import hashlib

def bitwise_not(data: bytes) -> bytes:
    """Inverts all bits in the byte array."""
    return bytes(~b & 0xFF for b in data)

def shift_right_1(data: bytes) -> bytes:
    """
    Shifts the entire byte array to the right by 1 bit.
    Note: This implementation assumes a forward-flowing carry (byte 0 to byte N).
    If the VM's BigInt implementation is little-endian, you might need to reverse 
    the carry logic so it flows from index i+1 to i.
    """
    result = bytearray(len(data))
    carry = 0
    
    for i in range(len(data)):
        # Shift current byte right by 1, and OR it with the carry from the previous byte
        result[i] = (data[i] >> 1) | carry
        # The lowest bit of the current byte becomes the MSB carry for the next byte
        carry = (data[i] & 1) << 7
        
    return bytes(result)

def check_flag(test_flag: bytes, target_hash_blob: bytes) -> bool:
    """Simulates the VM's flag verification logic."""
    # 1. Length Check
    if len(test_flag) != 29:
        print(f"[-] Incorrect length: {len(test_flag)}. Must be 29 bytes.")
        return False
        
    # 2. Initial Mutation (BITWISE_NOT)
    current_state = bitwise_not(test_flag)
    
    # 3. The Shift-and-Hash Loop
    generated_blob = bytearray()
    
    for iteration in range(8):
        # Compute SHA256 of the current state
        current_hash = hashlib.sha256(current_state).digest()
        generated_blob.extend(current_hash)
        
        # Shift the state right by 1 bit for the next iteration
        current_state = shift_right_1(current_state)
        
    # 4. Final Verification
    if generated_blob == target_hash_blob:
        print("[+] Correct! Flag matches.")
        return True
    else:
        print("[-] Incorrect! Hash mismatch.")
        return False

# ==========================================
# Example Usage
# ==========================================
if __name__ == "__main__":
    # TODO: Load the actual 256-byte target blob from 'romfs:/dragonfly.bin'
    # Here is a dummy 256-byte array for testing the script structure
    with open("./romfs/damocles.bin", "rb") as flag_hash: 
        dragonfly_bin_data = flag_hash.read()
    
    # The flag you want to test
    my_test_flag = b"dach2026{dummy_test_flag_pay}" # Exactly 29 bytes
    
    check_flag(my_test_flag, dragonfly_bin_data)