여부 (open 전에는 주문 불가)

    def next_id():
        nonlocal order_id
        order_id += 1
        return order_id

    def cancel_all_bond_orders():
        """BOND 주문 전부 한 번에 취소 (mass_cancel 사용)"""
        exchange.send_mass_cancel_message(symbol="BOND")
        active_orders.clear()

    def place_bond_orders():
        """포지션 한도 안에서 bid/ask 양방향 주문"""
        if not market_open:
            return

        cancel_all_bond_orders()

        # 포지션이 음수면 매수 가격을 올려서 빨리 사들임
        # 포지션이 양수면 매도 가격을 내려서 빨리 팖
        skew = position // 10  # 포지션 10마다 1틱 조정

        buy_price  = min(FAIR_VALUE - 1 + skew, FAIR_VALUE - 1)  # 최대 999
        sell_price = max(FAIR_VALUE + 1 + skew, FAIR_VALUE + 1)  # 최소 1001

        buy_size  = min(ORDER_SIZE, MAX_POSITION - position)
        sell_size = min(ORDER_SIZE, MAX_POSITION + position)

        if buy_size > 0:
            bid = next_id()
            exchange.send_add_message(
                order_id=bid, symbol="BOND",
                dir=Dir.BUY, price=buy_price, size=buy_size
            )
            active_orders[bid] = {"dir": Dir.BUY, "price": buy_price}

        if sell_size > 0:
            ask = next_id()
            exchange.send_add_message(
                order_id=ask, symbol="BOND",
                dir=Dir.SELL, price=sell_price, size=sell_size
            )
            active_orders[ask] = {"dir": Dir.SELL, "price": sell_price}

        print(f"  BOND 주문 → 매수: {buy_price} x{buy_size}, 매도: {sell_price} x{sell_size}, 포지션: {position}")
    # Set up some variables to track the bid and ask price of a symbol. Right
    # now this doesn't track much information, but it's enough to get a sense
    # of the VALE market.
    vale_bid_price, vale_ask_price = None, None
    vale_last_print_time = time.time()

    last_refresh = time.time()

    # Here is the main loop of the program. It will continue to read and
    # process messages in a loop until a "close" message is received. You
    # should write to code handle more types of messages (and not just print
    # the message). Feel free to modify any of the starter code below.
    #
    # Note: a common mistake people make is to call write_message() at least
    # once for every read_message() response.
    #
    # Every message sent to the exchange generates at least one response
    # message. Sending a message in response to every exchange message will
    # cause a feedback loop where your bot's messages will quickly be
    # rate-limited and ignored. Please, don't do that!
    while True:
        message = exchange.read_message()

        # Some of the message types below happen infrequently and contain
        # important information to help you understand what your bot is doing,
        # so they are printed in full. We recommend not always printing every
        # message because it can be a lot of information to read. Instead, let
        # your code handle the messages and just print the information
        # important for you!
        if message["type"] == "close":
            print("The round has ended")
            break
        elif message["type"] == "open":
            # 시장이 열렸을 때 주문 시작 (open 전에 주문하면 reject됨)
            print("Market opened:", message)
            market_open = True
            place_bond_orders()
        elif message["type"] == "error":
            print(message)
        elif message["type"] == "reject":
            print(message)
            # 거부된 주문은 active_orders에서 제거
            oid = message.get("order_id")
            active_orders.pop(oid, None)
        elif message["type"] == "fill":
            print(message)
            # 체결 시 포지션 업데이트 후 주문 재보충
            qty = message["size"]
            if message["dir"] == Dir.BUY:
                position += qty
            else:
                position -= qty
            place_bond_orders()
        elif message["type"] == "book":
            if message["symbol"] == "VALE":

                def best_price(side):
                    if message[side]:
                        return message[side][0][0]

                vale_bid_price = best_price("buy")
                vale_ask_price = best_price("sell")

                now = time.time()

                if now > vale_last_print_time + 1:
                    vale_last_print_time = now
                    print(
                        {
                            "vale_bid_price": vale_bid_price,
                            "vale_ask_price": vale_ask_price,
                        }
                    )

            # 주기적으로 BOND 주문 갱신 (주문 만료 방지)
            now = time.time()
            if now - last_refresh > REFRESH_INTERVAL:
                last_refresh = now
                place_bond_orders()